preferred LR308 bolt catch?

[ehall]

Hi folks,

I built an LR-308 over the past couple of years, using a pair of Aero M5 receivers and their LPK (rest of the parts are mixed). I also bought a bunch of Lancer mags, and a single Magpul magazine. I was doing some testing with it last week, and noticed that the bolt catch wasn't properly working on LRBHO for any of the Lancers, instead it was catching the bolt carrier and missing the bolt lugs (it would catch once in a while, but not repeatably). I did a little followup testing with the Magpul and it catches the lugs fine. Researching here and elsewhere shows its a common issue, and my options are either buy a new bolt catch/release, or buy new Magpul mags. I have the FCD on my AR15s, but I can't find the dimpled ABC/R 7.62 in stock anywhere. I also see that the FCD ABC/R isn't in the 308 AR Bolt Catch Study thread.

What is the preferred bolt catch these days?

Thanks

[unforgiven]

What is your recoil system?

I use M5 LPK upper receiver parts and run Magpul and Lancer mags without issues on my .308's. Just my 2 mags

[ehall]

23 minutes ago, unforgiven said:

What is your recoil system?

I'm using an SLR adjustable gas block on a Criterion barrel with a JP silent captured spring recoil system. I was actually in the process of tuning the gas block with the variety of 308 and 7.62 ammo I've collected when I noticed that the bolt catch was only grabbing the body of the BCG and not the lugs. The system cycles all of the ammo perfectly, 10- and 20-round mags, zero FTF or FTE (after it was tuned), but it only caught the lugs a couple of times in a couple of dozen mag swaps.

This is what I saw that made me realize that the Lancers are my problem (verified with testing my Magpul 10-round mag) https://forum.308ar.com/topic/12327-lancer-l7awm-20rd-magazine-reviews/

27 minutes ago, unforgiven said:

I use M5 LPK upper receiver parts and run Magpul and Lancer mags without issues on my .308's. Just my 2 mags

Its possible that I'm using the Aero AR-15 catch instead of the 308 catch, but I don't think so (it looks physically larger).

I have found an FCD 7.62 gen2 catch and ordered that, will see if it improves anything.

 

[unforgiven]

Don't forget to start your gas block wide open then go from there. I also use Armalite recoil system for large platform ARs on all my rifles. Simple is good.

[shooterrex]

Does it lock back on an empty mag every time? If it does sometimes but not others that's you gas/recoil system more than the bolt catch.

A lot of folks have the same problem with the JP recoil set up on the large frame Ar's. That's race gun parts not battle rifle parts.

Armalite designed these things. Their recoil system works.

Lancers are top shelf mags.

[ehall]

The bolt locks back on the BCG body everytime.

 

[ehall]

3 hours ago, unforgiven said:

Don't forget to start your gas block wide open then go from there.

I ran it wide open to test, thinking it was possibly the problem, but same results.

 

[ehall]

9 minutes ago, ehall said:

The bolt locks back on the BCG body everytime.

 

can't edit or delete here ... alright

The bolt catch locks the BCG body everytime, and misses the lugs almost everytime, with the lancers, but it catches the lugs everytime with the magpul (so far)

I agree that it should work with the lancers so I am blaming the catch not the mags. If I can't find a better catch, I will have to replace the mags, but that seems like the wrong fix--it would be best if the gun was reliable with more than one kind of mag.

[98Z5V]

44 minutes ago, ehall said:

The bolt locks back on the BCG body everytime.

 

That means your buffer is too long.  Give up the recoil system specs.  What's the model number of the JP SCS you used?  What's your receiver extension internal depth?

Edited April 28, 2022 by 98Z5V

[ehall]

On 4/27/2022 at 10:16 PM, 98Z5V said:

That means your buffer is too long.  Give up the recoil system specs.  What's the model number of the JP SCS you used?  What's your receiver extension internal depth?

It cycles completely for rounds, and locks back on the lugs with the Magpul

Its an A2 rifle tube with the JPSCS2-10H2 and spacer

[shooterrex]

Ok how about pics w/o the upper . One with Magpul and one w/ lancer from above so we can see what you have going on.

[ehall]

Aero on the left, Forward Controls on the right. AR15 on the top, 308 on the bottom (I have been using the Aero 308). The only thing that jumps at me is that the FCD 308 has a thinner leading edge and a smoother surface--its possible that the taller rougher surface of the Aero is putting more drag on the BCG, causing it to lose some momentum.

I'll post measurements in the spec thread and report back after the next range trip.

 

[ehall]

Interesting observation already just from cycling manually: the FCD will not catch the Lantac BCG body, only the lugs. Evidence that the problem is that the Aero catch is too tall.

 

 

[98Z5V]

6 hours ago, ehall said:

Interesting observation already just from cycling manually: the FCD will not catch the Lantac BCG body, only the lugs. Evidence that the problem is that the Aero catch is too tall.

I saw that exact thing happen when I was building my Matrix Aerospace set.

[98Z5V]

7 hours ago, ehall said:

AR15 on the top, 308 on the bottom

 

Do me a favor, if you will.  AR15 bolt catches on top.  Blow that little corner off them, like the .308AR catches on the bottom.  That little right-angle corner gains you nothing, but it can hinder upward travel, and affect the range that the BC will move.  Any .308AR catch that you ever find, that has that little corner - removed it with a 45* angle, just like the ones in your pic here.  That WILL affect a .308AR. 

[DustBuster]

Sounds like this problem has been solved, Ehall.  I also discovered that my bolt catch was too “tall” and was coming up on an empty lancer mag and catching the bolt carrier in the same spot, not in front of the bolt lugs.  I didn’t have any bolt stops to compare at the time, so I just shaved a tiny bit off the Plastic follower on my Lancer to solve that.  For a different bolt that I have, I might buy one of the Forward Controls stops because it looks pretty wide, which might solve the different issue I’m having with the different bolt.  Good investigative work, Sherlock... Better than mine

[ehall]

I had a little time after yardwork today so I ran to the range real quick. Only tested a little bit.

The Lancer 20-round mags hold open with the FCD and the gas port almost all the way open, but the 10-round mags do not catch the FCD even with the gas port all the way open. I only had some 7.62 M80 and I forgot to grab the Magpul mag. Need to order some more steelcase and M80 and another Magpul mag, and do some more testing. Looking at getting another bolt catch / release sometime too.

 

[josiahg52]

The ArmaLite AR-10A catch always worked for me.  After I installed a Norgon magazine release, I felt I needed a more pronounced bolt catch.  I tried a few and they all worked for me as intended but were clearly sized differently which concerned me in the long term.  Ended up using the Badger Ordnance Enhanced Bolt Catch.  It's the right size in the right places and looks like it'll last.

[ehall]

On 5/5/2022 at 4:02 PM, josiahg52 said:

The ArmaLite AR-10A catch always worked for me.  After I installed a Norgon magazine release, I felt I needed a more pronounced bolt catch.  I tried a few and they all worked for me as intended but were clearly sized differently which concerned me in the long term.  Ended up using the Badger Ordnance Enhanced Bolt Catch.  It's the right size in the right places and looks like it'll last.

The only Badger bolt catch that I can find has the AR-15 style ramp. I have been looking at the Armalite catch but frankly I was not impressed with the last part that I bought from them.

Edited May 7, 2022 by ehall

[ehall]

I bought one of the BAD 308 Enhanced Bolt Catches, the one they market as Investment Cast. Its similar in dimensions to the FCD but has a slightly taller wall surface. This one is able to catch the Lantac bolt body if I wiggle everything right. It looks like a Strike part with the stylization but it has a good feel to it.

 

I also got the ammo that I ordered, so I will report back after testing, after it stops raining.

 

[josiahg52]

2 minutes ago, ehall said:

The only Badger bolt catch that I can find has the AR-15 style ramp. I have been looking at the Armalite catch but frankly I was not impressed with the last part that I bought from them.

What does the AR-15 style ramp look like? What was wrong with the ArmaLite part you got?

The EBC I purchased was sold and packaged as SR-25 and AR-10 compatible. It has worked in my AR-10 thus far.

[josiahg52]

7 minutes ago, ehall said:

I bought one of the BAD 308 Enhanced Bolt Catches, the one they market as Investment Cast. Its similar in dimensions to the FCD but has a slightly taller wall surface. This one is able to catch the Lantac bolt body if I wiggle everything right. It looks like a Strike part with the stylization but it has a good feel to it.

 

I also got the ammo that I ordered, so I will report back after testing, after it stops raining.

 

Hope it works for you. I did not like how it worked for me. Just didn't seem like there was enough purchase on the bolt face. I liked that the Badger EBC was machined.

[ehall]

 

28 minutes ago, josiahg52 said:

What does the AR-15 style ramp look like? What was wrong with the ArmaLite part you got?

The AR-15 style only covers half the ramp, while the large-frame style covers the full ramp. Look at the ramped part of these (from above), the upper two are missing the right half of the ramp:

I can tell from your pictures that yours is using the AR-15 style ramp. If its working for you then I will look at it. I'm a little worried about material thickness, plate width, etc., the large-frame BCGs are much larger with much more mass

The ArmaLite part that I bought was their larger mag release. Nothing wrong with it, just didn't seem to be a very thoughtful design.

[josiahg52]

24 minutes ago, ehall said:

 

The AR-15 style only covers half the ramp, while the large-frame style covers the full ramp. Look at the ramped part of these (from above), the upper two are missing the right half of the ramp:

I can tell from your pictures that yours is using the AR-15 style ramp. If its working for you then I will look at it. I'm a little worried about material thickness, plate width, etc., the large-frame BCGs are much larger with much more mass

The ArmaLite part that I bought was their larger mag release. Nothing wrong with it, just didn't seem to be a very thoughtful design.

Nice. Thank you for that. I agree that ArmaLite mag release button is nothing special. I went with an Aero Precision button as it's taller. I'm using a Norgon ambidextrous release.

[josiahg52]

26 minutes ago, ehall said:

 

The AR-15 style only covers half the ramp, while the large-frame style covers the full ramp. Look at the ramped part of these (from above), the upper two are missing the right half of the ramp:

I can tell from your pictures that yours is using the AR-15 style ramp. If its working for you then I will look at it. I'm a little worried about material thickness, plate width, etc., the large-frame BCGs are much larger with much more mass

The ArmaLite part that I bought was their larger mag release. Nothing wrong with it, just didn't seem to be a very thoughtful design.

Also, I'm using the standard PMAGs (not the M118LR) and KAC magazines.