300 PRC Build . . . What twist rate are you finding successful?

jgs8163 said:

I'm running a 1/10 and a 1/9.5 in my 2 PRCs and shoot bug holes with both shooting 200-225 gr projectiles. I called and spoke with Berger, Krieger and Proof when building both of mine.

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Questions for due diligence . . . . what elevations and distances are you typically shooting? At distances beyond 1K do both twist rates maintain similar accuracy or does one emerge as more accurate beyond a certain distance?

Note: My primary interest in this build is 1500-2000 yards. (I shoot at the Cameo Shooting Complex in Cameo, CO . . . they have a 2k range . . . and it's a pretty awesome range.) So, more extreme distances are in view for this build.

Do not do a 1 in 8" twist.

My first 300 Norma Improved had an 8" twist and it was hard to load for. Over turning the bullets made the barrel very picky. Went with 8" because I wanted to shoot the new Sierra 230s. Of course Berger shot better so now I was over twisting the Bergers. Big mistake.

Next barrel was a 1 in 9". Shoots good with the Berger 220gr LR Hybrid but when I pushed speeds over 3200 fps, I had a bullet fly apart in mid flight during load development. Again too much stress on the bullet jacket. Had to back it off to 3175 fps.

My next barrel will be a 1 in 10" twist because the 220gr Berger is my favorite bullet so far and do not plan to shoot anything else. 10" twist will allow me to get up over 3200 fps without any issues.

Moral of the story: Do NOT over twist bullets. If a 9" or 10" is all that's required by the manufacturer for the bullet you want to shoot, then go with that twist. No reason to go tighter unless you are shooting really low muzzle velocities.

***Shooting at an elevation of around 3700 ft. Used to load test at 500 yards but have recently started testing all my loads at 635 yards. I don't shoot loads at shorter ranges because I feel the farther out you can test will give you much more valuable information on the characteristics of each load.

DrillDog said:

Do not do a 1 in 8" twist.

My first 300 Norma Improved had an 8" twist and it was hard to load for. Over turning the bullets made the barrel very picky. Went with 8" because I wanted to shoot the new Sierra 230s. Of course Berger shot better so now I was over twisting the Bergers. Big mistake.

Next barrel was a 1 in 9". Shoots good with the Berger 220gr LR Hybrid but when I pushed speeds over 3200 fps, I had a bullet fly apart in mid flight during load development. Again too much stress on the bullet jacket. Had to back it off to 3175 fps.

My next barrel will be a 1 in 10" twist because the 220gr Berger is my favorite bullet so far and do not plan to shoot anything else. 10" twist will allow me to get up over 3200 fps without any issues.

Moral of the story: Do NOT over twist bullets. If a 9" or 10" is all that's required by the manufacturer for the bullet you want to shoot, then go with that twist. No reason to go tighter unless you are shooting really low muzzle velocities.

***Shooting at an elevation of around 3700 ft. Used to load test at 500 yards but have recently started testing all my loads at 635 yards. I don't shoot loads at shorter ranges because I feel the farther out you can test will give you much more valuable information on the characteristics of each load.

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Thank you for sharing your experience. This is very helpful. I've ruled out the really fast twist rates. The differences between the 1:9" and 1:10" seem pretty negligible. Honestly, I'm with you on the 1:10" twist after some research and shared experience from others. Also, the barrel maker I want to use doesn't recommend the faster twist rates anyway. (Mark Chanlynn here in Colorado is an excellent barrel maker.) So, I settled my mind earlier this morning and placed the order for the 1:10" twist. I think it will accomplish all of my intended goals for this build.

Sam Pace said:

Thank you for sharing your experience. This is very helpful. I've ruled out the really fast twist rates. The differences between the 1:9" and 1:10" seem pretty negligible. Honestly, I'm with you on the 1:10" twist after some research and shared experience from others. Also, the barrel maker I want to use doesn't recommend the faster twist rates anyway. (Mark Chanlynn here in Colorado is an excellent barrel maker.) So, I settled my mind earlier this morning and placed the order for the 1:10" twist. I think it will accomplish all of my intended goals for this build.

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Won't make much of a difference on muzzle velocity a person is able to achieve but there's a big difference between 9" and 10" when you calculate rotational stress forces exerted on a bullet jacket. The significantly higher the RPM of a 9" twist at the same velocity is magnified to a much greater force than a 10" twist.

Matching twist rates correctly becomes more important as the bores get bigger and the bullets get heavier because the diameter and weight of an object plays a huge part in the equation for determining rotational stress on a bullet jacket

DrillDog said:

Won't make much of a difference on muzzle velocity a person is able to achieve but there's a big difference between 9" and 10" when you calculate rotational stress forces exerted on a bullet jacket. The significantly higher the RPM of a 9" twist at the same velocity is magnified to a much greater force than a 10" twist

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Right. Agreed. I should have added that it is negligible for my application. I won't attempt the 3K+ velocities. I'm a bit too conservative for some folks. I'll probably stick with the 2800-2900 FPS range. Either twist rate will meet my needs, I think. So, going with the 1:10" should be perfect.

Sam Pace said:

Right. Agreed. I should have added that it is negligible for my application. I won't attempt the 3K+ velocities. I'm a bit too conservative for some folks. I'll probably stick with the 2800-2900 FPS range. Either twist rate will meet my needs, I think. So, going with the 1:10" should be perfect.

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Good choice Let us know how it turns out

Sam Pace said:

Questions for due diligence . . . . what elevations and distances are you typically shooting? At distances beyond 1K do both twist rates maintain similar accuracy or does one emerge as more accurate beyond a certain distance?

Note: My primary interest in this build is 1500-2000 yards. (I shoot at the Cameo Shooting Complex in Cameo, CO . . . they have a 2k range . . . and it's a pretty awesome range.) So, more extreme distances are in view for this build.

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I'm in Tucson Az and shoot usually at 2200-3000 elevation in most target shooting situations. I've not taken it to those distances you mention. I can attest that at 700-800 yards it's money. Either twist rate is spot on. I'd call Berger or Krieger and talk with them about twist rates. They will guide you down the proper road. I am in process of building a 6 Creedmoor and the specific bullet I want to shoot is the 115 Berger VLD hunting bullet. This will be primarily used to hunt Coues Deer. Both Krieger and Berger spent quality time explaining everything to me and asked me numerous questions. Both advised I buy a 1-7 twist for that bullet and stated I should be ok going down to some of the lighter projectiles, 95-105 gr, but I'd have to "tune" the load a little more. If you think you will be shooting those heavier projectiles primarily from your PRC then you will want to build around them. I built my PRC to shoot 200-225 projectiles primarily. Call Berger, call Krieger, both offer a wealth of information and guidance. So my 6 Creed build is off with the Smith now. 1-7 Krieger mated to a Mackbros SS EVO Action. Grayboe Terrain stock and Grayboe hunter bottom metal, TriggerTech primary. Anyways.... good luck and let us know how it all comes together.

thwatson2 said:

I am using a Badrock with 26 in 1:9 twist shooting 230 grain Atips. I'm getting awesome groups out to a thousand yards. Using Ramshot Magnum to achieve @2840fps. I have also used the 225 ELD, 212 ELD, and Nosler 210 accubond LR. They all shoot sub MOA but the ATips shine. Shooting this past month at 600 yards I was grouping at slightly under 2inches. I'm using Ramshot Magnum as a technicality in that I couldn't find retumbo or H1000 so Loaded up on Ramshot. It loads right between the 2 of them so easy to develop. As with everyone finding and keeping primers is tough so my shooting has become less frequent. My last case of federal 215s are slowly diminishing. Hard to believe a primer making company can't tool for increase production of something so badly needed. But that's for a different forum!

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I see numerous retailers selling primers on gunbroker and gouging folks. I don't think the shortage on primers is as bad as we are led to believe. Go on GB and look around. I saw a gunshop from SD selling primers for $200 a 1000 and he had 20 different auctions going. Not only hoarding by customers but also some retailers hoarding and gouging us. As you said, different forum. My apologies to the op, had to vent some.