6 PRC gun build help

cb4128

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I've been looking at a fast 6mm for a while now and finally got my hands on 300 of the 115gr berger vld's. The purpose of this rifle is pronghorn, coyotes and general fun long range shooting - no high volume shooting at all.

***I need some help on advice on twist rate for the speeds I'm expecting. Berger lists the recommended twist rate for this bullet as 1-7, which when I run the numbers on 3,450 fps (pretty realistic I think) that lines up correctly.

All of the barrels I can find are 1-7.5 twist. So, I can either shoot the 105 berger vld's around 3,600 fps (which may be too much speed and risk explosions on impact) or be borderline on the twist with the 115's and maybe run them fast enough to stabilize them?

The other thought I had was to run an 8 twist, which a lot of guys are doing, and run 90gr accubonds really fast - 3,700-3,800 fps. Hopefully they would hold together at those speeds? Makes me wonder if excellent accuracy is attainable with that much powder and that small of a bullet...

I live in Texas at 600 ft elevation but hunt in South Texas at 0 ft elevation often - and I will hunt pronghorn in NM at 4,000ft yearly with this rig.

Thanks for any help you guys can provide!

 

Masterdunbar

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Is the PRC a typo and you meant 6mm ARC?


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cb4128

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PRC, not a typo…

Cup and core meaning the Accubonds?
 

cb4128

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Oh ok gotcha. Hmm, make look into those and or the hammers.
 

Jasent

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I’ve run the 115’s in an 7.5 twist 243. They are stable even at zero degrees. They do transition better with my 7 twist. At those speeds the 7.5 will be great
 

Broz

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I’ve run the 115’s in an 7.5 twist 243. They are stable even at zero degrees. They do transition better with my 7 twist. At those speeds the 7.5 will be great
What speeds were you running the 115's ?

I just have seen this quite a few times in my life and I love big cases and fast bullets. But my concerns are will a jacketed cup core design bullet be able to withstand the acceleration through a 7 or 7.5 twist to the speeds of 3400 ~3600 fps. If they dont come apart the first 200 yards they will be ready to explode on impact. These negative effects will only be amplified by any barrel with 3 or 4 grooves due to the fact these barrels inscript the bullet jackets wider and some times deeper.
 

Jasent

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I run the 115’s at 3130. 1:7 from 28” 243 win single feeding. I’ve even shot some of the varmint bullets from this barrel. 64 gr Berger coulomb bullets at almost 4K. They made it to 835 yards no problem. Six groove button rifled.
 

Broz

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I run the 115’s at 3130. 1:7 from 28” 243 win single feeding. I’ve even shot some of the varmint bullets from this barrel. 64 gr Berger coulomb bullets at almost 4K. They made it to 835 yards no problem. Six groove button rifled.
awesome. Great data here. Thank you
 

Jasent

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awesome. Great data here. Thank you
My pleasure. On my 5th barrel on this setup. Was the first rifle I ever took to a mile. Spotting was tough till I got it figured out. Love the 6mm’s.

I’ve thought about doing a 6prc as well but the 243 does so well for me and I’m already setup for it so I’ve just stuck with that
 

cb4128

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What if I ran Barnes bullets? I know guys shoot the lighter bullets in weatherby rounds at light speed…

My concern with those is they would fly right through Antelope or coyotes without a lot of resistance.

Trying to find the happy place for bullet toughness and terminal performance at these speeds
 

Jasent

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There are many solids you could run if the 115’s don’t survive the speed. I have a idea they will though
 

Broz

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I have ran very fast 6mm before like my old 6mm x 284 and it ran 70 gr bullets at 3800 and 85's at 3600 and was for for the 350 rounds of good barrel life I got. But it was a 10 or 12 twist, don't remember. The fast twist for the larger bullets when accompanied by the velocities over 3400 is where the problem could come to play. Again, especially with the 3 or 4 groove tubes.

So this is going to be a coyote and antelope rifle? What would be the longest shot taken? That info is what I would use to decide what bullet to shoot.
 

Broz

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What if I ran Barnes bullets? I know guys shoot the lighter bullets in weatherby rounds at light speed…

My concern with those is they would fly right through Antelope or coyotes without a lot of resistance.

Trying to find the happy place for bullet toughness and terminal performance at these speeds
They are not shooting a 7 twist

At those speeds I do not think "Flying through" will be an issue, explosive expansion and low penetration could sure be.
 

Jasent

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With my rifle explosive is a good way to put it. Cantaloupe size exits on coyotes at over 500 yards. Deer haven’t been so bad. 500-700 yards exits are about 1-2”. I’m sure close range may not exit on deer
 

Broz

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I am not too worried about a bullet at 3150, but 3400 to 3600 I do have some concerns.

I would try what you want, but be ready to move on to Cutting Edge Bullets if there are issues. They do cost more than some, but for a reason. They in my opinion are the best of the solids. And when you look at the life expectancy of this rifle, top shelf bullets will not be the biggest expense.
 

cb4128

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I’d say 600 yards and in probably on target range. I could an 8 twist if over twisting is a concern?
 

Broz

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I would pick the bullet of choice, that you can get, then order the barrel for it. Just know that faster twist rates and high velocity can warrant a barrel with 5 or 6 grooves and a tougher bullet design to hold up.
 

cb4128

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I guess this idea came about from hunting with multiple guys shooting 240wby with 100gr partitions over the last 10 years. They flat out hammer Antelope, whitetail, 300lb mule deer, hogs, etc.

I could just go that route but trying to be different.

100gr partitions at 3,350 fps is what they’re shooting.
 

cb4128

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true, ok what about an 8 twist Bartlein 5R? 90gr accubonds - 115gr vlds is my range of bullets Id like to try
 

cb4128

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I love that idea but I already shoot a 6.5 SAUM with 140 berger elites at 3,160 fps - it’s just so close to what I already have that it got me looking ay the 6mm instead…
 

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I’ve had really good luck w a 6 PRC and the Berger 108 Elite hunters. I’ve killed a lot of critters with them in the last 2 years and really happy with the performance. You will be good with the 115’s at sea level, no issues. When looking at freebore options for the Berger bullets, look for something around .140”. My current set up is a 22” bbl and the 108’s at 3270. Can definitely push them harder but it consistently shoots in the .2’s. Good luck w your build and I’m sure you’ll be happy w the 6 PRC
 

Jasent

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I’ve had really good luck w a 6 PRC and the Berger 108 Elite hunters. I’ve killed a lot of critters with them in the last 2 years and really happy with the performance. You will be good with the 115’s at sea level, no issues. When looking at freebore options for the Berger bullets, look for something around .140”. My current set up is a 22” bbl and the 108’s at 3270. Can definitely push them harder but it consistently shoots in the .2’s. Good luck w your build and I’m sure you’ll be happy w the 6 PRC
What twist you running
 

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