Magnum AR Project

[Masczek]

Are you using factory ammo or rolling your own? If you feel it's still overgassed then try a faster burning powder that'll have less volume and less pressure at the gas port. For the 6.5prc ar10 barrel I've ordered (22") with a +2 on gas the port size is .100". I feel I might not be able to use a carbine buffer due to no weighing enough, but I'll find out when the time comes (7/5/23 for expected arrival)? I can and will send you a very heavy rifle buffer to try if you want to? It'll also let me know if it's needed? Always willing to help a fellow shooter and designer!

I'm using my own reloads as well as factory ammo, both are showing signs of it being over gassed. Thank you for the offer for the heavy rifle buffer, however, I'm going to hold off on that for now. I may try something like that in the near future though, but we'll see. I'm really hopeful that shrinking the gas hole in the barrel will help out quite a bit.

 

[ARlife4me]

I'm using my own reloads as well as factory ammo, both are showing signs of it being over gassed. Thank you for the offer for the heavy rifle buffer, however, I'm going to hold off on that for now. I may try something like that in the near future though, but we'll see. I'm really hopeful that shrinking the gas hole in the barrel will help out quite a bit.

It'll keep the bcg from being overgassed, but the primers might pop? What seems to be overgassed? The bcg or cartridges?

 

[ARlife4me]

In the vid it seamed to cycle well.

 

[ARlife4me]

On a side note, having a single fed over a double stack fed is a plus in my book. If it were like Glock's double stack single feed would be a good option, but I understand you're not going as far to make special mags, only using what has been made. 1 less thing to adjust for. Did you make/design the bcg for this or able to use parts from something else?

 

[codyadams]

Tag.

 

[Masczek]

On a side note, having a single fed over a double stack fed is a plus in my book. If it were like Glock's double stack single feed would be a good option, but I understand you're not going as far to make special mags, only using what has been made. 1 less thing to adjust for. Did you make/design the bcg for this or able to use parts from something else?

I was able to start with a standard AR308 BCG and modify it slightly to work with the AICS mags.

 

[UncleDano]

Haven't had a lot of time to do some extensive testing, but here's a video I got of it last week.


This is the 6.5 PRC upper, it works a bit better, but is still over gassed. I tried both the Griffin Armament +15% extra power spring, and standard AR 308 carbine spring, both seem to operate the same when firing. I've got the Superlative Arms bleed off adjustable gas block installed on it now, so I'll see if this helps the over gassed issue by bleeding the excise gas out. I'm also going to try this on my 300 WSM barrel as well. I haven't ordered another test barrel yet, but I can get one with a .064 sized gas port. I'll start testing with that and drill the hole bigger if I need too.

I've decided to try all of this before going with a rifle length buffer tube and much heavier buffer, I'd like to see how my theory works with the bleed of gas block and smaller gas port.

Looks like it is kicking them out at about 4:00 o'clock. So, maybe not really too over gassed ?

 

[Earnhardt]

Looks like it is kicking them out at about 4:00 o'clock. So, maybe not really too over gassed ?

I never paid attention to where the brass was getting thrown…
You are right, That is NOT over gassed at all…
OP, what about the brass ejecting makes you think it's over gassed?

 

[Masczek]

The video is a little decieving, it's actually ejecting the brass out at the 2-2:30 position. The rim on the case is also very very slightly raised due to the dwell time being a bit short as well.

 

[Masczek]

New barrel with a .0625" gas port came in yesterday. Work's been busy, but I'm looking forward to getting it installed and trying it out soon.

 

[Masczek]

I tried the gun out this afternoon, here's what I found:

With 2 rounds in the magazine, the bolt seems to short stroke. Sometimes it will eject the spent case at the 4-5 o'clock position, sometimes it will barely unlock from battery. It never picks up the next round, and I don't have a bolt lock installed yet, so it don't know if it will lock back on empty (I'm guessing it probably won't). I see these symptoms through all the adjustments I made with the gas block, even with it all the way open, it acts like it's not getting enough gas.

I believe I'm on the right track. My theory is that the gas port is just too small, even with the gas block open all the way, the port is just not letting enough gas through. I'm debating on opening up the gas port around .073" but don't want to go too big too quick. What do you all think?

 

[doctorjj]

I'd use the next size wire drill and recheck. Then repeat until I had enough gas. The next size up is a #52 at 0.0635. Obviously check the existing hole and see if it's really 0.0625

 

[Earnhardt]

My 358 WSM has a .082" gas port I believe…it's perfect.
The SLR Adj gas block (AGB) is at 8 Clicks
But…that's in my caliber.

Personally, I like to have the AGB set in the mid-range of 6-9 clicks.
Just in case I want to experiment with loads.

I'd try close to .070"

 

[UncleDano]

I tried the gun out this afternoon, here's what I found:

With 2 rounds in the magazine, the bolt seems to short stroke. Sometimes it will eject the spent case at the 4-5 o'clock position, sometimes it will barely unlock from battery. It never picks up the next round, and I don't have a bolt lock installed yet, so it don't know if it will lock back on empty (I'm guessing it probably won't). I see these symptoms through all the adjustments I made with the gas block, even with it all the way open, it acts like it's not getting enough gas.

I believe I'm on the right track. My theory is that the gas port is just too small, even with the gas block open all the way, the port is just not letting enough gas through. I'm debating on opening up the gas port around .073" but don't want to go too big too quick. What do you all think?

You will find the proper diameter between .075-.085"