Foxtrot Mike 9mm BCG (not bufferless) SS compatibility?

patriotpa

https://store.fm-products.com/products/fm-products-5397-866a385f-576d-4c31-9957-4c319b7f5250

WIll it work? A quick eyeball of the bcg looks like it might to me.....

undeadchew

patriotpa
Yes it works without modification to the bcg.

patriotpa

NICE! Thanks for the quick reply. I'm an old hand at ARs, but not the AR9

Stock FM buffer OK or is a Maxim buffer gonna work better?

undeadchew

patriotpa I haven't gotten around to testing my maxim buffers at all, standard works.

ACWick

Hi,
I may have a different setup than you or undeadchew but this bolt won't work for me using the original SL-9 design. The underside of the bolt has a slightly different cutout pattern or geometry that won't allow the extractor to fit. I'm debating whether to modify the extractor or the bolt to try to fix the fit but currently the upper won't close onto the lower properly because the SL-9 extractor won't fit into the groove on the underside of the FM bolt. I'm away from the original and FM bolts currently but can send pictures tomorrow if it will be helpful.

undeadchew

ACWick Is it the VFM9 bolt?

ACWick

I think so? It's the link at the beginning of this thread. I was excited to not grind more buffer masses down so I took a chance 🙂 I have my current SL9 (HT kit) mass ground from .66in to about .40in) but I haven't been able to field test it yet. Hopefully tomorrow!

undeadchew

ACWick Oh my bad yes I see the link you posted, that's weird that it's not compatible with the ejector, I would think that BCG has the same profile as the rest of theirs with the exception the part with two screws ontop for dual charging. I'll wait for pics.

ACWick

undeadchew
Here's a picture of the bolts side by side. The VFM9 bolt is on the left (as you're looking at it). I think you can see how the channel just left of midline is somewhat shorter than the channel of the bolt on the right (which is a KAK from HT). This doesn't allow the ejector to fit due to its width/length (depending on your perspective) without pushing the buffer rearward with the bolt (which you obviously can't do while trying to close up the weapon. I could either extend the channel in the bolt a little or, alternately, cut about a 1/4' off the top rear of the extractor, which would obviously be a lot easier (and I don't think would compromise its function any).

undeadchew

ACWick I'm with you on modifying the ejector to be shorter. If you could can we see a picture of the face of the bolt?

ACWick

Is this the face you meant?

undeadchew

ACWick Yes that is a good profile view thanks. I see now that it's different than my FM9 bolts.

Also I realize now you are not OP who posted the link, is yours that same product listing, or you got it in a VFM9 kit?
One last thing so the ejector fits into the groove, but the groove doesn't extend back far enough for the bolt to go into battery? Am I understanding that right?

ACWick

Yes, I got the one in the OP link at the top of the thread.
And, basically, yes; the ejector groove is too short for the printed ejector (so the upper could not be closed fully onto the lower due to interaction of the ejector and the "absent" groove). I made a slight modification to the ejector which seems to have fixed that issue.

As you can see I cut a notch out of the rear 1/3" or so of the top rear part of the ejector; it now functions properly and I don't imagine this will impact its long-term durability (any more than a printed ejector has "long-term durability". 🙂