Lower out of spec causing bolt catch failure to engage. Need a solution.

[mrbieler]

That's what confused me about his comment with the 9mm part not holding up. I found similar comments on other posts around the net saying the same thing, but from what I can tell, all the stress and contact points between the 5.56 and 9mm version are the same thickness. The body of both catches have to fit in the same slot dimensionally. I don't see how one would be stronger than the other, but I'm far from an expert.

Going to meet up with Roger later today to try some part swapping. His design is to Colt's TDP so we're not holding out much hope, but if we can find one that is thicker than mine and just a little longer. If we can eliminate the slop in the slot causing forward and backwards movement AND get a little longer tooth, it might bridge the gap and solve this. I also ordered a 9mm Colt catch from Brownells.

Searching the net last night, this seems to be a fairly common issue. With all the different manufacturers out there pumping out AR lowers and small parts, I'm a little surprised no one has come out with a catch that can be trimmed to function.

[mrbieler]

Spent a bit of the morning with Roger at Forward Controls Design. The opportunity to talk and hang out with him was great and the chance to try 20+ catches until we found one that works was very much appreciated.

We found a catch at the extreme of the TDP numbers and it works. My other lowers work better, but this has enough length to get polymer mags to function and there are no issues with GI mags.

I still think that a bolt catch 0.02" longer (.47 OAL) than TDP would be perfect as it would easily solved my problem and would remain short enough to function in lowers correctly cut without risking running into cartridges in the magazine. Looking at TDP blueprints, my original bolt catch was within spec. This replacement bolt catch was .014" longer. The thicker body on the polymer magazines and the resulting shorter length follower clearly can cause issues when tolerances stack the wrong way. From my reading that last 36 hours on line, I am far from the only one with a lower that has issues with bolt catches not grabbing polymer magazines.

But I'm no expert or even an amateur at that.

Anyway, I now sport a new sexy bolt catch and I picked up another for my BCM lower. Also got two of his mag release buttons while I was there. Much improved over the original part.

Top it off with a stop at Bay Cities Italian Deli (a must go if you're in Santa Monica) and a beautiful drive up the PCH, I would say Sunday has been pretty good.

New catch with Hexmag


New catch with a GI mag


Sexy and functional


Roger, thanks again for your help. It was a pleasure to meet you. I appreciate your time.

[Duffy]

Any time Jeff, it was a pleasure meeting you, I'm glad we were able to help

ABC/R may incorporate some changes in the future based on the findings today.

[opngrnd]

Roger is always great to work with.

If there becomes a "max TDP" bolt catch, I'll spring for one. My buddy has the same bolt catch issue the OP was having.

[556BlackRifle]

Roger's a good guy.

[Diamondback]

Any time Jeff, it was a pleasure meeting you, I'm glad we were able to help

ABC/R may incorporate some changes in the future based on the findings today.

Roger, can't make any promises when or what, but this has put you on the "FIND/MAKE A Reason To Do Business With Someday" list.

[everready73]

Roger, can't make any promises when or what, but this has put you on the "FIND/MAKE A Reason To Do Business With Someday" list.

Yeah that is pretty awesome. Even on a Sunday

[Diamondback]

Yeah that is pretty awesome. Even on a Sunday

Short notice on a Sunday is ESPECIALLY awesome for Going The Extra Mile.

[Wake27]

Roger, can't make any promises when or what, but this has put you on the "FIND/MAKE A Reason To Do Business With Someday" list.

Roger and FCD are absolutely on that list. He is awesome and so are the products. Even my beater gun is loaded with FCD parts: EMR, LDFA, and 6315. Plus several components from the buffer system/RE.




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[ssc]

Roger is definitely one of the good guys in the industry. This is just one more example of why so many people share the same view of FCD. Glad it all worked out.

Cheers, Steve