[dsk]

When the 1911 was first introduced the technology of the time didn't enable Colt to heat treat the slides at all. There was no way to machine a hardened slide blank, and if one attempted to heat treat a slide after machining it would warp. As a result the early slides were prone to cracking and severe wear from peening. In 1925 Colt began hardening the front 1/3 of the slide by heating them up then quenching them in oil. Later they also installed a hardened insert in the breech face where the firing pin hole was to prevent deformation. In 1943 the slide stop notch was flame-hardened to reduce peening damage. By 1944 experiments were being made with new technology that allowed the slides to be fully heat-treated throughout, to include the locking lugs and to eliminate the need for the hardened breech insert. Remington Rand and Ithaca both made slides using the new processes and were in the testing stage when the war ended. Colt adopted the new techniques after the war in their commercial production, and by the time the military started buying replacement slides they were all "hard slides" that were fully heat-treated throughout. That's all I can tell you going off of memory, as I'm not home at the moment and can't look at my reference books.

 

[dsk]

Colt started to produce full hardened slides only in 1948.

Colt didn't begin using the new "hard" slides in their commercial guns until the supply of unused GI surplus slides were exhausted (Colt was stuck with a LOT of excess components when the war ended and the government contract was abruptly canceled).

As for heat treating and cracking, any metallurgist will know that a part that is too soft or to brittle for the application will easily fail. Soft parts are too weak and will quickly fatigue, while ones that are too hard and brittle have no flexibility and will also break. The old WW1-era slides were weak and failed easily due to the stress of firing, and many of them cracked right at the sharp junction at the rear edge of the recoil spring tunnel. They were also prone to peening at the barrel bushing lug cutout. Colt tried to solve both problems by hardening the front third of the slide as I mentioned previously, but areas like the breech face, slide stop notch and barrel locking lugs continued to be a problem until the "hard slides" were finally developed.

 

[dsk]

According to Scott Meadows' book US Military Pistols 1920-1945 the Ordnance Department first began to experiment with hard slides in July 1944. Colt, Remington Rand and Ithaca each submitted 250 pistols that were assembled with hardened slides, and they also submitted an additional 250 pistols that had their slides austempered at Springfield Armory. The barrels were austempered as well and were marked with "SA" in front of the lugs. The slides were hardened to Rockwell "D" 50-58 and were identified by a large "MD1" stamp on top in front of the rear sight. The tests were not completed until January 1946, so apparently there wasn't a lot of urgency associated with the project.

 

[dsk]

Look closely at the breech face and try to discern if there if a roughly 1/4" diameter dark ring around the firing pin hole. If there is then that is a hardened plug that was pressed into the slide and machined flush, and would mean you have an earlier WW2 surplus non-hardened slide. What Clawson was basically saying was that Colt used up their GI surplus slides in 1946 and by 1947 was using the new hard slides. However I've seen no written proof that Colt stopped using GI slides on Dec. 31 and started using hard slides on Jan 1st, so it pays to check if you have a 1946/47 pistol and verify.

 

[dsk]

Here is my 1943 Colt, with the hardened insert clearly visible as a dark circle around the firing pin hole. Yours looks too off-center to be an insert to me.

 

[dsk]

Don't forget that besides the breech face plug an unhardened slide will also show spot-hardening of the slide stop notch and a darker forward third of the slide. I don't see any of those on your pistol.

 

[dsk]

I bought a Beretta M9 Special Edition (the early ones that looked more like a GI M9) when they came out, but avoided shooting it when I saw prices were going up on those. I later bought a Colt O1918 WW1 Replica, but again decided against the temptation to shoot it once they were discontinued and prices went up. More recently I bought one of the CZ 1911s for use as a carry gun and hard-use shooter, but they just stopped making those after only 1000 were built so it looks like that one is going to become a collectible too in the future. No wonder why so many people shoot Glocks, because nobody will ever pay a collector's premium for one of those things! :hrm:

 

[dsk]

I agree, there's no insert.

 

[dsk]

Colt was a bit known for over-polishing their commercial pistols during the 1970s and 80s and partially wiping off their own rollmarks. The old master polishers were gone by then and the newer workers seemed to be learning on the job.

 

[dsk]

That doesn't look bad at all. My favorite was when the Colt polisher became so enthusiastic about his work that he started flattening and polishing the points on the cocking serrations as well.

 

[dsk]

The hardened insert was also known as a recoil plate.