1911Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter · #1 ·
I have noticed vertical hairline cracks developing on both sides of the receiver just forward of the slide stop holes. The line follows the lip serving as the stop for the rear of the recoil guide rod(inside the frame at the front end of the slide rails).
Any ideas as to the cause?
 

·
Registered
Joined
·
22,122 Posts
Impact of the slide in recoil. There is no direct load on the dustcover but when the slide bottoms out against the head of the recoil spring guide, the metal distorts minutely. It fatigues and cracks.
Use a stronger recoil spring and buffer in your new frame.
 

·
Registered
Joined
·
1,347 Posts
If you can live with it, live with it. Those cracks only go so far and then start getting into material too thick to continue at a rate that would result in any real harm. Heck, even if the dust cover fell off, you're not disabled. You can get it welded, though. Buffers would have helped but truthfully, some guns just seem crack prone. I have one that i drilled a .013 hole at the end of the crack but it didn't stop. Drilled another a little further out-- didn't stop. Now I'm just ignoring it!
 

·
Premium Member
Joined
·
7,098 Posts
I have repaired about a dozen frames cracked at the end of the rails/start of the dustcover.
On EVERY one, there was evidence of hard contact between the top edges of the dustcover/bottom of the slide. Visual inspection of minimum clearance is not always adequate, as both the slide and frame flex during firing.
I now file the top of the dustcover to provide a gap of about .007" minimum, then 'ink' the area and test-fire the gun.
All contact areas are filed to prevent any further contact.
I've seen these cracks on Springfield, Caspian and Colt frames, both steel and aluminum.
Can anyone give me some info on weld repairing aluminum frames in this area?
Even using TIG,on the alloy frames, the material in the 'heat-affected' zone, about the size of a dime, is annealed to Condition Zero. A little harder than peanut butter!
Surely George or Ned has weld-repaired an alloy frame and can suggest a solution.

Chuck
 

·
Premium Member
Joined
·
2,130 Posts
Not even chunky Jiff just regular peanut butter.
Sorry Chuck, have not had luck in that area.

What would be Kool is if the manufactures of the frames would use a .015 fillet where the dust cover meets the frame, the stock guide rod has pleantly of radius.

I wonder if the shock buff, bulging out the sides contributes to the cracking? and surely cranking on a 2 pc guide rod does not help.

Chuck we did have a para bowling pin gun come in one time with a C-some. when we took the scope off the dust cover fell off! it was cracked all the way around! first time for me


geo ><>
 

·
Registered
Joined
·
1,347 Posts
No, Pistolwrench, I have not done a weld repair of a cracked aluminum frame. I'd hate to try it, even though I practically worship the guy that does my welding, I mean the guy can weld the edge of a razor blade... but not in aluminum. My aluminum welding experience comes from my prototype aluminum injection mold days. These were pretty much always 7075 T6, and welding was always a last resort because even on a good-sized, solid block, you got that Peanut Butter Syndrome as mentioned above. We welded when there was no choice or it didn't matter. Otherwise we made it over or inserted it.

BUT-- there was one little product I discovered and used the shXX out of... well, that is, I mean, on those RARE occasions when I made a mistake.... Lumiweld. I haven't had a call to mess with it for a long time. It was kinda finicky to apply. I did it with an oxy/acetylene rig, the Lumiweld was an uncoated rod. When it stuck, it stuck well, you could mill it, drill it, EDM it, whatever, but I often had to take two stabs at getting it to take. It either did or didn't, there was no in between. Once done, the Lumiweld itself was harder than the original base aluminum, but the 7075 was usually peanut-butterized by the heat. And I don't think it would be a good thing for crack repair anyway.. more like for building up where there's missing metal.

As to TIGing an alloy dust cover, George probably knows better than I, but with the amorphous nature of aluminum, and the thin section in question, I doubt that it can be done easily. I'd think there would be a large risk of just blowing the whole thing away with the arc-- or, George, am I just outta touch with what can be done?

Pistolwrench, your observation about slide contact with the top surface of the dustcover: brilliant! Never gave it any thought. Sounds totally viable and with what you have seen on cracked guns, I bet you're right. I think George had a good point too with Shok-buffs squishing out to the side, but I don't feel that would do it. A little high speed video could prove me wrong though, that material has to go somehwere when it's compressed.

[This message has been edited by Ned Christiansen (edited 11-07-2001).]
 

·
Premium Member
Joined
·
11,723 Posts
...there was evidence of hard contact between the top edges of the dustcover/bottom of the slide...
Some old military bullseye shooters have told me about bending the dust cover up to bear on the bottom of the slide
, removing some of the slop. This was before there was a well established AMU or AFMU to build guns for them. Doesn't make much sense when you think about it, but I've heard it from more than one person. I know that Pachmayr made a slide tightener that worked similarly & attached to the outside of the dust cover with a screw bearing on the front of the trigger guard, but that was on full build guns.
...What would be Kool is if the manufactures of the frames would use a .015 fillet where the dust cover meets the frame, the stock guide rod has pleantly of radius...
Best idea yet! An easy fix for an occasional problem that will result in a more durable gun.
...a good point too with Shok-buffs squishing out to the side, but I don't feel that would do it. A little high speed video could prove me wrong though, that material has to go somehwere when it's compressed.
Perhaps marking the inside of the dust cover channel where the shock buff rides & looking for how much of the dykem/magic marker is wiped??
...and surely cranking on a 2 pc guide rod does not help...
Always makes me nervous!
 
1 - 7 of 7 Posts
Top