Diamondback Question... and malfunction

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Dr_B

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Looking for a little advice from those "in the know" regarding Colt revolvers:

I just found two Diamondback .38's in great condition at a local shop. However, the serial numbers are a bit confusing. One begins with "P" and the other begins with "M." There is a thread here on THR that suggests the "P" serial number dates to a limited run in 1982. The "M" serial number prefix has me baffled. Proofhouse shows serial numbers beginning with "N" in the late 1970's and then continuing with "R."

Anyone have any ideas where I might look for info on these serial numbers?

Another issue is that the action locks up on one of the Diamondbacks. They both appear to be in excellent external condition. However, the trigger and hammer occasionally lock up on one of them. This happens after a dry firing, once the trigger has been released and has traveled all the way forward. I have not been able to determine any clear pattern as to how often the lock ups occur. Once it is locked, I cannot pull the trigger or the hammer, but I can open the cylinder. Opening the cylinder or jiggling the trigger/hammer solves the problem. I have removed the grips and have seen nothing obvious that would explain the lock ups. The parts seem to be in good condition, no corrosion or other damage that I can tell.

Again, any ideas? These guns will not be used for any defensive purpose, so I am not entirely concerned with reliability. But it bugs me that one of them does not work properly.
 
I own a pair of diamondbacks. Unless you work on them all the time it's difficult to spot a broken or worn part without a new one to compare it with. The damage is often only a 1/16" worn off a part. I have given up on trying to repair revolvers unless the damage is obvious. All I can do is throw parts at the gun until it shoots properly. So I just take all my revolvers to a qualified gunsmith every couple years for cleaning and repair of worn parts. It turns out to cost about the same and I never have a problem in the field.

My gunsmith charges $60 for cleaning a revolver. When he finds damaged parts he only charges me for the part and 1/4 hour for labor above the cost of cleaning the gun. If I shot the gun until it broke I would have to wait for several weeks to get my gun repaired and he would stick me for at least $100 labor.

Sadly without seeing the gun I cannot tell you what the problem might be. It could be anything from a worn hand to a cylinder that hasn't been fitted to the gun. The barrel/forcing cone works loose on Diamondbacks quite often. That is the most common problem my diamondbacks have had over the years. When the clearance between the forcing cone and the cylinder (cylinder gap) is to close it will cause a zillion ghost problems to come up.
 
I have two diamondbacks myself so I understand the fun.

One of mine would do what you describe when the gun was going "out of time". I sent it back to Colt and for $75 they fixed it and replaced the mainspring. I suggest you call Colt and talk with them about it.

Diamondbacks and Colts in general are not really shade tree mechanic type guns to work on. Just study one for a while and you will see why I say that. I have been very pleased with the work Colt did on my guns.
 
The parts seem to be in good condition, no corrosion or other damage that I can tell.
Click to expand...
Take the grips off and Hose it out with WD-40 while working the action.
Then blow it out with a 100 PSI air compressor.
Then re-lube with Rem-Oil spray and blow it out again.

The thin film of Rem-Oil you can't blow out will be 'just right'.

N serial prefix was used in 1976 & 1977.
N1001 - N1800 in 1976.
N1801 - N15674 in 1977.

rc
 
WD-40 cuts through old grease & packed dirt better then any degreaser / brake cleaner I have tried in the shop.

And the fumes won't kill you while you are using it.

rc
 
Of all the Diamondbacks I've owned I still have only one, the first one I ever bought. I bought it in the mid 1970s and the serial # is N082xx. Never had a bit of trouble with any of them but do agree you can't always see slight wear that can jam one. Same goes for the Python.
 
I haven't had a chance to spray it with anything yet. In the meantime, I have dry fired it a little more and it has not stuck again. This gun was someone's baby and I suspect it spent a lot of time in the wooden, red velvet-lined box it came in. It has been shot some. I can see wear on the recoil shield, but no signs of it being out of time. No drag line, the lock up test went fine, etc.

I will have to degrease and lube it and get back to you guys. I have yet to actually shoot it.

Still baffled by the serial number beginning with "M" so if anyone happens by this thread and knows anything, please share.
 
I suspect the problem with the revolver locking up is that the rebound lever is not (re) engaging with the bolt; since the bolt won't move down to allow the cylinder to turn, the gun locks up. For a first try, I would go with what rc says, but I like G96 Gun Treatment instead of WD-40.

Jim
 
I have taken the grips off and soaked more than one Colt overnight in Ed's red, then let drip dry on a towel.
 
Sure, a little toothbrushing the carbon. However, the idea behind the soak is to clean the internals and leave behind a light coat of oil. ER does both.
 
What do you think of Carbon Killer 2000 (spelling?) I am converting all my cleaning to nontoxic.
 
Slip 2000 Carbon Killer is just another water-based citrus detergent cleaner.

So, it seems to me you are going to have to thoroughly dry the gun after every use of it.
And apply a rust preventive oil of some kind to everything it touched.

Might as well use a petroleum based cleaner & lube that leaves an oil film to start with.

rc
 
It is new to me. I bought it on a recommendation from a trusted gun dealer. Then I saw an endorsement by drfariswheel who is usually right on the money. Don't mistake my asking for inexperience. I have my routine but always keep my eyes open for improvements.
 
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Regardless of the cleaner used (and I don't recommend water based cleaners) the idea is to hose down the insides and flush out crud without taking off the sideplate. Once you do that, you run the risk of marring the screws, the sideplate, or the frame, plus not being able to get the gun back together.

Jim
 
About 25 years ago, I had a Python that did the same thing, locking up on a couple of cylinders. We were having the revolver nationals just down the road so I took it out there and found a Colt gun smith. He took the side plate off and had it fixed in about 7 minutes. It's been flawless since. There have been years between shooting it but it's still working great what few times I did take it out.

It's my understanding the Diamondback .22's have more problems with shaving lead and having accuracy issues than the .38's. I have a 6 inch Diamondback that does that. The story I heard is the guys who fixed the .22 problems have retired from Colt and there is speculation they were not replaced. Since Colt has not produced many revolvers in the last few years, I wonder how many Colt smiths who can fix a revolver are still around? kwg
 
I believe that in post #9 Jim K correctly defined the reason for the problem. When the cylinder is locked the hammer and trigger can't move very far (if any at all). When the cylinder is opened or the revolver otherwise lightly impacted the cylinder bolt resets and thereafter everything works fine - at least for a time.

The probable solution is a solvent/oil soak as explained in previous posts. Unless one knows the correct way too do it and has the proper screwdriver, removing the sideplate should not be attempted.

One of the issues with Colt's "bank vault door tight" lock-up, that should occur when the trigger is held at it's most rearward position, is that it can shave bullets if the chamber and bore are not absolutely concentric. This can be determined by using a gauge called a "range rod." By the time the Diamondback came into being Colt's management was pushing final assemblers to turn out more guns in less time. Sometimes the results of this policy are obvious. :banghead:
 
I just noticed something else about one of them. The one with the serial number beginning with "SS767#" one the frame has a different number on the crane that begins with "S766..."

To my knowledge, when the serial numbers on a colt do not match up, it means a part was replaced. Should I assume that is the case?

I am doubting my knowledge of serial numbers matching up and what that may mean. The reason is that this particular Diamondback has some signs of being used a little bit. But the forcing cone, the recoil shield, etc just don't have much wear on them. And yet if the cylinder was replaced for some reason I would assume it was due to wear or perhaps even an accident of some kind having occurred.
 
I called Colt when in doubt. It was surprisingly easy to reach a live person.
 
Should I assume that is the case?

Yes.
Colt stamped the serial number on the frame under the barrel where the crane seats, on the crane, and inside the side plate.

A non-matching part means it's been switched, which should cause loud alarms to go off in your head.
Cylinder assemblies are not drop in parts, and no revolver part is more fitted and adjusted.
Whether just the crane or the entire cylinder and crane assembly was replaced is troublesome.

This one is one that very definitely should be seen by Colt and no one else.
 
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