Spikes tactical 9mm AR pistol build issues

[zachomega]

Kind of as an aside, how did you hold your upper when you installed the barrel? I had to modify my clamshell upper vice block with a Dremel.

-Zach

[HanzMcFeely]

https://www.joeboboutfitters.com/Spi...sp-st9bg01.htm

In stock.

Says it is 15 oz. But maybe the geometry is different than the Odin works bolt.

-Zach

https://ar15discounts.com/products/o...carrier-group/

Looking at the bolt faces there might be a slight difference. I’ll call spikes again on monday and see what kind of tech support they can offer. Gotta get it feeding properly before i swap to a drop in trigger. 9mm pcc with frt15 and magpul d50 go *brrrrrrt* lol not-quite-a-subgun without a tax stamp and ATF hoops...and way less money (now if anyone has a spare $40k around i can have, then i’ll buy the real thing...or a select fire beretta m92fs)

Kind of as an aside, how did you hold your upper when you installed the barrel? I had to modify my clamshell upper vice block with a Dremel.

-Zach

I slapped it in by hand and put the free float barrel nut on hand tight then took it to my LGS to torque the barrel and castle nut for $15 and a free function test its worth it. So far i’ve done that with 3 uppers, dont have vice/vice block/AR wrench to work with (yet)

[HanzMcFeely]

Quick update:

I tried shimming with quarters in the buffer tube. No go on the quarters, it wouldnt lock the bolt back at all (too little travel to clear the bolt catch). That rules out short stroking, unless i need to take a touch off the buffer bumper.

I also tweaked the LRBHO and bent the mag follower tab down. Bench testing, no live fire It will lock open on an empty 33rd mag every time now. 17rd mags wont lock now. Its almost like the mag isnt putting enough upward pressure to push the lrbho bar at the bolt catch with enough force. I have to cycle it by hand violently to get it to lock 1/3 of the time on a 17rd mag. This setup is some serious short bus engineering.

Might try and pull the bolt catch and bend the tab for the LRBHO up a bit on that end. I dont see a spring in there and suspect the LRBHO lever acts as the bolt catch spring

[zachomega]

Quick update:

I tried shimming with quarters in the buffer tube. No go on the quarters, it wouldnt lock the bolt back at all (too little travel to clear the bolt catch). That rules out short stroking, unless i need to take a touch off the buffer bumper.

I also tweaked the LRBHO and bent the mag follower tab down. Bench testing, no live fire It will lock open on an empty 33rd mag every time now. 17rd mags wont lock now. Its almost like the mag isnt putting enough upward pressure to push the lrbho bar at the bolt catch with enough force. I have to cycle it by hand violently to get it to lock 1/3 of the time on a 17rd mag. This setup is some serious short bus engineering.

Might try and pull the bolt catch and bend the tab for the LRBHO up a bit on that end. I dont see a spring in there and suspect the LRBHO lever acts as the bolt catch spring

I didn't play with mine at all, but when I first got it, i looked it over and the lrbho is definitely not the best engineered thing. I figured if (when) it broke, I'd deal with it at that time. I seem to recall that it barely took any tension from the magazine to engage the lrbho. But I'm working from memory here.

If you were short stroking, you'd want to have the bolt move further back. I wouldn't remove the bumper. But again, make sure that your buffer tube is the correct depth. Your stock should be able to lock in that very first position. If it doesn't lock, you are one turn too far.

-Zach

[HanzMcFeely]

I didn't play with mine at all, but when I first got it, i looked it over and the lrbho is definitely not the best engineered thing. I figured if (when) it broke, I'd deal with it at that time. I seem to recall that it barely took any tension from the magazine to engage the lrbho. But I'm working from memory here.

If you were short stroking, you'd want to have the bolt move further back. I wouldn't remove the bumper. But again, make sure that your buffer tube is the correct depth. Your stock should be able to lock in that very first position. If it doesn't lock, you are one turn too far.

-Zach

I dont really need the LRBHO honestly, its just a convenience that im used to and would like to make work. If i can get it working and it solves me feeding problems, even better.

As for short stroking (thats what she said): i dont want to remove the bumper from the buffer, just shave it down a few mm. If i pull the bolt allthe way back and hold it while manually locking the catch, theres a gap of a few mm or so between the parts.

My SBA3 doesnt lock at pos 1 on the buffer tube (6pos tube, brace is only long enough for 5pos according to SB tactical :shrug: )... its a standard milspec carbine tube that came with the 9Q buffer and spring. Ill grab some pics tomorrow morning of the tube>Buffer detent. Tube is only turned in far enough to catch the first couple mm of the detent and hold it in place. Worst case i’ll swap over to the tube that came with the SBA3

[smit308]

I had a similar problem with a colt mag 9mm setup. The bullets were getting stood up before they could get in the chamber. Also no last round hold open. Turned out that the mags were not seating high enough in the lower for everything to line up. It was only the tiniest amount, but once the mags seated a bit deeper, all the problems stopped. I don't know how how the Glock mag version is configured, maybe you could put a dummy round in and slowly cycle it while holding the mag up and see if that affects how the bullet slides into the chamber. Problems like this can be such a poa to diagnose. Hope it works out for you,

Smit

[HanzMcFeely]

I had a similar problem with a colt mag 9mm setup. The bullets were getting stood up before they could get in the chamber. Also no last round hold open. Turned out that the mags were not seating high enough in the lower for everything to line up. It was only the tiniest amount, but once the mags seated a bit deeper, all the problems stopped. I don't know how how the Glock mag version is configured, maybe you could put a dummy round in and slowly cycle it while holding the mag up and see if that affects how the bullet slides into the chamber. Problems like this can be such a poa to diagnose. Hope it works out for you,

Smit

Thanks Smit. Doesnt seem to make a difference if i push the mag up further. Still tries to chamber at 45*.

Some google searching suggests it could be the geometry of the feed cone on the barrel extension. I am getting the half moon crease in my cases when it FTF

https://www.ar15.com/forums/ar-15/He...2980/#i7292615

[jkl56]

Quick update:

I tried shimming with quarters in the buffer tube. No go on the quarters, it wouldnt lock the bolt back at all (too little travel to clear the bolt catch). That rules out short stroking, unless i need to take a touch off the buffer bumper.

I also tweaked the LRBHO and bent the mag follower tab down. Bench testing, no live fire It will lock open on an empty 33rd mag every time now. 17rd mags wont lock now. Its almost like the mag isnt putting enough upward pressure to push the lrbho bar at the bolt catch with enough force. I have to cycle it by hand violently to get it to lock 1/3 of the time on a 17rd mag. This setup is some serious short bus engineering.

Might try and pull the bolt catch and bend the tab for the LRBHO up a bit on that end. I dont see a spring in there and suspect the LRBHO lever acts as the bolt catch spring

On the bolt hold open, I had a similar problem with the bolt barely catching. It turned out that the bolt catch lever was not rotating enough to bring the catch high enough. If I remember correctly, the roll pin hole was ever so slightly off. Manually push the lever on the bottom to see how far it will rotate by comparing the gap between the top and the receiver.

[HanzMcFeely]

Pics of everything and how it all meshes up:










I kicked the LRBHO follower tab down even further still to apply more upwards pressure to the rear (bolt hold open) leg. Took the slop out of the bolt catch dang near entirely.

One thing ive noticed is that the “eyelets” for the lrbho bar are huge in comparison. Theres a lot of forward movement in that bar and the slot it sits in at the bolt catch has a lot of space to move. So the bar, when it moves forward, wnds up sitting right at the very edge of the bolt catch tab and makes it very sensitive when bolt is open. Im going to try pushing it back ans squeezing those “eyelets” shut a bit tighter. When a mag is inserted it pushes up on the tab, and the entire bar moves up

Its locking open perfect with 33rd mags now in bench testing. 17rd mags still wont lock open right, could be weak mag springs. They will lock open on empty 1/5 of the time on bench testing.

Have to go to the range today and live fire it now that its been tweaked. Trying 4 different 115gr brass case brands (cci, S&B, norma, federal black pack) and we’ll see what feeds correctly

[HanzMcFeely]

Live fire test, ~75x federal black pack 115gr fmj, 50x sig jhp 124gr, 10x Seismic 185gr Coated lead HP, 1x G9 124gr copper jhp

Sig ammo had difficulty feeding about 10rds, kept feeding low and pushing bullets into case. No more 45* feeding.

Federal 115gr fmj fed flawlessly. Seismic ammo fed flawlessly. G9 fed flawlessly.

Failed to lock open on empty mags all the time now, might be short stroking just a tad. I’ll trim off a tiny sliver of the buffer bumper to allow more travel.

Zero’d the vortex red dot. This thing is stupid accurate at 10-15yds. Sub MOA. Next trip i’ll run out to 50yds






A lot of near single hole shots and a nice tidy pile of brass. Ejection is excellent

Edit to add: pushing up on the mag allowed the bolt to lock back and feeding corrected itself with the Sig JHP ammo. This leads me to think its 2 problems: barrel feed cone geometry and mag well issue (either something out of spec with the lower or mags themselves)