Tx635

So I've got a new PA-10 lower on order, thanks to my fiancee and would like to build it into a 7.62 NATO hunting/ target shooting carbine. I do know that 308 does loose quite a bit of velocity when you step down to a 16in barrel and that an ar10 isn't the optimal platform for it with as theirs very little standardization will cause some fits. But I've never shot 308 let alone used it for hunting and have a few questions about the cartage.My first is what are some good weights on bullets that people like? I've been looking into 142gr tracers for bulk reloading but was wondering if they are any good, even at around $.10 each.
my next one would be if anyone has a preference twords 7.62 NATO or 308win? I know that their are chamber and brass differences just like 5.56 vs 223 so I'm wanting to know if one is better than the other.
my last question is what's a good all around twist rate for 308 caliber bullets or if it's something that I'll have to settle on after I find what weight range bullets I'll be using?
Thanks and hopefully this post doesn't seem too odd.

Nomercy448

The differences - really the lack thereof - between 7.62x51mm and 308win are not the same as the differences between 223rem and 5.56x45 NATO. I posted this response a few years ago, take a read, forget all of it and shoot the rifle...

https://www.huntingnet.com/forum/reloading/406951-problems-reloading-gas-gun-3.html]Gas Gun reloading problems - page 3 7.62x51 Nato vs. 308win[/url]

MudderChuck

A 16 inch barrel is going to spit a lot of unburned powder out the barrel, or in other words, it is going to have a rather large flame coming out of the barrel. Likely with a logical reduction in muzzle velocity. I really can't think of many rifles designed to fire either the 7.62 Nato or the .308 with a barrel shorter than 22 inches, most have a 1 in 12 twist rate. Most of the more accurate varieties have a 25.5-26 inch barrel 1 in 12 twist rate. There is one model of the Rem 700 that has a 16.5 inch barrel, with a 1 in 10 twist rate, internet knowledge take it for what it is worth.
The 7.62 Nato is slower with a lower chamber pressure than the .308.

Nomercy448

Lots and lots and lots of firearms chambered for 7.62x51 and 308win have been designed and built with barrels shorter than 22”. The standard AR-10 was originally designed with a 20” barrel, the Rem 700 P LTR also at 20”, as are the M110 and SR-25, as was the Ruger XGI. Cetme’s are 17.7”, as are HK G3’s. The 308win and 308 family cartridges are common choices for specialty pistols - usually with barrels shorter than 15”. In LFAR’s, 16” and 20” are by FAR the most common barrel length offerings. I have to imagine hundreds of thousands if not millions of AR-10/LR-308’s have been sold or built with 16 and 20” barrels. 20” has been the most common request for 308 LFAR’s I have received - I’ve built dozens of them over the years. Ruger’s SR-762’s were available in 16” and 20”, Savage MSR-10’s are 16” and 20”, Remington R-25 were 20”...

Yes, we get more blast from short barrels, but if we were blast averse, we wouldn’t be shooting firearms at all.

I have a 6mm Creedmoor with a 15” barrel, which was originally a 243win and had a 14” barrel...

Personally, I don’t care for 308win’s, but when I do build them, I prefer 1:10” twist. 20” is capable of doing a lot of things in an LFAR, but your desired application really dictates which barrel length might be appropriate. For a fighting carbine, a 16” barrel makes sense, while a long range steel banger will benefit from 24” or longer. I shoot frequently with a guy who has a clone of an SF rifle he used when deployed which is a gain twist 10” barrel. For hunting, a 20” works out nicely.

Nomercy448

By the by, moderators - this really should be moved to the Guns forum, not hunting gear.

Bocajnala

Done.
-Jake

MudderChuck

My default in most situations is accuracy and then functionality. I see few upsides to a shorter barrel, it may make you feel tactical, may be easier to store, maybe practical for a truck gun. I have a short 5.56 (30 inches) it has a folding stock and an 18-inch barrel (compromise) if it came in twenty I'd have a twenty. A little research with a barrel length/velocity calculator might be illuminating.
IMO barrel length other than the optimum for accuracy, designed operating envelope, and functionality is a fashion statement and has few practical applications. Especially for a hunter, where accuracy can make the difference between making or wasting a shot you may have been waiting for, for weeks. I became a believer when I chased the optimum round for my .308 sniper rifle and eventually ended up right back where the manufacturer recommended in the first place.

Nomercy448

Are you saying you feel 22” 308win’s are inherently more accurate than 20” 308s?

MudderChuck

What I'm saying is it is likely that barrel length affects velocity. And velocity can affect accuracy. Are you saying a 24 or 26 inch barrel is wasted metal?
My statement about a 22-inch barrel was just me voicing my belief that most manufacturers know what they are doing when they design a firearm. And a 22-inch minimum for the 7.62 seems to be the choice in many firearms, I doubt it was decided upon without a reason. Likely multiple reasons. And many rifles designed for accuracy are made with a relatively longer barrel.

Nomercy448

My contention is that 22” is not and was not defined by optimization of the .308win cartridge.

Take a look through Ruger’s Standard American webpage, they use 22” for all of those chamberings. So if 22” was determined because it is optimal for the 308win, why would they use the same length for the larger cased .30-06? Why would they use it for the smaller bore .243win and 7-08? Larger case AND smaller bore 270win...? Did they design the American rifle with only the 308win in mind, then purposefully deoptimize the barrel length for every other chambering? Savage’s 110 Classics are the same - all 22” except the 300win mag. Howa uses 22” for all short and long action cartridges. Winchester uses 22” for Classics in all short action, 24” for long action, and 26” for magnums, again - is a 243win optimized in a 22” tube, if a 308win is? Remington offered CDL’s in 24” for 308. Tikka’s T3x Hunters are all 22.4”, again, from 243win to 30-06.

22” is generally chosen for standard hunting rifles because it’s portable. Quite likely a very apt choice for optimal length for portage, with nothing to do with internal ballistics.

Lilja’s analytics showed the optimal length for a tactical competition rifle in 308win to fall between 24-27”.

Different powders, different bullet weights, we can completely flip the “optimal” length of a rifle barrel with the smallest of tweaks. No sense painting ourselves into a corner of a specific barrel length just because all standard hunting rifles in all cartridges use the same generic 22”. Frankly, 20” is by far the most common barrel length available for a large frame AR.