.762x39 for 100 Yard Group

[AlNyhus]

It does surprise me that the Lapua case has that much less internal volume than the others. The only reasoning for this, I would assume, is Lapua was going for strength, especially for someone reloading fo a gas gun.

That's what I'm thinking. It should play right into what you're looking for. The only question mark for me is the case taper and whether that will cause any issues, But with the faster powers, it might not. I know on the straight 220R necked to .22, the case taper seemed to be an issue...but I wonder if the total shoulder contact area wasn't a contributing factor as well? The short shoulder length on the 7.62X39 case (compared to the 220R) could prove beneficial. -Al

 

[gunsandgunsmithing]

That's what I'm thinking. It should play right into what you're looking for. The only question mark for me is the case taper and whether that will cause any issues, But with the faster powers, it might not. I know on the straight 220R necked to .22, the case taper seemed to be an issue...but I wonder if the total shoulder contact area wasn't a contributing factor as well? The short shoulder length on the 7.62X39 case (compared to the 220R) could prove beneficial. -Al

I've played with these small 30's on different actions and I can't say for sure but it would be a consideration of mine, to think about feeding with some actions. The same taper may never caue feeding issues with a 52 or 68gr 22/6mm bullet, that might, when the bullet becomes a 110-120gr 30 cal bullet. This isn't purely speculative but I can't say that I've tried it in every action either.
The case taper and bullet weight tip the bullet down. Just keep that in mind. On a Stiller DP in 220 Beggs, I did run into issues occasionally with this..mostly when running fast. Different cone angle... It may never be an issue with the more common 25° and 30° breeches. I can't say for sure. It was close with the dp and a 22 meplat. fwiw. I will say that problem went away with the straighter case taper of the 30 Major, even though the meplat is slightly different. Frankly, I'd try it without much concern on a common 30° breech but just pointing out a less than obvious thing that I have seen with steep case taper. The extra bullet weight does make this more pronounced. I saw that, even with a 30 Major. A 30BR has both a bigger chamber opening and a higher center. No problems there!

Jackie,
Just giving you some things to think about that are less than obvious, that I've dealt with already with different case tapers and their center of gravity. You can work with a gun that doesn't feed really well by getting in the habit of starting the round in the chamber before closing the bolt. So, even if it's an issue, it's not really dead in the water because of this point. You should just be aware of it.
Ultimately, as I've already alluded to, necking up a 6.5 Grendel case has it's benefits, for a small 30 cal alternative to a 30BR. If the idea is to optimize capacity, I'd consider what Al said, and think about bumping the shoulder back and necking up Grendel brass...but I'm all about testing ideas, so, have fun with your project.

 

[jackieschmidt]

I learned years ago to literally flip the round into the chamber when shooting in competition. It’s a old habit now.

Iwant to try this case because I have no desire to push shoulders back or any other functions aside from turning the necks and fire forming. If it doesn’t pan out, it will become a 30BR.

Making the 30BR is already pretty labor extensive. But the payoff is the darned cases last forever.

My 30PPC, which I shot before going to the 30BR, was a real pain. I first had to make a 220 Russian into a 6 PPC, then blow that out to make the 30PPC. I then neck turned them, fired them again in the regular chamber, and they were ready.

keep in mind, my whole idea behind this exercise is a low recoil 30 to shoot in Light Varmint Group. Anything else is 30BR territory.

 

[gunsandgunsmithing]

I learned years ago to literally flip the round into the chamber when shooting in competition. It’s a old habit now.

Iwant to try this case because I have no desire to push shoulders back or any other functions aside from turning the necks and fire forming. If it doesn’t pan out, it will become a 30BR.

Making the 30BR is already pretty labor extensive. But the payoff is the darned cases last forever.

My 30PPC, which I shot before going to the 30BR, was a real pain. I first had to make a 220 Russian into a 6 PPC, then blow that out to make the 30PPC. I then neck turned them, fired them again in the regular chamber, and they were ready.

keep in mind, my whole idea behind this exercise is a low recoil 30 to shoot in Light Varmint Group. Anything else is 30BR territory.

Have at it and good luck with your project. You know well, what you're venturing into. But I'll tell you what you told me before, "there is very little that hasn't been done before"..or something similar to that. I've enjoyed my path and I wish you the same. Clearly, you are on a path that you choose not to involve my input on. I get that and wish you well with it.

 

[jackieschmidt]

. Clearly, you are on a path that you choose not to involve my input on. I get that and wish you well with it.

Not at all. I welcome all Ideas.
just because I don’t follow someone’s advice does not mean I don’t respect their input.

Sometimes I make up my mind to do something just because I can, without much thought as to whether I should,

 

[AlNyhus]

Sometimes I make up my mind to do something just because I can, without much thought as to whether I should,

That's what I love about experimenting!

When I sketched out my idea on a napkin (literally) of a 30BR with the shoulder blown forward enough to hold 45.0 gr. of water to meet the HBR rules of the day, Stan and my big question was the resulting .085 neck length. We knew from our experience working with throats on our .30 WareWolf (308W -.165) that seating the bullets pressure ring below the sized portion of the neck....despite the commonly accepted BR 'truths'...had no adverse effect on accuracy as long as the neck tension was fairly snug...which these .30's love, anyway. The .30 WolfPup was the result and it shot just as well as a 30BR.

If a person has an idea, there's nothing to it but to do it! -Al

 

[jackieschmidt]

Got these today. One step closer.
@cayennejon was nice enough to send me a Redding S style sizing die and body die. Ineed to turn a neck and seat a bullet so I can figure out the freebore so PTG can grind a reamer.
I have a 300AAC Blackout competition seater ordered that I will convert to the .762x39.

 

[RGRobinett]

The main thing I am looking for is minimum case capacity. Something in the 25 grain range. By my calculations by retaining the case taper, the 7.62x39 case will hit this just about right, using 4227 as the powder under a bullet 112 or less. Maybe even H110.
The Grendal, Major, 30PPC, etc all have over the capacity I am looking for.
I have a real nice .332 neck 30PPC reamer. I actually shot that before switching to my 30BR. Making brass was a major pain, and the things did not last that long.

Alex might be right about the primers. That might be the stick in the mud about the whole idea. There is the option of necking up 220 Russian, but that gets pretty labor intensive. If it turned into a major hassle, I would just put up with the recoil of the 30BR In a 10.5 pound rifle.

And, if you've got 'em, don't overlook Acc. 1680, Win. 680, Acc 5744 . . . "back in the day", when I was dabbling in this vein, [the late] George Myer provided some "Quick-Load" predictions for the necked-up 220 Russian - the 5744 was particularly efficient.

With proper fitting FL die, I don't see a problem with the taper - long ago, to minimize capacity without extra effort, this is where I went with my .22 Cal., as opposed to making & maintaining WALDOG brass. I had Niel Jones make a FL/Shoulder/NK die - I've no regretts. I believe this is pretty much the same reason Gene Beggs developed the 220Beggs.

Presuming proper case preperation, I'm not much of a believer in case quality equating to precision. I've collected all of my personal "BIG" wins using Remington .308UBR(30x47HBR) and Rem. 7mmBR brass(30BR). You were present for two of the decent 7mmBR efforts: Lake Charles (3rd) & Greeley (1st) . . . the sole "issue" is somewhat shorter case-life. Between Rem., LAPUA, etc., I have never been able to shoot a measurable, valid, difference is precision.

Keep thinking "outside the box" - you're already good at it, and THAT'S where the fun lies!
RG

P.S. I agree with Al Nyhus: EXPANSION RATIO trumps all.

 

[gunsandgunsmithing]

And, if you've got 'em, don't overlook Acc. 1680, Win. 680, Acc 5744 . . . "back in the day", when I was dabbling in this vein, [the late] George Myer provided some "Quick-Load" predictions for the necked-up 220 Russian - the 5744 was particularly efficient.

With proper fitting FL die, I don't see a problem with the taper - long ago, to minimize capacity without extra effort, this is where I went with my .22 Cal., as opposed to making & maintaining WALDOG brass. I had Niel Jones make a FL/Shoulder/NK die - I've no regretts. I believe this is pretty much the same reason Gene Beggs developed the 220Beggs.

Presuming proper case preperation, I'm not much of a believer in case quality equaling precision. I've collected all of my personal "BIG" wins using Remington .308UBR(30x47HBR) and Rem. 7mmBR brass(30BR). You were present for two of the decent 7mmBR efforts: Lake Charles (3rd) & Greeley (1st) . . . the sole "issue" is somewhat shorter case-life. Between Re., LAPUA, etc., I have never been able to shoot a measurable, valid, difference is precision.

Keep thinking "outside the box" - you're already good at it, and THAT'S where the fun lies!
RG

P.S. I agree with Al Nyhus: EXPANSION RATIO trumps all.

I agree Randy. 5744 and 1680 are good choices. Both are very good alternatives in my 30 Major, to the n120. The old n120 was nothing less than spectacular but they played with burn rates on it and had it all over the place for a while, with some lots being both way slower and faster. The new stuff seems to be pretty close to the old..maybe a tad slower and not as clean, it seems. I still like the old n120 better than any other powder in it but when it's gone, that certainly brings other options more into consideration. I got really spoiled by the n120 of old. It was super consistent from lot to lot for a good 10 years, and very clean. Frankly, it was the best powder I've ever used in anything. I just wish it was more versatile and could be used in more cartridges. Old or new both meter great and build pressure smoothly and predictably. That's why I steered clear of the 4227s. The Canadian version was scary "spikey". The Aussie, not as much so but still a bit tempermental compared to the others. mentioned. They'd really lure you in, as it just kept getting better and better(with more powder) and then pressures would spike fast on ya.

 

[Fuj]

Not at all. I welcome all Ideas.
just because I don’t follow someone’s advice does not mean I don’t respect their input.

Sometimes I make up my mind to do something just because I can, without much thought as to whether I should,

Jackie, I'm a bit late to this party, and of late has me caught up
in shortening 284 Winchester brass for two cats, I'm doing fair
with. To make a long story short, I stumbled on a 7.92 x 33 Kurz
case, It's a really shortened 8mm Mauser case that the Germans
used in their WW2 assault rifle......I'm thinking, maybe worthy of
taking a look over the winter months. Find some decent small
primer brass and do a 30 mini ??

 

[jackieschmidt]

Here is my final print for my reamer. Also the file print for a SAAMI .762x39 reamer.

the biggest changes are the bore, (308), throat, A, B, E, T, U, C, AND H dimensions. Zero freebore.

It will be a while for JGS to fill my order. 16 weeks.