Fail to lock into battery?

>>33416810
>rifle gas system
>.223 rem
.223 short strokes my 20" too. Options are to run hotter loads or swap buffers.

>>33416829
Swapping buffers is probably the cheaper option. >>33416829

>>33416810

Dunno. Try opening it up from the rear takedown pin and pull the BCG almost all the way out and let it fall. It should fall all the way back down in to the full battery.

>>33416810
yeah just get a stronger buffer

>>33416829
I can understand under power loads, but options for not entering battery when charging the rifle? would that be buffer or spring?

>>33416810
I'd wager you need a different buffer. Either that or the gas block is slightly misaligned. I had the latter as a problem when I assembled my first.

>>33416861
>would that be buffer or spring?
Could be. If this is your first rifle you could also be riding the bolt home.

>>33416810
>my bcg won't go fully into battery after racking the charging handle
are you easing it forwards like everyother noob with babbys first ar?

what would be a good weight and spring for a full a2 stock setup?

>>33416875
nah, i'm not new to ar's just building them..charging handle goes back and let go to have the spring take the bcg home

not joking, you have to get a cleaning round and use a mallet to push it open from the barrel. your ammunition is most likely out of spec causing it to get stuck at that exact spot. just dont stand over it while you do this.

>>33416844
can confirm that bcg fully locks in place using that test

possbile magazine binding the bcg? I have a magpul gen 3 20round mag

any recommendations on a spring and buffer weight for an A2 stock?

>>33416871
This

Try an actual 5.56 load, XM193 or equivalent. Alternatively, try a stronger recoil spring.

One other thing to check would be the spring and o-ring under the extractor. If the extractor's too stiff it may not be allowing the bolt close.

>>33416810
Do you have M4 feedramps on both barrel extension and upper receiver?

Chances are, your upper does. In the event your barrel does not, M4 feedramped upper and rifle feedramped barrel extension are the worst possible combination for reliability.

Upper/Barrel extension
>M4/M4 you are good
>Rifle/M4 you are good, almost always, may have a hang up from time to time
>M4/Rifle literal shit
>Rifle/Rifle fine

The only reason M4 feedramps came into existence was in the early days of carbine development, faster carrier movement was not yet fully considered, and the combination of shallow rifle ramps caused carrier to overrun magazine or hangups

Deeper M4 ramps allowed for faster moving rounds under a faster moving carrier to run up ramps more reliably at the expense of deformed bullet noses (whether or not this really matters is dubious, as plenty of M4 ramped barrels are capable of extreme accuracy... as are rifle extensions... autists will debate it though)

Heavier buffers, various spring rates, different gas port sizes, adjustable carriers, adjustable gas blocks so on and so forth that have come into existence over the last 20 years more or less sort out carrier speed issues and magazine overrun... or at least they can.

I digress..

Given the rifle gas length, I could see you potentially having rifle extension on barrel, while the flat top upper almost assuredly has m4 feed ramps

>>33418999
fucking witnessed

I've built a couple ARs and never heard of these concerns....possibly because the longest I've gone is a 16" midlength?

Good info though. tl;dr M4 barrel extension or bust?

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>>33418999
to illustrate this guy's point

>>33419062
The only one that is really going to cause issues is M4 receiver, Rifle extension

M4/M4 always fine
Rifle/Rifle always fine (potential issues if its basically 1979 construction IE lop off barrel and just pick a new gas port location willy nilly etc.) you will not encounter this one as a problem however

Rifle receiver, M4 extension almost always good to go. I have seen a number of builds like this, typically people trying to do XM177 clone or Colt Commando/CAR etc. with A1/A2 uppers that will never have M4 feedramps, but using new production short barrels. I have seen a few with dremeled receiver ramps to match M4 profile, I thought this would lead to premature wear going through anodizing like that, but I see very little evidence bullet tips are even contacting interior of receiver


But rifle extension on M4 receiver creates a notch that is prone to malfunction

>>33418999
The issue isn't feeding though, it's that his bolt carrier isn't locking home and returning to battery. The bolt itself seems fine since opening the upper and dropping the bolt towards the chamber puts it in battery, but when the rifle is together it won't always go into battery, either when fired or hand charged.

That's making me think it's a spring issue. Maybe a buffer issue as well, but more likely a spring issue.

OP, do me a favor real quick - yank your buffer spring and measure it from tip to tip. Should be somewhere from 11 3/4 Inches (29.85 cm) at minimum to 13 1./2 inches (34.29 cm) at
maximum. I'm wondering if PSA fucked up and put a carbine spring in your rifle kit.

>>33416810
Check your gas tube alignment in the receiver. You've got a little room to work with but if the gas key's dragging the side of the gas tube hardcore it'll sometimes fail to into battery.

It should look centered.

>>33419091
true, guess I was overthinking things, and looking at photo the bullet is well beyond the feedramps, typically the hangup is either the bullet nose or case mouth

>>33419091
>it's that his bolt carrier isn't locking home and returning to battery.
bolt not locking back is a mag issue or ammo but most likely magazine op have you tried any other mags?

>>33419120
It's not an issue of locking back. The bolt is not locking into battery in the forward position. He says he has last round bolt hold just fine in the OP.

It's almost certainly the spring or buffer, unless it's some kind of other bizarre assembly fuckup. My money is on PSA having dumped a carbine spring into a rifle kit, resulting in a spring that's too short and weak to return the bolt to battery.

>>33419092
I've always had these concerns. but even with the amount of play in AR gas tubes it seems like there's enough to guide and center it (eg gas key riding in channel of charging handle)

>>33419091
>carbine spring in your rifle kit
would put money on this

>>33419087
this all makes sense. thank you for elaborating good sir

>>33419120
Bolt Hold Open is working fine according to OP. Bolt is NOT returning to battery reliably though - solved by forward assist but happening way too often to be acceptable (by the sound of it)

>>33419158
Gas tube has to be way out of alignment for it to really matter, yeah.

>>33416810
Did you pull the damn thing?

Spray CLP all over the locking lugs on bolt and barrel, rack it 10 times, see if things get better.

>>33419174
Did you oil the damn thing*

Fuckin Android keyboard

>>33419166
Hypothetically, if it were so out of alignment would it exhibit any play at all? I feel like it would be binding against the barrel ext/nut. Probably noticeably off center, but also completely locked up/immobilized

>>33416886
>nah, i'm not new to ar's just building them.
>i'm not new

Which explains the placement of your scope mount.

>>33416810
>doesn't know if rifle or m4 feedramp
>bridging the gap
>PSA

First build? by any chance you put the upper together yourself?

I am surprised that no one here mention Checking the head space... if it is in or out of spec.

http://www.sinclairintl.com/GunTech/Headspace-Why-It-s-Important-How-To-Check-It/detail.htm?lid=17125

http://www.brownells.com/GunTech/Checking-Headspace-Part-II-The-AR-15/detail.htm?lid=17140

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>>33416810
Don't do any of this crap you see in this thread. I had the same problem as you when I finished my build. You need to take some oil or lube and spray it down on the inside of the rifle, the AR platform likes to run wet. I finished slapping my rifle together and went to run the charging handle with some snapcaps, and it took me a few hours to overcome my autism and just oil the damn gun.

>>33416810
PSA bcg
I had this same problem and I'm done with buying their shit parts

>>33416871
This. I did this so much on my first AR build which was also my first gun

>>33419275
Not if your barrel nut is also out of alignment. Which is most likely the reason the gas tube would be.

>>33421133
good point. Any way to check barrel nut alignment? Wouldn't my freefloat rail be off somehow too?

>>33416810
Sounds like either your cam pin is binding against your receiver or headspace is too tight.

Check if the cam pin is rubbing against the receiver. The fix for this is a stronger spring. If you don't have a headspace gauge you could check which rounds are chambering and measuring the dimensions and seeing if there's a trend with the larger ones not chambering.

Here's a video about the cam pin.

https://www.youtube.com/watch?v=6JmIQXkoog8

POF also makes a proprietary cam pin that alleviates this issue.
https://pof-usa.com/product-category/upgrades-accessories/roller-cam-pin/

>>33421384
My guess was barrel nut alignment as well.

Check the gas tube for wiggle. You want it to wiggle.

When I install a barrel I use an alignment tool which is just an appropriately sized metal rod. It fits into the gas key and then you cycle the bolt to see if the metal rod goes through the gas tube hole cleanly.
I suppose you could use a drill bit or something.

The other way is to eyeball it and make sure you have equal left/right play in the gas tube.

On my first barrel install I had the nut too tight and it caused the same problems you are having.

Remember to alway adjust the nut by tightening. Never loosen to adjust. If it's too tight, loosen it first, then retighten to the proper spot.

Of course it could be something else entirely.

>>33420464
I've built several guns with a mix of PSA parts, but I always opt for their "premium" line stuff. All of that has so far been just fine. Hell, in my two personal rifles the LPKs were PSA Premium and they are mostly S-stamped bits. The BCG in my 10.5" is a PSA Premium and it just ran through 500 rounds straight with no problems. I don't expect any either.

My god /k/ does not know how to diagnose guns.

It is not your spring, and definitely not the buffer.
It's either your headspace, barrel extension alignment, or your bolt/barrel is out of spec.
Your gas tube is not a way to check barrel alignment. When torquing your nut, if the receiver wasn't properly clamped or you didn't use enough grease, you could have twisted the extension inside the receiver alignment notch.
If you have another bolt I would swap it out and try different bolts in the gun and the gun's bolt in other guns.

>>33421632
Thank you. I am not OP but am trying to surreptitiously hijack this thread to squeeze some more info from it.

>>33422454
How can you check barrel ext alignment on an assembled upper? How do you ensure alignment when assembling your own upper?

>>33421766
>S-stamped
pls elaborate? I have heard that Toolcraft (?) is the OEM for Premium PSA BCGs. exceptional quality afaik

>>33422517

>How can you check barrel ext alignment on an assembled upper? How do you ensure alignment when assembling your own upper?

Not him, but you don't. The extension is attached to the barrel. For practical purposes the extension might as well be a part of the barrel. Not something the typical home assembler would deal with.

It's either in spec or it isn't. The alignment notch on the receiver and the pin on the barrel extension fit together. There is no checking. It only goes together one way unless something is broken.

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OP here

possible winner? pic related, spring lenght

>>33419120
not yet as i only have a single mag (poor man here) but i have my suspicions
>>33419174
yes cleaned and lubed
>>33419653
nah, fully assembled upper from psa

>>33419091
see
>>33422797

>>33422738
Nice. So it's simple - don't buy from shit manufacturers. Thanks for the info m8

>>33422517
I meant the lower bits like the fire control group are S-stamped, its one of the major forges that makes the same parts for a lot of companies. Colt for example, and others.

In other words, actually good bits.

>>33422797
That looks like a carbine spring to me. I was under the impression that rifle springs were in the 12" range while carbine were roughly 10.5".

>>33422797
http://www.ar15.com/forums/t_3_4/452815_rifle_vs_carbine_buffer_spring_length___.html

The US Army says that's a carbine spring. Rifler springs are apparently 11.75" minimum.

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>>33423773
>>33423798
Well shit...best to just drop the couple dollars and buy the correct ones since they fucked up? or fight psa for a new spring?

which brings a new question...if they gave me a carbine length spring, should my rifle have a rifle buffer? because i have THIS buffer

>>33423876
Yes.
Or you could get a carbine extension/stock.

>>33423876
If it came with an A2 stock, then yes you should have a rifle buffer and spring. Or at least I would have thought so.

>>33424432
would i be damaging my rifle if i continue to use a carbine buffer but got the appropriate spring?

>>33425537
Depends on whether or not you have an A2 stock, which was the question.

>>33419091
>PSA
>Fucking things up
Good guess anon.

>>33423876
what extension is on your gun? please post a picture of your stock
if you have a rifle tube with a carbine buffer and carbine spring the gun would have broken the first time you shot it

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>>33423876
>rifle buffer

>>33416810
Pull that shit back and just let it go while holding the release latch.

>>33422797
>>33423876
Hey, I was right last night. Cool.

You need a rifle-length buffer and spring in your A2 stock or the issue will not go away. I don't think it will damage your rifle to continue using a carbine buffer and spring, but the problems won't go away until you either swap the stock to a carbine extension tube and carbine stock, or replace the buffer and spring with the correct rifle-length components.

I'd firstly call PSA and tell them what happened because they should know better and might send you the correct parts. If they don't, and you do have an A2 stock with a rifle-length buffer tube (i.e., does not have detent holes on the bottom for a carbine stock), you will need these parts:

https://www.bravocompanyusa.com/Rifle-Buffer-M16-AR15-p/buffer%20rifle.htm
https://www.bravocompanyusa.com/Rifle-M16-Action-Spring-p/spring%20rifle%20m16%20%20action.htm

I went through BCM because if PSA won't replace your carbine spring and buffer with the right parts, then fuck 'em, but you can get these two components in quite a few places. Personally, I said "fuck 'em" after my CC info got stolen after ordering from PSA, but you might still want to shop there and that's your decision to make. Regardless, $20 minimum should put you right back where you need to be.

>>33423876
note to self, never buy from PSA

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>>33427282

I bought my 9:1 mid length upper from their "dent and ding" section and have never had a problem.

>>33427282
You get what you pay for. They sell cheap pmags at least.

>>33429388
Guess how I know you are a cuck?