243 AI or 6 XC or 6 CM pros and cons

airb080

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Minuteman
Apr 25, 2017
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So this is my first post to this forum. I learned of it from a Savage forum that I follow. I like this forum because it has a lot of great info on shooting at distance. My question is what's the pros and cons of each caliber? I already have a Savage mod 11 in 243 and it shoots great for a factory gun with 70 and 80 GR noslers​. Awhile back I picked up 1500 105 RDF'S from SPS at $15 per 100. The mod 11 shoots them well at 100-200 but beyond that they just aren't stabilized. It has a 9 1/8 twist barrel. So I wanted to rebarrel my older mod 110 in 6mm and not sure which one to go with. I know the 243 is a barrel burner but what is the difference with the other 2 calibers. I've heard that they aren't as hard on barrels, but i don't get it, I thought they would all be the same using the same twist, bullet and speed. Any insight to the pros and cons would be much appreciated.

Sorry for the long Post.

Air

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The shoulder angle of the AI and Creedmoor are supposed to make the throat last longer. Barrel life is such a relative thing, it would be pretty tough to get any conclusive answers.
 
Thanks for the response. I've researched this a bit and haven't seen any conclusive answers between the three calibers.

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My 02...

Brass is the most important decision first. Fireform vs factory is a big deal and if you're worried about barrel life you'd have to scratch 1-200 rounds off your 243AI barrel for fireforming. Factory brass is just simpler and easier, so in my book that puts the 6XC and 6 Creed ahead of the 243AI. Then you're looking at large rifle primer Norma brass with the 6XC vs small rifle primer Lapua brass with the 6 Creed. Assuming your Savage firing pin can handle small rifle primers without piercing/cratering (don't know on that front) then in my book 6 Creed wins on both.

In terms of barrel life they're all pretty similar. More total powder volume = shorter barrel life, assuming equal pressure. So perhaps that means 6XC > 6 Creed > 243AI. However if you backed off pressure on the larger cases and ran equal velocity then it may be less of a factor.

Biggest thing you can do to drive up barrel life is run a moderate pressure load of a cool slow burning powder like H1000. However, that will be a full case of powder so the smaller 6XC isn't going to get you the same velocity the 243AI will. If your application requires 3100 fps from a 105 then you probably need to go to 243AI for the case capacity. If 2950-3000 is fine then you could probably do 6 Creed or maybe even 6XC.

If I were spinning on a new 6mm barrel (in something other than the 6 Dasher that I'm currently running) it would be a 6 Creed running H1000.
 
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What Sheldon N said. Since lapua is making 6Creed now, I guess that sort of kick the 6x47 to the curb, which I run. Dasher is one, nice shooter.


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What sheldon said....

The 243 AI does nothing for me, and I would never consider it due to the fireforming step. If you wanna be different, look into a 6 SLR. It uses a .243 case which is sized in one step to steepen the shoulder angle. No fireforming needed, and elongates the neck length.

The Creedmoor's are just such a simple solution though. With the intruduction of lapua creedmoor brass, and factory hornady 6CM brass, it's hard to rationalize taking a longer road for little to no performance gain. The XC is a cool cartridge, but has near identical capacity to the CM. And as sheldon said, it's a brass choice, and for me, small primer lapua trumps norma easily.
 
Well it looks like Ill go with the creedmore. I guess now it's time to find a barrel. I'm thinking of running a 26"-28" bull. Any suggestions on length. I'll be mostly shooting to 300 or less, but I do plan on shooting some LR matches out at peacemaker national. I really want to try my hand on some LR steel.

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I like my 243 AI. Fire forming a couple hundred pieces of brass was no big deal. my fire forming load shot about as good as my final load. If I was going to do it over I would have had them do a 6.5 Creedmore.
 
On my first 6 creed barrel now. I really like it so far but would recommend that if you are set on running Hornady 105's BTHP that you go with a longer freebore. I made the mistake of going with a .109".

It shoots great but with the design of the 105gr I'm wasting case volume. If you plan on shooting the other heavier 6mm bullets than stick with the shorter freebores.

the shorter freebore will allow you to seat in the lands and still be at short action mag length
 
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I like my 243AI a lot. 105s at 3250fps without pushing it through the roof. Whether fireforming is a big deal really depends what you do with the rifle. I blew up a few hundred prairie dogs using the foreforming rounds inside 300 yards, ballistically the difference was negligible in close. No big deal at all.

I shoot it out to 1000 yards so I do care about the velocity an AI can deliver. If I never shot it past 4-500 then there are tradeoffs I'd consider more important.