[riderrick]

Picked up this gun at estate sale. Did a field strip clean noticed the firing pin safety plunger missing, figure it had been removed because of trigger feel. Went shooting the slide cycles really slow, could tilt the gun up and probably watch the slide close after firing with a few failures to fully eject spent case. Manual cycling feels normal. Have full disassembled the gun the only thing I noted was the 2 metal pieces for the firing pin safety plunger are there instead of the one piece replacement part. The other problem I found accidently was the grip safety not working. Do these problem relate to each other or is there more than one issue?

Side note my friend picked up the same gun as me at the same sale, turns out the guns are consecutive serial numbers, both had an identical part failure within 20 rounds. The piece of the slide release that preforms the hold open on empty mag broke of both guns.

 

[dfariswheel]

The fact that the pistol has been modified from original condition is probably related to the problems.
When you find one modification, that immediately raises the question of what else was done.

The fact that the slide stops both broke almost certainly means the stops were not Colt factory original parts.
That two stops would fail, when Colt stops seldom ever fail pretty much means that someone replaced the factory parts for some reason.

The non-functioning grip safety also is a strong indication of a modified gun.

When the Series 80 firing pin lock is removed from the slide, the two activating levers in the frame must also be replaced.
There's a chance the lever that operates the plunger could be catching on the hole in the slide.

Bottom line, you appear to have been sold guns that have been home gunsmithed and God only knows what's been done to them.
Unless you're an expert with the 1911 pistols, I'd strongly recommend taking them to a 1911 qualified gunsmith, or return them to the Colt factory for a top level diagnosis and repair.
Given the problems and odd, slow operation of the slide, and possible further unknown alteration or damage, I would not shoot the guns.
If possible, you might come out way ahead by just returning them to where you bought them and demand your money back.

 

[riderrick]

The slide stops match the slide finish so I think they are original. The firing pin safety arm that engages the (missing) plunger was cut off so I ordered new parts to return to original.

 

[dfariswheel]

Virtually any slide stop will match the Colt's finish.
The fact is that Colt slide stops almost never break, and I've never seen one break off the lug that's engaged by the magazine follower.
That part is actually subject to not much stress.
When a slide stop breaks it's almost always the pin portion.

Again, you obviously have a gun or guns that have been modified and home gunsmithed. That means trouble and who knows what problems or issues.
There are several possible causes for the slow slide operation, most of them not good news.

 

[riderrick]

The guns is Mark IV series 80 combat elite with shiny stainless fame and brown(?) slide with release matching the brown of the slide, Not saying it isn't aftermarket, just never seen aftermarket match so perfect.

 

[dfariswheel]

There were several Colt Combat Elite Series 80 models.
One was similar to the Colt Gold Cup, with wrap around rubber grips, Colt Accro adjustable rear sight, beveled magazine well.
This had a stainless steel frame with a bright polish blue steel slide.
NOTE: This model was recalled by Colt for possible issues with the safety.
The recall guns were those with serial numbers from CG10000E and CG11293E.
If these guns are this version Combat Elite they should be returned to Colt for correction.

Another version Combat Elite was the Colt XSE Combat Elite.
This version had a combat hammer with an enlarged hole, a skeletonized trigger, and rosewood checkered grips.
This version has fixed sights.
This model has also been recalled by Colt for possible problems with the safety and guide pad hardness which can cause the parts to crack allowing the gun to accidentally fire.
Guns in this recall have serial numbers between CG10000E and CG11293E X.

Colt does say that in these models the slide stop may be defective and not made to Colt standards:

Recall info:

http://www.coltsmfg.com/CustomerServices/RepairRefinish/RecallRequest.aspx

In all cases, the frame is stainless steel and the slide is bright polish blued steel. The slide finish IS NOT "brown" in color.