The PX4 Compact might be my DA/SA Glock 19

[perlslacker]

Y'all, I swear to God I'm snakebit with PX4s.

I had issues with my original PX4CC returning to battery 5 years ago when it was new. It eventually wore in, somehow, and has been very reliable through several years of practice, a handful of classes, and a match or two.

Fast forward to this year. I had previously grabbed a PX4 Compact off Gunbroker for cheap; I'd shot it a bit to be sure it functioned but mostly it sat in the safe. It did the same FRTB thing I'd experienced previously, but I noticed a lot of carbon buildup (and no lube) on the locking block so I chalked it up to the previous owner not knowing how to maintain the gun. I cleaned it up and it mostly sat in the safe. I also replaced the recoil spring just as a matter of course.

Then I sent the slide to LTT to get cut for an EPS, and the frame to Boresight for texturing. Now I finally had a reason to shoot this pistol for real, and so it started making it out to the range. Unfortunately, the pistol just doesn't run. It fails to return to battery in the same way that my first one did, but worse. I found this video where the author had the same issue, and someone from Beretta CS (who's now FN CS, I think) told him that PX4s had some kind of coating that could make them malfunction. So I hit the feed ramp with a stiff copper brush and some solvent. On the next range trip, it was a little better (it ran a box of SIG FMJ and a mag each of 124gr HST and 147gr HST without complaint) but after a box of S&B 124 it jammed with everything. Disassembling the pistol and using a toothbrush on the feed ramp and other contact surfaces did not help.

I compared the new and old PX4s, and the only difference I could find is the feed ramp. Here's the old one:


And here's the new one:


There's some plastic flashing around the edges of the metal feed ramp insert on the frame. It's possible, I think, that rounds running over the feed ramp dislodges some of the plastic and it gets in the way of a feeding cartridge. Then the stiff copper brush I cleaned it with broke some off. More rounds broke off more plastic when shooting, but the toothbrush I have in my range bag wasn't stiff enough to dislodge it so it didn't help.

Has anyone else had this problem? I'm kinda at my wits' end with this gun. I took an Exacto knife and cut the excess plastic from the edges of the metal insert but I haven't test fired it yet.

E: I also noticed that the new (new to me, it could have been made earlier) PX4 has a defined ramp in the polymer in the center, while the old one doesn't. IDK if this is a rolling change that Beretta made in the frame or if my old one just got worn away.

[perlslacker]

I should add that I don't think LTT or Boresight did anything to cause this.

[CraigS]

I remember several threads over the years describing this problem w/ the plastic. I don't remember exactly the best solution though. Maybe post the Q on the b forum?

[PX4 Storm Tracker]

I should add that I don't think LTT or Boresight did anything to cause this.

Though it is difficult to guess from here, your description is detailed enough to take make some suggestions.

With 1911s (especially) and many other pistols the feed ramp is a source of possible loading issues. With PX4 Storms I have found that it is not usually a contributing factor. I have seen some feed ramps that look like they have been in a fight and some that remain smooth and fine. They all load the same.
The incoming round will quickly bounce off the metal insert and contact the feed ramp built into the barrel.

So, failure to get past the feed ramp or getting stuck on it is different from failure to go all the way to battery. Yes, it seems conceivable that pieces of polymer are getting in the chamber, but it seems less likely and would run out of polymer to come off after a few rounds of that. I have also seen polymer damage that was more extreme from a blown barrel, that did not affect feeding. It would be good to make sure that under the extractor claw is clean.

Once the round is far enough in to be a failure to go to battery, it is past the ramps, anyway. The only time we have found FRTB (especially with a new rebound spring) is because of lubrication. It usually is helped with a ring of grease around the cam lug and some in the barrel's cam slot. Of course, some lube on the rails and barrel tube help, as well. This post goes into more detail of lubrication suggestions: https://pistol-forum.com/showthread....ull-size/page3 post 27

I would not rule out the possibility that something in the re-finishing of the slide might be a factor. There have been more reports lately of issues after getting slides refinished.

[medmo]

How is it not retuning to battery? When is it failing?

[perlslacker]

Though it is difficult to guess from here, your description is detailed enough to take make some suggestions.

With 1911s (especially) and many other pistols the feed ramp is a source of possible loading issues. With PX4 Storms I have found that it is not usually a contributing factor. I have seen some feed ramps that look like they have been in a fight and some that remain smooth and fine. They all load the same.
The incoming round will quickly bounce off the metal insert and contact the feed ramp built into the barrel.

So, failure to get past the feed ramp or getting stuck on it is different from failure to go all the way to battery. Yes, it seems conceivable that pieces of polymer are getting in the chamber, but it seems less likely and would run out of polymer to come off after a few rounds of that. I have also seen polymer damage that was more extreme from a blown barrel, that did not affect feeding. It would be good to make sure that under the extractor claw is clean.

Once the round is far enough in to be a failure to go to battery, it is past the ramps, anyway. The only time we have found FRTB (especially with a new rebound spring) is because of lubrication. It usually is helped with a ring of grease around the cam lug and some in the barrel's cam slot. Of course, some lube on the rails and barrel tube help, as well. This post goes into more detail of lubrication suggestions: https://pistol-forum.com/showthread....ull-size/page3 post 27

I would not rule out the possibility that something in the re-finishing of the slide might be a factor. There have been more reports lately of issues after getting slides refinished.

A quick note about lubrication: I’ve ran my old PX4 for 7-8 years and have followed Ernest’s “how to lubricate a PX4” video for most of that time. The cam block, slide rails, and bearing surfaces where the barrel interfaces with the slide all have a healthy coating of ALG lube on them. I’m confident that insufficient lubrication isn’t the issue here.

I had considered that cerakoting the slide could have increased friction. On my old PX4, reliability dramatically improved after the barrel lugs wore through the Cerakote on the slide. However, those surfaces are already pretty shiny so I’d ruled that out.

I brushed under the extractor hook, because I thought the case rim might have had trouble sliding under the extractor. I might try pulling the extractor to make sure I get it cleared out under the hook.

[revchuck38]

FWIW, I sent one of my PX4 slides to LTT for the RDO cut, and they ceracoated it after doing the machining. I’ve put more than 500 rounds through it since I got it back with zero issues.

ETA: The date on the slide was IT17, don’t know if that matters.

[PX4 Storm Tracker]

A quick note about lubrication: I’ve ran my old PX4 for 7-8 years and have followed Ernest’s “how to lubricate a PX4” video for most of that time. The cam block, slide rails, and bearing surfaces where the barrel interfaces with the slide all have a healthy coating of ALG lube on them. I’m confident that insufficient lubrication isn’t the issue here.

I had considered that cerakoting the slide could have increased friction. On my old PX4, reliability dramatically improved after the barrel lugs wore through the Cerakote on the slide. However, those surfaces are already pretty shiny so I’d ruled that out.

I brushed under the extractor hook, because I thought the case rim might have had trouble sliding under the extractor. I might try pulling the extractor to make sure I get it cleared out under the hook.

I believe that I remember a previous discussion about lubrication that we had had before. You have reminded me of that now.

[perlslacker]

I believe that I remember a previous discussion about lubrication that we had had before. You have reminded me of that now.

You’re good. I don’t expect people to remember one-off Internet conversations from years ago :-D

[perlslacker]

I did some more digging on my problem child PX4C and noticed that the extractor would barely move when I tried to wiggle it by hand. My other PX4’s extractor was firm, but would move with finger pressure pretty easily.

I took the extractor out and cleaned the extractor & extractor channel. It moves much better now. Hopefully that fixes it.

I had thought that the extractor might be the problem for a while but I had avoided looking at it because I didn’t want to take the optic & plate off :-P