Need Help from the Revolver Experts

[Bwana Six-Gun]

Ok, I am at a loss. I have some theories, but they are just that. I need help.

I have a 625 that I got 7 yrs ago from a member of this forum. Shoots great for accuracy. About two yrs ago I started having problems making major at matches. (Went Minor at Gator Classic. A week later made major by one (1) FPS at Memphis CC.) Took it to my gunsmith and he said I had leading in the forcing cone. He cleaned it out and it shot fine for a couple of matches. Been shooting it since then and after every match, have to clean out a boat load of lead from the forcing cone. Tried different bullets but nothing changes. Used FMJ and had no problems making major, but after the match noticed that there was some leading in the FC. Jacketed bullets had an exposed lead base.

Yesterday went to range and took some of the bullets and load that I had been using and tried them through a different 625 and a 25. Made major with room to spare.

Noticed that my 625 with the problem has about a 1/16 inch play in the cylinder when open, meaning it slides back and forth that much. I assume that is what is called end shake. Could this be the problem? If it is, do I need to stretch the yoke or can it be shimmed? Would this be the cause of the leading?

Any suggestions appreciated.

[hopalong]

Carmoney should be able to cover this subject. If we can get him out of litigation long enough to get his gun smith hat on ;-)

Hop

[wheelie]

End shake is determined when the cylinder is closed and locked in the frame.

You need little bit of play or the gun won't work when dirty and/or hot.

What you describe is normal, but not end shake.

I see 2 problems you ask about:

1. Leading

2. Low velocity.

As to # 1, its probably just a poor fit of bullet in the throats of the cylinder. What bullet are you shooting? What powder and how much?

For #2, you may just have slow gun. Add more powder.

[Toolguy]

It's hard to make an accurate assessment not being able to look at the gun. Was everything OK before 2 years ago? What might have changed?

Some things that may contribute to this type of problem -

Out of time, cylinder not lining up with barrel, shaving some bullet off one side. Reset timing. This is a normal maintenance issue on a revo that gets used a lot.

Powder too hot, melting some lead. Use cooler powder.

Forcing cone too small, too rough, off center. Recut forcing cone.

Cylinder gap too wide. Set barrel back one turn.

Cylinder throats bigger than the bullet, allowing some hot gas to go around the bullet and melt some off. Bigger bullets or new cylinder.

As mentioned above, endshake is checked with the cylinder closed. Ideally you want just enough that the cylinder can turn freely and no more. This is about .001. The main problems related to too much enshake are misfires and the front of the cylinder rubbing on the back of the barrel which makes it hard to pull the trigger. The excessive play with the cylinder open is probably due to a worn frame lug. That is the part at the bottom right corner of the square hole that the cylinder goes in. Those can be replaced.

Edited November 22, 2013 by Toolguy

[Carmoney]

Not sure I have any suggestions that Warren hasn't covered.

Kind of a strange problem.

Maybe check the center-pin hole in the frame to see if it's egged out.

Plated bullets with no exposed lead?

[pskys2]

Didn't by chance stick a bullet in the barrel? Almost sounds as if your bore is too wid beyond the forcing cone. Cracked frame where the barrel screws in?

[Bwana Six-Gun]

It's hard to make an accurate assessment not being able to look at the gun. Was everything OK before 2 years ago? What might have changed?

Some things that may contribute to this type of problem -

Out of time, cylinder not lining up with barrel, shaving some bullet off one side. Reset timing. This is a normal maintenance issue on a revo that gets used a lot.

Powder too hot, melting some lead. Use cooler powder.

Forcing cone too small, too rough, off center. Recut forcing cone.

Cylinder gap too wide. Set barrel back one turn.

Cylinder throats bigger than the bullet, allowing some hot gas to go around the bullet and melt some off. Bigger bullets or new cylinder.

As mentioned above, endshake is checked with the cylinder closed. Ideally you want just enough that the cylinder can turn freely and no more. This is about .001. The main problems related to too much enshake are misfires and the front of the cylinder rubbing on the back of the barrel which makes it hard to pull the trigger. The excessive play with the cylinder open is probably due to a worn frame lug. That is the part at the bottom right corner of the square hole that the cylinder goes in. Those can be replaced.

Firearm has run fine with no issues up until two years ago. U sing the same type and brand of bullet then and now. Same powder, only having to up the charge now. When I took it to my smith, he checked timing, slugged the barrel and gauged the cylinders chambers. All were right on specs. Cylinder gap is tight. Bullets were checked at random and all measure .4515. Crimping with a taper crimp at .471.

I was thinking that the problem may be with the bullets being swaged, and perhaps the alloy is now softer than before, but they shoot fine out of the other firearms. I am at a loss.

[Bwana Six-Gun]

Didn't by chance stick a bullet in the barrel? Almost sounds as if your bore is too wid beyond the forcing cone. Cracked frame where the barrel screws in?

Had no squibs since I have had the 625. Can't see any evidence of crack in frame.

[Toolguy]

Swaged bullets are the most prone to leading of all because they are the softest. I would get the forcing cone recut a little bigger. This comes under the heading of "can't hurt, might help".

Edited November 23, 2013 by Toolguy

[wheelie]

Will your bullets drop through the chamber throats?

I bet they will, and I bet they are real loose.

It'd be better if you had to push them through.

Larger bullets might help.

[earplug]

Whats the chance that your power scale is off? Curious if your using .451 bullets that would be undersized, Also wonder what powder and charge your using.

Life was easier thirty years ago when we did't have so many variables.. .

[Bwana Six-Gun]

Will your bullets drop through the chamber throats?

I bet they will, and I bet they are real loose.

It'd be better if you had to push them through.

Larger bullets might help.

Tried your suggestion, with five different brands of bullet, cast, swaged and Jacketed. Had to push all of them to get them through.

[Bwana Six-Gun]

Whats the chance that your power scale is off? Curious if your using .451 bullets that would be undersized, Also wonder what powder and charge your using.

Life was easier thirty years ago when we did't have so many variables.. .

Thought about the scale early on, and checked the charge with two different scales, balance beam and digital. both gave me the same charge weight. Using Clays. Started at 3.8 and moved up to 4.0.

[pskys2]

In Open guns or rifles the velocity starts falling off as the rifling wears out. With the leading you are having it sounds as if the rifling/barrel has expanded/smoothed out from the forcing cone on. That would change your velocities and lead to leading. Usually it will also show up with jacketed though, maybe to not the extreme as lead.

Have you tried JHP and Plated to see what they do, especially in comparison to the other revolvers?

Next time you clean it, look down the bore and see if it looks like it's bulged or if the rifling looks uniform the whole length of the barrel.

May be time to find a 6 1/2" barrel and trick it out! Or start shooting Plated/Jacketed Bullets.

It's not shaving lead as you fire it? If it was really out of time that could cause both issues, but you would see lead building up on one side of the FC.

Edited November 24, 2013 by pskys2

[wheelie]

Will your bullets drop through the chamber throats?

I bet they will, and I bet they are real loose.

It'd be better if you had to push them through.

Larger bullets might help.

Tried your suggestion, with five different brands of bullet, cast, swaged and Jacketed. Had to push all of them to get them through.

How big are those jacketed bullets that have to be pushed through?

Can you measure the groove diameter of your barrel?

Next guess is that the cylinder throats are sizing the bullets down smaller than your barrel wants.

You my need to open them up a bit. But don't do this until you measure and consider carefully.

In an ideal world, you want the bullet to fit the throat snugly, then still fit the barrel snugly when it gets there.

You want a good seal of the gas as the bullet starts to move in the throat and a good seal and full grip when the bullet engages the rifling.

An undersize bullet in the throat will lead and an undersize bullet in the barrel will lead. (or be more prone to lead)

If the throat is smaller than the groove diameter then the bullet will exit the throat too small for the groove diameter.

The throat may have sized the bullet down.

.451 throat with a .452 bullet = a .451 bullet entering the barrel. If the barrel is larger than .451 you don't have a good fit.

But all that is conjecture until you measure.

[Tom E]

Next guess is that the cylinder throats are sizing the bullets down smaller than your barrel wants.

Not if he can push them thru with just his fingers.

[wheelie]

Next guess is that the cylinder throats are sizing the bullets down smaller than your barrel wants.

Not if he can push them thru with just his fingers.

You're right, unless the groove diameter of his barrel is larger than one might assume.

And then there's the assumed diameter of the jacketed bullets (particularly) he's shooting. If they're .451 they'll slide right through a .4512 throat.

Anything bigger will, when pushed through, come out .4512.

With a .4525 groove he's got a misfit. (just throwing out a number)

And until everything gets measured, we're just guessing on the internet.

[Tom E]

And until everything gets measured, we're just guessing on the internet.

It appears there's an acceptable bullet throat fit. I'm not sure how you're going to measure the barrel. They're tapered. Smaller at the muzzle end, larger at the forcing cone end. Edited November 26, 2013 by Tom E

[Agent #1911]

how long is the barrel on your 625? I have a 4" 625JM and it took 4.2gr of clays (exceeds max) with 230 LRN to get major PF with some cushion. 1" of barrel length is about 50 FPS

Edited November 26, 2013 by Agent #1911

[FWSixgunner]

And until everything gets measured, we're just guessing on the internet.

It appears there's an acceptable bullet throat fit. I'm not sure how you're going to measure the barrel. They're tapered. Smaller at the muzzle end, larger at the forcing cone end.

I've never heard of the barrel being tapered, but you can drive a slug from the forcing cone end just up to the rifling to measure FC diameter. You can go a little bit past the FC to get groove diameter on that end, but I have never been able to measure it on an S&W due to the 5-groove rifling.

Throats & forcing cone are the critical dimensions for cast revolver bullets.

Commercial cast bullets are usually undersized. If they are requiring a little push through the throats, I would be concerned that the throats are too tight. I would next slug the forcing cone as described above. If you've never "slugged" a barrel or chamber before, you drive an oversized pure lead bullet in and measure diameter using a micrometer to at least .001. 50-caliber muzzle-loader bullets would be good for your .45 if you can find some. You really should slug the throats, too.

The forcing cone diameter should be smaller than the chamber throats.

"Hard" cast commercial bullets are the worst offenders when it comes to leading, because they're too small and too hard. The base won't expand and seal the throat. This would be my prime suspect for the leading in the chamber throat..

As someone mentioned, if the throats are too tight, they can be opened up.

I don't see any mention of accuracy. Issues with timing, excessive cylinder play, or, with cast bullets, throat/cone dimensions will cause accuracy to go to pot. If it shoots jacketed bullets OK but not cast, this, again, points to an issue with throat/forcing cone dimensions.

Are you getting lead on the butt of the barrel? This would point to timing, especially if it's on one side.

Good luck.

[Toolguy]

Only Colt revolver barrels are tapered. Smith and Ruger are straight bores.

[Intel6]

Dan Wesson barrels were tapered also, I read somewhere that they took inspiration from the Colts.

[Tom E]

Only Colt revolver barrels are tapered. Smith and Ruger are straight bores.

Sorry Warren, the barrel in my 625-8 is clearly tapered as is the new 5" 625 barrel I have sitting here. I realized it was tapered when I went to cut a taylor throat. The pilot rattled around in the forcing cone end and fit the muzzle correctly. Same with the new barrel I have.

[Toolguy]

OK - must be something new I haven't run across yet.

[Tom E]

OK - must be something new I haven't run across yet.

Surprised me too.