An acquaintance of mine is having an issue with a 6.8 that has a smaller gas port than his other rifles. He’s developed handloads for these rifles and he can’t make his new rifle function with his current handloads. He’s confirmed it’s undergassed by re-checking gas block alignment, switched lowers, and switched BCG’s. He is definitely short stroking.
On my 5.56 carbines I’d just switch to more powerful ammo or reduce buffer weight. In his situation he doesn’t want to mess with his handloads, so ammo is out. He has an A2 stock and rifle buffer system, so moving to a lighter buffer is out unless he wants to buy a JP low mass buffer for big $$. He could open up the gas port but I think it’s melonited which would make it tough to drill. Would a reduced power spring work?
If he knows the gas port size of his other guns just buy a solid carbide drill bit and open it up. That steel is no match for carbide, melonited or not.
This. Buy two rifle buffers. Take the aluminum spacer out of one and replace two steel weights in the other (so it only has 3 steel weights inside and two spacers). Should be around 3.3oz.
OR, get a Wolff RP rifle action spring.
Also, consider having him polish the bolt carrier rails (and the bottom of the carrier where the hammer rides) with flitz to make it slicker.
Thanks Buford. I was having trouble finding out what was on the inside of the rifle buffer. I know what’s in the carbine buffers and A5 buffers, but I couldn’t find what was in a rifle buffer.
No prob. The spacer takes up the space of roughly two steel weights. It weighs almost nothing.
EDIT: a mil spec rifle buffer just has 5 steel weights and the rubber spacer disks + 1 of the above mentioned aluminum spacers.
I have a buddy who shoots heavy 80gr handloads and he had me remove the spacer and insert two additional steel weights from a carbine buffer (I think it ended up between an A5H3 and A5H4 in weight…just above 6oz). He prefers to use the std power rifle spring and he has been quite happy with the results.
Thanks Mark. I also suggested that. Frankly, I think he just needs to hop up his handloads a bit to make them work. Unfortunately that will make them too hot for his overgassed 6.8’s and then he’ll need a heavier buffer for them.
Adding these terms to the thread should help finding the helpful comparison photo again. I too forgot that as a photo the words would not (I think) show in a thread search.
Yeah, Clint that’s the one. I sold him a lower earlier this year and I hate to see him have so much trouble. Constructer says he uses .093 gas ports on rifles. I advised MT to check and make sure his is as least that large.
I agree on cutting springs, but I figured changing buffer weight might be a reasonable avenue.
.093" is the standard gas port size for 20" rifle gas 5.56 barrels.
6.8 (and 300BLK) have shorter, faster pressure curves and will require bigger sizes with the same barrel and gas system length.
This faster pressure curve is also the reason an 8.5" 6.8 or BLK barrel with pistol length gas works fine, while pistol gas 5.56 barrels can be more troublesome.
