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Old September 22, 2014, 11:23 AM   #26
RickB
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Wilson Combat installs square (reduced radius, anyway) FPSs on their 10mm pistols, so it's not just a theory cooked-up by hobbyists.

Quote:
The radiused FP stop is an improvement specified by the US Army Ordnance Department
I don't know that a response to, "Hey, some of the guys would like you to make the slide easer to rack" would necessarily result in an improvement?
It's just as likely that it was decided that changing the FPS from its original configuration would not be detrimental enough to the gun's performance to deny the request.
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Old September 22, 2014, 02:38 PM   #27
polyphemus
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Quote:
"Hey, some of the guys would like you to make the slide easer to rack"
That sounds like an apocryphal story.And rather disrespectful too.
The U.S.Army was looking to deploy a solid reliable sidearm and it is unlikely
they took into account frivolous requests from "some of the guys".
Revising history does not change it.The fact that a custom pistol smith installs
square bottom stops does not alter one bit the fact that for many decades the radiused FP stop has been the standard of manufacture and it remains so on account that it works.
If you have objective evidence that a squared bottom FP stop is functionally
superior then bring it out for all to study.
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Old September 22, 2014, 06:41 PM   #28
RickB
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The M1911 had been deployed already for five or six years when the change was made to the larger radius.
Later still, the army decided that it would be an improvement to shorten the trigger and replace the flat mainspring housing with an arched one, but 100 years later, there is hardly a 1911 variant on offer than doesn't have the original long trigger and flat housing; change doesn't necessarily mean improvement.
If you like your gun in its current configuration, good on ya'.
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Old September 22, 2014, 08:12 PM   #29
polyphemus
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current config.

I was thinking that doing away with the trigger finger relief cuts might be the
newest retro fad,who knows? there may be folks who'll claim it improves
accuracy and functionality.I just can't find in my heart to add one of those
funky icons at the end of this.
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Old September 22, 2014, 08:57 PM   #30
James K
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Probably the silliest "improvement" to the 1911 was the full length guide rod, which not only served no useful purpose except to make the sellers rich, but was the direct cause of the expensive and complex "firing pin blocks" now required on almost all 1911 clones, not to mention making the gun much more difficult to disassemble for cleaning.

Yet some people still swear that the FLGR does this or that and makes something or other so much better.

Jim
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Old September 22, 2014, 10:58 PM   #31
HiBC
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When I worked over my Randall Raider 70's Commander clone,I "improved it" by eliminating the guide rod.We agree.

And,with a 10mm build,as with a 460 Rowland build,the envelope is being pushed.Tradeoffs get made.We give up this to get that.

Perhaps(I do not know) a squared off FP stop lessens frame cracking at the slide stop,trading off ease of racking and maybe extra stress on the pins...

And maybe(I don't know) the gun is in trouble at 3000 rds.

Hotrodding engines,big cams make more high rpm horsepower,but,higher valve speeds require stouter springs to keep the valves off the pistons,loads go up,pushrods fail,the oil has a harder time protecting cam lobes....

For hotrodding purposes,the squared off stop offers something,but there is no free lunch.

Unless you have good reason,there are some "gentle" to be gained from the radius stop,

Last edited by HiBC; September 22, 2014 at 11:06 PM.
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Old September 23, 2014, 10:31 AM   #32
polyphemus
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Quote:
higher valve speeds require stouter springs to keep the valves off the pistons,
That is why you have the desmodromic system.
No free lunch for sure.But empirical evidence suggests that the standard FP stop
is the right part for mil spec pistols.As far as the squared bottom stop goes there are no dimensions specified for the attack angle if it is an angle at all it could well be a radius,and the part that is sold aftermarket is over size causing it to be forced in place by many owners who wish to lock the extractor over perceived rotational play issues.The best explanation I know of so far is that it
harkens back to the original design.
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Old September 25, 2014, 10:42 PM   #33
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Wow some interesting points.

I have to admit that I approached the square slide stop idea with some questions. Frankly I believe very little that I read if I can not see / try / feel and appreciate in real life.

Seeing that Wilson among others whom I respect were putting them on some of their guns convinced me to give it a try. Not that I am a Wilson fan boy but they do have my respect for design and build quality. Not that I worry too much about my guns that don't have them yet...

To my mind no matter how you model it -- either as leverage or contact area you end up with the hammer exerting more force on the slide when the hammer is forward and thus retarding unlocking, slightly.

As other have mentioned the cycle is violent with the hammer bouncing about so to some degree intuitively we look at a regular slide stop vs. a square one and figure there must be more wear or some other effect between the square profile and the smooth / rounded one, in fact there seems to not be.

For me I do think that it slightly delays unlocking and decreases recoil a small amount. It does also make the slide a bit harder to rack but if you have racked a 10 mm or 45 super or whatever it is not up to that level. I would love to set up a gun and just drop in a regular and a square profile and measure the force needed to rack it to evaluate more precisely the change from one to the other.

I find it very believable that the slide stop change was due to the ease of racking the slide, given that military doctrine at the time (as well as for most of the 1911's service) was to carry the piece empty and rack it when drawn. Given that it was still in use by mounted troops I would want anything possibly to ease / speed the deployment of the weapon.

In addition regardless of if JMB loved or hated the idea at the time slides were not heat treated and considered a wear item so I do not think much debate went into considering if a minor change like this might amount to much.

As to clocking, if your cases eject all over the place SOMETHING is changing in the cycle of the gun. Often eliminating clocking seems to change this. Or so I have seen. I have to assume if you can move the extractor any amount that the hand / eye can observe then during the firing cycle it must be a bit more.

Or so I see it that way. I enjoy thinking of these things. My try a few clocking trials with some dychem next time I hit the range.
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Old September 26, 2014, 03:24 AM   #34
DAVID NANCARROW
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Rsq, I too approached the idea of a square bottomed stop with a lot of questions even though I had read a lot by folks here and on other sites who said it was a worthwhile addition.

I began with my Officers model, where I thought it might do the most good, or at least show the most significant results. Although some suggested rounding off the bottom ever so slightly, I decided to try it out with a perfectly square edge. After fitting it to the slot, I loaded up some light target loads consisting of 4 grains of accurate #2 behind 200 gr lead semi wad cutters. Because of what I had heard about the modification, I wasn't certain that the pistol would function correctly because of the light load, but I also didn't want to damage anything.

I noticed two things immediately.
First, the oversized stop held the extractor correctly and my case ejection was much more uniform. The brass cleared the ejection port cleanly but instead of the cases going 10-12 feet from the weapon, they landed about 6 feet and to my right rear. No brass marks on the slide-this pistol has a slightly lowered ejection port compared to the GI issue and the lower front edge is radiused to clear loaded cartridges from the chamber.

The second thing was recoil. I cannot say that it lessened the kick but it felt different-more of a push back into my hand and less muzzle rise than with the standard firing pin stop, or so it seemed to me. To test what I thought was going on, I loaded some full power 200 gr JHPs to see if it was a fluke. Of course, the recoil was more pronounced but here again I did notice less muzzle flip.

After a few hundred rounds through this pistol, I decided to try it out on my government model with similar result. It functions with any reasonable load that I have tried. Although I have less than 2000 rounds with this modification on this particular pistol, one additional benefit I have noticed so far is that the spur hammer has not bounced off the standard grip safety, or at least not enough to show any marks on it. I have an older government model which shows a very slight wear on top of the grip safety from the hammer touching it in recoil.

When you finish your testing, I would like to hear of your personal experience!
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Old September 26, 2014, 06:52 PM   #35
James K
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Regardless of the shape of the bottom rear of the FPS, it has nothing to do with extractor clocking, which would be a function of the fit of the upper right side of the FPS.

Jim
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Old September 26, 2014, 07:25 PM   #36
DAVID NANCARROW
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Regardless of the shape of the bottom rear of the FPS, it has nothing to do with extractor clocking, which would be a function of the fit of the upper right side of the FPS.

So very true. That's why I went to the oversized stop so I could fit it properly.
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Old September 26, 2014, 10:33 PM   #37
polyphemus
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We have P.O.A
and P.O.I
and P.O.L that is Point of Landing
The target being 6.5' away,4 O'clock within a 6" circle,no amount of after market gadgets is to be spared to accomplish this all important objective.
just kidding.
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Old September 26, 2014, 10:48 PM   #38
DAVID NANCARROW
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Its rather nice for me, polyphemus, as I don't spend quite so much time picking up my empties for the reload bench. If I didn't reload, I wouldn't be bothered by a scattered ejection pattern just so long as they clear the pistol.
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