Get lots of calls about doing a Glock lower for the 9r in DI. I tell them technically it will work, but it will be more expensive than a magazine.
While on break between barrels today I put my TCM pistol upper on a PSA Glock lower with the ejector removed. The BB mags sit up higher than DI mags and the single feed Glock is narrower than even the Uzi style mags. I did an Uzi adapter DI conversion once and its a lot of work.
Worked over the bolt and carrier and it will hand cycle with the mag in there, but.... still need some mods to see if it will work.....
It takes some work on the BCG to get everything to clear the feed lips and I was concerned the mag was too high, but the single feed mag tucks up inside the modified carrier and bolt better than I thought.
Spent the weekend on the Glock TCM 9R lower. Got things hand cycling better and messed with mag heights and angles a bit. Things would work for a while then get the dreaded nose high jams. Messed with that a bit then pulled the barrel off and cycled the system with no barrel to see if I could capture the action on my camera. Wish I could slow it down more, but the bottom line is: with no barrel, the shells come out of the upper with the nose in the air. I believe its part the bottle neck design of the case and the high attack angle of the mag that is causing it. As the bolt moves forward and picks up a round, things are fine until the rim hits the shoulder of the round below it. This allows the feed round rim to drop and points the bullet up in the process. Can't get it on video, but I would bet a cold beer that's the problem. I know with PPs-43 mags, the feed lips would grab the rim if they were sharp. To counter act that motion we need to rotate the mag forward in the magwell so the feed round sets more horizontal (like our mags do... that still have nose high jams...)
So, to test that theory, I machined out the magwell of the Glock lower to let the Glock mag rotate a couple of degrees forward. Again, sometimes it would feed good, sometimes not.
Throughout the weekend, I was getting more and more failures to chamber... rounds would feed and just stop dead. Polished the bolt and extractor and then took a good look at my used brass rounds.... I keep saying the TCM brass is soft and the rims were pretty beat up so I hit them with the polishing belt to clean them up. Looking at the reloads with the 9r bullets, the necks looked like crap. I pulled the seating die apart and modified the seater to better fit the round 9r bullet and polished up the inside of the die. After a few more adjustments, the rounds came out much better. And less dragging on the shell holder with the polished rims. Then I pulled the barrel and polished up the chamber some more.
The failures to chamber went down after that.
I had two glock mags to try and again, sometimes they would feed great, sometimes, nose high jams. So, I ran out of reloads and contemplated my next move....
The TCM mag... It almost fits in the PSA glock lower.....
I ran out of the 9R reloads for the Glock so set up the lower in the mill and went after it...…
I ran two mags of the TCM reloads through it with ZERO failure to feed, and ran out of ammo.... I had some 33gr spitzers loaded that I re-set down to 1.28" and swapped out a new upper to see if it would have an effect on feeding. Fed 100%. Sure feels good to have something work!
The TCM mag will need a new notch cut in it, or machine a new Mag Release for the lower..
Got confirmation from customer with couple original BB barrel set ups: Stock rounds blow up - made TCM from 556 brass and has run 200 rounds through his glock lower TCM blowback. Now if we can get Armscor to make decent brass, we'll supply barrels.