.308 Load Development?

[TacticalHits]

Hey guys, my cousin has a Panther Arms AR with a 24"bull barrel (1" in 10" twist) in .308. This is the load development he has been playing with but he keeps getting high pressures?

42gr. to 44gr. Varget Powder, Black Hills Match Brass, Magtech 9.5 Primers, 168gr. Sierra MatchKings, and COAL 2.800.

He thinks he might have been crimping them to hard?

Either way what do you guys think would be the best load for long range target shooting? Bullet, powder, primer, brass? The COAL of 2.800 is with the bullet just off the lands, so he can't seat the bullet further out.
His gun has shot half inch groups at 100yds with off the shelf 168gr. MK's from Black Hills also.

Thanks for the help!
Nathan,gun)

 

[eddybo]

Man if his gun dont shoot with that load it is broke I shoot about the same load with the 168s. First time I shot a group with that load I had to shoot a hole outside the group I was shooting, just to make sure I was hitting the target. I had fired 4 shots and it still looked like one bullet hole I like reloaded 15 in my other 308. with the 168s, or more specifically my other 308 likes RL15. For some strange reason it doesnt like varget.

 

[TacticalHits]

So should he try RL15? He told me he really thinks he crimped it way to tight, so that could be the whole problem! What do you think is the maximum range is of his gun? He just put a new trigger in it and a solid butt stock also.

Thanks Nathan,

ps. Here is a picture of him and his gun before the new butt stock and trigger.

 

[RazorCityDen]

Winchester makes the cases for Black Hills and the brass is good, thin walls, high tensil strenth with excellent capacity. No reason you can't stuff 45 grains of Varget in them with no drama. I've had several rifles that 45 grains of Varget and Sierra 175 MK's was the bomb loaded COL 2.800.

I prefer RE15 because it runs though powder measures more accuratly and run 44.7 grains under 175 SMK in Win brass, F210M primers at COL 2.800. I get 2725 fps for 10 shot samples over my chony and it shoots into 1 3/4" at my AR10 SPR's 300 yard zero.

Loaded progressive on a Dillon 550.

In your case I would take a look at case prep first.

He's going to need a Stoney Creek case comparator set so he can measure case length from the case shoulder. He's got to make sure he has the shoulder bumbed back around .002 to .003 with a gas gun or it will stick cases and of course full legnth resize.

I would also dump the crimping, unless it's with a "factory" taper crimp die and then make sure it isn't heavy handed. Using a standard seating/crimp die heavy handed will distort the case and cause a raised ring that will hamper feeding in a gas gun and, or stick cases in the chamber.

I've never found the need to crimp for gas guns. I take the expanding ball out of my sizing/decaping die, shaft and all, chuck it in a drill press and take it down in diamater some (.001) with some emery paper, then polish it bright. This gives me plenty of neck tension to keep bullets from moving around when they feed from the magazine.

I have loaded for many gas guns AR10, AR15 and M1A's for both NRA Service Rifle comp and tactical matches. You can invite alot of problems trying to load them like benchrest rifles. Probably the most useful tool you can use is a run-out gauge to make sure the rounds are loaded straight, if they ain't straight to begin with, they won't get any straighter when they make that magazine jump. If groups are important an electronic scale so you can group your loaded rounds by weight. This is double true if you throw powder charges. I don't bother for tactical matches since it has nothing to do with grouping.

Something else I've found is that most of these 50,000 +, getting up there .308 loads have much better ES and SD's when I use magnum primers.

The DI gas guns can be accurate as hell don't make your life more complicated than it needs to be with dubious loading practices

Den

 

[old_heli_logger]

What are the high pressure signs you're seeing? If it's flattened primers...are they Federal? Federal primers are relatively soft...don't get me wrong; I use them.

Good luck!
xLogger

 

[GSoD]

What are the high pressure signs you're seeing? xLogger

Yep, do tell because that should be right in the zone for that round. If you haven't measured exactly where the lands are could you be perhaps contacting them and thus spiking pressure?

 

[TacticalHits]

I did measure the lands and groves and they are very close. It was like .008. I am using Magtec Large rifle primers 91/2 which in my understanding are equivalent to Federal Gold Medal Mach. I have considered to switching to Tac powder.

 

[TacticalHits]

For those of you wondering the reply just above is my cousin writing not me.

You guys are probably like ,he just switched persons on us or something?

 

[TacticalHits]

My cousin just bought some 175 VLD's, but is thinking of sticking with the 168Mk's. I told him he should get more range with the VLD's. What are your guys opinions on these bullets and weights? Thanks,

 

[milanuk]

How does that saying go...

"Friends don't let friends shoot 168gr SMKs past 800yds..."

Me personally I like the 155s... BCs up around that of the 168s, and you can push them faster - i.e. flatter trajectory, shorter TOF, less wind drift. 175s have a little higher BC, but you can't push them as fast. Gets to be a balancing act.

Also... I'd skip the VLDs and go for the newer Berger BT 'thick' designs... more tolerant about seating depth, as in will shoot just fine 20-40 thou off the lands, rather than preferring to be jammed into the lands (always a little dicey w/ an auto-loader).

 

[TacticalHits]

Thanks, How fast have you been running your 155's and in what length of barrel?

 

[milanuk]

I normally go for 2940-2960fps and have pretty good results. Other people I shoot with run 'em as high as 3050-3100 with good results. I personally kind of cringe at those speeds, but thats just me. This is from 30" barrels; in the past I've run in the low 2900s from a factory 26" barrel, but with a much warmer load.

 

[overbore]

2,950fps with sorted 155 moly match Sierras is my ticket to dance also. Overbore

 

[Michael Eichele]

How does that saying go...

"Friends don't let friends shoot 168gr SMKs past 800yds..."

Me personally I like the 155s... BCs up around that of the 168s, and you can push them faster - i.e. flatter trajectory, shorter TOF, less wind drift. 175s have a little higher BC, but you can't push them as fast. Gets to be a balancing act.

+1

Couldnt have said it any better myself.

I have driven the 155's up to near 3000 FPS in a 26" 308 pipe. The SCENAR has delivered .499 G1 real world BC in my 24" 11.25x barrel at 2900.