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Old December 3, 2018, 03:38 AM   #1
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Join Date: October 31, 2009
Location: Ohio
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Barrel fitting: slide hesitation

Hey all, I’ve just about completed a polymer 80 Glock 19 build.

- resolved. I added oil, I racked the daylights out of it pointing down at a 45 degree angle, and then down towards the floor, and repeated several times. The hesitation and slide getting stuck stopped today no matter the angle. There is now a palpable burr at the forward lockup interface on the top of the barrel, and bits of the oxide finish (what I'm guessing is the blackened finish) were coming off and coloring the oil I added/wiped black. The slide and barrel just needed to interface and deform to match normal operation. Dropping the slide from slide lock also sped things up I believe. I've learned that a rough finish may not mean just burrs, sharp corners, or machine marks, but also the lapping/polishing left undone may make for a longer break in period with dramatic changes. Thanks for the advice to hold back, that turned out to be very correct.

--------old problem below------
When I point the pistol downward while racking / cycling the slide there is enough hesitation on the forward travel to delay going into battery. Resistance occurs mostly at the start of forward motion. I can see the barrel travel forward a little before resistance is felt. Racking slide with pistol held level is smooth with no hesitation.

I suspect I need to file the barrel part that rides on the locking lug. Thoughts ?

Last edited by dyl; December 4, 2018 at 06:30 PM.
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Old December 3, 2018, 07:19 AM   #2
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Put away your file!! Use only some fine abrasive paper. A burr of only 0.001"
can seriously effect operation of the gun. As it's a new gun or mod just some shooting may cure the problem . Some can be improved with lapping compound.
And Watson , bring your revolver !
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Old December 3, 2018, 09:11 AM   #3
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Location: Ohio
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The first thing to try is just burnishing. Oil the gun and the top inside of the slide a bit excessively with very light mineral oil, like honing oil, or even just dip the assembled gun in mineral spirits, and then rack it by hand, replenishing the oil or mineral spirits when it starts to stiffen. After a hundred cycles or so, clean it and put a proper lube in and see if the problem is still there. If it is, by then there should be rub marks visible where the fit is off and in need of deburring or polishing.
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Old December 3, 2018, 05:52 PM   #4
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Ok, will try burnishing, firing / break in period, then if that doesn't work will consider abrasives. I had polished the locking lug of the barrel already by Mothers Mag, but the matte finish of the slide is still present since I haven't racked it much (Daddy what are you doing in the office?)

Just for documentation sake I'll state the other tweaks I had to do in case it can help others.

Polymer80% pf940c "ready mod" black frame (untextured) Glock 19- had to redrill the holes with frame inserts present as I believe the jig holes didn't line up perfectly with fully inserted frame parts, or drilling by hand (as instructed) I was not able to drill straight.

Rear rails too high - an occasional phenomenon by internet search, my rear rails higher than front by ~0.025 inches. Less resistance when rear rail insert removed and stoned on generic coarse/fine bench stone. Polished with Mothers Mag by hand. Now nearly same height as front rails but it may be enough. Less wiggle than some stock factory pistols at rear rail. Perhaps this is an issue with the rear rail insert pin being positioned too high by the jig. Or maybe just tolerances, or my own handiwork.

Swenson Slide - bought at record low price by my observation ~$130, right angle next to breech face not cut cleanly on non-extractor side. Instead of filing it to be a cleaner angle, I left it and filed a rear edge of the barrel to get a hand fit. Inserts without pressure but does not wiggle. Of note, the top of slide and barrel are not flush against each other although the barrel is in full lockup.

Slide binding on initial assembly and when racking - make sure channel for recoil spring is milled (dremeled / filed / shaved) completely, smoothed edges briefly with Dremel's buffing wheel. cut the tiniest of bevels on guide rod edge

Takedown Spring not fitting deeply enough - caused slide binding issues. In my case this may have been a poorly made OEM spring, the short side that fits in to the frame had a forward curve in it that videos appear not to have. I filed the offending tail flatter so the overall shape was straighter. Spring fit flush into the frame after this. Others in videos filed from the bottom decreasing the overall depth of the spring. I found that unnecessary. Perhaps the P80 frame was not cast in a way to accommodate this forward (towards the muzzle) bend in the spring but accommodate straight springs better.

Last edited by dyl; December 4, 2018 at 06:23 PM.
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