Slowing down slide/barrel unlocking?

[EdMc]

Sounds about right. My 20LS slide weighs 20 oz, probably the same as your 21LS, just different scales. My RMR'ed G21 slide weighs 16 oz, and my G19 slide weighs 12 oz.

Yeah, I used some food scales with calibration referenced back to ...........China?  That's why I used the '~'.  Also, there would be a slight difference in the weight of the Glock plastic sights and the metal Dawson's on the LW long slide.

BTW, I ordered the cyl throat reamer to use on the Blackhawk. You'll bankrupt me yet. 

[Yondering]

Yeah, I have the plastic Glock sights on mine.

How's that 21 LS working for ya?

[EdMc]

How's that 21 LS working for ya?

It's not...as I posted in the original thread Lone Wolf has extended the backorder date till 5 Oct. from 24 Aug. on the threaded barrel.  I get the feeling they don't order from their supplier until they get X number of 'pre-paid' orders. A shame the OEM doesn't sell direct. heh........

[Mike_Fontenot]

  Beyond that and the slide will start to abuse the slide stop pin and frame when returning to battery.

Where on the frame does the potential abuse occur?  I know that the slide-lock pin contacts the forward-facing vertical portion of the barrel under-lug, and I THINK that's what normally stops the forward motion of the slide.  Also possibly (at least in some non-Mil-Spec 1911's) the slide is stopped when the slide contacts the barrel hood, and forces the barrel forward until it's stopped by the slide/barrel lugs.  So in that case, presumably there could potentially be wear on the barrel-hood/slide-breechface contact point, and/or on the rearward-facing slide lug surfaces and the forward-facing barrel lug surfaces.  But what part of the frame is potentially subject to abuse?  Maybe at the two  holes in the frame where the slide-lock pin goes through?  Or is my picture (from memory), of how all the parts move, mistaken?

[sqlbullet]

Where on the frame does the potential abuse occur? ...  Maybe at the two  holes in the frame where the slide-lock pin goes through?

That is the spot.  The slide stop pin holes will become oval over time.  Once that occurs a new frame is needed to correct the problem.  You will also see abuse in the barrel link, usually before the frame damage becomes severe.  That is a much smaller concern since the part is only a few dollars and is replaced with relative ease.

[Mike_Fontenot]

[...]  You will also see abuse in the barrel link, usually before the frame damage becomes severe.  That is a much smaller concern since the part is only a few dollars and is replaced with relative ease.

I would have guessed that the abuse in that case would be on the forward-facing vertical surfaces of the barrel under-lug (the two sides of the lug that the slide-lock pin smacks against when stopping the slide's forward motion).

As far as to abuse on the link itself (as opposed to the barrel under-lug structure that the link is attached to), where does the abuse typically occur?  In the hole that the slide-lock goes through, or the smaller hole where the link is pinned to the under-lug, or somewhere else?

My purpose here is to learn enough to know exactly where to look to spot wear before it becomes a big problem.  I need to know exactly what areas to closely inspect, in order to detect wear both from the slide slamming rearward AND slamming forward.  The rearward case might be the more likely in my case, because my gunsmith put a lighter-than-stock mainspring on my gun (18 lbs, in order to get a lighter trigger), and I've also stuck with the 18.5 lb stock recoil spring.  I also shoot full-power (commercial) 10mm loads.

[sqlbullet]

Yes...Lower hole the slide stop pin goes through.

18.5 should be fine, if you are running a flat bottom firing pin stop and a 25 lb mainspring.  You should not see any different wear to the frame with 10mm and that combo than with a stock 45 acp 1911 setup.

Slide is a different story.  The 1911 service life data is based on the 45 acp.  This cartridge operates at 21,000 psi for standard ammo and 23,000 psi for +P ammo.  The 38 super has identical service life data in 1911 as a gun running 45 ACP +P ammo.  This is because though the pressure is higher for 38 Super (36,500 psi) the area is less, resulting in the same actual force to be contained.

The 10mm is slightly more pressure than the 38 Super at 37,500 psi, but is also more area than the 38 Super.  This means the total force the slide/barrel lockup must contain is 30% higher for the 10mm than for 38 Super or 45 ACP.  The result is the slide will stretch and ultimately crack much sooner in a 10mm 1911 than a 45 ACP or 38 Super 1911.

That said, the service life for a 45 ACP slide is 100,000-150,000 rounds.  In 10mm a slide failure will probably occur before the 100,000 round mark, but well after the 50,000 round mark.  Having a slide replaced should cost at the most $400 including fitting by a good gunsmith.  That works out to about $0.008 per shot at the very high side.  Quite acceptable, and most shooters will NEVER put that many rounds through a gun.

[Mike_Fontenot]

18.5 should be fine [for the recoil spring], if you are running a flat bottom firing pin stop and a 25 lb mainspring. 

But that's my problem: my gunsmith reduced my stock 21 lb mainspring to 18 lbs, in the process of lightening my trigger pull.  I would like to take the advice to go with a heavy mainspring, but I don't want to give up that nice trigger ... it's a "catch 22".

Slide is a different story.  [...] The result is the slide will stretch and ultimately crack much sooner in a 10mm 1911 than a 45 ACP or 38 Super 1911.

Just to be sure I understand, does the slide tend to crack at the junction between the vertical surface at the aft end of the dust-cover and the upper part of the slide?  My understanding is that that vertical surface slams into the guide rod flange (which is already pressed against a vertical surface in the frame), and that's what gets most of the "stopping-load" of the aft movement of the slide.  I tried to mitigate that problem by installing a Wilson shock-buff, but immediately took it out because I could no longer "slingshot" my slide to manually chamber a round.

[Yondering]

18.5 should be fine [for the recoil spring], if you are running a flat bottom firing pin stop and a 25 lb mainspring. 

But that's my problem: my gunsmith reduced my stock 21 lb mainspring to 18 lbs, in the process of lightening my trigger pull.  I would like to take the advice to go with a heavy mainspring, but I don't want to give up that nice trigger ... it's a "catch 22".

You might want to explain to your gunsmith what you want, or find a better gunsmith. Reducing the mainspring weight works to reduce trigger pull, but is just a shortcut around setting the hammer and sear contact surfaces correctly. You can have a heavy mainspring and a nice trigger too.

[REDLINE]

The slide stop pin holes will become oval over time.  Once that occurs a new frame is needed to correct the problem.

Would it work to refill the ovals with JB Weld and redrill the holes out to proper size?

[Mike_Fontenot]

[...] Reducing the mainspring weight works to reduce trigger pull, but is just a shortcut around setting the hammer and sear contact surfaces correctly. You can have a heavy mainspring and a nice trigger too.

My current trigger pull is about 3-1/2 lbs.  I had asked him for 2-1/2, but after trying to accomplish that, he said he couldn't get it below 3-1/2 lbs and still be safe, because the sear-pin holes weren't quite positioned correctly ... about 0.002" off, he said.

Given a 3-1/2 lb trigger, with an 18 lb mainspring, and assuming that the other aspects of the trigger job were done correctly (which I suspect is the case, for my gunsmith's job), what do you think the trigger weight would be if I replaced my 18 lb mainspring with a 25 lb mainspring, with no other changes?

[sqlbullet]

I would guess 4lbs.  Mainspring weight really doesn't impact trigger pull that much if the sear and hammer have the proper angles in relation to each other.

Your mileage may vary, especially if the gun is out of spec.

[sqlbullet]

Would it work to refill the ovals with JB Weld and redrill the holes out to proper size?

I wouldn't want to trust such a gun.  A frame is only about $200 from a good vendor like Caspian, and relatively easy to fit a slide, barrel, etc to.

At such a low price, why risk JB Weld.

[Mike_Fontenot]

I would guess 4lbs [an increase of 1/2 lb].  Mainspring weight really doesn't impact trigger pull that much if the sear and hammer have the proper angles in relation to each other.

You were right-on.

This morning, I got my gunsmith to replace my 18 lb mainspring with a 25 lb one.  He measured the trigger pull before the change to be between 2-1/2 lbs and 3 lbs, and after the change he measured it to be between 3 lbs and 3-1/2 lbs ... about a 1/2 lb increase.  When dry-firing, I definitely can feel the increase, but I think I can live with it.

I'll probably be able to test it next weekend ... snowstorm predicted this weekend.   I THINK it will make the full power 10mm loads that I shoot easier on my gun ... it's noticeably MUCH harder now to rack the slide with the hammer down ... hard to get the motion started, which is exactly what I'm looking for.

I think the stronger mainspring (combined with the flat-bottomed firing-pin-stop) will also eliminate the firing-pin-wipe I've been seeing on my primer craters.  I had replaced the extra-strong firing-pin spring with an extra-extra-strong one, and it helped some, but didn't eliminate the problem.

Thanks for all the useful comments.

[Mike_Fontenot]

I think the stronger mainspring (combined with the flat-bottomed firing-pin-stop) will also eliminate the firing-pin-wipe I've been seeing on my primer craters.  I had replaced the extra-strong firing-pin spring with an extra-extra-strong one, and it helped some, but didn't eliminate the problem.

Surprising (to me at least), there was little if any reduction in the "firing-pin-wipe" on the edge of the primer craters.  The increase in the mainspring stiffness (from 18 to 25 lbs) was so large that I was almost certain that it would solve the firing-pin-wipe problem.  (This was with a (fairly) flat-bottomed firing-pin stop, and an extra-extra-stiff firing-pin spring).  I even saw it on a few casings of the fairly wimpy American Eagle rounds.

I'm out of ideas, so I'm going to try to ignore it, and hope it never causes me any problem.