School me about 300 Norma Magnum

Feb 11, 2017
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#54
I use a 9 twist with the berger 230s and it works well. The new sierra 230 has a recommended twist rate of 8 or faster though if you're intending on using those projectiles.
 
Aug 9, 2012
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#55
To guys shooting 300 Norma, what is real world barrel life for the 300 Norma, in a target shooting environment, quicker strings. How close is this cart. Design to the 300Lapua or 30-338 whatever you want to call it. Thanks
900-1000 rds depending how hard you push them.
 
Feb 20, 2013
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#57
How much a gain in velocity the NM actually has over the WinMag with the same barrel length and same bullet weight? It's my understanding that not much over 100 fps at the same pressure level. Just wondering if it's worth the replacement. Any real world experience will be much appreciated.
 
Jan 26, 2014
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#58
How much a gain in velocity the NM actually has over the WinMag with the same barrel length and same bullet weight?
I would spend some time reading through the Reloading Depot thread on 300 Norma to get an idea of the performance level. Everyone has different objectives when reloading and different tolerance for pressure signs and brass life. For the 230s, I have seen posted 300 Norma muzzle velocities everywhere from 2900 to 3100+. Brass life at 2900 will be great, and at 3100 it will be very short.
 
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Lowlight

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#59
I don't think the 8 twist works, that is what A1st Sold the Army on, and his rifle was a 20" barrel. In that context yes, you have an argument for an 8 twist. But when guys are squeezing every bit of velocity of out of them the 8 twist is a bad idea.

Almost every week I get a call or email asking what twist my 300NM is and how it shoots. They are struggling to get the 8 Twist rifles to work right.

My 300NM is a 1-10, and it's a 1/4 MOA shooter at 100, and carries out to beyond 2400 with the same accuracy. I have taken to 2550 yards with awesome results. I just did a series of load development shots and it was again, sub 3/8s with most of the loads, and I am getting 2997fps out of a 25" barrel with no pressure signs shooting a 230gr Berger.

I would honestly avoid the 1-8, but I know everyone is going that way because the Army says it's better for transonic. Not sure how much more past 2550 you have to go in order to see this "better" but I would be curious how well it works up. The complaints I am fielding seem to be strong and valid.
 

THEIS

Sergeant of the Hide
Nov 27, 2017
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#60
Hi,

LL what type projectile are they having issues with the 8 twist? Jacketed or Solids?
I am going to guess jacketed since you are referencing "squeezing" velocity out of them.

Thanks,
Theis
 

bjay

Private
Oct 19, 2009
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#61
I called sierra and they told me their new (LONG) 230s required 8 twist as bullet being longer than 230hybrids not much longer..one of my 300nm has 9 twist shot that 230mk no issues at all besides asking for CIP length mags
 
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Gilly

On Target
Feb 27, 2009
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#63
I called sierra and they told me their new (LONG) 230s required 8 twist as bullet being longer than 230hybrids not much longer..one of my 300nm has 9 twist shot that 230mk no issues at all besides asking for CIP length mags
Loading up round 1 of development with the 230 Sierra to test this weekend in a 9 twist 300 norma. I will let you know what I find, everything I ran on calculators showed good stability but I'm at 4200' elevation. I'm gonna use Frank's mantra and trust the bullet not the number on the box or in a solver, if its stable out of my rifle I'm not going to worry about what Sierra says.

Side note, I was pretty happy this morning when I figured out my die setting for my 198 Flatline load is a .015 jump on the sierra so I may get lucky and not have to change die at all or very little between the two loads. Going to try H1000 since that is what I have on hand, even though RL33 or N570 might get me a little more speed. If I'm not happy with velocity I'll break down and order something else.
 
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Gilly

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Feb 27, 2009
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#65
What freebore youre using mine touching land where 2/3 of neck is on bullet secant..
230 smk
Not 100% on freebore I bought barrel used for my AXMC. It was chambered by APA for the 215 berger. OAL is 3.700" at the lands so I ended up with a 3.685" OAL to start out with.
 
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bjay

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Oct 19, 2009
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#66
Not 100% on freebore I bought barrel used for my AXMC. It was chambered by APA for the 215 berger. OAL is 3.700" at the lands so I ended up with a 3.685" OAL to start out with.
Im guessing with 215 the bullet not contacting whole neck of the case while its 3.700? Im just trying to see what freebore would be good for matchking
 

Gilly

On Target
Feb 27, 2009
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#67
Im guessing with 215 the bullet not contacting whole neck of the case while its 3.700? Im just trying to see what freebore would be good for matchking
Sorry the way I wrote that was hard to follow. Chamber cut for 215’s I don’t know exact freebore. The load with 230 Sierra is 3.700 at rifling. Haven’t loaded any 215’s to get that length.

Ladder on 230’s got cut short today with H1000 I started at 81 and by 82.5 around 2900 pressures were too high to move on. Going to try some retumbo I was able to borrow to try out see if I can’t get better results.
 

Gilly

On Target
Feb 27, 2009
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#68
Round 2 with the 230 Sierra today using retumbo made it past the 3000 fps mark on lab radar but pretty good crater on primer. Really nice wide node at 2945 fps and amazing accuracy so I’m gonna load up 20 of them and move out further.

Shot the 198 Flatline load at 1360 & 1580 while I was out. Needed .1 more elevation from AB call but was on the plate with both. Spotting hits and misses at 1500+ is challenging with this bullet for sure! Magneto speed impact indicator was a huge benefit! first time using one.
 
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biffj

Sergeant
Jan 23, 2010
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#69
The length issue is really a non runner in some rifles. My Desert Tactical SRS magazine will allow a really long seating of the bullet. I run my standard 250 gr load at 3.745" and because of the magazines the bullets don't ding off the front of the mag from recoil. The magazine stops the round at the shoulder which is nice for the 338 lapua but not so good for the 510 whisper type stuff....

Frank
 
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christopher.dow

I can use measuring things
Apr 28, 2017
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San Francisco, CA
#71
Round 2 with the 230 Sierra today using retumbo made it past the 3000 fps mark on lab radar but pretty good crater on primer. Really nice wide node at 2945 fps and amazing accuracy so I’m gonna load up 20 of them and move out further.

Shot the 198 Flatline load at 1360 & 1580 while I was out. Needed .1 more elevation from AB call but was on the plate with both. Spotting hits and misses at 1500+ is challenging with this bullet for sure! Magneto speed impact indicator was a huge benefit! first time using one.
I’m waiting on the same barrel and am planning on using the Flatline 198s. Would you care to share some information on your load?
 

Gilly

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#72
I’m waiting on the same barrel and am planning on using the Flatline 198s. Would you care to share some information on your load?
Running 84 grains RL26 at 3.765 OAL jumping a long ways I’m sure it was freebore set for 230’s based on my 230 OAL. I ran ladder up to 85.3 where I saw pressure. 84 gets me 3145 SD of 6 and 3/8 accuracy. Had it to 1580 so far and they get there quick. Cci 250 and Norma brass
 

christopher.dow

I can use measuring things
Apr 28, 2017
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#73
Running 84 grains RL26 at 3.765 OAL jumping a long ways I’m sure it was freebore set for 230’s based on my 230 OAL. I ran ladder up to 85.3 where I saw pressure. 84 gets me 3145 SD of 6 and 3/8 accuracy. Had it to 1580 so far and they get there quick. Cci 250 and Norma brass
Thanks for that. I’ll start lower and work up. This will save me time and money, so thanks again!
 

Gilly

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#74
Thanks for that. I’ll start lower and work up. This will save me time and money, so thanks again!
Yeah you want to condense load development as much as possible on these. I must be lucky everyone says these bullets don’t like jump but at my OAL they are like .140 jump and I see no issues. My seating die actually stays on exact same setting for 198 and the 230 Sierra at .015 jump so I’m pretty happy to not have to mess around there between bullets. Pretty excited about my 230 Sierra load just need to get out one more time to test it.
 

Sowers64

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Feb 21, 2018
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#75
Has anyone used a gain twist? Talked to Bartlien and Sierra about the 230 Matchking. Looking at 8.5 - 8 maybe. 27 - 28 inch barrel
 

Gilly

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#76
Has anyone used a gain twist? Talked to Bartlien and Sierra about the 230 Matchking. Looking at 8.5 - 8 maybe. 27 - 28 inch barrel
Running a straight 9 twist with good results on 230 Sierra now. My next one might be a gain start at 9 finish at 8 or 8.25 but part of me says stay with what is working.
 

Sowers64

New Hide Member
Feb 21, 2018
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#77
Running a straight 9 twist with good results on 230 Sierra now. My next one might be a gain start at 9 finish at 8 or 8.25 but part of me says stay with what is working.
If it’s not broke don’t fix it maybe? Had read about gain twist barrels years ago but never gave them much thought. Theory seems sound when your target distances start at 1000yd and end North of 2500 yds give or take. 1:8 seems fast when that is what I have for a 6.5 Cm and a 6.5 Gap 4S. Don’t want to deal with solids so I don’t want to over spin either! It was recommended to not spin up over maybe a 1/2” on this. The bullet will be regroving all the way down the barrel on the gain twist. Maybe increased jacket damage, or is it less damage due to not starting so fast?
 

Gilly

On Target
Feb 27, 2009
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#78
If it’s not broke don’t fix it maybe? Had read about gain twist barrels years ago but never gave them much thought. Theory seems sound when your target distances start at 1000yd and end North of 2500 yds give or take. 1:8 seems fast when that is what I have for a 6.5 Cm and a 6.5 Gap 4S. Don’t want to deal with solids so I don’t want to over spin either! It was recommended to not spin up over maybe a 1/2” on this. The bullet will be regroving all the way down the barrel on the gain twist. Maybe increased jacket damage, or is it less damage due to not starting so fast?
I worry about going faster twist not getting the velocity before pressure. I know some folks smarter than me might argue and prove me wrong but seems like forcing a bullet down a bore of equal length forcing one to spin 200k rpm vs 250k (pulled numbers out of thin air for hypothetical ) would take more effort and therefore create more pressure. I know gain twist should help ramp it up more gradual so maybe the goal should be to average 9 in my case like a 9.25 to 8.75 but then have I really gained anything? In my 28” 9 twist I broke 3000 fps with the 230 and settled on 2950 accuracy. The more I think about it the more I should probably just get a 9 twist on order this summer.
 

Sowers64

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Feb 21, 2018
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#79
I worry about going faster twist not getting the velocity before pressure. I know some folks smarter than me might argue and prove me wrong but seems like forcing a bullet down a bore of equal length forcing one to spin 200k rpm vs 250k (pulled numbers out of thin air for hypothetical ) would take more effort and therefore create more pressure. I know gain twist should help ramp it up more gradual so maybe the goal should be to average 9 in my case like a 9.25 to 8.75 but then have I really gained anything? In my 28” 9 twist I broke 3000 fps with the 230 and settled on 2950 accuracy. The more I think about it the more I should probably just get a 9 twist on order this summer.
That’s about the velocity I hope to get. Are you using Retumbo? Maybe a 9-8.5 is what I should consider. Makes sense that the faster you try to spin the more pressure you build. I have very little experience at that Mile plus range but research says there will be some Benifit of a few more rpms to reach that extreme yardage. I have searched for anyone using gain twist on the 300NM but come up empty. I see 1:8, 1:9, & 1:10. Not very many complaints about any of them? Not sure on the ranges those are shot at. A good spin at 1200 might fall apart at 2200 with the longer projectiles!
 

bjay

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Oct 19, 2009
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#80
Since smk demand 8 twist for their new 230,which i really think way too fast..but ill try 9.25-8.50 gain twist and see what will happen..im pushing them with 1.9 bartlein 30" now 3100 fps no problem with my 30° improved with RETUMBO.. I might try rl50 since its more stable than rl33
 
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Sowers64

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Feb 21, 2018
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#81
Since smk demand 8 twist for their new 230,which i really think way too fast..but ill try 9.25-8.50 gain twist and see what will happen..im pushing them with 1.9 bartlein 30" now 3100 fps no problem with my 30° improved with RETUMBO.. I might try rl50 since its more stable than rl33
I have seen a few statements on a 30 and 40 deg improvements on this round. How much do you think that buys you? Does your ballistic data hold true and predictable out to 2300 at least? Will it still shoot factory decent at all? I hadn’t considered the improved version until just recently. I have just about talked myself into a 28” Bartlein with a 1:9 - 1:8.5. When I burn that one out if I feel the need I can go 1:8.5 - 1:8.0 maybe.
 
Nov 6, 2013
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#88
I am going to go out on a limb here, as I am by no means an expert on this subject, but hopefully it will get the conversation started, and maybe some more qualified experts will jump in.

There is talk here about barrel twist rates, and its impact on various parameters. Running through those:

Physical Impact on Bullet = Decreased BC - I have been arguing for years that the physical damage done to bullets can be a significant factor for consideration. If you look at how "hypothetical" BC numbers don't always work in External Ballistic Calcs, the bullet being damaged as it travels down the barrel can result in an altered/decreased BC.

Physical Impact on Bullet = Decreased Stability - Like the decreased BC, I have also been arguing that the physical damage done to a bullet can impact its physical makeup which can impact stability. If there is enough force/torque to distort/move the jacket in relation to the core, it would obviously impact stability.

I believe the 2 reasons above are why some shooters may be seeing less than optimal performance when they go to a faster twist rate. Basically the increased "twisting forces" does more damage to the bullet which has a negative impact.

Talking to Bryan Litz, he stated this should NOT be an issue with a "properly designed bullet" in a "reasonable twist rate" fired at an "appropriate speed". The key then becomes defining:
"Properly Designed Bullet" - this comes down to the jacket being strong enough, and the jacket and core maintaining their stability. It is a well known fact that a thin jacket bullet can be "blown up" by firing them out of a fast twist rate barrel at very high velocities.
"Reasonable Twist Rate" - I have no idea on this one? I am not sure if going from something like a 10 twist to an 8 twist in some situations could be enough of a change to produce negative consequences? The impact of this variable would obviously be heavily tied into the influence of the other 2 variables.
"Appropriate Speed" - I would normally say this could come into play if it is above 3,000 fps, but I am once again not really sure of the answer?

Increased Twist Rate = Increased Pressure - this is actually one that I DO NOT believe is an issue. If you look at Quickload there is no parameter entry for barrel twist rate. From my understanding that is because barrel twist rate has no impact on Internal Ballistics. Barrel Twist Rate also has almost NO impact on Muzzle Velocity, which would also support the argument that increasing the twist rate does not impact the Internal Ballistics.

IMHO, if people are seeing negative results by going with a faster twist rate in a .300 NM, it is because they are firing a bullet that is being damaged by the faster twist rate to the point that it is impacting performance. Obviously a thin jacket bullet, or a bullet with a poor jacket to core bond, could be susceptible to this.

I wish someone could fire some bullets with varying twist rates and speeds in a water tank so the physical damage to them could be analyzed and compared. I suspect if they did, there would be something there?

*EDIT - besides bullet construction, I also suspect that the Bullet Bearing Surface also comes into play here. The greater the Bearing Surface, the more interaction with the rifling, and the greater the potential for the issues listed above to come into play. In the pursuit of building better Long Range Bullets, the Bearing Surface sizes have gone up significantly.
 
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McCrazy

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Jun 4, 2008
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#89
I wish someone could fire some bullets with varying twist rates and speeds in a water tank so the physical damage to them could be analyzed and compared. I suspect if they did, there would be something there?
This would be an interesting experiment to perform as it would likely entail firing into a pond or lake at significant distance, then recovering the projectiles. Firing into water at close distance often damages the projectiles and would invalidate your results. Check out the Mythbusters episode where they were shooting into a pool point blank.

Other than that, you are largely asking a question that I asked here years ago which was what effect various types of rifling had on external ballistics. No one had much of an answer.
 
Dec 30, 2017
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Pacific Northwet
#90
This would be an interesting experiment to perform as it would likely entail firing into a pond or lake at significant distance, then recovering the projectiles. Firing into water at close distance often damages the projectiles and would invalidate your results. Check out the Mythbusters episode where they were shooting into a pool point blank.

Other than that, you are largely asking a question that I asked here years ago which was what effect various types of rifling had on external ballistics. No one had much of an answer.
Jim Boatright might be able to give you an answer. I believe that the rifling has little effect on the external ballistics since it is well under the boundary layer while in supersonic flight.
 
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Nov 6, 2013
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#91
http://www.dtic.mil/dtic/tr/fulltext/u2/a431357.pdf

This research addresses the issue of "Engraving".

QUOTE: "Variability in projectile engraving resistance can have a fairly dramatic effect on the peak pressure generated by the propellant. However, variability in peak pressure does not necessarily linearly translate into muzzle velocity variability."

That clarifies that the issue of "pressure spiking" being related to the process of the bullet meeting resistance during the engraving process. It does NOT come from and increase in the rifling twist rate.

Per the comments in posts above, and that research, the internal barrel design/geometry is going to have an impact on how much engraving or damage is occurring to the bullet. Also, the larger/longer the bullet bearing surface, the greater the percentage of the bullet that would be subject to damage.

Once again, I don't have all the answers, but I think there are some things going on there?
 

christopher.dow

I can use measuring things
Apr 28, 2017
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San Francisco, CA
#93
I am going to go out on a limb here, as I am by no means an expert on this subject, but hopefully it will get the conversation started, and maybe some more qualified experts will jump in.

8<
Talking to Bryan Litz, he stated this should NOT be an issue with a "properly designed bullet" in a "reasonable twist rate" fired at an "appropriate speed". The key then becomes defining:
"Properly Designed Bullet" - this comes down to the jacket being strong enough, and the jacket and core maintaining their stability. It is a well known fact that a thin jacket bullet can be "blown up" by firing them out of a fast twist rate barrel at very high velocities.
"Reasonable Twist Rate" - I have no idea on this one? I am not sure if going from something like a 10 twist to an 8 twist in some situations could be enough of a change to produce negative consequences? The impact of this variable would obviously be heavily tied into the influence of the other 2 variables.
"Appropriate Speed" - I would normally say this could come into play if it is above 3,000 fps, but I am once again not really sure of the answer?

8<
Expert or not, your post is thoughtful, and I appreciate it.

My 300 NM has a Bartlein 1:9 twist barrel. I shoot Warner Flatline 198s out of it at 3050. Both TRASOL and Kestrel get me on a 12" plate at 890 yards. I think if you want o go fast with linear and angular velocity, then solids are the ticket.
 
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