300 Norma Improved 35 degree

[Ledd Slinger]

As Alex said earlier, a lot of what we've seen agg out well, AND ON MULTIPLE BARRELS, has been around 1.8+- on the Miller scale.....not Miller Lite @GlennK

That being from pretty much strictly 6mm, fast twist benchrest rifles though, so who knows. What to watch for with marginal stability (around 1.5) is vertical that seems hard to tune out. Of course the one example in our 6mm world has been 105 hybrids in 8" twist barrels. Jim Richards shot the smallest 10 shot in history a few years back with that combo, and later a score record with the same gun. However most barrels would suffer from vertical problems at 1k....however they would shoot dots at 600! Alex ran them in a 7.5" back then and broke 2 different group agg records, which is a true testimony of how something is working, or not. I personally run 7.75" for shorter 103 class 6mm bullets, and in my opinion always error on the more stable side of things. I haven't seen any accuracy decay with a bit more stability, at least not with good bullets. I have seen a decay for certain if I miss it the other direction. In my opinion, something around 9.5 would probably be about perfect for these 1.6" 30 cals in question here, but I wouldn't be afraid of a 9".

Maybe @dkhunt14 can chime in here. I realize he mostly shoots 210 vlds in his 300s, and they're right around marginal in an 11" twist, but I would be open ears to his thoughts on his 30s. I can't think of anyone with a better idea on what makes 30 cals tick. Multiple agg and single target records, and a win percentage through the roof...What say you Matt?

Tom

Well there ya go Glen is out there winning with a slower twist. Of course comparing a WSM to a NMI is kind like comparing your 6BRA to a 240 WBY. Lol.

But this isn’t my first rodeo with 30 cals either. Long ago, I shot a 300 win mag for over 12 years. Well before there was hardly anyone else out there using one. My Father has been loading for a 300 Win Mag since 1982. I loaded for my rifle, and years later loaded for a couple other buddies when they picked up 300 win mags. Using barrels from 10 to 12 twist. Never over twisted any barrels for the bullets they were using and they shot great. I even tested the old style 240gr Sierra HPBT MKs in a 12 twist just for fun and it shot quite well. Not as good as it did with 180-200gr bulllets but there were no issues with stability I could find anywhere with the holes in the targets.

Nobody in BR shoots a 7.0” twist barrel in 6mm using bullets that call for an 8” twist, and nobody goes all the way down to a 9.0” twist for 33 cal bullets calling for a 10” twist, so it doesn’t make much sense to over twist 30 cals too far either. Unless planning to shoot past transonic ranges, then ok, maybe a little more twist like a 9.5” might help.

 

[Ledd Slinger]

What concerned me was the amount of point. Tom has a lot of experience here. From his testing we have learned there is a correct amount of point for a certain bullet. So without testing different points I was skeptical they would get it right from the factory and we are kind of stuck with it at that point. So far the 245s have just not shot as small as other bullets. Maybe we just dont have them figured out yet. It will be cool to watch theses 220s agg out as I am sure a bunch of guys are gonna try them this year.

Well I guess the tips are a little smaller than the 245s so not quite exactly the same. Below is a picture I forgot I had taken a while back for reference when I was testing all the different Bergers.

A meplat trimmer or drill bit could change them if a person wanted to do some testing.

 

[Alex Wheeler]

Well there ya go Glen is out there winning with a slower twist. Of course comparing a WSM to a NMI is kind like comparing your 6BRA to a 240 WBY. Lol.

But this isn’t my first rodeo with 30 cals either. Long ago, I shot a 300 win mag for over 12 years. Well before there was hardly anyone else out there using one. My Father has been loading for a 300 Win Mag since 1982. I loaded for my rifle, and years later loaded for a couple other buddies when they picked up 300 win mags. Using barrels from 10 to 12 twist. Never over twisted any barrels for the bullets they were using and they shot great. I even tested the old style 240gr Sierra HPBT MKs in a 12 twist just for fun and it shot quite well. Not as good as it did with 180-200gr bulllets but there were no issues with stability I could find anywhere with the holes in the targets.

Nobody in BR shoots a 7.0” twist barrel in 6mm using bullets that call for an 8” twist, and nobody goes all the way down to a 9.0” twist for 33 cal bullets calling for a 10” twist, so it doesn’t make much sense to over twist 30 cals too far either. Unless planning to shoot past transonic ranges, then ok, maybe a little more twist like a 9.5” might help.

We actually do use 9 twists in the .338. But they are for ELR. But they shoot as good as any at 1k too. I shoot 168 VLDs in my 280 ai in a 8.5 twist. Thats the most extreme case I have of over twisting. When tuning that thing shot a bunch of 1-1.5 inch 3 shot groups at 600. I think you need enough twist, but a little extra does not seem to hurt. I wouldnt want to be on the edge for long range. If you are on the edge you will get vertical fliers at 1k that you cant tune out. You wont see it at 100 or even 600. So unless you shoot a lot of groups at 1k you may not know if your on the edge of stability. And that doesnt mean every group will have them, but you will see a pattern of lost shots a little high and low.

 

[kthomas]

You guys have to remember that speed plays a big part in bullet RPM which equates to stability. With the speeds you get from the 300 NMI, there is NO reason to be twisting these things so tight. A 1 in 10” is plenty of stability for the 220gr Berger and even the 230gr.

I hated the 1 in 8” barrel on my first 300 NMI. It was really finicky. My current 1 in 9” on this NMI is definitely more accurate and forgiving, but I’ve still pushed the 220gr bullets fast enough for them to fly apart. My groove diameter might be a little tight too, but point is that I still have more twist than I need. All the other barrels I now have waiting for future builds are 1 in 10” and I know they will work perfectly fine, probably even better than the 1 in 9”

The Army was using 1:8 .300NM's and were experiencing a bunch of issues. They went with 1:8 because that's what Todd Hodnett advocates for (they have a bit of history together), but he uses a much shorter barrel then what the military went with. The velocity produced by the longer barrels were causing issues with such a fast twist. Projectiles weren't exploding or coming apart, but were acting not quite right downrange. Perhaps they were deforming the lead core? I'm not sure. But there's a reason why you don't hear the Army talk much about the .300NM anymore.

Frank Galli over on Snipers Hide has talked about this a few times. I personally don't have any inside info on the above, but he's very well connected in the industry. I tried to find some specific posts on this very subject from him (he goes by the handle 'lowlight' over there), but if I come across some I can reference them.

Unless you were planning on shooting solids, I would think 1:10 would be perfectly suitable to a .300NM Improved. I would caution with going with a 1:8.

 

[tom]

Well there ya go Glen is out there winning with a slower twist. Of course comparing a WSM to a NMI is kind like comparing your 6BRA to a 240 WBY. Lol.

But this isn’t my first rodeo with 30 cals either. Long ago, I shot a 300 win mag for over 12 years. Well before there was hardly anyone else out there using one. My Father has been loading for a 300 Win Mag since 1982. I loaded for my rifle, and years later loaded for a couple other buddies when they picked up 300 win mags. Using barrels from 10 to 12 twist. Never over twisted any barrels for the bullets they were using and they shot great. I even tested the old style 240gr Sierra HPBT MKs in a 12 twist just for fun and it shot quite well. Not as good as it did with 180-200gr bulllets but there were no issues with stability I could find anywhere with the holes in the targets.

Nobody in BR shoots a 7.0” twist barrel in 6mm using bullets that call for an 8” twist, and nobody goes all the way down to a 9.0” twist for 33 cal bullets calling for a 10” twist, so it doesn’t make much sense to over twist 30 cals too far either. Unless planning to shoot past transonic ranges, then ok, maybe a little more twist like a 9.5” might help.

I'm not positive what rifle of Glenn's you're referring to, but if it's the NMI I believe you'll find he was thinking he needed more twist for the 250s.?

We actually do use 9" in 338s, and 9.3, and 10s as well. The 10s clearly have more vertical problems in actual group matches. I only relay what I've seen on paper north of about 800 yards where this shows up more than 600 and in. 400 fps increase in velocity is worth about 7 one hundredths of a point in stability fyi, you would get a bigger value if you climbed the hill until out of breath lol. Exactly how many groups have you put on paper past 800 in your entire lifetime? I'll be putting about 30 on this weekend while you play with the stability calculator

I guess all I'm saying is that I recommend error on the north side of 1.5, which BTW your 10" at NMI speeds does do that. That's from personal experience and access to others data over the years.....Thousands and thousands of groups, in the sole quest to shoot groups. So nothing I post will ever be misleading on purpose and without actual experience...I do however reserve the right to change my mind, as the results on paper lead me to do so.

Tom

 

[Trevor60]

Based on my observations I agree with Tom staying north of 1.5sg and would look at a slightly faster twist then 10... min of 9.75 twist.

BACKGROUND
I have shot 1,000 of rounds of 215's in both 9 and 10 twist in 308win @ 2740fps at 900 meters' Additionally i have built a 300wsm with a 9.5 limited rds.

My testing shows the 10 twist groups better overall than a 9 twist but the groups are marginally larger in general. If my groups were limited to 4 shot then 9 twist all day but without fail i will get a flier within the 5 shots that throws the group or i will get two unexplained vertical shots during a 15 shot relay.

The 9 twists will hold better horizontal at distance in more conditions than the 10 twist. It appears the additional spin allows the bullet to cut conditions better.

Bergers stability calculator shows 215's at 2740fps 50 degrees 0 altitude
9 twist 1.73
10 twist 1.41

The spin of the 10 twist reduces RPM by 11% this slower rate has proven to show rounder groups which are slightly larger on avg than my 9 twists BUT I get more spoiled groups shooting a 9 twist.

Staying above 1.5sg selecting a 9.75 twist would show a 8% reduction in RPM but still suggest it could buck the conditions.

The other data points with the 10 twist being below the new norm of 1.5sg; it is more susceptible to the environment. My group will shoot smaller then the avg for specific weather conditions and conversely worse if shot below the lower limits of my load development.

It is similar but not as pronounced (when i was at the other end of the spectrum) and shooting slow twist for bullet weight barrels, eg. 14 twist shooting 185 bergers and 187 BIBs and shooting 200 hybrids in a 12 twist.

with the 10 twist and 1.4sg the 215's would seem to benefit from a two loads a cold weather load and a hot weather load.

I tried to take as much variation out of the bullets.... Prep of the 215's

BTO - hoover tool
trimmed to length- smallest OAL from measured sample of 100 bullets
Pointed - Hoover tool
Ogive to secant - Bob Green tool

Cheers
Trevor

 

[B23]

All do respect, but suggesting pointed bullets be used for hunting seems irresponsible and using pointed bullets for hunting bullets on game animals sure seems like a recipe for disaster and not really a if they don't perform but rather a when. I'd expect a pointed bullet to perform more similar to that of a FMJ.

 

[Ledd Slinger]

Well then don’t use the 220gr Berger for paper punching OR hunting for all I care. Just makes it easier for me to get my hands on them and keep the supply stocked

 

[LA50SHOOTER]

 

[kthomas]

Use a Tubb Nose Ring tool on your pointed Bergers and it should devastate anything it comes across, from the reports I've been hearing.

Turns a projectile with mediocre terminal ballistics into something devastating.

 

[MTlager]

I have seen too many pencil holes with elite hunters, and vld’s on elk that I would not trust a pointed one myself, unless I did some testing with it first .

 

[Alex Wheeler]

I have seen too many pencil holes with elite hunters, and vld’s on elk that I would not trust a pointed one myself, unless I did some testing with it first .

You have probably done more bullet testing than anyone I know. Your testing media and methods seem to work quite well. Let us know if you do ever test them. Thanks

 

[bobinpa]

View attachment 1240356

That's just mean....

 

[Ledd Slinger]

The one Berger bullet that seems to have many stories of inconsistencies and poor performance is the 7mm 195gr EOL. I believe Tom and Leo's stories on that bullet and I have heard the same stories echoed from my wife's cousin in Oregon who is a big game biologist and a huntin fool. Seems to be either massive expansion with no penetration on shoulders or pin holes with hardly any damage behind the shoulder. Saw the pictures of it too so that helps with confirmation. It's just very inconsistent from what I've heard and seen.

I have also heard stories of failures or poor performance on one of my favorite bullets over the years, the Berger 6.5 140gr VLD, but it's funny how people can say they lost animals at the fault of the bullet yet they 'know' they mad e a good shot. LOL. Sorry, but there's no way of telling exactly how well you hit an animal and how well the bullet performed unless you recover the animal. Then there's the stories of recovered animals with poor bullet performance, yet it always seems so hard for most people to post any pictures that back up their claims...Myself, friends, and family have shot so many animals the 6.5 140gr bullet I've lost count. That bullet has even dropped elk flat dead in their tracks for us using the high shoulder shot. Can't imagine how many different lots of bullets we've gone thru over the years, yet every single shot placed on an animal accurately in a kill zone has performed flawlessly for us. So it's hard for me to believe many of the failure stories.

I'm sure there can be failures due to a manufacturing defect in a bullet as well, that could happen to any bullet. The worst performance I have personally seen from bullets was the 6.5 Lapua 139gr Scenar, the 30 cal Swift Sccirrocco II 180gr, and 30 cal Nosler 180gr Ballistic Tip.
Lapua Scenar hits any sort of bone on entrance (even small doe deer ribs) and it will break into two or three sections all the way thru the base, and where those pieces go after that in the chest cavity is a roll of the dice. Never a pass thru.
The 180gr Swift Scirrocco II just won't expand. Killed a bear and a couple elk with it, but the hole thru the double lung shot on the bear had absolutely zero expansion. It was exactly the size of a pencil all the way thru the entrance, both lungs, and exit. One bull elk I shot with the swift showed better expansion, but not until penetrating very deeply the finally at the very end started to open up a little. The bear died with one shot, but the elk all took multiple finishing rounds.
Nosler 180gr BT works on deer and elk, but you better not try to take a shoulder shot on them. Seen two bucks run hard due to lack of any penetration and after long treks to track them down finally finished them off. Initials shots were well placed high on the shoulder right where my father was aiming but just never made it thru.

So what I guess I'm trying to say is that I don't need to shoot 10 or 20 animals with a bullet to see how it performs because the bullets I've seen fail usually show their true colors right away, especially on a shoulder shot. I purposely had my son take the shoulder shot on his buck because that's a good spot to test the penetration performance of a bullet since you are hitting plenty of muscle and big bones in spine and shoulder blades on both sides. The normal broadside behind the shoulder shot tells the tale of expansion on impact where there's not much resistance before it enters the vital cavity. The frontal shot was a just a bonus on the test and not normally a shot I will take, but the buck wouldn't turn. I became impatient and thought to myself "what the heck, let's see how it does". In all cases the 220gr Berger performed perfectly. Call me irresponsible if you will, but I know that the 220gr is a good hunting bullet.

 

[Ledd Slinger]

Hey guys, I deleted my argumentative posts to get the thread back on track. I know I’ll never change any of your minds on certain things until you try it for yourself. I’m actually the same way so I understand that. I apologize if I ruffled any feathers.

We have differing points of view and differing methods of testing from differing personal experiences and that’s ok. I’ll do things my way and you guys do things your way, then we will all share the information. My sample sizes may not be vast for certain things on this cartridge but it’s the information I have at the moment. All welcome to take it or leave it. I don’t shoot out 20 barrels in a year on one cartridge trying to figure out every detail. I prefer getting a barrel tuned in then getting the most use and life I can from it so I can enjoy it in the field for a long time. And also because I love my fishing and would rather be doing that during the spring and summer

Every barrel I change out never seems to shoot exactly the same. So with each different barrel, I start all over from scratch and approach my load testing like I’m dealing with an entirely different animal. I follow in the direction the paper tells me to go, whether that’s with a different powder, primer, or bullet. I have a lot of powders that seem to work well with certain cartridges but I don’t try to force things if the barrel is telling me no. I have about 20 lbs of N570 and I hope my next NMI barrel will like that powder, but i will still try other powders and it may not fully prefer N570 over something else. If that’s the case then so be it. I’ll just have to buy a bunch of different powder. This thread is still very interesting and informative so I want to keep it going in the right direction. I appreciate all the info.

 

[Mulligan]

Hey guys, I deleted my argumentative posts to get the thread back on track. I know I’ll never change any of your minds on certain things until you try it for yourself. I’m actually the same way so I understand that. I apologize if I ruffled any feathers.

We have differing points of view and differing methods of testing from differing personal experiences and that’s ok. I’ll do things my way and you guys do things your way, then we will all share the information. My sample sizes may not be vast for certain things on this cartridge but it’s the information I have at the moment. All welcome to take it or leave it. I don’t shoot out 20 barrels in a year on one cartridge trying to figure out every detail. I prefer getting a barrel tuned in then getting the most use and life I can from it so I can enjoy it in the field for a long time. And also because I love my fishing and would rather be doing that during the spring and summer

Every barrel I change out never seems to shoot exactly the same. So with each different barrel, I start all over from scratch and approach my load testing like I’m dealing with an entirely different animal. I follow in the direction the paper tells me to go, whether that’s with a different powder, primer, or bullet. I have a lot of powders that seem to work well with certain cartridges but I don’t try to force things if the barrel is telling me no. I have about 20 lbs of N570 and I hope my next NMI barrel will like that powder, but i will still try other powders and it may not fully prefer N570 over something else. If that’s the case then so be it. I’ll just have to buy a bunch of different powder. This thread is still very interesting and informative so I want to keep it going in the right direction. I appreciate all the info.

Nice work!

 

[bobinpa]

Regardless of what was in your posts, making an attempt to get this thread back on track is a class move. This is a great thread with a ton of info in it. Thanks

 

[kfreeze]

Have any of you tried 24n41 powder in the 300 nmi? I saw Ryan Pierce was running h50bmg with good results. Just trying to keep an open mind for a 300 nmi 40° build with the reamer I picked up from LA50Shooter.

Thanks,

Kyle

 

[Wildcats]

In my opinion the 24N41 would be a bit to slow for the 300nm imp.
I 've been using mosty N570 in my 300 Normas
Btw interested in your 40 degree reamer spec

 

[LA50SHOOTER]

Have any of you tried 24n41 powder in the 300 nmi? I saw Ryan Pierce was running h50bmg with good results. Just trying to keep an open mind for a 300 nmi 40° build with the reamer I picked up from LA50Shooter.

Thanks,

Kyle

Kyle,
I haven't tried 24N41 yet in the 300 NMI but I will say this. - In Larger capacity cartridges (338 Lapua Imp. being one of them) 24N41 has a very similar burning rate to V/V N570 but doesn't yield the velocity that the high energy double based V/V N570 does. - IMO it (V/V 24N41) would be a very viable option in the 300 Norma Mag. Imp. - My observations of V/V 24N41 are that it is slightly faster in burn rate than Alliant Reloder 33 in the 338 Lapua Imp. - I can also state that 24N41 is faster burning than H50BMG in larger capacity cartridge cases without a doubt. (In a "50" I would use 24N41 for lighter bullets - i.e. 640 gr but not anything over 700 gr. and a 750 gr. A-max or a 800 gr. lathe turned solid are considered as "standard" competition weight bullets in a 50 bmg.)
I applaud you for keeping an open mind and thinking when it comes to using "available resources".

All The Best !