Heavy .308 bullets from a short barrel

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Geckgo

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Hi all, this is a hypothectical for me but if anyone has experience I would appriciate it. Doing a lot of window shopping and wishing for the day when I get my AR-10, and I'm curious.

First, I've heard a lot of stories in threads on here that the .308 will be less stable with heavier bullets like 180-200gr. Does this same argument apply to the 30-06 or is there some other factor at work here??

Second, has anyone tried heavy bullets in the .308 cartridge from a short barreled gun like an AR-10? I'm wondering how much damage a 16-18" barrel would do to a 200 grain bullet in terms of velocity. My lyman book is showing 2000-2400fps from a 24" barrel, the 30-06 from the same barrel is a tad faster.

Don't know why I do this to myself, if I spring for an african safari then I'll probably just throw down some cash on a 50cal. Compared to the cost of the trip it shouldn't be that noticable, but I always wonder if my little "at home" gun will be at home popping bigger game. I have faith in my 30-06 but I would not want two different types of 30 cal ammo, so I would either trade in my deer rifle when I get the AR or rechamber it for .308. I have decided against getting a garand.

Just a thought experiment more than anything, unless someone has fired heavy rounds from an AR platform.
 
  • usually heavier bullets loose less velocity from short barrels than do lighter ones.
  • a 30-06 will usually be a couple hundred fps faster with any given bullet weight.
  • I wouldn't worry about mixing up 308 and 30-06 ammo, they look pretty different.
  • don't bring a 50 bmg on safari, get a 416, 375 etc. there is a reason they are known as "African calibers"
 
I hunted Africa with a .30-06... unless you are going for buffalo or dangerous game you don't need anything heavier (and that's just because of the law not b/c an '.o6 isn't capable of it). I downed an extremely large greater kudu with one well placed shot from my good old .30-06 and the only thing larger calibers are going to do is upset your taxidermist.
 
hehe, that was more like my plan and how I feel about my -06. It's plenty, but either way I would want something with semi-auto capability for those cases where you really NEED follow-up shots. ;)

Not going to Africa anytime soon though.

So, I should still be able to get some decent performance out of even a short barrel then?? that's good to know. My AR-10 just earned premium status on my wishlist in that case. I'm going to get the reloading setup before I start really looking for one, so theres still a long time to look and compare before I buy it. Thanks NOLAEMT.

It's not about mixing the bullets up, it more just about having redundant calibers laying around. My -06 was my first rifle and I got a good deal on it. ADL for 250 bucks. But to me the .308 and -06 are so similar for most everything that I don't see a need for having two different types of ammo to stock up on. When I get closer to buying my "black gun" then I will have a better idea what to do. If I talk myself back into the garand idea, or an M1A in -06, then I'll stick with the -06, otherwise I'm changing to .308/NATO.
 
Don't know how this will relate but I shoot 200 grain Sierras from my 16 inch AR in 300 Whisper and get great accuracy. I also get great accuracy from the same bullet in my Ruger 77which is a 20 inch set up.
 
A bullet that is not stabilized properly will result in bad accuracy regardless of the case used. The speed and length of the bullet has to do with it.
Higher grain means longer bullets and this means you need a higher rate of twist on the rifling of the barrel to stabilize the bullet. In .308 caliber a 1:10 (means a bit over 1.5 turns in one 16 inch barrel) should stabilize bullets up to 210gr.Watch out for solid coppers as those are even longer since they do not have lead.
Follow manufacturer recommendations for the bullet and make sure the bullet can be seated properly so your chamber allows a potentially larger bullet and you do not need to seat the bullet too deep, both easy ways to rise unwanted pressures quickly.
Solid copper (long) vs GI FMJ bullet....
rifle30_145vs175SMKvs168TSXb.gif
rifle038.gif
 
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I have a 22" barrel on one of my .308s. Although I wouldn't call it short, it isn't long. I have a 1:10 twist and haven't had any problems shooting the heavies, although I prefer 175s.

I don't know what your velocities will be like, due to chamber differences, but I don't have any problems at all getting 2600 fps at the muzzle with 175s with a relatively mild load.
 
You can stabilize a heavy bullet .308 Win IF you have one of 2 things: a 1-10" twist OR a long barrel using a load that drives the bullet at a high enough velocity. I shoot 190SMK's out of my 1-12" FN SPR, but with a 26" barrel and the right load, I am able to get 2700fps. Since you have an autoloader with a short barrel, I doubt that you will have much success.

Don
 
If you're looking at 16" AR-10 variants (nearly all of whom seem to have a 1:10 twist barrel), anything up to 180 grains will run great. 200-230 grain may be iffy. For best range and accuracy, a lot of people report that the 168gr SMK works wonderfully in the 16"/1:10 barrels. Your supersonic range is out to about 750-825 yards, depending on powder and atmospheric conditions.
 
When I had my DPMS LR rifles, I only shot 168 and 178gr Hornady's through them and they stabilized fine...I just never saw the need to shoot a heavier projectile since the BCs on the 178s were good enough for me.

Good luck with finding a rifle light in a 50cal.
 
Thanks all for putting my mind at ease on this. All that's left for me to decide which AR-10 to buy, save up some money, and get one :) I imagine that I'll be burning a lot of bulk ammo at the range and using 150's or 168's for hunting, but if I ever needed to, I wanted to make sure that I could go heavier.
 
I've shot 180 grain btsp's out of my Remmy 700 SPS 20" barrel, with a upper mid-range load, I can get about 2500 fps out of them. These are handload's. Although I much prefer the Hornady or Nosler 168 hpbt's, since my longest shots are typically 400 yards.
 
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