More fuel on the 30BR powder fire . . .

[gunsandgunsmithing]

RG Robinett and Larry Kock, does the 30BR have an advantage over the 30 major? I would like for simplicity sake to use the PPC bolt face on my rifle and just change the barrel. Does this in any way result in a chambering that is more complicated to load for than 30 BR or create problems?

No I never knew Norma 200even existed until I looked at the burn rate chart that RGR posted and it looked closer to H 4198 than the powder he tested. Somewhere in the back of my mind I had a thought that one of the 30 caliber PPC based chamberings held a world record that even the 30 BR didn't have, but my mind isn't what it used to be. I have a 6PPC and I used to get to shoot with some real BR shooters that had some pretty good guns until the guy that had the range, we shoot at passed from cancer. So not any exposure since he is gone. He had a 30BR that would really shoot, but I think if truth be known he had a 22waldog that he sold to a lady that shot at the same range that would outshoot the 30BR. She has a son that is into tactical rifles and used to show off when she took him to the range when he was visiting. She bought this rifle just to put him in his place, and she did every time he came for a visit.

I'm sorry. I just thought since it hasn't been available for a while now you might be sitting on some. You're very right, though. It's very near H4198 in pretty much every aspect. It does shoot very well if you can put your hands on some. I just wouldn't bother with it much unless you can come up with quite a bit of it, to be worthwhile.

As for the 30 Major, popularity has very little to do with it. The BR was around and firmly established in VFS long before the first 30 Major. Both are excellent and from a performance standpoint, we're splitting a really fine hair. Any advantage goes to the one with the best barrels and bullets. Otherwise, obviously, the biggest reason to do a Major is that it fits a PPC bolt face. Really, nothing more or less of substance there. The BR has a little more capacity and a little longer neck. Otherwise, flip a coin. You just can't conclude much from a barrel or even a few barrels chambered in both. I love my friend Jim but honestly, he might have 10% or probably far less than that, of my actual experience with a 30 Major. Technically, it sounds like he has zero experience with it but I won't dismiss his 30 Gorilla experience because they are very close to one another.

I'm happy to talk with you and honestly give you what I see as pro's and con's for both. I have a lot of experience with both. With a Major, the next guy still probably doesn't have half of my experience with it. I was arguably the inventor of the Grendel necked up to 30 cal in Jan of 2007, IIRC. I can say that I've tested it with many, many barrel makes, twists, lengths, all that, as well as most every suitable powder and multiple lots of them over several years since then. That's how you really have to test something like this. There are no shortcuts with them being so close in every aspect. You just can't say "I wore out a bbl trying", etc. You gotta get with it over a really long time with as many possible variable as possible. Even still, the results are like I said...a coin toss that comes down to the better bbl/bullets will be the one that shoots best.

Rather than getting into a pissing match with anyone about it, I'd prefer to talk with you by phone. If you're serious about it, I'll spend whatever time you need to go over the pros and cons and be very honest about everything. You can decide for yourself and it doesn't matter if someone else does the work. It's not about that but I'd be happy to chamber either one for you. I've got a couple of different Major reamers and can do pretty much whatever you want but lets talk if you're interested in trying it and just go from there. I'm very happy to help if I can. Been through all the reamer design stuff and can make that very easy should you wish to order your own reamer for either.

I'll post a pic though. It's a couple of 5 shot groups. I'll describe the test I was shooting when we talk. Those two groups are really nice but the agg was even more impressive to me. You're also right about the 5 shot 100 yard world record. It was with a 30 Major but it was just a few thou shorter than a Major mostly due to the way they went about things. They went a long way around to get there but ultimately what they wound up with that broke that record was a 30 Major, I think .015 short, iirc and fwiw. It is what it is but detractors will point out he didn't shoot well in the agg on that day. I don't disagree. The stars have to align for most any records. Not worth arguing about but it does hold that record, so...Lol!

Here's that pic. Just pm me and we can talk tomorrow about it if you want. Again, happy to help either way.--Mike

 

[JimPag]

I'm sorry. I just thought since it hasn't been available for a while now you might be sitting on some. You're very right, though. It's very near H4198 in pretty much every aspect. It does shoot very well if you can put your hands on some. I just wouldn't bother with it much unless you can come up with quite a bit of it, to be worthwhile.

As for the 30 Major, popularity has very little to do with it. The BR was around and firmly established in VFS long before the first 30 Major. Both are excellent and from a performance standpoint, we're splitting a really fine hair. Any advantage goes to the one with the best barrels and bullets. Otherwise, obviously, the biggest reason to do a Major is that it fits a PPC bolt face. Really, nothing more or less of substance there. The BR has a little more capacity and a little longer neck. Otherwise, flip a coin. You just can't conclude much from a barrel or even a few barrels chambered in both. I love my friend Jim but honestly, he might have 10% or probably far less than that, of actual experience with a 30 Major. Technically, it sounds like he has zero experience with it but I won't dismiss his 30 Gorilla experience because they are very close to one another.

I'm happy to talk with you and honestly give you what I see as pro's and con's for both. I have a lot of experience with both. With a Major, the next guy still probably doesn't have half of my experience with it. I was arguably the inventor of the Grendel necked up to 30 cal in Jan of 2007, IIRC. I can say that I've tested it with many, many barrel makes, twists, lengths, all that, as well as most every suitable powder and multiple lots of them over several years since then. That's how you really have to test something like this. There are no shortcuts with them being so close in every aspect. You just can't say "I wore out a bbl trying", etc. You gotta get with it over a really long time with as many possible variable as possible. Even still, the results are like I said...a coin toss that comes down to the better bbl/bullets will be the one that shoots best.

Rather than getting into a pissing match with anyone about it, I'd prefer to talk with you by phone. If you're serious about it, I'll spend whatever time you need to go over the pros and cons and be very honest about everything. You can decide for yourself and it doesn't matter if someone else does the work. It's not about that but I'd be happy to chamber either one for you. I've got a couple of different Major reamers and can do pretty much whatever you want but lets talk if you're interested in trying it and just go from there. I'm very happy to help if I can. Been through all the reamer design stuff and can make that very easy should you wish to order your own reamer for either.

I'll post a pic though. It's a couple of 5 shot groups. I'll describe the test I was shooting when we talk. Those two groups are really nice but the agg was even more impressive to me. You're also right about the 5 shot 100 yard world record. It was with a 30 Major but it was just a few thou shorter than a Major mostly due to the way they went about things. They went a long way around to get there but ultimately what they wound up with that broke that record was a 30 Major, I think .015 short, iirc and fwiw. It is what it is but detractors will point out he didn't shoot well in the agg on that day. I don't disagree. The stars have to align for most any records. Not worth arguing about but it does hold that record, so...Lol!

Here's that pic. Just pm me and we can talk tomorrow about it if you want. Again, happy to help either way.--Mike

View attachment 1503421

Mike your right I have zero experience with a 30Major but plenty with the 30 Gorilla which is the same case as a 30 Major but with 5 degrees more shoulder which Randy will tell you a bullet doesn't know whether it came out of a 35 or 30 degree shoulder. I love you too Mike but facts are facts as far as which one is a better cartridge for SR score shooting.

 

[ebb]

Well with Jon passing and all the BR crew scattered to the wind, it may be along time till i shoot out the 6ppc barrel. The 6 shoots really well but I don't reload well enough to keep it in tune or know how to get it in tune when it been a while since Ive shot it. I soot some nice groups with it when we all shot together and I have that load, but it was cooler than usual for South Florida when that happened. I think it was in the mid 50s when I shot the "0" group with it. We are going to get a cool down this week and I need to check it out.

 

[gunsandgunsmithing]

Mike your right I have zero experience with a 30Major but plenty with the 30 Gorilla which is the same case as a 30 Major but with 5 degrees more shoulder which Randy will tell you a bullet doesn't know whether it came out of a 35 or 30 degree shoulder. I love you too Mike but facts are facts as far as which one is a better cartridge for SR score shooting.

The fact is two things...more people shoot a BR, which is not even good evidence, much less proof of anything else and two, with my experience, flip a coin between the two, Jim. So if they are that close, it's gonna take untold thousands of rounds, many, many barrels and an almost infinite number of combinations of powders, lots, loads and bullets...in all of those barrels. That's where my experience with this particular cartridge is of value. I'm not bragging at all to say that I simply don't know of anyone that comes even close to how much I've tested with it. It just is what it is...nothing more or less. It just means I was determined and hard headed in learning as much as I could about it. Still am but in UBR, I shoot a 6mm rather than a 30 and I'm just as determined with it. It has not let me down either. Ultimately, I can see more advantage to it and more reason to shoot it over a ppc than I do a Major over a BR. Either way, there's nothing earth shattering left but I see enough reason to shoot it that I can't see myself going back to a ppc, but I have a couple of good bbls still laying around in case I do as well as just to go back to for testing periodically.

Another fact is that very few people really, really test a new cartridge enough to conclude much. If people spent as much time with a new cartridge as they do a known commodity, who knows what they'd conclude. Fact is, they don't. Or at least the vast, vast majority don't. Hell, even with something like a ppc, there are some that give up on a bbl if it doesn't shoot one of their two or three loads, right outta the gate. There's value in that but not when testing something you aren't intimately familiar with already.

And yes, I do give you credit for your experience with your Gorilla. They are very close. I would not expect one to be much different from the other but stranger things have happened.

 

[gunsandgunsmithing]

Well with Jon passing and all the BR crew scattered to the wind, it may be along time till i shoot out the 6ppc barrel. The 6 shoots really well but I don't reload well enough to keep it in tune or know how to get it in tune when it been a while since Ive shot it. I soot some nice groups with it when we all shot together and I have that load, but it was cooler than usual for South Florida when that happened. I think it was in the mid 50s when I shot the "0" group with it. We are going to get a cool down this week and I need to check it out.

That's the best part of the small 30's, both BR and Major. They are both super easy to tune and they both hold tune very well. It appears to be a byproduct of case efficiency...large bore relative to case capacity. They perform very similarly in that regard too. I strongly suggest to some new shooters, especially in vfs, to go with either of these two due to how easy they tune up and hold tune while they learn, at least.

 

[mikecockcroft]

I have three pounds of IMR4198 in the metal cans. How did it perform in the past?

 

[gunsandgunsmithing]

I have three pounds of IMR4198 in the metal cans. How did it perform in the past?

It'll shoot too but too bulky to get enough in there to perform its best. If you don't have anything else, shoot it. Meters like firewood but shoot it.

 

[JimPag]

That's the best part of the small 30's, both BR and Major. They are both super easy to tune and they both hold tune very well. It appears to be a byproduct of case efficiency...large bore relative to case capacity. They perform very similarly in that regard too.

Well Dean Breeden and John Cascarino both tried shooting a 30 Major variant and both of them basically gave up on it so that should tell you something because both of them guy's are better shooters than me or you will ever be. I know one other person who tried a 30 Major and he's back to shooting a 6PPC in VFS. You want to see how good a 30 Major is vs a 30BR go join the IBS and take up where I left off. Go shoot some IBS score matches especially at 2 & 300 yards and meters at Orangeburg SC at Cline's range with that cartridge and let me know how you make out against the BR's. Nobody I know shoots a 30 Major in IBS score so I'd like to see how good that cartridge fairs against a BR. My experience with the Gorilla. It's a good 100 yard Cartridge. At 200 it's fair and at 300 it's anemic.

 

[WSnyder]

Somewhere in the back of my mind I had a thought that one of the 30 caliber PPC based chamberings held a world record that even the 30 BR didn't have,

Well one variant does. Might even be the holy grail of all BR records.

.0077" -- Smallest 5-Shot Group In History

If you have ever wondered what is the smallest, 5-shot group ever shot in competition, here’s the answer. In 2013 Mike Stinnett drilled a 0.0077" group at 100 yards. No it wasn’t a 6 PPC. Mike was shooting a 30 Stewart wildcat, basically a 6.5 Grendel necked up to .30 caliber. This is a NBRSA...

forum.accurateshooter.com

 

[gunsandgunsmithing]

Well Dean Breeden and John Cascarino both tried shooting a 30 Major variant and both of them basically gave up on it so that should tell you something because both of them guy's are better shooters than me or you. I know one other person who tried a 30 Major and he's back to shooting a 6PPC in VFS.

I don't recall shooting against you Jim but I have shot against John and Dean. Both excellent shooters, for sure. I think I've finished both ahead of and behind both of them. Not saying I'm better than they are but you honestly don't know either way and them giving up is very much my point, as that's what happens unless you're willing to stick with something for the long haul, to really get the best from anything. We won't and shouldn't get into that but I remember talking to Dean years back...maybe 2008 or so about n120. His experience was a lot different than mine then. I stuck with it and it works great, especially the old stuff.

I've heard people claim that the 30 Major would shoot but only with n120. Well, that's far from my experience. I could give a pretty long list of powders I've won with in it. But that's not the point. The point is the irony we now face with H4198 not being available and everyone looking for an alternative to it when that was supposed to be the problem with a Major. Lol! Sucks and it's not funny but it is ironic. I have alternatives and I have had for a long time.

 

[gunsandgunsmithing]

Well one variant does. Might even be the holy grail of all BR records.

.0077" -- Smallest 5-Shot Group In History

If you have ever wondered what is the smallest, 5-shot group ever shot in competition, here’s the answer. In 2013 Mike Stinnett drilled a 0.0077" group at 100 yards. No it wasn’t a 6 PPC. Mike was shooting a 30 Stewart wildcat, basically a 6.5 Grendel necked up to .30 caliber. This is a NBRSA...

forum.accurateshooter.com

Long story how they got there but yes, the new record, fwiw, was shot with essentially a 30 Major. Knowing the story, had they thought about it ahead of time, I think they would've just done a straight up 30 Major. In the end, they did end up using the same Grendel brass but had to bump the shoulders back just a bit because they originally designed it as a 30 ppc long. IIRC, it wound up a 30 Major .015 short. fwiw.

 

[gunsandgunsmithing]

Well Dean Breeden and John Cascarino both tried shooting a 30 Major variant and both of them basically gave up on it so that should tell you something because both of them guy's are better shooters than me or you will ever be. I know one other person who tried a 30 Major and he's back to shooting a 6PPC in VFS. You want to see how good a 30 Major is vs a 30BR go join the IBS and take up where I left off. Go shoot some IBS score matches especially at 2 & 300 yards and meters at Orangeburg SC at Cline's range with that cartridge and let me know how you make out against the BR's. Nobody I know shoots a 30 Major in IBS score so I'd like to see how good that cartridge fairs against a BR. My experience with the Gorilla. It's a good 100 yard Cartridge. At 200 it's fair and at 300 it's anemic.

FWIW, the last IBS match I shot in, I won the 100, but being a UBR regular and because it was only for that match, I did not re-join IBS but shot as a FUN shooter. It was at Somerset, Ky and Cline cam over and served as match director. It was a night shoot and we had a really bad storm come through. Trying to remember the details but we did not have lights for the second day of the match because we should've been done before dark. Due to the storm and the delay, along with soaked targets...it became a crap shoot late and I don't think anyone could see their bullet holes. Bottom line, I won the 100 and had a terrible last target at the other yardage. Again, trying to remember the details but I think it was a 100,200 300 match but it may have been a 100,200. Nevertheless, it is what it is. I didn't win but it was not a typical day/night either. No excuses, just saying that it didn't go as planned in regard to lighting and weather. That might have been when a funnel cloud went through. I know a match I shot there, we had hail and vehicle damage as well as a tree going down, down range that went took down power lines. Interesting, no matter how ya look at it. Not saying I would've won either but I distinctly remember I think the last target, shooting soaked targets in the dark. So there. That was the last IBS match I shot in. I won, by creedmoor at 100 and now you know the rest of the story. It was a pretty big match with 20-30 shooters, as I recall. But just going by my bad memory now. I know Mike Niblett was there, a former IBS national champ. Danny Hensly, another former IBS national champ and not sure if Brud was there or not, a 2 time former IBS national champ. Yes, I may suck but they don't.

It doesn't matter. All I know is I never felt out gunned...fwiw. Anyone can do whatever they want but I do my own work and have had some success. If I felt like a 30 BR gave me a better chance of winning, I'd be shooting one before I go to bed tonight. Simple as that. You can look up the results if you want. As I recall, my name is at the bottom of the list because I was a fun shooter, not a member..but check the scores if you wanna spend your time on it, Jim.

edit...It might have been Aug 2014. If so, my name as a non-member was removed from the official results. I don't think that is the case because I remember seeing them posted at some point on the ibs page. Also, the winner in 14 had 24 x's. I think I won by creedmoor with 23x's in the match I'm referring to. But it was along that time frame. It's supper time now but I hope you figure it out. I do think it was a pretty big match...maybe a state match, fwiw. I remember my friend Jep Sumpter telling me I needed to anty up(membership) in case I won the whole thing either right before or right after I won the 100. Lol!

 

[JimPag]

FWIW, the last IBS match I shot in, I won the 100, but being a UBR regular and because it was only for that match, I did not re-join IBS but shot as a FUN shooter. It was at Somerset, Ky and Cline cam over and served as match director. It was a night shoot and we had a really bad storm come through. Trying to remember the details but we did not have lights for the second day of the match because we should've been done before dark. Due to the storm and the delay, along with soaked targets...it became a crap shoot late and I don't think anyone could see their bullet holes. Bottom line, I won the 100 and had a terrible last target at the other yardage. Again, trying to remember the details but I think it was a 100,200 300 match but it may have been a 100,200. Nevertheless, it is what it is. I didn't win but it was not a typical day/night either. No excuses, just saying that it didn't go as planned in regard to lighting and weather. That might have been when a funnel cloud went through. I know a match I shot there, we had hail and vehicle damage as well as a tree going down, down range that went took down power lines. Interesting, no matter how ya look at it. Not saying I would've won either but I distinctly remember I think the last target, shooting soaked targets in the dark. So there. That was the last IBS match I shot in. I won, by creedmoor at 100 and now you know the rest of the story. It was a pretty big match with 20-30 shooters, as I recall. But just going by my bad memory now. I know Mike Niblett was there, a former IBS national champ. Danny Hensly, another former IBS national champ and not sure if Brud was there or not, a 2 time former IBS national champ. Yes, I may suck but they don't.

It doesn't matter. All I know is I never felt out gunned...fwiw. Anyone can do whatever they want but I do my own work and have had some success. If I felt like a 30 BR gave me a better chance of winning, I'd be shooting one before I go to bed tonight. Simple as that. You can look up the results if you want. As I recall, my name is at the bottom of the list because I was a fun shooter, not a member..but check the scores if you wanna spend your time on it, Jim.

edit...It might have been Aug 2014. If so, my name as a non-member was removed from the official results. I don't think that is the case because I remember seeing them posted at some point on the ibs page. Also, the winner in 14 had 24 x's. I think I won by creedmoor with 23x's in the match I'm referring to. But it was along that time frame. It's supper time now but I hope you figure it out. I do think it was a pretty big match...maybe a state match, fwiw. I remember my friend Jep Sumpter telling me I needed to anty up(membership) in case I won the whole thing either right before or right after I won the 100. Lol!

Mike I remember that match even though I wasn't there. I didn't want this to get out of hand which it didn't. This is nothing more than a Ford vs Chevy vs Mopar thing. I won a handful of matches with my Gorilla all at 100 yards but to me it never shot as well as any of my 30BR's. They were just more accurate and out X'd my Gorilla time after time. I just was never impressed with the 30 Grendel. To each is own.

 

[Evan]

Thanks for sharing! I’d urge caution with AA2200 as you go up. In my 20 Vartarg it was the most unstable powder I have ever worked with - massive changes in pressure with temperature. Could never get it turned down far enough to stay out of brass-trashing pressure across a 30 degree temperature swing without losing the tune. Of course I wasn’t loading before each relay where I might have been able to map it and compensate for it. I was treating it like long range and loading up the day before. But when literally every other powder produced similar or better precision without the pressure problems moving from morning to midday, it made sense to put the AA2200 back on the shelf.

I am just a tourist - I don’t have a 30BR yet - but have you tried win 296? Seems like if 4227 works, 296 might too. I only have passing experience with it in 357 - nothing precision.

 

[Chris Roland]

FWIW, the last IBS match I shot in, I won the 100, but being a UBR regular and because it was only for that match, I did not re-join IBS but shot as a FUN shooter. It was at Somerset, Ky and Cline cam over and served as match director. It was a night shoot and we had a really bad storm come through. Trying to remember the details but we did not have lights for the second day of the match because we should've been done before dark. Due to the storm and the delay, along with soaked targets...it became a crap shoot late and I don't think anyone could see their bullet holes. Bottom line, I won the 100 and had a terrible last target at the other yardage. Again, trying to remember the details but I think it was a 100,200 300 match but it may have been a 100,200. Nevertheless, it is what it is. I didn't win but it was not a typical day/night either. No excuses, just saying that it didn't go as planned in regard to lighting and weather. That might have been when a funnel cloud went through. I know a match I shot there, we had hail and vehicle damage as well as a tree going down, down range that went took down power lines. Interesting, no matter how ya look at it. Not saying I would've won either but I distinctly remember I think the last target, shooting soaked targets in the dark. So there. That was the last IBS match I shot in. I won, by creedmoor at 100 and now you know the rest of the story. It was a pretty big match with 20-30 shooters, as I recall. But just going by my bad memory now. I know Mike Niblett was there, a former IBS national champ. Danny Hensly, another former IBS national champ and not sure if Brud was there or not, a 2 time former IBS national champ. Yes, I may suck but they don't.

It doesn't matter. All I know is I never felt out gunned...fwiw. Anyone can do whatever they want but I do my own work and have had some success. If I felt like a 30 BR gave me a better chance of winning, I'd be shooting one before I go to bed tonight. Simple as that. You can look up the results if you want. As I recall, my name is at the bottom of the list because I was a fun shooter, not a member..but check the scores if you wanna spend your time on it, Jim.

edit...It might have been Aug 2014. If so, my name as a non-member was removed from the official results. I don't think that is the case because I remember seeing them posted at some point on the ibs page. Also, the winner in 14 had 24 x's. I think I won by creedmoor with 23x's in the match I'm referring to. But it was along that time frame. It's supper time now but I hope you figure it out. I do think it was a pretty big match...maybe a state match, fwiw. I remember my friend Jep Sumpter telling me I needed to anty up(membership) in case I won the whole thing either right before or right after I won the 100. Lol!

The very first nignt match at somerset was won shooting LT-32 in a standard 30br, which at the time many said can’t be done‍ Fact ot the matter is there is more than one way to skin a cat. Go to the line with what you have most confidence in and shoot your game, to many get held up in this game as to what the rest are doing or shooting

 

[Fuj]

It's mostly been said that, although Vhitavouri 133 is the go to
powder for the 6ppc, it's too slow for the 30 BR.....I think I have
a way to make that powder work. I have another cat to skin....LOL
And Mike....Is that new tuner design coming along ?? I may need
it for the 30BRAT.....I have another bad idea in the works....Stay tuned !!

 

[RGRobinett]

Thanks for sharing! I’d urge caution with AA2200 as you go up. In my 20 Vartarg it was the most unstable powder I have ever worked with - massive changes in pressure with temperature. Could never get it turned down far enough to stay out of brass-trashing pressure across a 30 degree temperature swing without losing the tune. Of course I wasn’t loading before each relay where I might have been able to map it and compensate for it. I was treating it like long range and loading up the day before. But when literally every other powder produced similar or better precision without the pressure problems moving from morning to midday, it made sense to put the AA2200 back on the shelf.

I am just a tourist - I don’t have a 30BR yet - but have you tried win 296? Seems like if 4227 works, 296 might too. I only have passing experience with it in 357 - nothing precision.

You are overlooking EXPANSION RATIO: what is "spiky" in a .20 VarTarg (think case-capacity and bore volume) is a completely different animal via the thirty caliber model. A good expansion ratio comparison is to use the popular Remington BR case - obtain barrels chambered for each bullet diameter, from .20 Cal., through .30 Cal., pic a single offering from the burn-rate chart, and work up loads across the [caliber] spectrum . . . "been there, done that, didn't print the t-shirts" . . .

A word of caution - a charge weight which is quite safe via a 30 BR, propelling a 118 Gr. bullet WILL be extremely dangerous via a .20BR, propelling only a 40 Gr. bullet . . . it would be best to cover the .20BR with
old tires and tarps, and release the trigger via using a 100 foot long string. Expansion ratio is, "where it's at".

Safety can never be over done - wild-caters, "not all of us are". John Wooters' articles/writing (worth looking up & reading) provided good mentoring for exploring the fringes and even the untested middle ground. Reaching all the way back to my long lost youth, Jack O'conner's method of determining maximum powder charge holds up well: monitor case-head diameter, and when expansion exceeds 0.001", don't go any higher . . . this will happen prior to a "pressure spike". RG

P.S. if another decent day pops up, I will complete the AA-2200 exploration, using 34.7 Gr. of powder, and three-shot groups at 0.010" seating-depth intervals: from 0.030" jam-seat, to 0.020" jump. Looking to identify a trend/tendency to "shoot in a hole", thus, possibly identify vicinities to explore more precisely.

Then, I'll break out the MagnetoSpeed and chronograph the 35.0 Gr. charge weight. Due to the weight of the "bayonett", albiet on a varmint profile barrel, the chrono groups could get better, or, worse . . . but, we'll have a decent idea velocity potential. To repeat - throughout the testing, there has been no (as in ZERO) measurable case-head expansion (via regularly checked STARRETT 0.0001" micrometer) on the Petersen 7mm BR brass - the primer-pockets on the three "sacrificial" cases remain quite snug.

 

[AlNyhus]

To dovetail a bit on Randy's comments.....while coming up with an expansion ratio number is fairly cumbersome, it's something that every serious experimenter should explore.

If you've never done this before, I'd suggest starting with the 222 Remington case with a 22" barrel and use that expansion ratio (ER) number as your 'standard' or '0' reference number. As you figure the E.R. for other cases/bore sizes, definite trends emerge.

The juice is worth the squeeze.

 

[gunsandgunsmithing]

You are overlooking EXPANSION RATIO: what is "spiky" in a .20 VarTarg (think case-capacity and bore volume) is a completely different animal via the thirty caliber model. A good expansion ratio comparison is to use the popular Remington BR case - obtain barrels chambered for each bullet diameter, from .20 Cal., through .30 Cal., pic a single offering from the burn-rate chart, and work up loads across the [caliber] spectrum . . . "been there, done that, didn't print the t-shirts" . . .

A word of caution - a charge weight which is quite safe via a 30 BR, propelling a 118 Gr. bullet WILL be extremely dangerous via a .20BR, propelling only a 40 Gr. bullet . . . it would be best to cover the .20BR with
old tires and tarps, and release the trigger via using a 100 foot long string. Expansion ratio is, "where it's at".

Safety can never be over done - wild-caters, "not all of us are". John Wooters' articles/writing (worth looking up & reading) provided good mentoring for exploring the fringes and even the untested middle ground. Reaching all the way back to my long lost youth, Jack O'conner's method of determining maximum powder charge holds up well: monitor case-head diameter, and when expansion exceeds 0.001", don't go any higher . . . this will happen prior to a "pressure spike". RG

P.S. if another decent day pops up, I will complete the AA-2200 exploration, using 34.7 Gr. of powder, and three-shot groups at 0.010" seating-depth intervals: from 0.030" jam-seat, to 0.020" jump. Looking to identify a trend/tendency to "shoot in a hole", thus, possibly identify vicinities to explore more precisely.

Then, I'll break out the MagnetoSpeed and chronograph the 35.0 Gr. charge weight. Due to the weight of the "bayonett", albiet on a varmint profile barrel, the chrono groups could get better, or, worse . . . but, we'll have a decent idea velocity potential. To repeat - throughout the testing, there has been no (as in ZERO) measurable case-head expansion (via regularly checked STARRETT 0.0001" micrometer) on the Petersen 7mm BR brass - the primer-pockets on the three "sacrificial" cases remain quite snug.

Thanks Randy! Yes, expansion ratio for the small 30's really changes suitable powders and the way they act. I incorrectly called it efficiency in a prior post. They're very much related but different things. Small case, big bore= good things can happen! Lol! It's probably a lot of why the small 30's shoot so well, are easy to tune and maintain tune as well as they do.

 

[gunsandgunsmithing]

To dovetail a bit on Randy's comments.....while coming up with an expansion ratio number is fairly cumbersome, it's something that every serious experimenter should explore.

If you've never done this before, I'd suggest starting with the 222 Remington case with a 22" barrel and use that expansion ratio (ER) number as your 'standard' or '0' reference number. As you figure the E.R. for other cases/bore sizes, definite trends emerge.

The juice is worth the squeeze.

Some correlation can be seen in this chart linked below...an overbore comparison chart on this site. I don't think it's a coincidence that some of the worlds most accurate cartridges ever are also some of the least overbore cartridges as well.

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