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Discussion Starter · #1 ·
I'm going to have the slide on my 1991-A1 tightened to go with the new barrel installed. I was told that sometimes the stainless steel used in 1991s is so hard that it is almost brittle and can break. Is this true? Also, why is th frame squeezed for 20 seconds and then stress relieved(whatever that is) by rapping on the flat anvil part of the vise with a hammer? Any information anyone could give me would be much appreciated. The 1991 I'm building is for kicks, not self defense, but I would hate to have the slide ruined nontheless.
 

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Your post confuses me a little. First Stainless is seldom brittle and it's actually very soft compared to typical chrome moly when we are talking gun steels. Not much reason to tighten the slide to get a more accurate gun, fitting a match barrel will do 99% of it. That last bit isn't worth the effort or relaibility risk for the vast majority of guns, uses or shooters. Just an opinion of course. Sounds like you could use few more opinions on what actually makes a good gun.
 

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As to your point about stress relieving with a hammer, that's a new one on me. This
may be some kind of half logical bastardized version of the following.

There is a process of stress relieving known in industry as Formula 62. It involves the use of vibration rather than heat to relieve internal stresses in steels. It is basically used AFTER machining to relieve stresses from the machining operations. We used this process back in the late 70's to relieve helicopter transmission housings. You basically shake the part at a specified frequency for a defined period of time. This process does not change the part dimensionally.

I assume someone thinks hammering inputs enough random vibration energy into the piece to relieve internal tensions and make the part stay in the new position.

I have my doubts.

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If it flies it dies, If it runs it's done.

[This message has been edited by Peter Zahn (edited 03-22-2001).]
 

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Discussion Starter · #4 ·
Thanks a lot for the info guys, I was really in the dark there about some of that stuff. I know how little frame tighness affects accuracy, but the rest(brittleness of stainless, rapping the anvil, etc.) was pretty confusing mumbo-jumbo from a gunsmith I have doing the work. Maybe I should find someone else to be working on the pistol. (mmmm...Burns, Burns, why is that name rattling around in my head...Ha!) And thanks Peter for your insight on the stress relief aspect. I doubt very highly that the person I have working on my gun could even come close to giving me such an accurate and detailed reason for smacking the anvil with a hammer. Perhaps he needs a little stress relief himself!
Thanks a bunch guys,
Jhickman
 

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Slapping the anvil with a hammer is an old technique used for many years by smiths to "stress relieve" a slide that has been tightened. Supposedly , it allows the slide to "take a set" with the rails in the new position instead of springing back to the pre-squeaze position. The vibrations are the key. I've tried it with mixed results. Not worth it in IMO. If you want a tight slide, just buy one.
 

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Discussion Starter · #6 ·
Thanks BBBBill, I am thinking about doing just that. Perhaps Caspian. I thought that since I was having this 1911 built for fun and target shooting that I could save some money by starting out on a relatively inexpensive platform. I'm starting to see the error of my logic. Live and learn I guess!
 

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Hi jhickman,your smith is probably right about the SS slide, the Colt SS is on the harder side compaired to the Colt blued, we are compairing a RC- 40-41 blue steel to a RC-45 SS, I think they make them extra hard to help with the galling of SS running on SS, Colt SS slides are the hardest I've Rockwelled, you'd need carbide to cut this slide, its only a few points difference but a coulpe points mean alot when you get this hard. But the heat-treat on these slides do vary, you'll only know for sure if you test it, I have tested some softer. Your post above are good advice. I would not sqeeze this slide. MetalSmith
 

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My impressions:

I do a LOT of sight installations. These days it seems there has been an increase in the percentage of Colt SS slides to be fitted with Lo-Mount Novaks or Bo-Mars.
I use only HSS 8% Cobalt end-mills and standard HSS dovetail cutters with no problems at all.
On the Colt slides, maybe 20% seem to be a bit more difficult to machine, but this occurs on the blued slides as well as the stainless.

As to slide tightening, well I use a technique that incorporates a .0005" indicator, internal slide support to prevent cracks, and vise jaws with 3/4" pads that allow me to 'adjust' small portions of the slide seperately.
I do 'strike' the vise plate, HARD, with a deadblow hammer, and can see the effect on the dial indicator. The 'strike' definitely causes the slide to 'take a set'.

More later.......



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Chuck Rogers
Rogers Precision
 

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A Little More:

I agree with Dane and others, that a tight slide to frame fit contributes but a little to accuracy.

But there are two areas in which a nicely fitted, hand-lapped, no play fit are important.

The first of these is merely one of aesthetic considerations. Many of my customers demand the no rattle, silky-smoothness of a fine slide to frame fit on their custom guns.
I find ZERO negative effect on reliability,
on a properly done job. Indeed, there is less room for dirt to infiltrate and enhanced repeatability/predictability of the moving parts.

The second involves serious 'bullseye' shooters. A Ransom Rest is a critical tool for a serious bullseye competitor. The Ransom allows a shooter to properly evaluate the accuracy of his equipment and ammo, without the sporadic 'human factor'.
A Ransom rest holds the gun by the frame, independently of the slide, barrel or sights.
Any play in the slide to frame has a negative impact on the results.

I have seen more than a few slides ruined by attempts at squeezing. This if far more relevant now in this era of harder slides than it used to be. My advice to the amateurs......leave this job to a proven competent 'smith with LOTS of 1911 experience.

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Chuck Rogers
Rogers Precision



[This message has been edited by pistolwrench (edited 03-22-2001).]
 

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Hi jhickman,
It is difficult to explain all the aspects of metallurgy in a couple of paragraphs, some harder steels may machine better then softer steels depending on the content of elements. A few points of rockwell hardness mean more on the higher end then the softer end, Chuck's post above is accurate. If you had to have the SS slide tightened send it to him, he does have some proprietary methods to tightening without cracking. Metalsmith

[This message has been edited by Metal Smith (edited 03-22-2001).]

[This message has been edited by Metal Smith (edited 03-22-2001).]
 

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This all sounds like good advice. The spirit from all the educated guys seems to say "Don't sqeeze the slide". I agree with them. One thing to check is are the sides of the slide flat now. If they are flat now, chances are that what happened was the machining was done, the slide relieved, or relaxed, and then the sides were grinded flat. If you were to try and sqeeze the sides in, and were by some rare chance able to actually get a flat inside edge, you would have concave sides. A little experiment to show how screwed up it could get is to bend a coat hanger about 90 degrees. Then try to return it to straight. Wrinkles, and cracks........BAD NEWS!!!
Just my opinion of course.....

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Really interesting....Don't ya think??
 
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