Reloading for gas guns, tuning the gas system?

[Mr45auto]

I'm reloading for my LR308 with a Krieger 1:11 twist 20" barrel. I can get some great velocity of course at the cost of killing my brass after very few loadings. I was easily passing 2750 with 168gr AMAX bullets and Varget but my primer pockets were getting pretty loose and I tossed the brass rather than take a chance on it, the effort to reseat primers just was too close to zero for my liking.

I was curious if an adjustable gas block may help with brass life by prolonging how long the bolt stays locked or if I'm all dicked up and just need to back off a bit. I have found a super accurate mix with no brass problems but it's a 168SMK at around 2550fps and I'm not sure that's even gonna be decent at 600 let alone any further out.

 

[FCS]

Re: Reloading for gas guns, tuning the gas system?

Gas guns are not bolt guns, don't expect bolt gun velocities.

H4895 and 168 SMK should give you 2650ish velocities w/o trashing brass.

Varget and 175s should be about same 2650ish velocity w/o trashing brass.

Varget with 175s or heavier for a gas gun.

168s I'd be looking to N-140, H4895 or similar burn rate.

 

[Mr45auto]

Re: Reloading for gas guns, tuning the gas system?

Considering I've got 8lbs of Varget and a couple hundred 175SMKs any suggested loads to try? I'd rather err on the side of long brass life and maybe limiting performance to 800yd-ish range.

I'm loading SMKs primarily for my 1:11 twist 20" Krieger barreled LR and a 1:10 twist 16" LR308 with factory bbl. I'd like to have a load that performs well in both rifles. My other 308 platform is a FAL so I dont really think it warrants SMKs

 

[FCS]

Re: Reloading for gas guns, tuning the gas system?

44.4 gr of Varget, Win brass, GM210M, and 175 SMKs worked well for me. I'd start about 43 to 43.5 and work up.

Who chambered rifle?
Have an adjustable gas block?

 

[Mr45auto]

Re: Reloading for gas guns, tuning the gas system?

It was sold through ADCO but I believe it left Krieger as an AR10 barrel/bolt. No adjustable block yet, primary rifle uses a LaRue low profile block.

 

[mscott]

Re: Reloading for gas guns, tuning the gas system?

Yes, an adjustable gas block would be your friend. I just drilled and tapped a friends DPMS LR308 and added an 8-32 set screw to make his an adjustable gas block. Those things are way over-gassed. It turns out that one full turn from closed will cycle his rifle and do so much more smoothly than before. His brass is also coming out in good shape where before it was getting trashed.

 

[MR3GUN]

Re: Reloading for gas guns, tuning the gas system?

Make your own adj gas block or call John at JP enterprises and order one of his.