Hi everyone. I've been lurking here for a while but thought I'd make a post. A year or two ago I bought a used bushmaster a2 20" barrel type off of a guy from this site. I finally got a chance to take it out to the range this past saterday. This is my first AR-15 so I'm really new to all of this. It shoots great and all but about every round or every other round the bolt stays back and I have to pull the charging handel to get it to chamber another round. Now I just read a post about a screw in the buttstock that maybe to long? but if its a stock factory gun wouldnt that not be a problem? I didnt know if perhaps it was just dry and needed oil or greese. Also when you fire it you can hear a loud "twang" from the recoil spring. Its very loud to the person fireing it even while wearing hearing protection. However if your standing nearby (with hearing protection) you cant hear it. Is this a problem at all? My only other semi auto long gun is a benelli and its recoil operated. It dosent make any noises like that.
Thanks again all for your time

twang is normal. rember recoil spring is in the stock.

your rifle may be  a "short cycle"  I would check for a loose carrier key and screws first. esp if the rifle has over 1k down range.

What type of amm are you using?

ok.

Is your bolt staying locked behind the bolt catch or is it not fully chambering the rounds.

The twang is okay, its just the recoil spring smacking around.

My first thought is bad magazine.  Does it do this bolt thing if you only load a few rounds in the mag?

Also, check your bolt catch.  Does it have spring tension?  or does it just flop around on a whim?

Matt

Ok guys thanks. As I said im new to this so I'll have to dig up an online manual and find out what your talking about and get back to you. As far as ammo its winchester 55grain fmj. I was thinking of going to remmington umc 55gr fmj next as its 20$ cheaper/1000. I dont think its the mag. I used 1 20rd, 1 40rd, and 3 30rd and it did it for them all. I would guess the bolt is staying back as its not jamming a round or partially loading one. When its "stuck" you can look in the ejection port and clearly see the round is still completely seated in the magazine.

Quoted: Ok guys thanks. As I said im new to this so I'll have to dig up an online manual and find out what your talking about and get back to you. As far as ammo its winchester 55grain fmj. I was thinking of going to remmington umc 55gr fmj next as its 20$ cheaper/1000. I dont think its the mag. I used 1 20rd, 1 40rd, and 3 30rd and it did it for them all. I would guess the bolt is staying back as its not jamming a round or partially loading one. When its "stuck" you can look in the ejection port and clearly see the round is still completely seated in the magazine.

You know when the mag is empty after you fire the last round.  The bolt is automatically locked to the rear by the bolt-catch.  Its the boot shaped pedal on the left side of the receiver..

If the spring is broken, weak, or dare say missing, it will flop around when your shooting.  This could cause it to snag the bolt on occasion and hold it to the rear prematurely.

ok its on the lower right above the mag release? Whille I cant see a spring it deffintly seems to be there. Its not particularly strong but its strong enough to firmly pull the catch back down every time I pull it open. I just took the bolt assembly out too. Its very dry looking. I assume that it should be well oiled all over? Also is there a spring inside there that pushes the front forword? The portion that moves and locks into the barrel?

this is the bolt catch:


I swiped the pic from the BIY section. so credit to them is due.

anyway, there's a spring behind the catch inside the receiver.  On a good day you shouldn't be able to see it

It should have some decent tension when you press on it.  the lower part that is.

As for lube...I normally just put a drop or two of CLP or other lube on the rails of the bolt carrier.  They are on the bottom.  Its what the bolt essentially "rides" in; in the upper receiver.

When the bolt gets "stuck" back is it caught by the bolt catch.  As it would be if the mag was empty?

I'd say its stuck back probably about that far. But I cant say if its the catch or not holding is as I never thought to press it to release thebolt and see if it went forword or not. Most of the time pulling the charging handel would release the bolt. Unfortuntaly who knows how long it will be befor I get to the range again to test it out. Thanks for the picture. Thats what I thought you ment.

Something to keep in mind next time your out.

I know the feeling about not being able to shoot as much as you would like.  Unfortunately that work thing gets in the way most of the time.

Good luck!

Quick check would be to just shotgun the rifle open (like when you clean it), and press on the top of the bolt catch and confirm that it does move back to the downward position with spring tension. Also, while you have the action open, take a look at the top edge of the catch it's self.  If you find that the tip edge has been penned with a high lip, then it may need to be filed back down flush to normal.


If the catch looks to be working, then you may want to pull the Buffer and spring out and check them and the receiver extension for a piece of debris (blow primer).

Also, while you have the buffer out, look at the bumper end. If the butt stock screw is too long, then the bumper will have a center-punched hole.

As for manuals, we have everything that you will need here at the site.  Press the Information button in the quick links, and go to guides.

Don't know if any has said it yet, but welcome to the site!!!

P.S. when you get a chance, you may want to add where you're from.  It really helps out if someone is close to you and takes a look at the rifle.  Sometimes we can write novels, only to really dance around a problem that is beyond obvious the first time someone just looks at the rifle.

As mentioned, sounds to me like a missing or bad bolt catch spring or the detent is improperly installed or missing... The spring and detent could both be installed improperly (spring on top of detent instead of below)...

For whatever reason my profile isnt saying where im from. At least its not showing it to me. Dano had mentioned that would be a good idea to put up. I'm in bucks county PA. The bolt catch spring seems to be ok of course I dont really know how strong it should be really. The recoil spring deffintly seems strong enough though its very loud. And on a slgihtly side note. This was made during the ban so it has no bayo lug or threading on the barrel. Would it be better to have the barrel threaded and the front sight tower replaced? or buy a whole new barrel. I think I have a 1 in 7 twist. Seems very accurate (at a whopping 40yards houldThanks aga everyone you have all been very generious with your suggestions.

Quoted: For whatever reason my profile isnt saying where im from. At least its not showing it to me. Dano had mentioned that would be a good idea to put up. I'm in bucks county PA. The bolt catch spring seems to be ok of course I dont really know how strong it should be really. The recoil spring deffintly seems strong enough though its very loud. And on a slgihtly side note. This was made during the ban so it has no bayo lug or threading on the barrel. Would it be better to have the barrel threaded and the front sight tower replaced? or buy a whole new barrel. I think I have a 1 in 7 twist. Seems very accurate (at a whopping 40yards ) If i should replace it is it better to get a 1 in 7 again or a 1 in 9? I want a 20inch barrel again. I'm looking for a sort of veitnam issue look. I also dont know what flash supressor they used then. Or if i cant fix it what should I get as a new ar? Thanks aga everyone you have all been very generious with your suggestions.

I'm located in Washington county, if we were closer, id take a look at it for you...

If your looking to have your post-ban barrel upgraded to pre-ban\no-ban status, ADCO is the place to get that done...

About you wanting the Vietnam M16 retro look, you probably want to get a pencil barrel upper with 3 prong flash hider and no forward assist or shell deflector... That's pretty much the way the original M16's were set up at the very beginning of that war...

If you want better details about the retro Vietnam era look, IM or email Ekie, he's very knowledgeable about those things...

Quoted: It shoots great and all but about every round or every other round the bolt stays back and I have to pull the charging handel to get it to chamber another round.

Another thing to take a look at is the buffer tube... Examine it to see if it is dented, loose, bent or out of round...