.243 AR-10 magazine length

[mljdeckard]

So I now have a functioning .243 AR-10, after much procrastinating and a little bit of tweaking. I have always wanted a ,243, and I wanted to build something unique.

I like to keep things simple. I got a 1/8 barrel, because I want to be able to push it to 1000 yards. I would like to make one load to use for everything, but if I need a couple, that's ok too. I am thinking 105 hybrid Bergers for shooting at distance. I was looking at their hunting bullets, but they got mixed reviews for performance. I may drop back to one of the lighter Barnes bullets for hunting. (Hogs, mule deer, Texas pigs. I know some guys do hunt elk with a .243. My brain says it will work, my gut says to stick with something heavier, which is fine, I have other rifles.) I prefer getting accuracy out of the heavier bullets, I'm not really trying for blazing velocity. This barrel will have a short life as it is, I don't need to try to make it happen faster.

I am left with two questions.

1. Will a 1/8 stabilize any 6mm bullet as long as a stay away from the very lightest ones? 70 grain and up?

2. Will Berger 105s fit in a standard AR-10 Magazine? Will I be single-loading them? (If I have to, it's ok, that will be a slow-firing situation anyway.) Will I have COAL issues? If I have to make them sit right off the lands to be accurate out to 1000 I will, but it would be nice if I don't have to.

 

[Varminterror]

Berger shows 2.710” COAL for the 105’s in 243win. Plenty short for AR-10/LR-308 mags.

They also show ~2800fps for a 24” barrel, with 1:8” recommended for the 105 Hybrids.

I shot a mild 6 creed load last PRS season in a 24” 1:8” twist, hit targets out to 1,480yrds, trucking a paltry 2,800ish FPS. If you aren’t connecting at 1,000yrds with 105 Hybrids at 2800fps from a 1:8” 243win, it’s not going to be the fault of the twist or velocity.

The 1:8” will stabilize the lighter ones too, and only the rarest specific lightweight 6mm bullet models will come apart due to the excessive spin. Again, guys are shooting ~55grn 6 creeds in fast twists every day, running the same bullets at the same speeds as you’d see in 243win.

 

[mavracer]

Every barrel will be different but from what I understand 105 hybrids aren't real jump sensitive. I've had good results so far with mine using 107 SMKs.
The 103 ELD X looks like it might be awesome for critters.
Love my 243 AR

 

[mljdeckard]

Mavracer, that's helpful. It will come down to testing to see whether the jump is no big deal, if a smaller bullet will get me out to 1000, or if I will have to single-load them. But knowing it can be done is a start.

 

[mljdeckard]

And what barrel did you use?

 

[mavracer]

24" 3/4 ton axle from X caliber 1 in 7 twist

 

[mljdeckard]

Even more helpful. Mine's a X-Caliber 1/8 Dana 44.

 

[mavracer]

Just to be clear I haven't shot any of the 103 ELD X but it looks real good. I bought a case of Federal fusion 95 gr mostly for the brass and Federal had a rebate and they were like $10 a box after rebate. To be honest they shoot pretty good like 1.25 moa plenty good enough to hunt IMHO and from reviews the bullet works great on deer size game.

 

[mljdeckard]

I'm just glad to know I have the room to work with. Plenty of time to tinker with loads when I get home. (Even if the barrel life clock is ticking.)