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Noob question - lower bolt catch issues


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Hey Guys, 

 

New to the forum.

Buddy and I are building our first AR308.

Still building it and have not fired it yet.

 

We ordered a TM10 lower and a CMMG LPK. Installed the bolt catch and it didn't feel right. Pin was stuck so based in internet research grinding it out with a dremmel seemed like the best course of action.

 

Got  the pin out and replaced the bolt catch with a DPMS bolt catch. Just operating it without the upper feels way way better and correct.

 

***PROBLEM: reassembled the rifle I am have trouble locking the bolt the rear. It seems like it is not engaging enough and when It does I have to work at it to lock back. Has anyone run in to this problem?

 

I inserted a mag and the bolt will lock back, but if i remove the mag it sends the bolt home into battery...... Too sensitive for me.

 

I am still waiting for our bolt to come in from Shadow Ops weaponry so I have been using a bolt out of another buddies DPMS Sportical. Maybe this could be the issue?

 

TM10 Lower

DPMS LR308 upper

DPMS 18" SASS barrel

Fortis Switch 14" 

Magpul PRS

ALG ACT trigger

Shadow Ops Weaponry Bolt

A2 rifle buffer from Brownells

AAC muzzle brake

 

Added a photo below of the rifle assembled so far

 

Thanks guys!

Clay

 

 

 

post-14855-0-47158800-1402184723_thumb.j

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Well, we've done all the comparisons, and Armalite makes the best bolt catch. I'm not talking brand favoritism or any of that kind of nonsense, but there is a thread here with pics that clearly shows their piece is beefier where it contacts the bolt face. It can be used in a DPMS pattern lower as well

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Here you go Shibiwan: 

 (took me a while to figure out how to upload the pics)

 

photocopy.jpg
 
Edgecrusher: I will check those out as a replacement if it is indeed the bolt catch needing to be beefed up.
 
Washguy:  Supposedly it would just slide out but it was stuck so I grinded out a hole to work the pin out with a small slot screwdriver.
 
photo.jpg
Edited by Clay_FortWorth
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I thought TM used a screw on their Bolt Catch...did that change? There was a thread talking about issues caused by over tightening it. Do you have the right spring installed with it? That one is easy to mix up some times.

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I thought TM used a screw on their Bolt Catch...did that change? There was a thread talking about issues caused by over tightening it. Do you have the right spring installed with it? That one is easy to mix up some times.

Hey DNP,

 

Yes, they have a pin (not roll pin) that you insert and then they provided a small allen screw to tighten down. I ordered a DPMS spring and detent separate from the CMMG parts kit just to be sure.

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A2 rifle buffer from Brownells

 

That's your issue.  Well, first issue.

 

No AR-15 parts in a 308 AR recoil system.  None.  No buffers, no buffer springs.

 

Start there.

 

 

Everybody else that replied - how the fuk did you guys miss that one?  :bat: :bitchslap:

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  First off , the pin is hardened steel , if I remember correctly & if you over tighten the set screw or securing set screw , it will force the pin into the far side of the receiver . I would install the pin & use a removable loc-tite, like the Purple or a very ,very small amount of the Blue & lightly set the set screw . Making sure the pin is supported on both ends in the receiver .

 

As said by 98, make sure you use all 308AR receiver extension components.

 

   Make sure you don't have a AR 15 bolt catch , you need an 308AR bolt catch , below show the difference. Yours looks like the right one. Also make sure there is easy freedom of movement with the catch & its not hanging up.

  I have also had to make adjustments to the the Bolt catch to let it rise farther to engage the bolt .

post-11255-0-56852000-1402228686_thumb.j

post-11255-0-04084700-1402229480_thumb.j

Edited by survivalshop
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Just a note, I have solved many a 308 bolt catch problems with using the AR 10 type of bolt catch. The newer style is part number, Armilite 10203100 you will have to notch the bottom in order for it to sit flat to the lower receiver and not stick up but it will raise up higher than the DPMS style and provide more bolt catch surface and so far has solved magazine problems of not hitting the catch and the catch just barely grabbing the bolts! Yes, NO AR 15 bolt catchs for the 308!!

Edited by Masgtions99
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@Survialshop

 

It feels like it is moving correct, where as the CMMG was not.

 

What did you do to modify the bolt catch to rise higher? 

 

Also, something wierd is when I do lock the bolt to the rear and remove the magazine it sends the bolt into battery. 

 

@Masgtions99 I will order one this morning!

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So here is what Im thinking:

 

Purchase Armalite bolt catch

 

JP enterprises 308 buffer spring - (I have a David Tubb flat wound in my AR15, any thoughts on Tubbs spring vs. JP?)

 

I live down the road from DSG arms and they sell the AR10 Armalite buffer would this be a comparable buffer to the DPMS? (Quick delivery from DSG) My buddy is not ready to drop the scratch for one from Heavybuffers.com.... but will in the future.

 

From what i have read is that our A2 buffer tube will work but defintley need to change the spring and buffer. Can anyone confirm this?

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I think from what 98 pointed out, the buffer is your issue. It's too long and doesn't allow the carrier to move far enough to the rear. When it locks back, does it look like the picture Survival shop posted up?

Check out this page and read a couple of the customer reviews.

http://www.midwayusa.com/product/913498/dpms-buffer-dpms-lr-308-rifle

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Clay, that is a good plan of action. Start there and you should be all set.

Tom, my bad, I read the first post too quickly and missed the buffer listed. But your silverback gorilla ass has to get here to punish me quick.... As the next time I get out to you I'll be back up to a high speed dangerous ninja.

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Thanks guys!

 

DPMS buffer says 5.25 inches long

Armalite buffer says 5 3/16 inches long

 

Any thoughts on the differences?

 

If it's a standard "A2" buffer tube, use the DPMS style LR0308 buffer.

 

http://www.midwayusa.com/product/913498/dpms-buffer-lr-308-rifle

 

Armalite AR-10 buffer tubes are longer than standard "A2" buffer tubes and use the longer length "standard" AR15 rifle buffer.

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Armalite AR-10 buffer tubes are longer than standard "A2" buffer tubes and use the longer length "standard" AR15 rifle buffer.

 

I don't believe that is the case.  It's true for carbine receiver extensions, but not for rifle receiver extensions.

 

There's really only ONE length for rifle receiver extensions, and it's "A1 length."  The only thing that makes "A2" is the A1 receiver extension, with a 5/8" spacer for the end, and a vented screw that 5/8" longer than the A1 vented screw.

 

Armalite carbine receiver extensions use AR-15 carbine buffer - that's why their extensions are longer, in order to make use of the AR-15 part.  The use the H3 Carbine Buffer in the AR-10 rifles with collapsible stocks.

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