Colt M1911A1 arched mainspring housing question

[John R.]

I have a 1.6 million range Colt( S/N 1627638).

I know that all the frame parts are original to the pistol.I added the Colt Korean War (1951 dated on the box) "hard" slide and Vietnam era chrome lined S&W made barrel.

The frame came with NO slide and I wanted it that way to build the pistol the way I like it....I did !

The frame came with an arched GROOVED mainspring housing.Anyone here have any concrete ideas as to when Colt's transitioned to grooved from knurled mainspring housings ?

My thanks in advance !

John R.

[Scott Gahimer]

They were being phased in by mid-1944.

[Duane Hansen]

At about serial number 1,670,000 plus or minus.

[Scott Gahimer]

Actually, they were introduced in the early 1.6M range. I have several before 1.63M with serrated MSH. In the OP's serial range, either could be correct.

[Duane Hansen]

Yes, I guess that would be the "plus or minus" that I spoke of. LOL............

[John W]

Actually, they were introduced in the early 1.6M range. I have several before 1.63M with serrated MSH. In the OP's serial range, either could be correct.

Scott, what is the latest serial number you have seen with a checkered mainspring housing? I have a nice, original appearing 1.70 mil with a checkered Colt housing and a checkered Colt Slide stop.

[Scott Gahimer]

Earlier parts might always show up on later pistol. One would have to inspect the parts' wear patterns, condition, color of finish, etc. to form an opinion concerning originality... as 1.7M is getting pretty late for checkered MSH.