Accuracy and leading with undersized boolit questions

[Tripplebeards]

I know rule of thumb is to size boolits .001 over for best accuracy and no leading...which is the size I have gone by on every application untill I measured a bore yesterday. My vaquero cylinders all measured .451 and the slug I thought measured .451 but when I measured around it in several spots I had two measurements of .450 and .4505...so the barrel is .0005 smaller than the cylinder. I plan on sizing the boolits at .451 and trying it out before I contemplate sending the cylinder in to be reamed out. I feel .452 would be way too tight...the boolits would have to be pounded through the back side of the cylinders to fit. I would assume this would cause tons of pressure and eventually grenade my revolver like the horror pics posted all over the net with pistols blowing apart.

My question is has or dose anyone shoot boolits sized at .0005 (less than .001) over with descent accuracy and no leading? My boolits are pc and are 50/50 coww and pure mix w/2% pewter.

I'm sure there are other posters that have less than purfect cylinders and chamber sizes that have had similar experiences. I'd like to hear both good and bad. Thanks

[runfiverun]

it won't cause tons of pressure.
3-400 psi maybe but tons... no.

[Tripplebeards]

Well, I think about it as...if I size to .452, I shoot, it gets sized in the cylinder to .451, it enters the barrel and then is sized to .4505. The lead is not going ro spring back to a larger diameter when traveling through the barrel so why not size the boolit to .451 to make it fit better and cause less pressure? I don't see any accuracy advantage of sizing it larger when its going to end up the same diameter in the end?...unless someone can explain what I'm missing here?

[Rattlesnake Charlie]

A slip fit in the cylinder helps accuracy. A sloppy fits degrades accuracy. If it will chamber when sized to .452, I think you will be happy with accuracy, and pressure will not be a problem with normal loads. If you have been sizing to .451 with no problems and good accuracy, no need to change there either.

[sqlbullet]

If the round drops into and drops out of the chamber, and you have used reasonable and proper load data and techniques, it will shoot fine.

[Tripplebeards]

206116

The purple pc is .452 and would have to be knocked through like I'm slugging a barrel. The lead boolit with the "x" from slugging through my barrel is .451. The .451 fits tightly in the cylinder and can be firmly pushed in by my fingers. I pressed so hard on the purple pc .452 that is was lodged in and I had to tap it out with a scew driver. Never knew there was a tapper in a cylinder. ..learn something new every day. The other pc boolit I slid in from the back side. Almost feels l like a double post from yesterday. ..sorry for that. This post is to ask how sizing .0005 over would affect my accuracy and leading.

[sigep1764]

Load 10 at 451 and shoot them. The gun will tell you whats going on. Itll either shoot with or without leading. If it leads, send the cylinder to dougguy to have it reamed to 452 so you can shoot 452 boolits.

[Tripplebeards]

Sounds like a plan. I have 10lbs of boolits PC'd but have only sized 2 at .452. I'll size up a dozen or so at .541, fire all them through the barrel and check for leading. I'll see if they group at the same time.

[Gohon]

If the barrel groove is .0005 smaller than the cylinder and the .451 diameter fit the cylinder the load them up and shoot away. Especially if they are powder coated. You won't lead the bore...accuracy may be your only issue and I suspect it won't be a issue.

[dbosman]

If things are smooth, I don't see a problem. The forcing cone is reducing the bullet somewhat and the barrel such a small amount more that the only thing that might affect accuracy is the ever so slightly out of round barrel. Which might be a defect in the slug or how you tapped it.

[Tripplebeards]

This is where I got my info from....

https://m.youtube.com/watch?v=WCxFAjtlQPc

My boolit when I slugged it at .4505 fit a little tighter than his sized boolit. My gut tells me sized at .451 I will be fine.

Here's another video...my slug goes though about the same as his...


https://m.youtube.com/watch?v=bdj6cldgNzw

[fredj338]

I can only tell you I have never had an undersized bullet shoot as well as an oversized bullet. If your cyl throats are tighter then the bore, then you need to open the throats for best accuracy & least leading.

[Tripplebeards]

The cylinders and bore are the same diameter...or the bore is .0005 smaller. The cylinders are all .451 and the bore slugged between .451 and .4505 from the measurements I took.

After watching fortune cookie 45's video he said I should be shooting them .001 larger than the cylinder throat chambers which would be at .452 for me. It says it will keep from gas cutting...makes more sense than the looser, smaller size. I think I have changed my mind and will size at .452

I would have to pound a .452 sized boolit through the forcing cone to get it to pass where the .451 will push through with little force with my fingers. It seems like the videos I've watched are telling me two completely different things?

Here is his video I watched and it makes more sense with swaging the boolit down.

https://m.youtube.com/watch?v=8VNjn9aIlWY