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MK IV/SERIES 70 is it Stainless or matte nickel ??

4793 Views 11 Replies 6 Participants Last post by  bgenlvtex
I am doing a complete take down on a Colt MK IV/Series 70 Government Model for a relative. The gun was carried into the back country on a pack trip where it and the leather it was carried in got wet, it stayed in this condition for a prolonged period of time. The pistol has a dull matte finish typical of a beaded/blasted stainless. There are multiple pinpoint to pin head sized rust marks on the surface of both frame and slide. The owner had originally thought that it was a Matte nickel. The gun has some custom work done on it and the polished and cut surfaces have retained thier bright silver apperance and did not rust. Most of the rust is on the external surface where the gun was in contact with the holster. Also I would not expect the Nickel to rust and if it did I would expect the plating to be lifting or pealing in some areas.

The serial # shows the production date to be 1979 about mid way in the production totals for that year. 207xxB70. There also proof marks on the upper front sides of the trigger gaurd, left side a small sized M and the right size a larger sized B also a P inside of a triangle at the lower left rear (near mag. release).

The question is did Colt make Stainless pistols during this time ?? If so is there any way to determine the base metal of this gun. ( and please, no one suggest a magnet) Preferably by serial number or markings. I am checking into a refinish for him and a stainless gun that just needs to be rebeaded would be much better news than a plated gun that has to be stripped and refinished.

Help in this matter is much appreciated...

thank you

[This message has been edited by kahana (edited 03-14-2001).]
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Stainless was not introduced until after the introduction of the Series 80. Factory matte nickel was available, but if the gun was 'smithed on, it could be anything now. Does the finish have a yellowish cast to it? If so, it's probably the Colt factory nickel.

Thanks for the info... I will be in contact with the owner of the pistol this week some time and will get a more complete history. It was my understanding that the only thing done by the smith was action/accuracy related work, rails, ramp trigger etc. also the ejection port was lowered. What has me curious is that the machine and honing marks are visible on the metal's surface indicating that it was not replated following the work. These bare surfaces have retained there polished high luster without corrosion.....hmmm???

Well if Colt didn't introduce SS until the 80 Series than I guess I can rule out SS and figure that it is most likely Matte Nickel. Now the question becomes restoring the finish. I wonder if the surface will clean up will a little beading or if it will need a complete strip and total re-finish....????

Maybe a question for the gunsmithing section...

thanks again


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Once rust has started it's not only a bear to remove, but to keep from recurring. If the gun is going to be anything but babied for the rest of its life I suggest shipping it out to be given a rust-resistant finish like Metalife or Robar NP3.
That finish was called "Colt-Guard" and is otherwise known as electroless nickel.Flats on slide were probably polished out when the gun was customized.Nickel is like any other surface treatment and once rust/corrosion has gotten under it you wont stop it without stripping it.Nickel has a yellow or gold hue to it,chrome or stainless is normally white in the alloys encountered in guns.
Originally posted by bgenlvtex:
That finish was called "Colt-Guard" and is otherwise known as electroless nickel.in guns.
Yep, I own one and it did the very same thing even without getting wet. It's now a project gun at SM&A in California, who is giving it the "Tactical Auto" package and a new finish.
Hey all .....

Thanks for the replies....

I was really hoping it would be something less than the full strip an finish ......Oh well !!

Patrick , who is SM&A ?? and what part of Ca are they located in ??? I live in the central valley, a little over an hour south of Sac. I do travel the state alot, as far south as Tulare and north to Chico east to Nevada and west to the bay area fairly regular.....

What finish are you opting for ??? and if you don't mind the me asking whats a ballpark figure on the strip and finish ?? If you don't want to discuss $$ on the forum I understand and you can e-mail me or let me know how I can contact the people doing the work... any help is much appreciated.....

Also any body have recomendations on a type of finish and or shops that are known to do good finish work.

well I guess this wasn't the only gun to have this problem..

well thanks again


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Patrick , who is SM&A ?? and what part of Ca are they located in ???

SM&A is Scott McDougall & Associates.

They are located on the corner of Hwy 116 and Redwood Drive in Cotati, just 7 miles south of Santa Rosa. They are in the same building as the Montana Hawk gun store and range.

What finish are you opting for ??? and if you don't mind the me asking whats a ballpark figure on the strip and finish ??

I'm opting for the satin black GK coat. It's all explained on the web site. I am not sure what the going price for a strip and coat is. It's included in the "Tactical Action" package. I am paying just over $600 for the whole thing but Mac is giving me a cop discount so I am not sure what he would charge you.

Their work is impeccable and "no nonsense." He does what is necessary to make your gun comfortable to use, absolutely dependable, and more than acceptably accurate but doesn't get carried away with what I consider to be unecessary bells and whistles.

The GK coat comes in two colors. Stainless steel in color and black.
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The gun is definately carbon steel, two options you have, you can get the gun stripped and blued, but sometimes unless polished perfectly the blue may not look good. The best bet is to strip and re nickle. It is unusual to see a matte nickle finish rust we have found that it is the most durable finish we offer. Must of started with a nick or a scratch, a good nickle job is very durable and should hold up to holster wear for a long time.


Don't take this as a slight of your product but I would say that back in 1978 and 1979 a series of Colt's with electroless nickle plating left the factory with problems.

You will note that Kahana's Colt was a 78 model and so was mine. Six of us "Oinker's" out here in Northern Ca. bought the very same model. I bought it because, well, let's face it, they were just plain "purdy." Five of my friends who were also in law enforcement bought them when they saw mine.

Mine was already starting to pit by 1980. I never carried this gun on or off duty and I would venture to say that less than 300 rounds were ever fired through it. No amount of oil and care seemed to stop the spread of the pitting.

It has spent it's life packed in cosmoline and cosmoline paper since 1981 until last month when I decided to use it as a base gun for Mac's magic.

All of my other friends, who bought the same model, experienced the same problem, with the exception of one. This seems to indicate a problem with the plating to me. I can also tell you that, contrary to your belief that the problem started with a nick or scratch, mine started pitting in several places at once, so I am suspicious about the "nick" or "scratch" theory in this circumstance.
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To all,

Thanks for the repsone

I will try and get a picture posted so you can see the rust. I feel that what patrickl et al have experinced is the same as what I have here. There is no scratches where the rust is and the external surface have not had any work done on them. The internal surfaces that have been polished for action work show no signs of rust. It is many small pinpoint to pin head size rust spots that appear to be coming through the finish. There is no lifting or peeling of the plating.

Were these guns beaded or sand blasted to get the dull appearance?? I was wondering if they were over blasted, having actually gone through the plating in some areas as this could create this appearance........


thanks for the return on the info, I will have to contact my cousin as I am doing this for him and udate him to situation and info...looks maybe a trip to Santa Rosa might be in order..........

I will start out with the link you sent, definatley let me know how your project turns out, it is better to operate off of recomendations of satisfied customers than to take your chances...

perhaps we'll cross paths one day and I could see your final results, preferably at a match or event and not with the flashing blues in my rearview........

thanks again and I'll update with any progress


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The acids used to tan the leather in the holster are quite possibly responsible,having been irritated by the exposure to water.Nickel while fairly corrosion resistant is at best a very superficial surface coat.Nickel when applied will have a naturally "matte" finish and must be polished to achieve a higher gloss finish.Remember that the roll marks on the slide/frame are made before the nickel is applied,this will bear evidence to the superficial nature of this coating.While there may be no "lifting or Pealing" the corrosion is established is the carbon steel frame and all oxidized material must be removed in its entirety before recovering leaving a pitted or pock-marked surface to the material.As Mark indicated blueing will not conceal this well and some sort of surface coating such as nickel or hard chrome or one of the "moly" or "teflon" coatings will provide a better finish although depending on the degree of damage it may still be visible.Your mileage may vary.
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