16” barreled 300blk upper problem.

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

Moderators: gds, bakerjw, renegade

2BearArms
Silent Operator
Posts: 55
Joined: Thu Aug 23, 2012 11:53 pm
Location: SW CT

Re: 16” barreled 300blk upper problem.

Post by 2BearArms »

A little bit of an update.

I loosened the fixed gas block and slid it forward to get it out of the way (as I said before the Muzzle Brake isn’t coming off of this easily) it was against the shoulder. I got a JP Enterprises Adjustable Clamp On Gas Block and a new gas tube. I opened up the gas port a little bit. The JP gas block doesn’t rest square to the barrel until it is tightened down. So I had to assume I had it lined up properly. Well it was worse than before no matter how I adjusted the gas block it wouldn’t even cycle the Supersonic rounds that it did before. I tried to get it to work without any luck, till I went back to the original gas block and put it tight to the shoulder on the barrel like it had originally been. Because it would sit against the barrel squarely I took a piece of plastic tubing that fit over the gas tube where it would normally sit against the bolt and I blew into it while moving the old gas block around. Till it felt like I had it in a position where there was the least restriction of my blowing into it. I guess the port is closer to the barrel shoulder then it usually is. I am now back to it cycling the supers just fine with or without a suppressor. But it still won’t cycle the subs.

When I looked at the adjustable gas block off of the barrel it looked like it hadn’t been directly over the gas port. I think this was because I tried it out a little bit from the shoulder. My biggest problem with all of this was that I didn’t feel like I could be playing Gun Smith at a range. So I would work on it at home and then go test it at a range. And this indoor rage is about $38 an hour so that adds up quickly. But isn’t it true that if the non-adjustable gas block is aligned properly then it should be delivering the most gas to the bolt as is possible. And an adjustable gas block is basically to shut down the amount of gas. I initially opened up the port to .125” and then I think I opened it up to .140”. Is it possible that the original non-adjustable gas block is restricted internally to less than even .125”. And is it true that a gas tube is only .125”. So a gas port larger than .125” is of no help to get more gas to the bolt, or does it allow for a little bit of misalignment of the gas block??

I should try to put the JP gas block back on and see if I can get it properly aligned. But for now I am tempted to leave it as I have it now because it works with the supers. And when it warms up in the spring I may have access to a private range where I can play Gun Smith and see if I can get this figured out.

Thank you for your help.
Post Reply

Who is online

Users browsing this forum: No registered users and 114 guests