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Discussion Starter · #1 ·
dfariswheel,
Concerning the Diamondback, is there a Colt specification that specifies where the bolt/cylinder stop should strike the cylinder? I believe either the bolt or rebound lever is worn on one of my Diamondbacks. The bolt pops up and hits the cylinder very close to the notch. Once in a while, especially if the hammer is pulled back quickly, it strikes the cylinder just past the notch. Thanks.
Wayne
 

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Before DFW answers, I will offer my opinion on the problem and offer a fix.

It sounds like the cylinder stop spring is weak or rusted. Yes, maybe rusted. I once bought a NIB Colt D-frame that, for reasons unknown, had a rusted spring, with no other rust anywhere inside or out. The rust basically made the spring very short and weak so the stop would not rise fast enough to "catch" the cylinder in double action operation, and the cylinder would often "throw by." Replacing the cylinder stop spring cured the problem.

To check the cylinder stop spring, remove the side plate and all mechanism parts except the stop, which is behind everything else anyway. Push the stop up and down to see if it is free. Remove the stop to check the tiny spring further. If it is weak or rusted, cut an appropraite length (a bit less than 1/8-inch long - the length is not critical unless you make it too long so it coil-binds) from proper size spring stock (about 1/16-inch diameter - Brownells sells bulk coil springs in packs with varying sizes), smooth the cut ends on a fine Dremel wheel, slightly reduce the diameter of one end on the grinding wheel so it will fit snugly in the deperession on the cylinder stop lever, and install. That is what I did to replace the rusted spring on the D-frame mentioned and it has worked fine for 20+ years.

Let us know if that is the problem.
 

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Ideally, the bolt should start to pick up instantly with any trigger or hammer movement and drop in the middle third of the bolt lead. I would suggest a good flushing and lubing preferably with the sideplate off first before settling on any adjustments or replacements. /forums/images/graemlins/cool.gif
 

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Both A1A and the judge gave good advise. I would add that you ahould inspect the inside of the frame and ALL internal parts for gunk and crud. Especially the tiny window in the frame through which the bolt passes. Clean thoroughly and lightly lube, then try function testing before proceeding.
 

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Discussion Starter · #5 ·
Guys,

Thanks for your suggestions. After reading your responses, It's obvious I should have supplied more information with my question. I'm reasonably familiar with the function of each part of the Diamondback "D" frame action. I purchased the revolver as used, but it looks brand new and I have fired it less than 20 times. After noting the problem I removed the side plate and completely disassembled the action. All parts were factory clean and seem to be working fine. I thought some of the factory lube may have hardened and was causing the problem. No crud, hardened lube, rusted or bent bolt spring. The bolt moves freely and the spring seems to function fine. After cleaning and lubricating all components, I reassembled the action but the problem still exists. After reading your responses and with some additional thoughts, I removed the grips and closely watched the movement of the bolt and rebound lever, as the rebound lever releases the bolt. If the original owner has fired the revolver a lot I would have expected a worn bolt or rebound lever to exhibit just the opposite problem. In other words I would have expected the rebound lever to release the bolt early, striking the cylinder early in the notch leade. But, as noted earlier, just the opposite is happening. Now this may have been a problem all along and is one reason I got the revolver for a very good deal. If that’s the case then I may have to do a little work with a file and stone on the rebound lever.

So, ideally where should the bolt strike the cylinder notch leade? I check several other colt revolvers, including another Diamondback, a Python and an Anaconda. They all seem to be a little different. The bolt of the other Diamondback hits about ½ down the notch leade.

Wayne
 

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Here's my old style Colt action timing checks, I'll address your specific problem after the info:

Here's how to check the timing on the old style Colt revolvers.
This covers all old style Colt DA revolvers including:
The 1917 and New Service. Official Police, Officer's Models, Detective Special, Police Positive and Special, Old Model Trooper, Diamondback, and Python.

To check Colt timing:

BOLT RETRACTION AND "SNAP BACK".
Open the cylinder and look at the small "lug" in the bottom of the cylinder window. This is the cylinder locking bolt.

Cock the hammer, and watch as the bolt retracts into the frame and pops back out.

The bolt MUST begin to retract THE INSTANT the hammer begins to move.
There MUST be NO (ZERO) hammer movement possible before the bolt starts to retract.

The bolt should retract smoothly with no hesitation until it's fully retracted, then it MUST pop back out with a clean "snap".
There should be no hesitation, and no amount of "creeping" back out.

CYLINDER UNLOCKING.
Close the cylinder.
Use your left thumb or fore finger to again cock the hammer, closely watching the cylinder bolt as you SLOWLY cock the hammer.

As the hammer comes back, the bolt will retract away from the cylinder.

The bolt MUST retract far enough to unlock the cylinder BEFORE the cylinder begins to rotate.

If the bolt is still slightly engaged with the cylinder lock notch, the cylinder will be attempting to turn while still partially locked.

This produces a "catch" or "hard spot" in the trigger pull and will damage both the bolt and the cylinder lock notches.
This often appears as metal "pulled out" of the lock notches, with rounded off and burred notches.

BOLT DROP TIMING.
Continue to cock the hammer, laying your right index finger on the cylinder just enough to prevent "free wheeling".

Watch for the bolt to drop back onto the cylinder. WHERE the bolt drops is CRITICAL.

The bolt MUST drop onto the lead or ramp in front of the actual cylinder notch.
If the bolt drops too soon, (in front of the notch ramp), it will mar the finish of the cylinder.

The bolt SHOULD drop into the MIDDLE 1/3rd section of the ramp.

If the bolt drops late, (farther toward the actual locking notch) the revolver may display "cylinder throw-by".
In this condition, during double action shooting the cylinder may rotate PAST the locking notch, and fire in an unlocked condition.

It's the nature of the Colt action, that a hesitant or jerky trigger pull by the user can induce throw-by in even a properly tuned Colt.
The Colt trigger should be pulled with a smooth, even pull, with no sudden jerks at the beginning.

CYLINDER LOCKUP.
Continue to pull the hammer back and both watch and listen for the bolt to drop into the cylinder lock notch.

The bolt MUST drop into the actual lock notch BEFORE the hammer reaches full cock.

The most common Colt mis-time situation is the hammer cocks before the bolt drops into the lock notch. (Hammer is cocked, but cylinder isn't locked).

In this condition, with the hammer fully cocked, you can push the cylinder slightly, and you will hear the "CLICK" as the bolt drops into lock.

In my experience, most Colt's leave the factory with the bolt dropping a little late into the lead, but usually wear in to correct timing.

If the bolt drops onto the cylinder early, no real problem, but there will be extra finish wear.

If the bolt drops late (closer to the lock notch) the cylinder may "throw by" or rotate TOO far in double action and this can cause off-center primer hits and firing while unlocked.

Each of these checks should be done on EACH chamber. All of these checks are better done individually. In other words, do the bolt retraction check on all six chambers, then do the bolt drop test, and so on.

A properly tuned Colt will:
Have a smoothly functioning bolt with no sticky or hesitant movement.

Unlock before the cylinder begins to turn.

The bolt will drop onto the middle 1/3rd of the ramp.

The bolt will drop into the lock notch before the hammer reaches full cock.

Have a smooth trigger pull, which does "stack".
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The "D" framed guns can be timed a little earlier, into the border area between the first third and the middle third of the bolt ramp.

What's happening on your gun is, the bolt is timed to drop TOO LATE, and you're getting "cylinder throw-by".
In other words, the bolt is dropping too late and it's "skipping" over the locking notch.

It's the nature of the old Colt action that the shooter can INDUCE throw-by by improper manipulation of the trigger.
Any jerky or hesitant trigger pull can cause the cylinder to rotate past the locking notch BEFORE the bolt has dropped.
So, even a properly tuned action can throw-by.
In other words, a jerky trigger pull can give the unlocked cylinder a push and it free-wheels past the locking notch before the bolt is allowed to drop.

In your case, the bolt needs to be adjusted to drop earlier.
The correct method is to SLIGHTLY bend the bolt tail AWAY from the rebound.
There is a tiny triangular surface on the right side of the rebound that activates the bolt.
DO NOT ALTER, POLISH or otherwise touch it.

The bolt tail that contacts the rebound is what times bolt drop.
This is adjusted by SLIGHTLY bending the bolt tail TOWARD the rebound to delay drop, and AWAY to drop earlier.
NEVER, EVER for any reason touch the tail of the bolt. DO NOT polish or alter it in any way.
If you're having timing problems, cutting, polishing, or altering the bolt is NOT the "fix" and will only destroy the bolt.

If the bolt or the rebound bolt activation "triangle" is damaged or worn, REPLACEMENT is the ONLY "fix" and attempting to alter them will only make a problem MUCH worse.

Again, this takes VERY little bending and depending on the situation, it can sometimes be done while the bolt is still in the gun.
You need to be extremely careful here since the bolt CAN break, and it's very easy to over adjust.
The tail of the bolt is the "brain" of bolt timing and it's very easy to damage it or cause problems elsewhere.

Again, the tiniest bit of bend has a big effect on bolt drop timing.
In this case, bend the tail AWAY from the rebound a TINY amount.

Adjustment can be aggravating since you have to disassemble the action, adjust, then reassembly to check function.
This can make the wife, kids and neighbors hear words they've never heard before.
 

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Discussion Starter · #7 ·
dfariswheel,

Thank you very much for the timing and adjustment information. I'm sure glad I waited for your response. Following your instructions I bent the bolt some until it snaped up and hit the notch ramp about 1/2 way up the ramp. Worked like a charm and seems to reliabily snap into the locking notch now, no matter how fast I pull back the hammer or pull the trigger. This technique implies to me that there is a slight slope designed into the front of the triangular surface on the rebound. I assume this is to allow adjustment for wear. Thanks again.

Wayne
 

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Glad Dr. D hit it on the head for you. I should have hit on it though as I recently had the opposite experience with a 357 model that was dropping early. Could actually see the bolt tip drop off the side of the triangle early instead of following it around. Bending in slightly brought the timing back in. Works both ways. /forums/images/graemlins/wink.gif
 
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