I have this 16" freefloat midlength PSA upper mated with a lower that has a A1/A2 buffer tube (5.2oz buffer). The problem I'm having is that the bolt isnt picking up a fresh round after every shot or few which I thought was odd because I emptied a 20 round brownells USGI-type aluminum mag with no problem first thing I did when I got to the range. After that I used a Lancer L5 20 rounder and it seemed to empty the first time if I recall correctly but hiccups started happening after that.
The gas block seemed to be where it should be because I used loctite on the set screws, so I initially suspected that the A1/A2 buffer was too heavy and causing shortstrokes and undergassing but the brass ejection looked rather healthy.
This is maybe the third time I've been out shooting with that particular build. The 2nd and 3rd trip I was seeing this problem.
Recap:
-Not picking up rounds (after every shot or every few shots)
-Not locking back on last shot fired
-Ejection looks decently healthy

I had very limited time on the range so I wasn't thinking about any experiments to figure out what exactly the problem was. What I'm speculating right now is either the Lancer mags, PMC bronze 55gr 223 is too light of a load, or the buffer weight is too heavy BUT I've always heard that rifle length fixed stocks works no matter what the build is, PMC is good ammo, and that Lancer mags are good. I would like your opinions before I start start dumping money on things that may or may not solve the issue here.
Specs
-16" Nitride barrel Midlength PSA freefloat upper
-Fullauto bcg
-0.750 low profile gas block
-5.2oz A1/A2 buffer and buffer tube


I'm on a really small budget so....
What are your thoughts? Suggestions? Fixes?

From White Oak:
How to identify a short cycling issue

One of the questions we get a lot is “Why doesn’t my bolt lock open when I fire the last round in the magazine?” Here is a simple test to help you identify the cause.

    -A live round must be fired for this test so you must be in an appropriate location to perform this test.
    -Manually lock the carrier to the rear by pulling the charging handle to the rear and depressing the small tab on the bolt catch.
    -Insert one round into a magazine and then insert the magazine into the rifle.
    -Close the bolt by depressing the large tab on the bolt catch or by pulling the charging handle to the rear and releasing it.
    -While applying pressure to the small lower tab on the bolt catch, fire the round in a safe direction.

If the carrier locks to the rear with the bolt stop engaging the front of the bolt, then there is an issue with either the magazine or the bolt catch being used or the lower receiver. It is not a short cycle issue.

If the bolt does not lock to the rear or engages on the front of the carrier, then you do have a short cycling issue.

Certainly I can say that the bolt catch is working as it should and locked back when I used the 20 round aluminum mag. I just took the empty Lancer mag I had with me at the range and it locked the bolt back too.
So considering that the rifle length buffer is supposed to work with all gas systems, would an adjustable gas block be the best course of action? I like the length and feel of the A1 stock that I have on right now.
If there are cheaper options like different buffer springs, or buffer weight (which I've never heard of) then I'm willing to consider them as an option.

Well. It seems that you found a solution to your problem. I gave you a suggestion / method that worked for a lot of shooters. Eliminate variables. Divide and conquer. I'm not a good sample and I hate to say "in my experience" but I've shot a few middies with A2 stocks with a regular buffer tube and weight with no problems. I'd say get rid of that whatever buffer and put in a regular one. Again eliminate variables starting with cheaper obvious ones.

Need to systematically eliminated variables. First thing I would try is different ammo. Such as 193 or 855. Essentially confirm combinations that work, or things that aren’t the problem.

I have shot thousands of rounds of PMC Bronze 55 gr and it’s one of my favorite training ammo. However, I have noticed some occasional short stroking with my BCM middy upper and H2 (correction) buffer. The BCM uppers of that production had gas ports that were meant to run well with the higher/full pressured 193 and 855. I played around with the H2 buffer on my own for another reason. Anyways, noticed the occasional short stroke (or failure to eject). Changed to H1 buffer and haven’t noticed it again.

Another possible explanation is that the gas port gradually started opening up and helped to facilitate cycling of the lower powered ammo.

I think the PMC thing may have happened with my LMT, but that gun had both an H2 buffer and stiffer SpringCo spring. That was early on in my AR learning and I was wanting to get the ejection at a somewhat consistent 3-4 o’clock position with 193. Don’t pay attention to that anymore, but just throwing it out there as a lesson I learned.

My next guess would be mags. The test Ren mentioned is a good one. I don’t really have any bad mags. I have been trying the newer (to me) Lancer AWM mags. I experienced some short stroking with those mags, but I was also shooting cheap Remington UMC 55 gr ammo that I suspect was underpowered. I want to give that ammo and mag combination a try with my Colt carbine upper.

Sorry, no experience with the fixed rifle stock/buffers. But I always assumed they were on the softer side. At least compared to the carbine buffers/springs combinations.

Yeah the A1/A2 buffers shoot real nice, part of the reason why I don't want to buy a new carbine stock kit and a H1 buffer. I really think it's the mag, I've never had any problems with that AR using the 20rnd usgi (on the mini range trips much before what I mentioned above) until I got my hands on my first lancer mag. I only have maybe 200-300 rounds put into that particular AR.
I'm sure I wasn't shooting any m855, not a huge fan of those.

I'll definitely try and do a quick test out at my farm hopefully soon but I'm hoping that the lancer mags just don't like my DMR-ish build. This is my first midlength AR and I'm still learning the way around the AR ammo/gas/buffer compatibility.
In the meantime, I'll wait for more input.

Does the Lancer L5 have the same follower as the AWM?

Just curious as I had initially thought the followers in the AWM were essentially the same as the Magpul followers. I have always had good experience with the Magpul mag and Magpul followers in my USGI mags. Though upping closer inspection, they are quite a bit different.  Not saying that I think they are bad, just something I want to test out more. I’ve shot Lancer AWM with PMC Bronze, but that was with a different gun.

I also forgot to mention that my experience with PSA uppers has been that they tend to be overgassed. In fact, that was one of the reasons I sought out one of their carbine uppers. To test a theory that carbine uppers will run cheaper (and lower powered) Tula ammo reliably. Haven’t really been able to do the tests yet, but my experience and other feedback from friends and on gun forums were that PSA uppers are at least “generously” gassed.

Oh sorry guys, it’s actually a lancer 20 round AWM. The followers are anti tilt but not the same as the magpul ones. I’ve recomended psa uppers to two of my friends and they love it, both are midlength and they run fine with carbine buffers and pmags. I’m the oddball Between the three of us using the rifle buffer and a small assortment of mags even though I have pmags that I could’ve used.
The aluminum 20 rounders are small and....cute. The lancers are new to me, and I only intend to use 20 round mags in this build.

Just looked into the Lancer L5 mags and they are the L5AWM, so same mags that I have and was referring to. Just never really heard of them as L5. Sorry for any confusion.

5.2 oz seems extremely heavy for a 55gr bullet. Sounds like the heavy buffer would cause lock back issues. Perhaps there's not enough gas to push back the BCG. Also, perhaps there's something blocking your gas tube.

https://www.ar15.com/forums/ar-15/Gas_system_length_vs_Buffer_weight/118-582401/

Nah I think that’s bad on my part, the mags clearly had AWM engraved to them.

Anyway I managed to get to my farm today since it’s New Year’s Eve and I wanted to shoot off a few and get some results to you guys to help me out. I shot magtech 62gr, PMC bronze, and some federal 5.56 (the box that’s very colorful with the eagle and American flag) and loaded 5 rounds each to a pmag, 20 round usgi, and the 20 round lancer. The results were somewhat erratic but I had more luck with the federal 5.56 which chambered every time but failed to lock back at least twice iirc.
The ejection pattern looked rather healthy about 4:20-4:30 from me. I still had failure to lock open on last shot with all mags especially with the PMC stuff and didn’t pick up a new round every during one group.
I’m trying to remember everything from the top of my head but yeah it was kinda all over the place, sometimes it won’t lock open and sometimes it did.

I might end up going to a carbine buffer and slap a MFT Utility stock since I know the carbine buffer worked before I threw the A1/A2 buffer system on.

Did you try the troubleshooting I suggested?

Not exactly, I tried to remember everything I could. I was pretty focused on ammo. I loaded the mags 5 rounds each time I was going to shoot them so I figured it would suffice. I was also shooting longer distance than usual so my mind was pretty occupied with that too, not every day I get to shoot 300 yards before vegetation overgrows.
At this point I think it's a problem with the combination of ammo, buffer weight, and gas system length.
I have a spare carbine buffer lying around so I really am thinking about swapping to it as soon as I get a good stock for it than wasting ammo by doing more tests.

Having to worry about ammo in an AR seems wrong.  Tune it for anything you may need to use.

That said, my first build gave me issues similar to yours, though with a .308,  Decided after much reading that it was a gas issue, took everything apart again.Gas block was on properly.  Inspection of the port in the barrel with a drill bit showed resistance to passing through.  Entered the port fine, but stopped before entering the rifling area.  A burr or unfinished drilling.  Cleared it out and back together.  Absolutely no issues and used the adjustable gas block to tune for just enough to lock back.  Softest shooting .308 you could want.

Long time ago I found a chart of gas port hole sizes and typical uses.  They do vary.  If you take it apart, make sure a drill bit of the right size passes through.  Any material pushed inside can be cleared with a cleaning,or quickly shot out.

Edit: This was a 16" DPMS barrel, not a primo part from a top maker.

This is a good listing of common port sizes:
http://www.tacticalmachining.com/learn/ar-style-rifles/ar-15-gas-port-sizes.html

Try a lighter buffer if you have. Measure your spring it should be a 10.5" spring if using an H buffer. A1/2 springs could be as long as 12.5".  See if the ammo cycles then. H buffer should cycle anything you put in the mag. If It doesn't it's the spring.

Yeah I’m swapping out to a carbine buffer tube, will get an H1 buffer eventually. Seems like the easiest fix.
I have a H2 on my carbine AR and it’s sweet on the felt recoil.

Yeah I’m swapping out to a carbine buffer tube, will get an H1 buffer eventually. Seems like the easiest fix.
I have a H2 on my carbine AR and it’s sweet on the felt recoil.

You’re going to swap out the rifle buffer tube to a carbine buffer tube? And change to the appropriate spring and buffer?

I was just thinking it would be a quick check to put the upper on a separate carbine lower. That is if you have one or a friend with one. I’m sure you’ll have no problems finding someone on here even to help.

When I was experimenting with different buffers, I tried a bunch. H1 thru H3. A Spike’s one (not sure which off the tip of my head). I don’t recall feeling any or much difference in felt recoil, but it’s not like the AR recoils much in 5.56. I have a carbine upper with the A5 system and that seems pretty smooth in terms of recoil, but I wouldn’t say super different. I’d have to try them side by side with a lower with a standard carbine buffer tube, spring, etc.

Nah I think that’s bad on my part, the mags clearly had AWM engraved to them.

Anyway I managed to get to my farm today since it’s New Year’s Eve and I wanted to shoot off a few and get some results to you guys to help me out. I shot magtech 62gr, PMC bronze, and some federal 5.56 (the box that’s very colorful with the eagle and American flag) and loaded 5 rounds each to a pmag, 20 round usgi, and the 20 round lancer. The results were somewhat erratic but I had more luck with the federal 5.56 which chambered every time but failed to lock back at least twice iirc.
The ejection pattern looked rather healthy about 4:20-4:30 from me. I still had failure to lock open on last shot with all mags especially with the PMC stuff and didn’t pick up a new round every during one group.
I’m trying to remember everything from the top of my head but yeah it was kinda all over the place, sometimes it won’t lock open and sometimes it did.

I might end up going to a carbine buffer and slap a MFT Utility stock since I know the carbine buffer worked before I threw the A1/A2 buffer system on.

Darn. That it didn’t function well with the 5.56 at least possibly eliminates ammo as the main culprit. Sounds like the failures to lock open occurred with 5.55 in each of the three mag types. Then the bolt didn’t even pick up a new round with the PMC.

Was the 5.56 you shot the full pressure 193? I’ve seen some ammo listed as .223 Rem and also has 193 on the box, but if you look closely, the FPS is much lower than the standard 193 loads. I’m referring to Federal XM193 in the brown boxes. Or the American Eagle variety in the black and white boxes.

I’ve used the American eagle black boxes earlier that morning and it didn’t fare too well, the magtech 62gr is 5.56 and it didn’t fare too well either, neither did federal 5.56. I wish I had some of that brown box xm193 but my local shop doesnt have any in stock. I haven’t seen any of that ammo in ages. I guess rifle buffer is too heavy?
I’ve already swapped to a carbine tube with a basic collapsible stock waiting to be replaced by a mft utility stock that’s on the way.

I’ve used the American eagle black boxes earlier that morning and it didn’t fare too well, the magtech 62gr is 5.56 and it didn’t fare too well either, neither did federal 5.56. I wish I had some of that brown box xm193 but my local shop doesnt have any in stock. I haven’t seen any of that ammo in ages. I guess rifle buffer is too heavy?
I’ve already swapped to a carbine tube with a basic collapsible stock waiting to be replaced by a mft utility stock that’s on the way.

I have a bunch of her brown box stuff. But not sure when I’ll be able to head to the range again. Prob not for another 2 weeks.

To clarify, you’re not mixing and matching rifle and carbine system components.

Then rifle buffer is the same weight as the H3. Not any real experience with rifle systems, so I’m not sure if there are other buffer weights you can try. The different carbine buffer weights are easy to come by.