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View Full Version : New build, bolt catch doesn't hold on empty mag


Jimmy310
06-05-2012, 4:41 PM
Im trying to trouble shoot an new build. The lower im using isnt new. The lower went from a A2 style stock, to a retractable stock. Im pretty sure its not the mags or the bolt catch itself as they worked fine using the A2 stock/buffertube kit and the magazines themself empty lock the release when a upper isnt attached. (the a2 stock lower setup ran perfectly)

Im pretty sure its the buffer setup. The setup is a standard carbine upper, with a 3oz buffer and a 11" carbine buffer spring. I have not shot this setup, but when retracting the charging handle, the bolt catch 7/10 times does not hold the bolt open.

I stupidly cut a few links off the buffer spring as i read this worked, it did not work.

My setup is a bushmaster dissipator upper, on a YHM lower, with a RRA lpk, milspec carbine buffertube, 3oz buffer, and 11" carbine buffer spring and MOE stock.

Any advice is greatly appreciated!

seal20
06-05-2012, 4:50 PM
Any chance you are running a Magpul B.A.D. Lever? I have heard of this happening to people using that tool. Probably want to get a new budget sorting since they are cheap being that you modified yours.

G60
06-05-2012, 4:53 PM
Why did you cut your buffer spring?

Jimmy310
06-05-2012, 4:59 PM
Any chance you are running a Magpul B.A.D. Lever? I have heard of this happening to people using that tool. Probably want to get a new budget sorting since they are cheap being that you modified yours.

Nope, no BAD lever on this rifle.

Why did you cut your buffer spring?

I read multiple places that sometimes the buffer spring inside the buffer tube fully compressed with the buffer and the bcg doesnt always clear the bolt catch by the magazine so if you cut a couple of coils off the spring, it has enough room to clear and fully cycle without obstruction.

that guy
06-05-2012, 5:11 PM
How confident are you that the bolt release spring and plunger are properly placed under the bolt release? I wouldn't want to drive out the roll pin to check, but the source of your problem might be here.

Also, is the magazine in good condition, with a good spring, and is it making contact between the magazine follower and the bolt release? This would be the first thing I checked. I'd also slap the bottom of the magazine to make sure its securely in place. (I have personally failed to properly firmly install a mag in the mag-well on more than one occasion, so don't take this suggestion personally).

Also, were you able to get the bolt catch to work at all by hand before the buffer spring was cut? If so, I can't see how there would be enough room intermittently. Either way, aren't you better off getting a spring that fits your tube properly, rather than risking too weak a buffer spring?

Merc1138
06-05-2012, 5:21 PM
Nope, no BAD lever on this rifle.



I read multiple places that sometimes the buffer spring inside the buffer tube fully compressed with the buffer and the bcg doesnt always clear the bolt catch by the magazine so if you cut a couple of coils off the spring, it has enough room to clear and fully cycle without obstruction.

Maybe if you're using a rifle length spring in a carbine tube.

Now you should go buy a new buffer spring. Here's a tip: If anyone ever says to cut/trim/file/sand/etc. to anything on your gun, verify it first instead of assuming that person is correct, no matter how many people you see repeat that.

clutchy
06-05-2012, 9:02 PM
did you assemble the bolt catch properly?

did you put the spring in there?

does it just flop around or is it tensioned?

Jimmy310
06-05-2012, 9:45 PM
How confident are you that the bolt release spring and plunger are properly placed under the bolt release? I wouldn't want to drive out the roll pin to check, but the source of your problem might be here.

Also, is the magazine in good condition, with a good spring, and is it making contact between the magazine follower and the bolt release? This would be the first thing I checked. I'd also slap the bottom of the magazine to make sure its securely in place. (I have personally failed to properly firmly install a mag in the mag-well on more than one occasion, so don't take this suggestion personally).

Also, were you able to get the bolt catch to work at all by hand before the buffer spring was cut? If so, I can't see how there would be enough room intermittently. Either way, aren't you better off getting a spring that fits your tube properly, rather than risking too weak a buffer spring?

All i did was swap out buffer assembly's/stocks. When the old buffer was on the bolt catch worked. It still does now. I am 99% confident that its not the source of my problem.

I was using P-mags, Gi mags, and a newer bushmaster mag with the good orange anti-tilt follower, its not the mags....and yes, i smacked it into place.

The bolt catch would catch 3/10 times. If i pulled back the charging handle slowly, it would have a way better chance of locking back. Cutting the buffer spring honestly didnt do anything to better, or worsted the problem. I believe i had the correct bufferspring to begin with, a 11" carbine length buffer spring.

Maybe if you're using a rifle length spring in a carbine tube.

Now you should go buy a new buffer spring. Here's a tip: If anyone ever says to cut/trim/file/sand/etc. to anything on your gun, verify it first instead of assuming that person is correct, no matter how many people you see repeat that.

I was using an 11" buffer spring, the common size for a milspec carbine buffertube. I got them as a set for a carbine from a reputable gunparts e-retailer.

I will most likely have to buy a new buffertube, spring, and buffer. None the less, i will be buying a new buffer spring.

Trust me, i verified what i had and what i was doing

did you assemble the bolt catch properly?

did you put the spring in there?

does it just flop around or is it tensioned?

Yes, i assembled the bolt catch properly. When the lower and upper are seperate from each other and i insert a empty mag, the follower makes the bolt catch yaw downward like it properly should.

Yes the spring is in there and it is tensioned.

Merc1138
06-05-2012, 10:04 PM
Yes the spring is in there and it is tensioned.

What about the bolt catch detent?

Dhena81
06-05-2012, 10:16 PM
If all you changed is the buffer tube action spring and buffer that won't mess with your bolt hold open something else is wrong or not. You haven't shot the rifle go shoot it.

818gtiguy
06-05-2012, 10:25 PM
I just fixed a co-workers new Daniel Defense rifle that had the same exact symtom. It ended up being that the bullet button nut backed off and was not tight enough....Tightened it up and he problem dissappeared..

Jimmy310
06-06-2012, 12:44 AM
Just had a shooting buddy come over and bring his lower. I took his buffer and buffer spring and put it in my buffer tube. It worked fine. Since he had a 11" buffer tube spring, i blame it on the buffer.

I will replace my cut 11" buffer spring with a new one.Which buffer should i get for my 16" Dissipator upper?

that guy
06-06-2012, 1:10 AM
I'm not understanding how the buffer spring could contribute to this, so I have one more question. Did you look at the surfaces of the bolt catch and the bolt at their contact point? Does anything look worn down or rounded off?

Jimmy310
06-06-2012, 1:43 AM
I'm not understanding how the buffer spring could contribute to this, so I have one more question. Did you look at the surfaces of the bolt catch and the bolt at their contact point? Does anything look worn down or rounded off?

It wasnt the buffer spring. It was the buffer itself. Nothing on the bolt catch is worn.

jsipe007
06-06-2012, 8:19 AM
Glad to see you figured it out! I was gonna suggest that it was the buffer/spring. Im running a 16in PSA dissipator upper with a standard milspec buffer, spring and tube. It works flawlessly for me. Glad to see its all working proper! :)

Jimmy310
06-06-2012, 12:00 PM
Glad to see you figured it out! I was gonna suggest that it was the buffer/spring. Im running a 16in PSA dissipator upper with a standard milspec buffer, spring and tube. It works flawlessly for me. Glad to see its all working proper! :)

Thanks bud. I was sure it wasn't the catch. I used that lower on a different mid length build and knew it couldn't have been it....i never touched it.

It seemed like the head of the buffer was out of spec (diamater was too small and the buffer may have been coming out of the retainer.

I ordered a new spring and buffer from midway, both made from dpms....they got good reviews and were cheap. As long as they work, i'll be happy.


Anyways, How do you like your PSA Dissipator? Those things have been out of stock for the longest time now. Everytime i had the money to get one, Sold Out! I ended up getting a bushmaster dissy upper on the marketplace here.

jsipe007
06-06-2012, 1:26 PM
I love the thing :) she shoots like a champ! I just finished the build 2 days ago but ordered the upper a month ago lol. I know what you mean about them being out of stock... I ordered mine on a saturday and as soon as I ordered mine, it hasn't been in stock since.

PSA has great quality and price, but ship time sure does stink. The delivery date estimate and ship estimate are right on though, so I knew what i was getting into. I cant complain though because as soon as I received it, I knew it was going to be a good upper. It came in a heavily padded foam box and another box over that. The bcg and CH were already installed and zip tied (with a removeable tie) into the upper. The m4 feed ramps are perfectly aligned and the bcg is properly staked. Everything came oiled and ready to go.

This is my first ar and definitely a positive one. The upper fits really nice with my New Fronteir Armory G-15 lower, the seam between upper and lower is barely visable. The rear takedown pin is snug, not too tight to remove by hand but a good fit so I know that pin will not rattle out. I handled a lot of ar-15s before i puchased this one (including an m&p 15 sport, dpms, bushy, rra) and I think my ar has the best fit and feel out of all of em. I highly recommend it!

Jimmy310
06-06-2012, 2:50 PM
I love the AR15 system, but i need it to be in a specific layout to shoot decent with iron sights....... rifle length upper with fixed front sight.

My 2 options are a 20" rifle upper, or a dissipator upper. I dont know how people shoot carbines... even a midlength was challenging for me! I do think if 16" carbines /midlengths had a narrower front sight post it may do the trick.

jsipe007
06-06-2012, 2:57 PM
I agree! The long sight radius is a godsend. I actually ended up putting an Eotech on mine, and I really love it, but if I didnt have the longer sight radius, i would be terrible with irons. Peep sights help a little but just having that longer radius makes it so much easier for me to get on target and stay on. I may be incorrect, but I think spikes tactical also makes a sweet dissy upper... and its affordable. If you want another dissy anytime soon, I'd look there :) as soon as theyre not backordered that is lol

on a side note... i have the 12in MOE handguard and dang it looks sexy on my rifle :) i love the dissy look. Such a nice combo :)

Darklyte27
06-06-2012, 4:03 PM
Wow modding your rifle based on hear say im glad i dont live near you. Please have someone who knows what they are doing to show you how to safely handle, maintain and shoot your rifle safely before you hurt yourself or someone else

Jimmy310
06-06-2012, 4:29 PM
Wow modding your rifle based on hear say im glad i dont live near you. Please have someone who knows what they are doing to show you how to safely handle, maintain and shoot your rifle safely before you hurt yourself or someone else

http://nbchardballtalk.files.wordpress.com/2011/06/rage-wtf.jpg?w=236

Ive been shooting AR15's for years. Ive never ran into this problem before. This is a matter of getting a defective part (buffer) and troubleshooting my problem. I did not once put in a full mag...or chamber 1 round into my rifle... let alone shoot or testfire it. How could i hurt myself or others?

Lets say for instance i had a rifle buffer spring. The length of those are longer than the carbine buffer springs. If i cut that down to the size of a carbine buffer spring it wouldnt be such a big deal if i was going to replace it with a new part anyways.... like i said, i was just troubleshooting my problem to see why my bolt wouldn't lock back when i pulled back the charging handle/bolt on a empty magazine.

If you read my previous posts, i ordered another carbine buffer spring and buffer. Calm down with the finger pointing and telling people what to do.

Jimmy310
06-06-2012, 4:32 PM
I agree! The long sight radius is a godsend. I actually ended up putting an Eotech on mine, and I really love it, but if I didnt have the longer sight radius, i would be terrible with irons. Peep sights help a little but just having that longer radius makes it so much easier for me to get on target and stay on. I may be incorrect, but I think spikes tactical also makes a sweet dissy upper... and its affordable. If you want another dissy anytime soon, I'd look there :) as soon as theyre not backordered that is lol

on a side note... i have the 12in MOE handguard and dang it looks sexy on my rifle :) i love the dissy look. Such a nice combo :)

I didn't see it on their website. Last time i checked spikes was backordered 6 months! What i do know is they use some of the same manufacturers to make parts for them....and everybody knows spikes and psa is good stuff! :)

jsipe007
06-07-2012, 8:08 AM
I think the first place I saw Spike's dissy upper was on AIM surplus? I may be wrong about that though. I was debating between them and PSA, but ultimately went with psa. Im happy with my decision! hows your bushmaster teating you?

jsipe007
06-07-2012, 8:13 AM
In Jimmy's defense, he didn't just make a blind decision. While I agree modding parts could easily have unexpected or unwanted results, he did so with care and researched the problem, tried a solution, and came here once the attempted solution didn't work. Many people try very similar ideas with other guns. For example, have you ever swapped out a mainspring from a pistol or other weapons for a stronger or lighter one? That changes the physics of the gun, as well as the behavior of the gun. Cutting a few links off a spring may not be the best long term solution, but Jimmy never indicated he wished to use that solution long term. He thought the buffer spring was too long and attempted to modify it to the length of a carbine buffer spring.

Jimmy310
06-07-2012, 2:17 PM
I think the first place I saw Spike's dissy upper was on AIM surplus? I may be wrong about that though. I was debating between them and PSA, but ultimately went with psa. Im happy with my decision! hows your bushmaster teating you?


The bushmaster is treating me well, i haven't shot it yet. Since psa was out of stock i got this one at a great price. Its about 10 years old, but has no rounds through it. Back then, there weren't as many choices in ar manufacturers. Colt, Armalite, Bushmaster, LMT, Eagle Arms, and maybe Olympic were your few choices. The bushmaster has a 4150 chrome lined barrel, like alot of the higher end AR's do. I also have the magpul goodies on mine. Im going to put a red dot on it as well as a matach rear buis.

If it shoots almost as accurate as my 20" with no hickups, i'll be a happy camper!

Its hard to tell but the upper finish is mismatched from the lower...thats ok though, alot of AR's are:
http://i911.photobucket.com/albums/ac319/jbusman84/IMAG0202.jpg

Check out that muzzle break!
http://i911.photobucket.com/albums/ac319/jbusman84/IMAG0203.jpg