HI all...
So I figured I'd drop a little note about my range day yesterday with my new AR. I assembled it from scratch (including the upper) piecing it together over a 6-8 month period. I had actually finished it a while ago, but I recently moved and I had not had the chance to bring it out for a while.

Not to bury the lead; it's a .300 Blackout and supersonic worked fine, but sub's short-stroked. And I'm not sure if troubleshooting a variant should go to Variants forum or the Troubleshooting forum... but I'm gonna guess Troubleshooting (since the issues are not caliber-specific --I THINK -- ), so here goes....

Other than taking longer to sight-in that I would have liked (probably due to cheap optics performing like cheap optics do; which I obviously expected) things worked well. I do have one question for the group though...

As I mentioned, I had short-stoked shots with sub-sonic ammo (Remington factory loads). And all things considered, I was half-expecting that, with all I've heard. But I even had one or two fail-to-feeds with supersonic ammo (again, Remington Factory loads) that appeared to be misalignment due to a borderline short-stroke.

So I've either got A) too much mass; B) too much spring); or C) not enough gas.

I've got a nice hydrolic buffer, which is last on my list of things I'd prefer to replace, and the BCG is mil-spec, so I'm going to concentrate on B) and C). Obviously swapping out the spring is the easiest, but since I personally aligned the block/tube/barrel interface, I am actually most suspicious of that possibility.

So my question is; Are there any tricks to checking the gas block alignment that don't require you to disassemble the joint (thus requiring you to re-align the components and introducing a new opportunity to foul it up? OR... Does the almost proper function show that I'm obviously lined up and I should just shut up and buy a new spring?


thanks

300 Blk was designed to run with a standard spring and carbine buffer.  My bet is the "hydraulic buffer" is just too heavy.  Try a standard carbine buffer before you go to the trouble of drilling port holes and adjustable gas blocks.  Search www.300blktalk.com about the problem.  There are posts ad nausem about others with the same problem and their fixes.

thanks.. I hadn't looked for any 300-specific sites... (I have enough trouble keeping up with the sites I'm already on)   but I'll take a look at that one.

Thanks... And as a mechanical engineer who reloads...  I DO understand your point.   - But Since this was my first time out with this rifle, I was sticking to factory loads (in order to remove any issues from my hand-loads from the equation).   If it turns out that I just need a custom recipe to run sub' ammo, then I'm ok with that (I've already bought the dies for 300) but I was just hoping that the factory stuff would "just work"... That, and I usually dont' buy virgin brass (I just shoot factory ammo then keep the brass to reload) so I haven't even looked at 300 recipes yet.  I reload 45 acp, which is a 230gr slug at 900 FPS, so I figured that the recipe wold be close, ( i have the LEE Die to pour a 230 grain .308 slug) but with your point above, I would definitely NOT want to just duplicate an ACP with just a bit more powder to get it up around 1000 FPS. I'll need to start from scratch with a much slower powder than the W231 I use with .45

Good to know.   I think that way it will pan out is that if I'm going to shoot a supersonic bullet, I'll be using something else (M4 clone, or my AK). If I break out the 300, it will probable be only for suppressed shooting. I expect that I'll be loading 300blk to 1050fpss or less, so I should be good without a gas check.  - I'll do some experimentation, but I'm guessing with a power-coat and a low pressure load, I should be fine.

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Thanks for the info (again) Dano... Like I mentioned, I hadn't even looked into the recipes yet, but since you seem to have some direct experience, do you have a suggestion on which powder(s) might be in the range I'd be looking for?  This will be my first time reloading rifle rounds (except for once over 30 years ago when I reloaded a batch of 30-30 ammo for my Win-94... it got me started in reloading, but I haven't done any rifle rounds since then)

So, just to close this out...
It turns out that the hydrolic buffer was just too heavy.  I tried a reduced pressure spring, which DID allow the BCG to cycle all the bay back, but in order to handle that the spring had to be so weak that it couldn't even strip the next round off of the magazine (and I had to use the forward assist on each round.

So then I wen back to the full power spring and used a lightened carbine buffer, and PRESTO... a perfectly cycling AR-15 with all ammo types.

but.. on the up side... the next AR build I do will start with a nice buffer... :)


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