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GP100 action binding


Fishbreath
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Posted (edited)
26 minutes ago, Fishbreath said:

 

I'll make some up for testing this week.

 

Are you crimping at all? If so, how much? I had a fairly aggressive taper crimp (with a 9mm die) set up from when I was running plated, which seemed to want it. Maybe the Ibejiheads aren't liking it?

I Taper Crimp my 38 SC's w/.358 bullets at .370".  Both Plated and Coated "can" be pierced with a heavy crimp.  Had a 45 200 Ranier separate in 2008 at the Nationals.  Just too much crimp, and it didn't help with bullet pull out either.

You still having leading, but is it still binding after the reaming?

Edited by pskys2
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Posted (edited)
48 minutes ago, pskys2 said:

I Taper Crimp my 38 SC's w/.358 bullets at .370".  Both Plated and Coated "can" be pierced with a heavy crimp.  Had a 45 200 Ranier separate in 2008 at the Nationals.  Just too much crimp, and it didn't help with bullet pull out either.

 

Hmm, that's a stronger crimp than I have (.357" bullets, crimped at .372").

 

I made some testers anyway, at .379 (+0.002), .377 (spot on), and .375 (-0.002), with the relative measurements being against the case around the bullet. Hoping to make a lunchtime run tomorrow to see if that buys me anything.

 

Also putting together a clip or two of .38 Special, just in case that makes a difference.

Edited by Fishbreath
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3 hours ago, pskys2 said:

You still having leading, but is it still binding after the reaming?

 

Yup, after 20-30 rounds it read was hitching, and bound up fully not long after.

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8 hours ago, Fishbreath said:

Alas, still fairly serious leading issues. I'm inclined to think the bullets, at this point, but as I said, I also had some trouble with Berry's pre-ream, which I'd expect to be a little more resilient to leading issues than coated.

 

2124434912_PXL_20210502_1804028352.thumb.jpg.ab57170e6ac6eac1c0a6311a731cfd06.jpg

 

Not quite sure where to go from here. Any ideas, beyond trying some other bullet sizes/brands?

Are you using a Lee factory crimp die?

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Yes, but as far as I can tell with calipers, it's not swaging the bullet at all. It's a 9mm FCD, so I think that would make the ring oversize for .38 Short Colt?

 

I made a few dummy rounds with a light crimp, and disassembled one of my existing loads, and saw this:

  • After bullet seating, the neck diameter is .379". Case walls are 0.010". A stock bullet is .358". (I had the size wrong previously—these are labeled .358" bullets.)
  • After a light crimp, the neck diameter is .377". The pulled bullet measures .356-.357" below the crimp line, and .358" above it.
  • After a moderate crimp, the neck diameter is .375". The pulled bullet measures .355" under the crimp line and .358" above.
  • After the heavy crimp I was using before, the neck diameter is .372". The pulled bullet measures .351" under the crimp and .358" above.
  • There's not very much distance between the crimp line and the start of the bullet's taper, so heavy crimping might be behaving a lot like an undersize bullet?
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16 hours ago, Fishbreath said:

 

I'll make some up for testing this week.

 

Are you crimping at all? If so, how much? I had a fairly aggressive taper crimp (with a 9mm die) set up from when I was running plated, which seemed to want it. Maybe the Ibejiheads aren't liking it?

I taper my 38 specials with a Redding taper crimp die. I taper my 9mm with a Dillon die.

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10 hours ago, Fishbreath said:

Yes, but as far as I can tell with calipers, it's not swaging the bullet at all. It's a 9mm FCD, so I think that would make the ring oversize for .38 Short Colt?

 

I made a few dummy rounds with a light crimp, and disassembled one of my existing loads, and saw this:

  • After bullet seating, the neck diameter is .379". Case walls are 0.010". A stock bullet is .358". (I had the size wrong previously—these are labeled .358" bullets.)
  • After a light crimp, the neck diameter is .377". The pulled bullet measures .356-.357" below the crimp line, and .358" above it.
  • After a moderate crimp, the neck diameter is .375". The pulled bullet measures .355" under the crimp line and .358" above.
  • After the heavy crimp I was using before, the neck diameter is .372". The pulled bullet measures .351" under the crimp and .358" above.
  • There's not very much distance between the crimp line and the start of the bullet's taper, so heavy crimping might be behaving a lot like an undersize bullet?

I'd bet that if you stopped using the FCD your problems go away. They're not meant for cast bullets.

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13 minutes ago, PatJones said:

I'd bet that if you stopped using the FCD your problems go away. They're not meant for cast bullets.

 

I guess I'll do a small batch without it, using the seat-crimp die to take the flare off, and add it to my list of things to test on my next range trip later this week, once the rain rolls through.

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I made it up to the range today. A light crimp appears to have helped—no stickiness in the trigger through 40 test rounds of varying but light crimp, and no bullet creep even with the no-crimp ammo. I'm not sure it 100% solved the problem, however. I think I still have a patch of lead in at least one chamber throat. It's either that or unusually heavy, unusually white powder fouling.

 

It was cold and there was rain coming, and I also wanted to put a few rounds through my M9 before I play in Production next weekend, so I elected to leave it for now and see what patches and No. 9 clean out when I get home. (Photos to come.) If they take most or all of the gunk out, I'm going to assume I'm on the right path. I may try seating the bullets a little higher still, and I have a Redding taper crimp die on order to replace the Lee factory crimp die, just in case that's it.

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So, straight out of the bag, I think the area around the forcing cone looks a little cleaner:

 

frame.thumb.jpeg.3073fec1eae87fcd9bf429d769a1d412.jpeg

 

The cylinder has some clear fouling on the front, and some drag marks, but it didn't get to the point where it was locking up. I forgot to bring moon clips, so I was shooting loose ammo, though, which may play into it.

 

cylinder-dirty.thumb.jpeg.8bbefd9b40aa0e9afc5da2cdb9b3d11d.jpeg

 

Running patches through cleaned out most, but not all, of the fouling in the chamber throats.

 

cylinder-patches.thumb.jpeg.4a5c91768eb5fd69c0954e62eae399bf.jpeg

 

To get them to pass a .358" pin gauge, I had to hit them with some Chore Boy strands wrapped around a bore brush. I'm not sure how much fouling is acceptable. Previously, I'd occasionally see shavings at the start of the chamber throat. I didn't this time, so that's probably good.

 

I'm going to make 100-200 rounds to my new recipe (1.23" OAL up from 1.195" to avoid crimping onto as much of the full-diameter bullet as I was doing before, crimp only to straight wall) and try a match that way, I think.

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Posted (edited)

I was smart, and decided to take my test ammo to a live-fire practice session before a match.

 

The practice went well (60ish rounds of the Doubles drill suggests my grip is in a much better place this year than it was last year, and gives me some confidence in blazing away at 7-10y open targets; over 40ish rounds of 30-yard shot calling, the shot calling was poor but the accuracy was still good).

 

The ammo test was a bust: I still had serious lead deposits that prevented the cylinder from turning freely after 40 rounds or so. This is with ammo that I'd call perfectly crimped, too. On a pulled bullet, the line from the case mouth is almost invisible under a bright light, and I very nearly can't feel it with a fingernail. Calipers say the crimp die isn't swaging the bullet down at all.

 

At this point, I have to suspect the bullet itself, don't I? The coating seems awfully thin. One of the bullets I pulled out of the box tonight (not sure if it went through the press or not) had some streaks on the side where it was missing altogether, and the lead beneath was visible. Perhaps a bad batch? I'm ordering a sampler of the SNS 160gr bullet of the same profile, and will see if the gun likes that, and maybe I'll see if I can find .357" FMJ in stock somewhere. It'll be a bummer if I have 1800 of these Ibejiheads that won't run for me, but less of a bummer than a gun that doesn't run, I guess.

 

The other thing I'm considering pursuing is cylinder shims (again), since a bound-up cylinder will turn freely if I give it a little nudge backward with my finger while thumbing the hammer back. I'm not sure that's going to work, though. The cylinder has plenty of endshake to shim out when it's fully closed, but the surface of the recoil shield has a rough texture where the ratchet traverses when opening and closing, and the cylinder seems to use all of the clearance available. When it's halfway closed, the front of the cylinder drags lightly against the forcing cone, and the ratchet drags lightly against the recoil shield. Adding a shim means that there isn't room for the cylinder to open/close, unless I'm installing it wrong.

 

Anyway, if the SNS Casting bullets don't help, this is looking more and more like a 'trip back to Ruger' kind of thing.

 

edit: Well, I would be ordering an SNS sample pack, but the order form's not working.

Edited by Fishbreath
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I loaded some on the previous trip, and they didn't seem to behave any differently.

 

Hard to say without running a good 50 or 60 through, though, and I only made 20 (among some other test ammo). It did stick a bit while running the .38 Specials, though.

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I managed to finagle a 0.002" cylinder shim in by opening and closing the cylinder a few times to smooth out whatever burr on the recoil shield was keeping it from working. Endshake is a lot lower now, 0.001"-0.002", and the B/C gap is just within within Ruger spec at 0.008". (According to Ruger experts, which I am not, they run wider B/C gaps than Smiths.)

 

I'd expect much less frequent locking-up problems with that much B/C gap, but I wouldn't expect it to do much for the leading problems. (Although Iowegan's Book of Knowledge for GP100s says that excessive endshake can cause timing problems, I don't think I had excessive endshake.) It also means headspace is extremely tight, which may cause its own problems.

 

Anyway, still on the trail of the lead issues. Hopefully the bullets (both flavors shipped this morning) give me something to go on.

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It's possible I've been barking up the wrong tree altogether. While the amount of lead buildup I'm getting is clearly problematic, and may still be the primary cause, I managed to reproduce some of the symptoms with a clean gun and fired cases at lunch today. The firing pin was stuck forward. Sometimes, the shape of the dent in the primer allowed it to push the firing pin back into place as the action turns the cylinder. Sometimes, it stayed forward, effectively locking the cylinder in place. Pushing the cylinder out with my fingers was enough to pop the firing pin back in all cases, but the leverage from pulling the trigger or thumbing the hammer didn't seem like enough if it was seriously jammed up.

 

I don't know if this is a particularly likely failure mode in live fire, given the forces involved, but it's certainly worth investigating. This gun, like other late-model Ruger DA pistols, has a screw-in firing pin bushing, and Bowen makes a tool, so hopefully in a week or so I'll be able to open things up and see if there's some grit in there causing part of my trouble.

 

It would explain a few things:

1. Deep cleaning the cylinder and forcing cone didn't make a huge difference in how quickly things got bad.

2. I've been having light strikes lately.

3. Pushing back on the cylinder would free things up.

 

Like I said, I'm not really convinced this is the root problem, but it's plausibly a contributing factor, at least.

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2 hours ago, Fishbreath said:

It's possible I've been barking up the wrong tree altogether. While the amount of lead buildup I'm getting is clearly problematic, and may still be the primary cause, I managed to reproduce some of the symptoms with a clean gun and fired cases at lunch today. The firing pin was stuck forward. Sometimes, the shape of the dent in the primer allowed it to push the firing pin back into place as the action turns the cylinder. Sometimes, it stayed forward, effectively locking the cylinder in place. Pushing the cylinder out with my fingers was enough to pop the firing pin back in all cases, but the leverage from pulling the trigger or thumbing the hammer didn't seem like enough if it was seriously jammed up.

 

I don't know if this is a particularly likely failure mode in live fire, given the forces involved, but it's certainly worth investigating. This gun, like other late-model Ruger DA pistols, has a screw-in firing pin bushing, and Bowen makes a tool, so hopefully in a week or so I'll be able to open things up and see if there's some grit in there causing part of my trouble.

 

It would explain a few things:

1. Deep cleaning the cylinder and forcing cone didn't make a huge difference in how quickly things got bad.

2. I've been having light strikes lately.

3. Pushing back on the cylinder would free things up.

 

Like I said, I'm not really convinced this is the root problem, but it's plausibly a contributing factor, at least.

My wife's 627 broke the firing pin return spring and suffered intermittent strange lockups, like cant pull trigger cant open cylinder then I would look at it and it would be fine, so while rare it does happen and when the pin is forward it locks up hard till it doesn't then you don't know what you are chasing, I spent way too long looking for the problem. 

 

 

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Definitely seems plausible, then. Thanks for the added datapoints, guys.

 

I'm headed up to the range tomorrow with a batch of JHPs, a batch of .38 Special SNS 160gr RN, and a batch of .38 Short Colts with same, to see how the leading looks between those setups. If I have problems, I'll see if I can see the firing pin between the cases and the recoil shield.

 

If I can't, I guess I'll update when the Bowen tool arrives and I have some spare time to get the bushing out.

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12 hours ago, Fishbreath said:

Definitely seems plausible, then. Thanks for the added datapoints, guys.

 

I'm headed up to the range tomorrow with a batch of JHPs, a batch of .38 Special SNS 160gr RN, and a batch of .38 Short Colts with same, to see how the leading looks between those setups. If I have problems, I'll see if I can see the firing pin between the cases and the recoil shield.

 

If I can't, I guess I'll update when the Bowen tool arrives and I have some spare time to get the bushing out.

Jacketed bullets and lead in the same session? That could be done of your problem.

 

I won't switch between lead and jacketed without cleaning the barrel in between. Copper, once deposited in the barrel, attracts lead. I find it much harder to clean the lead fouling out when it's stuck to copper fouling and the leading builds up faster and thicker. Any lead in a clean barrel pokes right out with a little Kroil. It's a pain to get copper out, especially if there's lead deposited on top of it. The copper solvents don't work as well when there's layers of lead and copper in the barrel.

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To my recollection, I haven't gone straight from jacketed to plated/coated in the same range session, but thanks for the heads-up. I need to get a can of Kroil, sounds like—how does it compare to PB Blaster, say? Similar results, or is Kroil better at getting lead out for whatever reason?

 

I decided to call off the trip today anyway. With the reduced endshake from the cylinder shim, there's a lot less room for the cylinder to move around a stuck firing pin, so I figure it's better to wait until I can pull the firing pin and take a look.

 

Thank goodness Ruger switched to the screw-in bushing. Otherwise it would've been a back-to-the-factory thing, and I don't have enough 9mm to mess around in Production for more than another match or two, and on top of that, removing all the non-stock springs so Ruger doesn't remove them for me is a pain.

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