p80 rails unaligned causing slide binding

JimNorth · Jan 8, 2019

I built a Polymer80 PF940 V2 (full size) using a Brownells slide and otherwise all OEM parts including barrel. The front and rear rails are not in line. This causes binding of the slide. The result is the system will not always go into battery. Lubing and working the slide per P80 advice has not helped.

A way to visualize the problem is by placing a straightedge on the rails. One sees light instead of solid contact along the front and rear rails.

Several days ago I opened a ticket at P80. So far they haven't replied so I thought maybe people here would offer their thoughts.

I have a lot of photos but wanted to see if they'd be useful before uploading them.

I'd also be happy to show it to someone. It's a firearm now so probably a range would be the best bet. I go to AGC regularly if that's convenient for anyone. I've heard you're not allowed to help someone build a firearm so please let me know if this in-person idea is a bad one. This is already built and fires so I thought it would be OK to get someone's opinion as to the problem.

cantstop · Jan 8, 2019

Lot's of good info in the Polymer 80 compact thread. You might want to start with post #224

https://www.mdshooters.com/showthread.php?p=4748766#post4748766

Racer Doug14 · Jan 8, 2019

Also, contact Polymer 80. They might help you out of your problem. It's with a try, they have been very good to others here.

Rambler · Jan 8, 2019

Check the front rail metal insert to see if the pin holes are aligned. Apparently, some were made where one hole was higher than the other. If the pin was difficult to insert and remove, that may be the problem. Pin hole misalignment in the frame can cause the same problem.

Muleskinner · Jan 8, 2019

contact their customer service. The frame has a very good warranty and they will send you another after you send proof that you destroyed the original.

JimNorth · Jan 9, 2019

cantstop said:
Lot's of good info in the Polymer 80 compact thread. You might want to start with post #224

https://www.mdshooters.com/showthread.php?p=4748766#post4748766

Yes, a lot. Thank you.

JimNorth · Jan 9, 2019

I've been in contact with P80 several times. This build is the result of a new frame and "in spec" locking block and rear rail parts. Now I'm waiting for a reply to this problem as mentioned in the OP. I called them on Tue. They said they're behind on answering. I'll update here when there's news from them.

JimNorth · Jan 9, 2019

Here are photos of the front pins and rail. Do they seem OK? And how about the joint of the metal and polymer just above the upper pin?

The front pins went in fairly easily. The rear was hard.

Rambler said:
Check the front rail metal insert to see if the pin holes are aligned. Apparently, some were made where one hole was higher than the other. If the pin was difficult to insert and remove, that may be the problem. Pin hole misalignment in the frame can cause the same problem.

sinensis · Jan 9, 2019

I'm up in Columbia with a working PF940V2, I'd be happy to come take a look at it. I can bring my slide as well and test fit it on yours. PM me if you want to meet up?

revobreaker · Jan 21, 2019

Any word on how this turned out?

I am running into a similar problem. I think my front rail block is out of spec. I grabbed another, installed it and the slide works like butter now.

When installing the slide on the bad rail, the rear of the slide would hit the frame before getting to the rear rail, and the nose of the slide would be pointed way up. Straight edge across the rails confirms the front rails were high in the front.

How were you able to determine your rails are in spec?

Have not contacted p80 yet, wanted to do some research and also measure the two rails to compare.

Your front piins look the same as mine. May be the angle of the picture but your rear rail looks like it is riding a little high.

sinensis · Jan 21, 2019

His rear rails did look a little high, we didn't have calipers on site to measure. Also his slide is a bit more tighter on tolerances than my Swenson one is. But I have over 3k rounds through mine. Also I believe the connector isn't being pushed far enough by his slide causing light primer strikes when the slide returns to battery. I was going to check with a Glock Armorer at work when I can catch them in the office to see if my theories make sense.

JimNorth · Jan 22, 2019

Prior to the problem in the photos I had a different problem and contacted P80. They looked at earlier photos and determined my locking block rail system (LBRS) and rear rail module (RRM) were out of spec. They sent these new ones I'm using. I couldn't get numbers from them.

After looking at these new photos, they said it looks like both arms of the RRM are up a bit too high. That's consistent with your observation and similar to that of sinensis after he looked at mine live. They're going to send me new in-spec parts.

In the meantime I filed down the right front of the RRM which is where sinensis thought the problem was. Now the slide is much smoother and consistently goes into battery. Using the orange end plate, I can see the trigger functioning as I think is expected. There is still a bit of a "bump" as the slide forces the connector over. I don't know if that's normal.

I plan to test fire this week. I'll let you both know what happens. You're welcome to take whatever measurements you'd like of my stuff.

revobreaker said:
Any word on how this turned out?

I am running into a similar problem. I think my front rail block is out of spec. I grabbed another, installed it and the slide works like butter now.

When installing the slide on the bad rail, the rear of the slide would hit the frame before getting to the rear rail, and the nose of the slide would be pointed way up. Straight edge across the rails confirms the front rails were high in the front.

How were you able to determine your rails are in spec?

Have not contacted p80 yet, wanted to do some research and also measure the two rails to compare.

Your front piins look the same as mine. May be the angle of the picture but your rear rail looks like it is riding a little high.

sinensis said:
His rear rails did look a little high, we didn't have calipers on site to measure. Also his slide is a bit more tighter on tolerances than my Swenson one is. But I have over 3k rounds through mine. Also I believe the connector isn't being pushed far enough by his slide causing light primer strikes when the slide returns to battery. I was going to check with a Glock Armorer at work when I can catch them in the office to see if my theories make sense.

sinensis · Jan 22, 2019

If it's the bump I'm thinking about, that's normal, it pushes the connector over to allow the trigger to reset.

revobreaker · Jan 22, 2019

Good luck with your test firing.

I put a ticket in with p80 hopefully they come back with good news.

The batteries in my calipers are dead, so I will have to wait to try measuring mine.

JimNorth · Jan 24, 2019

I test fired yesterday. The filing job I did seems to have made a difference. I fired over 350 rounds of five types of ammunition. I got two light primer strikes with S&B, one failure to eject with Win NATO, and two failures to feed with Federal. Zero failures with Win White & Magtech.

The failures where within the first one hundred rounds or so. Then I cycled through the five types with no further failures. At this point I'll just note any failures but don't think it's something to investigate.

However a new problem has surfaced: The slide stop lever is so close to the frame that pulling the slide back to release it no longer works. Depressing the slide stop lever does charge the pistol. Any ideas?

And an occasional problem reoccurred: forcefully seating the magazine once in a while releases the slide when locked back. Thoughts?

revobreaker · Jan 24, 2019

Do you have multiple mags? Might want to test each of them to make sure the follower is engaging the slide stop properly to completely seat it in the slide. Could be a particular mag that isn't working right.

But if the slide stop is binding on the frame that that could also prevent it from engaging the slide properly.

Might also want to make sure the spring on the slide stop is working properly. Can you move it freely without much resistance when the slide is removed? Maybe it got dirty?

But I've had the slide 'auto release' when slamming a mag in on other guns, it's not necessarily a problem..

JimNorth · Feb 6, 2019

I don't have multiple magazines yet. I hope to soon. I cleaned everything. The slide stop lever wasn't binding on the frame. I couldn't reproduce the malfunction cycling several magazines of dummy rounds.

I tried shooting it this week. After four magazines of fire I thought the problem was gone when slingshot chambering stopped working.

Out of more than 300 rounds this week, I had three failures to feed and three clicks with no bang. The primers were struck and the rounds fired when hit again.

I'll try the new RRM that I received from P80 to see if it will help with the FTF and primer strike problem. For the slide stop lever I'm left with trying new magazines, changing the slide stop lever & spring, or ...?

Bert762 · Feb 8, 2019

My expierence with poly80 has been positive, when I have had a problem they corrected it. Had one lower I waited 6weeks for a new front rail, theywhere on back order. Rail arrived and all was good. I have built quite a few and they have always turned out as smooth as butter between the upper and lower. Good luck and have patience they do stand by their products.

JimNorth · Feb 8, 2019

Bert762, Thanks for your comment. Today I reassembled the lower with the new RRM. It seems smooth. And I couldn't reproduce the slide stop lever problem which is good. I plan to test this weekend.

p80 rails unaligned causing slide binding

The #1 community for Gun Owners of the Northeast

Member Benefits:

Active Member

Pentultimate Member

Thread killer

Doing the best with the worst.

Ultimate Member

Active Member

Active Member

Active Member

Attachments

Member

Active Member

Member

Active Member

Member

Active Member

Active Member

Active Member

Active Member

Member

Active Member

Users who are viewing this thread

Log in

Forum statistics