New 18" rifle length AR build short stroking

[stagpanther]

They'll probably simply replace it would be my guess--doubt they'll mess with it and then tell you what's wrong, but who knows. If I were you I'd ask for a mid-length port instead of rifle length.

[Mobuck]

"While at the range I was able to get the bolt to lock back fully by changing the A2 buffer with a standard carbine buffer ."

A2 and carbine buffers are not interchangeable.

[Metal god]

Maybe I used the wrong term . what do you call it when you take out the rifle/ A2 buffer and replace it with a carbine buffer ? They might not be " interchangeable but they both fit in my rifle .

[rickyrick]

If you're using a carbine buffer in a rifle reciever extension and the bolt carrier is not getting crammed into the reciever extension, I would guess that you are under-gassed or have one heck of a dragging bolt. My guess is under-gassed.

[DubC-Hicks]

Yeah, a short carbine buffer in a rifle tube is a good way to damage stuff. The rifle buffer is longer, meaning that the carbine buffer will let the carrier hit the lower receiver.

Just because it fits does not mean it's interchangeable. A carbine buffer and spring can ONLY go in a rifle buffer tube with a spacer.

[stagpanther]

If the buffer is the right size for your tube--it should bottom out when the back of the carrier just aft of the gas key stops just shy of contacting the "ears" on the lower buffer tube threaded collar.


I'll take a look at that as well today

[Metal god]

Just because it fits does not mean it's interchangeable. A carbine buffer and spring can ONLY go in a rifle buffer tube with a spacer.

I understand and really should not have asked Mobuck the question . I only put the carbine buffer in for 3 shots the first time out just to see if the lighter buffer would cycle .

If the buffer is the right size for your tube--it should bottom out when the back of the carrier just aft of the gas key stops just shy of contacting the "ears" on the lower buffer tube threaded collar.

Stag , I did manually push the BCG into to rifle tube and it does stop just short of the gas key touching the receiver collar .

As for actually shooting the rifle with a different BCG . I have not done that and should have taken one with me today . I should do that before contacting PSA because it's one of there Premium BCG I'm using in the build .

[stagpanther]

If you're using a carbine buffer in a rifle tube (and you haven't installed spacers in either the tube or buffer)--there is no way the buffer is going to stop the BCG from impacting the lower under heavier recoil--unless maybe the BCG itself isn't properly cycling, or your using an over-powered spring.

I noticed on PSA's website that you got a "cheapo special" 223 Wylde barrel. Not many free lunches in the world of quality barrels; I've seen manufacturer's unload "problem configurations" before at bargain prices. Two reviews is not a good sign IMO.

If it were me--I would "return" your lower to a standard carbine set-up--spring buffer and tube--and yank your gas block off and put a $9.00 .750 non-adjustable low pro on--that should not fail to cycle if the rifle is built correctly. If it does fail, then the problem has to be with the barrel. Yank it, get your money back, and cough up the extra $100 or so for a quality barrel from a quality manufacturer with known history of excellence.

But that's just me.

[marine6680]

The rifle buffer springs are lower power than the carbine springs, from my recollection...

If you remove all the weights from the buffer, and that helps or cycle, I would say it is definitely under gassed.

Could the gas block be faulty in some way? If not, then the barrel may have a small gas port, but that seems difficult to get unless several barrels with the same issues made it into the wild.

[Metal god]

Based on the drill bits i have and that fit and wont fit the gas port is .0890 to .0900 .

I can blow down the gas tube and air seems to flow quite well so no blockage there .

Im on my phone right now so I can't post pics but I'll post a pick of the gass block but I'll do that later . I can say the port on the gas block is big . If you look at the pic i posted of the barrel gas port you can see how much bigger the port on the gas block is just by to carbon cicle around the barrel port .

There's not much to the gas block really . Not sure how it may be malfunctioning. But I'll post pics later

[StaTiK]

There have been a lot of good suggestions (and some not so good ones) so I'll go a different direction just for variety.

this BCG is by far the stiffest I've ever owned . With BCG out of gun and bolt pushed in . I can not get the bolt to move forward by swinging the BCG like a hammer and it's quite stiff to pull the bolt out by hand . When I first got it I considered changing the gas rings and see if that lessened the resistance . I was hopping it would just work in to being perfect rather then working in and being sloppy

It's hard to diagnose over the internet but this might be part of the problem if the bolt ridiculously tight. It needs to move somewhat freely in order to unlock. Yours is obviously unlocking based on how you described extraction but I wonder if enough energy is being wasted early in the unlocking->extracting->ejecting part of the cycle to interfere with feeding. Add friction from rough machining and the problem is compounded.

Basically I think you're right not to drill the gas port. Try a known good BCG in the new rifle and the questionable BCG in a known good rifle. If that doesn't help call PSA and explain the problem and ask them what size the port should be. I've heard PSA is good about warranties when you can reach them.

[rickyrick]

There used to be a PSA customer service rep over at AR15.com that would handle things.
Just get to the manufacturers section and find PSA.
It's was the fastest way to get service a couple of years ago. It sounds odd but you will get an answer with 24hrs. He will even tell you order statuses and everything.

I've given up on PSA, but not because of their products. I love their products, my beef with them is of a different nature.

The rifle gas system length on the 18" is gives it 6 inches of barrel past the port. It's a bit short, but I've had much shorter work fine.

Dragging bolt is a possibility.

[marine6680]

For some reason or another... I got it in my head that this was a 308 build.

Definitely swap BCGs and see what happens.

[Metal god]

I had not been able to get out to shoot until today . How ever I had been thinking about this issue and tested a few things in the mean time .

I revisited the possibility of a gas leak at/in the gas block again . First thing I did was plug up the gas port in the block with my finger and blew into the gas tube . There was a good amount of air escaping from somewhere . My first thought was it was leaking from where the gas tube enters the gas block . Although the tube felt secure and tight I went ahead and reinstalled the gas tube using a new roll pin . I then repeated the test by blowing down the gas tube with the port blocked with my finger . I had the same amount of air escaping as last time .

Next I removed the adjustment screw and plugged that hole with another finger while still blocking the gas port and blew down the gas tube . boom perfect no leaks . So the air/gas that was escaping was "through" the threads of the adjustment screw . Really could that be it ? Well I went ahead and used blue loc-tite on the threads and let dry . When dry there was no air escaping when I blew down the gas tube . I went ahead and installed the gas block and waited for today to go shoot .

So today with the newly sealed gas block ( set wide open ) for obvious reasons . I started with the lower set up with full weighted rifle buffer and rifle buffer spring . Loaded one round in the mag , let the original BCG fly home and fired . The bolt locked all the way back . Cool so I loaded 3 rounds and fired . Gun cycled fine and the BCG locked all the way back again . I then loaded 10 rounds and fired all with the same result , gun is working fine now .

Now this was using my reloads so I tried some Wolf 223 gold and the rifle short stroked and the bolt did not lock back at all . I then tried some LC 5.56 NATO factory ammo and the gun cycled fine again .

So it appears I've found the main issue but it's still just a tad under gassed or there is still a small leak somewhere .

FWIW I did try a different BCG that has a very freely moving bolt . It had the same results as the above . My reloads worked fine , oh I also shot 7rds of 77gr Federal GMM and those worked just fine with the original BCG .

I happy I've narrowed the problem down to the gas block or at least the majority of the issue was clearly that leaking adjustment screw . Now I'm going to get a standard PSA low profile gas block and see how it works .

What do you all think ? Am I thinking along the right lines . I know stag suggested I just get a regular gas block . Looks like he backed into the right solution

[stagpanther]

Actually--I've never used a DI adjustable block that DIDN'T leak at the screw adjustment hole eventually--if you have it wide open--don't be surprised if it doesn't start "acting up" again at some point. It will more than likely form lots of carbon crud in the threaded hole--which unless you cleaned that out thoroughly and the screws as well--problem gonna come back to haunt you would be my guess.

If you're running it wide open anyway and it's barely adequate--you may not be able to get any benefit at all from an adjustable since it appears over-pressure is not an issue and you might as well try a non-adjustable.

[Metal god]

Stag , are you one of those speed reader types that just glances over the text ? There has been many times in this thread it appeared you didn't actually read what I wrote .

Originally Posted by Me today

Now I'm going to get a standard PSA low profile gas block and see how it works .

Originally Posted by Me today

I know stag suggested I just get a regular gas block . Looks like he backed into the right solution

I have no intentions on using this current adjustable gas block . If I were I'd seal it with sleeve retaining compound . which would not ever let go and has a heat tolerance of 600*

[stagpanther]

Stag , are you one of those speed reader types that just glances over the text ? There has been many times in this thread it appeared you didn't actually read what I wrote .

Quote:
Originally Posted by Me today
Now I'm going to get a standard PSA low profile gas block and see how it works .
Quote:
Originally Posted by Me today
I know stag suggested I just get a regular gas block . Looks like he backed into the right solution
I have no intentions on using this current adjustable gas block . If I were I'd seal it with sleeve retaining compound . which would not ever let go and has a heat tolerance of 600*

I have no idea whether the non-adjustable is the right solution or not--there may be many other things going on with your rifle that could be contributing to your issues. In my latest post I didn't suggest that you were ignoring what I said previously--if that's what you think. You posted NEW information regarding the leak in the adjustment gas port--and I made a nuanced NEW suggestion based on your updated information.

I'm just an average home hobbiest that doesn't know any more than the next guy--maybe less, so I would take everything I say with a grain of salt.

[marine6680]

Can't hurt to try a standard block.

[Metal god]

A $20 Joe Bob outfitter low profile gas block has solved the problem . It even cycles the wolf gold crap . I'll add that this build is the smoothest I've ever built . If the buffer is hitting the back of the buffer tube when fired . It ain't hitting it hard .

I have a Miculec DPMS muzzle brake on it and the recoil pules is pretty much non existent . It does not feel like the BCG is moving all the way back but it is and locking back every time .

I put a Primary arms 1x6x24 on it and think this may be my new fave

Thanks for all your help guys , I'm still a tad surprised the issue was the gas block but glad I did not call PSA complaining . I still need to contact Rainier arms who I bought the adjustable gas block from and see if they will except the return . I may also contact Seekins and see what they have to say about there gas block .