LF AR Bolt won’t hold open with no magazine

[JsnSanko]

GGP (Grey Ghost Precision) Billet Set. 15” GGP Hand Guard. JP SCS H2 buffer with spring set. Superlative Adjustable Gas Block (bleed off). Geissele NM Trigger. Proof CF 6.5CM barrel. Fat Bastard Muzzle Brake. Quality build……….

But skimped money and bought Areo BCG. Have tried 4 different bolt catches (GGP, 2-Areo, and CMMG) and 3 springs. Everything is well lubed. Ready to start grinding on my biggest catch.

The bolt will barely catch with a magazine in. If I set it down too hard it will close. It will not catch without a magazine. Not my first build and itjus put together correctly.

Any ideas. I would like to shoot this thing. Have a bit of coin in it and want to see how it shoots. Have a fresh batch of Lapua brass all loaded and ready for me to solve this problem to start ladder testing

Edit-

If I put the upper on a different lower (Aero) with no changes to others it will hold the bolt open either way. If I take that upper and put on the GGP lower it will no longer hold it open. I will swap the bolt catches tomorrow. They are all 308 bolt catches. I am thinking this might be a billet lower problem.

 

[hlee]

I am looking at a rifle right now that has a wonky bolt catch. I can manually actuate it from the side, but- for reasons that I cannot explain- the follower on a mag is not strong enough to push it up. Hell, it really doesn’t want to move when I press it up from inside the mag well. There is something about the geometry of either the bolt catch or the receiver that is off. It binds when pressed up (like a mag follower would), but operates normally when actuated from the side (like a shooter would).

So, make sure the bolt catch isn’t binding. Then, there are large frame specific bolt catches. Make sure you have the correct catch for your gun. Finally, do you REALLY need lrbho to shoot a rifle? I’m just going to live without it for a while and see how annoying it is. It will suck for public range “safe range” procedures- open actions and lock them open- but beyond that? Meh, we’ll see.

 

[msgriff]

When you pull the charging handle fully back, what is the distance between the bolt catch and the bolt lug face? Are you using the 308 version of the SCS? What RE are you using, rifle, carbine or intermediate (A5)?

 

[redneckbmxer24]

My money would be on the receiver set being out of spec somewhere.

I’d send their shit back to them and let them figure it out.

 

[bfoosh006]

Can you post some photos ?
Some with an empty mag inserted, and holding the BCG back.

And some with you manually actuating the bolt catch ?

In my case....

FWIW, I ground off some of the bottom back of a bolt catch ( the portion that is below the release pad for your thumb ) to help it have more travel and interaction with the bolt face in that specific upper... otherwise, the OEM setup ( bolt catch ) was just barely "catching" the bolt face. It also would release the bolt at the slightest movement.

I went slow and hardly removed any metal, that allowed more travel

FWIW... this photo shows a bolt face with to little contact with the bolt catch.

 

[MontanaMan]

GGP (Grey Ghost Precision) Billet Set.

If I put the upper on a different lower (Aero) with no changes to others it will hold the bolt open either way. If I take that upper and put on the GGP lower it will no longer hold it open. I will swap the bolt catches tomorrow. They are all 308 bolt catches. I am thinking this might be a billet lower problem.

After you swap the bolt catch between lowers, & if the GGP lower still doesn't work, I think you will have your answer as highlighted above.

GGP would be waaaaaaaaay down the list of an upper & lower to use for a "quality" build for me.

YMMV

MM

 

[JsnSanko]

Can you post some photos ?
Some with an empty mag inserted, and holding the BCG back.

And some with you manually actuating the bolt catch ?

In my case....

FWIW, I ground off some of the bottom back of a bolt catch ( the portion that is below the release pad for your thumb ) to help it have more travel and interaction with the bolt face in that specific upper... otherwise, the OEM setup ( bolt catch ) was just barely "catching" the bolt face. It also would release the bolt at the slightest movement.

I went slow and hardly removed any metal, that allowed more travel

FWIW... this photo shows a bolt face with to little contact with the bolt catch.
View attachment 8242915

I put a heavy buffer and tubs flat wire spring in tonight and it functions just fine. I am going to call JP next week. Both have JP SCS. I didn’t notice until your picture, and looking at some 15’s the other was not catching on the front of bolt, but the bolt carrier. The JP SCS isn’t cycling far enough. I took a look it is meant for a 10 and doesn’t have the plastic buffer (either of them). Now I just need to figure out how to get a couple springs and buffers in my communist state (WA).

Thanks for your help. I have had no luck with the JP SCS except in my AR-15, 458 SOCOM. At least I get to try this thing at the range. Need to buy a quality set for this barrel and another to build a couple nicer guns, after I move to a more friendly state.

 

[bfoosh006]

I put a heavy buffer and tubs flat wire spring in tonight and it functions just fine. I am going to call JP next week. Both have JP SCS. I didn’t notice until your picture, and looking at some 15’s the other was not catching on the front of bolt, but the bolt carrier. The JP SCS isn’t cycling far enough. I took a look it is meant for a 10 and doesn’t have the plastic buffer (either of them). Now I just need to figure out how to get a couple springs and buffers in my communist state (WA).

Thanks for your help. I have had no luck with the JP SCS except in my AR-15, 458 SOCOM. At least I get to try this thing at the range. Need to buy a quality set for this barrel and another to build a couple nicer guns, after I move to a more friendly state.

What buffer tube length are you using ? And what caliber is the firearm ?

 

[JsnSanko]

What buffer tube length are you using ? And what caliber is the firearm ?

Rifle length. It’s two. One is locking back on the bolt carrier not the bolt. One is as described above and a 6.5CM. The other is .308.

 

[Aftermath]

Now I just need to figure out how to get a couple springs and buffers in my communist state (WA).
after I move to a more friendly state.

Drive east on US12.
Stop just before you cross the Snake River and leave a huge turd for the commies to worry about.
Continue on your way into Nez Perce County.
Find your way to 525 Thain Rd, Lewiston, ID 83501

 

[greg1147]

If its a carbine buffer tube the buffer is specific to AR 10 shorter, ask me how I know. Bought the buffer from AERO works fine.
Being a 6.5 and suppressed its kind of picky on ammo specifically weight.