cause of over rotation

PJ Hardtack · November 14, 2012, 06:11:29 PM

What is the likely cause of over rotation?

If I 'speed cock' my new Uberti '71 in .38 Spl., it will go a 'tad' past the bolt notch. That's a metric 'tad' as I'm a Canuck .... ;>)

Either that or the bolt isn't coming up fast enough. Suggestions .... ? I'm thinking I need a new spring set.

Pettifogger · November 14, 2012, 06:24:35 PM

First, the 71s aren't really great for "speed" shooting, i.e., cocking and firing using two hands. They work fairly well shooting duelist. Over rotation is usually caused by the bolt not rising fast enough. This may require shortening the bolt leg that rides the hammer cam so the bolt will rise quicker. Or, a weak or broken hand spring. The hand acts like a mechanical handbrake on the ratchet and slows the speed of cylinder rotation. Fix the spring or the better solution is to replace it with a coil and plunger set-up.

PJ Hardtack · November 14, 2012, 08:21:14 PM

I intend to shoot my '71s 'Duelist', so perhaps I have a non-existent problem. And you know what they say - "If it ain't broke .... '

Just happened to notice it today using two paws while checking out a new bullet. I've got some spare parts coming I may install to see if it makes a difference.

Coffinmaker · November 15, 2012, 11:37:37 AM

I'd like to expand a bit. There can be several causes with an Open Top. Hand second step too long, weak or miss-adjusted hand spring, Bolt not rising fast enough, bolt not rising far enough, bolt doesn't fit the cylinder notches.

The most common are the hand spring (add some pressure). The bolt not rising far enough and bounding out (take a little off the bolt stop). And the one biggest cause, the bolt doesn't fit the cylinder notches.

I'd suggest working on all of the above. Take the bolt and cylinder out of the gun and try the bolt for fit. If it's really nice and snug, it's too tight. Remove a little material from the lead in side of the bolt. Then break the edge of the trailing side of the bolt. Polish the top of the bolt and polish the contact pad on the trigger/bolt spring, thin the trigger/bolt spring and polish the side of the bolt that contacts the side of the frame. Even if the gun seems to be working OK, the above need to be done to ensure long term function and reliability. Once properly set up, an Open Top will run just as reliably as any other SA.

Coffinmaker

PJ Hardtack · November 15, 2012, 04:42:37 PM

Coffinmaker - much appreciated!

I do have some parts coming, including trigger/bolt springs. I'll also be acquiring some piano wire springs for future use as well.

On a Colt 2nd gen '51 I recently sold, the over-rotation problem was an overlarge bolt stop. The cure was as you described. I'll check out the other things you mentioned while I'm at it. The gun is so new (200 rds + or -) that no wear pattern is developing. At least I know that the bolt isn't popping up prematurely, causing a drag mark.

What would tweaking the bolt spring accomplish? Would it kick up the bolt and hold it firmly, preventing over-rotation?

It makes sense that an Open Top would be no more or less mechanically functional than any other Colt SA design since they all use the same parts. My '71 5-1/2" model could serve as a model for it. It ticks over like a Swiss watch.

Coffinmaker · November 15, 2012, 07:32:11 PM

PJ,

You may well not like wire T/B springs. To me, they give the action a mushy feel.
Tweaking the T/B spring makes it so you can install it so it doesn't drag on the side of the frame. Polishing the contact areas allow it to slide over the top of the bolt.
A good reduced T/B spring is a Pietta. Unfortunately, VTI is currently out of stock.

Coffinmaker

PJ Hardtack · November 16, 2012, 01:22:58 PM

Thanks for the heads up re: music wire T/B springs.

I hate 'mushy', soft actions on my guns. I like 'crisp' and 'snap'. If I want 'mushy', I'll play with my stock OM Ruger Vaqueros.

When 'tuned' guns became all the rage, I remember handling a friends worked over Uberti '73 Winchester. It felt 'dead' to me and I was amazed that it even popped primers.

Flint · November 24, 2012, 07:07:08 PM

Pettifogger and Coffinmaker have it. I drilled the frame and installed a Ruger coil and plunger for my hand springs and I never get over rotation anymore. The set screw is not necessary, the backstrap holds the spring in place. I forget the diameter of the hole, but a few thousanths over the spring/plunger will do, or measure a Ruger. You can see the rub mark on the back of the hand in the picture. Remove tghe leaf spring and smooth the back of the hand.

PJ Hardtack · November 25, 2012, 12:56:17 PM

Good stuff! I may have a project for my gunsmithing pal over the winter.

Fox Creek Kid · January 13, 2013, 04:18:04 AM

Another contributing factor to over rotation IMO is centrifugal force when three or more chambers are spent and one is cocking two handed "fast & furious".

Short Knife Johnson · January 13, 2013, 06:07:12 PM

Tagging this for reference. My Uberti 1860 Richards conversion started doing this as well. Even when being used duelist. I have not had the opportunity to do surgery to see what is not working though.

rifle · January 28, 2013, 11:10:50 AM

If the bolt head is too tight in the cylinder notch it will have a hard time gettin down in and hitting the off side of the notch that stops the cylinder. The leading side of the bolts head is where the chambers to bore alignment is set so taking metal off that side of the bolt head isn't good when making the bolt looser in the notch. Take a hair off the last side of the bolts head to enter the notch.
Quite often the bolts head isn't centered in the notch so it doesn't catch the biggest bitr of the notches side/edge that stops the cylinder. Fitting the bolts head to get down to the bottom of the notch and centered cures a lot.
The bolt not coming up back to the cylinder soon enough is not happening as often as some think. As long as any of the bolt hits the lead/ramp that's before the notch it's not too late to get in the notch to stop the cylinder if the bolt head fits right. It's usually some ill fit of the bolt head to the notch that is the problem. There can be all kinds of ill fit to the bolt in the notch.
Makin a slight cant in the right direction on top the bolts head can get the bolts edge down even sooner than the lead-in/ramp does by getting the bolts side edge down lower than the top edge of the notch. The lead-in/ramp before the notch is there to lower the bolts head to insure it hits the off side of the notch and stops the cylinder. The slight cant to the top of the bolts head works to exaggerate what the ramp does. Can't get too much cant to the bolt head though or the side of the bolts head next to the ramp may not engage enough. Gotta have a good trigger/bolt spring tension too. Some like an action too soft or smooth fer "Cowboy Shootin". I don't recommend wire springs fer the "Cowboy Guns". Just my opinion is all.
The hands in the single actions aren't really there to stop the cylinder although enough drag from a stout hand spring can help remedy some of the over rotate. Any help a "Cowboy shooter" can get for his gun has to be used. The abuse is hardy indeed when shootin so fast so often. Thank the Good Lord Above fer the gunsmiths that keep them runnin strong.
I gotta get outa here and get some 44's loaded fer my Open Tops and Richards Mason. See yas.

Slamfire · February 01, 2013, 10:19:43 PM

From looking at the hand assembly in my 72 OT,asit comes up ( i'v cocked it severaly times ,,,,s l o w l y )to rotate the cyl., it hits the top of the grove,,leaving a little notch on each side of the lower lifter,, i thing there should be some gap ,,,,,but how much. I feel like when it tops out like it is it is still pushing up on the cyl., and the cyl., is locked in place,, somethings got to give or brake. After reading what you hands have explaned about over rotation,, i 'm giving my piece a good look, ya'll hav saved myself " time & misery" .

Hootmix. ( i'll be here till about 2;00am)

Abilene · February 01, 2013, 10:28:51 PM

Quote from: Slamfire on February 01, 2013, 10:19:43 PM
From looking at the hand assembly in my 72 OT,asit comes up ( i'v cocked it severaly times ,,,,s l o w l y )to rotate the cyl., it hits the top of the grove,,leaving a little notch on each side of the lower lifter,, i thing there should be some gap ,,,,,but how much. I feel like when it tops out like it is it is still pushing up on the cyl., and the cyl., is locked in place,, somethings got to give or brake. After reading what you hands have explaned about over rotation,, i 'm giving my piece a good look, ya'll hav saved myself " time & misery" .

I'm not sure I understand what you are saying. But if you are "looking at the hand assembly" as you cock it, then they cylinder must be out of the gun? On OT's and conversions, sometimes when the cylinder is removed the hand is pushed forward too far out of the slot by its spring, and it can hang in the frame slot as a result. When the cylinder is in place it keeps the hand pushed back into position.

Slamfire · February 01, 2013, 11:14:02 PM

COPY!!! gotcha, i will look at it with that in mind, man i'm glad ya'll are here!!!! Thanks Abilene.

Hootmix.

Fox Creek Kid · February 05, 2013, 04:37:53 AM

Quote from: rifle on January 28, 2013, 11:10:50 AM...The lead-in/ramp before the notch is there to lower the bolts head to insure it hits the off side of the notch and stops the cylinder...

Gotta have a good trigger/bolt spring tension too. Some like an action too soft or smooth fer "Cowboy Shootin". I don't recommend wire springs fer the "Cowboy Guns". Just my opinion is all...

The "lead in", or approach, is a peculiar thing historically. Interestingly, Colt's percussion revolvers had no approach (mostly). Neither did the conversions nor '72 Open Tops. However, after several thousand SAA's were delivered to the Military they complained of over rotation and Colt promptly added approach cuts afterward. Colt collectors can even help authenticate a 1st Gen. Colt cylinder by the bolt/approach cuts.

What is baffling is why the Military saw this as a problem circa. 1874 but never before with percussion guns.