.308 VLD's in the AR-10?

[Wannashootit]

At the range last weekend another shooter suggested VLD's over the 175 SMK's we were shooting from my son's AR-10 at 1000 yards. They "only" have minute of angle steel there- so hits ain't a piece of cake... and most shots were literally within inches of the gong- but no cigars.

As it was, it was a really nice day for LR shooting, very little wind and mostly none to quarter value at our backs.

My concerns about viability:
While VLD's would definitely perform better, they'd have a long jump...

Using Varget, we're already approaching a compressed load with the SMK's. VLD's will seat deeper in the case, either compressing the load more, or requiring to reduce (not really an option).
Would a different powder be more appropriate for use with heavy VLD's?

Suggestions appreciated!

 

[memo43]

Any change in the reloading process requires load development to get it "spot on" vice just there. Why not do a load development. who knows maybe less powder to achive the same results. Also your limitaions will be mag length. I know a few shooters who shoot nothing but VLD's with great success.
I would almost venture to say somewhere around the 43 grain mark but who knows until you try.

 

[dauntedfuture]

There are no issues with VLD bullets in a semi auto at all provided they shoot well. Most semi autos are set up for mag length bullets so you will likely have to seat the 175's so they are longer then mag length and single load them. Try .020 off and .020 into the lands and see what happens. 80 and 90g .224 bullets will not fit in magazines and we single load them for 600 and 1000 competition in AR-15's so its the same thing. With single round load you have less issues with neck tension and can go to less if the gun shoots well. Getting an AR-10 to shoot at 1000 is tough and your going to have to make sure the bullets stay supersonic, 175 VLD bullets will help a lot. check your velocity figures on JBM ballistics to make sure you are supersonic and that your ES is 25 FPS or less. Berger jackets are thinner then Sierra or hornady jackets so the same weight bullet will produce less pressure and or a little more velocity. Don't try to hot rod the AR-10, bad things will happen. You should be able to chamber and extract fired cases without too much effort.

 

[Wannashootit]

Single loading is far too much of a pain in the ass...I thought it might be feasible, but just too much effort involved with racking the BCG for every shot.

Far as hot loads, I'm always cautious- and our accuracy load with the 175 is 43.5 grains, across several platforms. BUT... I did push the envelope doing OCW and got to 46 grains- a full grain above Hodgdon's recommended max- and curiously enough, no obvious pressure signs. Not a scratch from the extractor, primer edges weren't flattened, though the primer strike was somewhat cratered- but that's on every load and I think it's more related to the FP. Have the same "look" from a Rem 700's primers. Everything above the 43.5 up to the 46 was less accurate- and then suddenly the 46 grain load shot 1/2 minute- with two in the same hole. Despite the "no pressure signs", I am somewhat leery of this given it's temperature...

I have the same problem with VLD's on my other son's .260 bolt gun in an AICS, but after single loading those seated .02 off, I seated others at max mag length (3.89) and the long jump didn't seem to bother it (hitting a 4" plate at 565 with some consistency) but more work is needed here.

I was mostly wondering whether, due to the decreased case capacity from seating VLD's to mag length, whether another powder might be worth a try. We did play with RE-15 a bit with good results on target, but have not checked with a chrono yet.

 

[dauntedfuture]

RL-15 and VARGET are both good choices for .308 w. 175g bullets. I would stick w. the varget. 0.1" decrease seating depth into the case is worth about 1g of powder of so. Crono you loads and you will know. Everything is telling me that 46g varget with a 175 is too hot as 45g is a hot load with 155g bullets in a .308 bolt gun. Some guns mask pressure signs better then others. If you are shooting at 600 yds a 100 fps difference in wind deflection between a 2550 and 2650 fps is not much, much-much less at 465 yds. The pressure difference between a 43g load and 46g load can be significant and its not worth it.

 

[Wannashootit]

The pressure difference between a 43g load and 46g load can be significant and its not worth it.

Yeah, I agree...
It's not like you can "feel" hard extraction like you can with a bolt gun.

We did try the 168 Amax, it didn't care for them (didn't like the 168 SMK's either, gun seems to prefer the heavies), but will get a box of the 178's, or Berger 175's if I can find them, and try them out.