Originally Posted by Bob Hunter
I'll have to respectfully disagree with the above statement.
Frames are different between calibers, the frame ramps are cut diffferent in angle and depth.
Bob, I have read this, but I don't think it applies across the board. I have an Armscor slide and somebody's 9mm barrel that I've slapped onto several different .45 Auto receivers with just a change of ejector and it has worked fine on all of them. And I know Colt used to sell multi-caliber pistol sets, with one receiver and two or three slides, barrels and recoil springs.
On the other hand, I know Gary Smith at Caspian says their 9mm frames have a different ramp, and that may be the case. What I found curiously fascinating is that the last frame I bought from Caspian is a "9mm" frame, but it will NOT work with a Caspian 9mm/.38 Super slide and either a 9mm barrel or a .38 Super barrel. The lip of the barrel ramp overhangs the frame feed ramp. Yet when I install the slide/barrel assembly from a Colt M1991A1 in .45 Auto, everything lines up and the pistol functions flawlessly.
There may indeed be a minute difference, but tat clearly doesn't guarantee either that a given receiver will work with a given caliber ... or that it won't.
I agree, one may get lucky and everything will work.
That being said the 1911 pistol is not as simple of design as many think.
Let's take timing for instance, this is one thing were deaing with when we are installing different barrels and slides on different recievers.
To just slap a new topend of a different caliber on a receiver and not go through the timing procedure is taking a chance.
If the timing's wrong there's a good chance the barrel and slide will be ruined.
The gun may run fine for a while, ( up to as much as 5000 rounds) then the radial lugs of the slide and barrel get destroyed enough the gun quits running or the lower lug shears off the barrel.
As for different frame ramps, Colt evidently thought there was a good reason to have different frame ramps for different calibers.
I have a Colt MKIV in 40 S&W caliber, the frame ramp in this pistol is much shallower and set at a steeper angle then the ramp in the Colt's I have that's setup for 45acp.
I can assure you this shallow steep feed ramp of the 40 will not work well or reliable with 45 acp ammo.
Keep in mind the smaller diameter bullets strike higher on the feed ramps then the larger diameter bullets.
I would be willing to bet that if I fit and timed a 45 topend for the frame with the 40 ramp the gun would experience nose dive jams with 45acp ammo.
I still believe the best way to set up a muti-caliber gun is to eliminate the frame ramp and use barrels with the ramps built on them (full ramped barrels).
As for your Caspian not working with the 9MM or 38 Super barrels because they over hang the feed ramp there's a lot of things that can cause this problem, radial lug spacing being one of them.
Again not trying to bore everyone to death here with the proper procedure for building a 1911 but the first step in barrel/slide fitting should be the measuements of the spacing of the radial lugs in the slide and on the barrel to make srue they are in spec for optimum performance.