View Full Version : 1911 questions

April 30, 2008, 12:46 AM
Thinking about building my next 1911, I would like to know the answer to these questions first though. Please only comment if you would like to answer my questions. Thank you.

Whats better...

Ramped or non-ramped barrels?

Regular or drop-in parts?

Bull or bushing barrels?

What exactly is a ramp cut?

Whats the difference between series 70 and 80? (pics would help)

Jim Watson
April 30, 2008, 07:25 AM
Non ramped for standard chamber pressure ammunition. Most IPSC Open guns have integral ramp barrels but the shooters routinely overload their ammunition and think the ramp improves casehead support.

"Drop-in" is better than mass produced "regular" parts if you can handle the fitting that is often required in spite of the advertising. Gunsmith fit parts are better yet, if you can handle the work.


The ramp cut is the mortise that has to be cut in the receiver to accept the integral ramp on the barrels that I recommended against. There are two main types cataloged as Clark-PO and Wilson-Nowlin. Not interchangeable.

A "series 80" is a Colt pistol with a trigger actuated firing pin block. Internet evolution of the English language has taken "series 70" to mean almost any gun without a firing pin block but it was originally trademarked for a Colt with a collet barrel bushing.

April 30, 2008, 08:38 AM
it was originally trademarked for a Colt with a collet barrel bushing

Jim, I've never been really clear as to whether the "Mark IV" or the "Series 70" designated the "collet" bushing, and I was there!

Colt has further confused the issue with their re-issue of the "Series 70," lawyer-free (pre-Series 80 firing pin safety) but also collet-bushing-free.

Colt never was big on consistency.



April 30, 2008, 10:54 AM
Thanks Jim.

James K
April 30, 2008, 11:48 AM
Being as confused as anyone about Colt terminology, I checked the 1971 Gun Digest, with its announcement of the MkIV/Series 70; FWIW, they refer to the collet barrel bushing as the MkIV system, saying it could not be applied to the Commander, and I don't think the "MkIV" name was ever applied to the Commander, though "Series 70" was.

But they continued to use the "MkIV" designation long after the collet type bushing had been discontinued, and used "MkIV/Series 80".

So, I am still confused. I am tempted to write Colt, but they would probably charge $100 for a reply.


Jim Watson
April 30, 2008, 01:36 PM
You are right about the lack of consistency, Walt.

Colt introduced the Mk IV Series 70 Government Model with the Accurizor collet bushing and some cosmetic changes in 1970. I never saw one marked ONLY Mk IV or ONLY Series 70.
The Colt design of collet bushing would not fit inside the shorter Commander slide so there never was a Mk IV Series 70 Commander. The Combat Commanders of the period had a 70 prefix on the serial number which gets them called Series 70 but they were not so marked.

In 1983 Colt introduced the Mk IV Series 80 Government Model. Sounds crisper than Series 83, doesn't it? It retained the collet bushing and added a trigger actuated firing pin obstruction. Naturally the Commanders got the firing pin block, too. When they brought out the 10mm, they did not use the collet bushing and soon dropped it from the rest of the lineup.

After that, it gets more complicated than I care to track down, what with roll mark and parts bin engineering. The English language mutated to the point that any 1911 pattern gun without a firing pin block has become known as "series 70." Even by Colt, who produces the Series 70 reintroduction without those superfluous parts but also without the discredited collet bushing.

April 30, 2008, 05:02 PM
Jim K., I also noticed that in the '71 Gun Digest (I happen to have it out for research on another, related topic) reported the "Mark IV" system.

Jim W., I wasn't aware that the original Series 80 pistols retained the collet bushing.

Both Jims, I'm in complete agreement and allied confusion :confused: .

Best regards,


Hunter Customs
May 1, 2008, 08:41 AM
Here's something else to think about. If you are building the gun from the frame up and the frame ramp is cut for the 45 and you decide to build something in the 9 or 40 family the ramp will be over cut and most likely will cause feeding issues.
So besides offering more case support the ramped barrel will be the best way to solve that problem.
Also if the ramp in the frame has been moved to far forward, cutting the frame for a ramped barrel just may save the use of that frame.
I like ramped barrels, however I feel many do not understand the timing issues involved when using a ramped barrel.

As for parts I would prefer top shelf parts that have to be fit, stay away from MIM.

As for barrel design, bull or bushing type, that should depend more on your intended use and what you want to achieve with the gun.

As for the ramp cut in the frame Jim explained that very well. I will add the Clark and Para are not really the same cut, they do look very similar. If you are cutting a frame for a ramp barrel I would choose the Para cut over the Wilson/Nowlin because the Para is a radius cut.

As for the series 70 or 80 difference, again Jim gave you a very good answer.

Bob Hunter