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  #1  
Old 05-11-2019, 08:37 PM
Moammo6 Moammo6 is offline
 
Join Date: Nov 2012
Location: Space Coast Florida
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Default Slide Spot Hardening, two-tone color

Am curious and a bit flustered after my bit of surfing on when spot hardening would have been done on M1911/1911A1 slides. Only in manufacturing? During rebuilds? Mandatory? Is there always a color change in the affected areas? My CMP R/R manu late 1944 (2 mil SN) has zero color change in any light, at any angle, with or without oil. Might it not be hardened? Would appreciate enlightened views.
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  #2  
Old 05-11-2019, 09:11 PM
thebearpack thebearpack is online now
 
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Hardening of the front of the slide started in 1940 and at the slide stop notch in 1943 so yours certainly would have had both done at the factory (if it's a late RR slide). It's more visible on some guns than on others depending on the finish used. The heat treatment probably is just not visible due to one or more refinishes.
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Old 05-11-2019, 09:35 PM
Moammo6 Moammo6 is offline
 
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Thanks to "thebeartrap." I just saw so many pics of others with obvious color changes that I started to wonder. My slide has some minor slide peening marks, but the slide/frame combo is otherwise a beautiful uniform parked color, and getting darker with grease/oil soaking.
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Old 05-11-2019, 09:51 PM
Moammo6 Moammo6 is offline
 
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Sorry, make that "thebearpack." :>)
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  #5  
Old 05-12-2019, 08:12 AM
tommyjoe tommyjoe is online now
 
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My theory: When a slide is machined and new; the grain of the metal is "open".
Then it is spot hardened and parkerized / blued, resulting in a uniform finish Comes now the rebuild. The slide is bead or sand blasted. The hardened spots do not peen in from the sand blasting, due to their hardness, resulting in a different shade of colour when it is re-parkerized. This not related to spot hardening on the slides but different alloys of steel will parkerize a different color when done in the same solution. Media size will result in a different colour, air pressure from the media nozzle will also make a difference. Media nozzle size will also make a difference.
Temp. and time in solution will also make a difference.
Just my .02.Tom
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  #6  
Old 05-12-2019, 08:45 AM
SDCoff SDCoff is offline
 
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Location: No. Virginia
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Do we know when the spot hardening ended? I rec’d a high serial numbered Colt (July-ish 1945) with a Colt slide that has been spot hardened. Trying to figure out if the slide is possibly original to the frame.
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  #7  
Old 08-18-2019, 10:08 AM
jwyatt jwyatt is offline
 
Join Date: Sep 2010
Posts: 6
Default slide is two different colors

I picked up my rack grade Remington-Rand Friday. Very nice pistol. I have a question about the slide. The muzzle end is almost black while the breach end is grey. The color change is just forward of the ejection port. The color of the frame matches the breach of the slide. Any one know what would have caused this color change on the slide?
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  #8  
Old 08-18-2019, 10:13 AM
bucketofgut bucketofgut is offline
 
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Pictures speak louder than words. I might venture a guess Heat Treat?
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  #9  
Old 08-18-2019, 10:17 AM
DDRode DDRode is offline
 
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Quote:
Originally Posted by jwyatt View Post
I picked up my rack grade Remington-Rand Friday. Very nice pistol. I have a question about the slide. The muzzle end is almost black while the breach end is grey. The color change is just forward of the ejection port. The color of the frame matches the breach of the slide. Any one know what would have caused this color change on the slide?
The hardening of the front end of the slide for a distance of 2-1/4"-2-1/2" to prevent wear & deformation originated on COLT commercial pistols in 1925. This hardened area is usually a darker color. (CLAWSON (3rd Edition) Page 37)

All manufacturers continued this practice to the end of production in 1945.

SEE CLAWSON (3rd Edition) Page 42 Figure 35: https://www.dropbox.com/s/1wb4k840n8...20024.jpg?dl=0

SEE CLAWSON (3rd Edition) Page 108 (Post-WWII Changes): https://www.dropbox.com/s/tpbm7u2as4...20057.jpg?dl=0

SEE Page 12 of 14: https://forum.m1911.org//temp/1911manufacture.pdf

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Last edited by DDRode; 08-20-2019 at 09:17 AM.
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  #10  
Old 08-18-2019, 10:47 AM
Gewehr43 Gewehr43 is offline
 
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Location: Denver, CO
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As DD pointed out, the slides were hardened in some areas and that is what you are seeing.
Since the slide was different hardness in places, the Parkerizing took a different hue or shade in those spots.
Normal.

PS...… linky…. no worky…….
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