629 Leading

[Master_Mechanic]

The first revolver I bought was a smith and Wesson 629 with a 6" barrel, I started reloading for it using commercial cast boolits and had leading issues in the first inch-inch and half of the barrel. I have recently bought another 629 with a 4.2" barrel and the leading is much worse in this gun. I have been casting 429421 and 429650's out of ww lead sized to .429. After reading a whole bunch on this site I decided to tackle my leading problem and try and get better accuracy out of these guns. Today I picked up some fishing sinkers to measure my bore diameter, being smiths it made it a little tough to get the measurements, but as best I can get with a micrometer the 6" one measures .429 grove and the cylinder throats are .430 (used a .430 j-word that snuggly fits the throat.) So now I'm going to have to switch to a .431 sizing die for that gun. The shorter barrelled 629 is a whole different beast the cylinder measures .429 and the bore at .430, the sinker I hammered through the barrel wont pass through the throats, so am I safe to assume I need to have the throats reamed out to .431 and size the boolits to .432 for that gun? or would .431 work? Thanks for all your help, I have learned a ton from all you guys.

[bhn22]

You are using dead-soft egg shaped sinkers aren't you. It's also important to make sure the barrels and cylinders are totally clean, and lightly oiled before slugging. I lightly oil the slug as well. One thing to watch for is a constriction at the frame juncture in S&Ws. The slug will suddenly get tougher to move when it reaches a constriction.

[MtGun44]

If you are measuring with calipers - you need to get a .0001" reading mic before
you do much, calipers are insufficiently accurate to do this work with any
consistency.

If you do have .429 groove and .430 throats, try using .430 or even .431 boolits and
let Mr. Target tell you the answer, along with a look at the throats and bore after a
few dozen have gone to the berm.

Bill

['74 sharps]

The "commercial cast" bullets are probably "hard cast" with an ineffective lube to withstand the rigors of shipping. Go to the LASC website to understand the pressure - alloy - obturation - leading relationship before removing non replaceable metal from any gun.

[44man]

Many bought boolits are just too small with bad lubes.
But the gun with smaller throats needs fixed.
Get a good mike too.

[uaskme]

I have a 629-3 that has 431 cyl throats and a 629-4 that was 428. S&W has reduced the throats. I have a couple of 29-2 that are 432. All measured with pin gauges. I had the throats opened up on my 629-4. I think they did this to reduce pressure in the barrel. My 629-4 would lead before I had it opened up.

[Master_Mechanic]

I have a good micrometer, both guns were spotless and oiled before I hammered the egg shaped sinkers through them. Neither gun did I feel any sort of constriction. I assumed the commercial cast were not up to par, so when I started casting my own and still had issues it concerned me a little. The gun with proper throat to bore relationship I'm sure will be solved with .430-.431 sizing. The gun with the small throats, I should go .001 over bore diameter, but is sizing the boolits to throat diameter going to be ok?

[Shuz]

If you are measuring with calipers - you need to get a .0001" reading mic before
you do much, calipers are insufficiently accurate to do this work with any
consistency.

If you do have .429 groove and .430 throats, try using .430 or even .431 boolits and
let Mr. Target tell you the answer, along with a look at the throats and bore after a
few dozen have gone to the berm.

Bill
To what Bill suggests, I'd add.............use a charge of 18 to 19g of 2400 or 21 to 22g of H-110/296 with the .430 or .431 boolits of your casting with a good lube, and I think you'll get better results than using the medium burners like Unique or Green Dot.
I have a couple of 629-3 Classix DX's with .4285 throats and I shoot .431 Bhn 11 to 12 boolits thru them with the slower powders with absolutely no leading.

[Mal Paso]

I opened the throats of 2 guns, a Colt and a 629-6. The Manson reamer for 44 cal is .431" with a tolerance of +.0005". I now shoot .431" boolits in everything now, even the Ruger with .432" throats and Colt with a 430" groove.

I think it's a balance. Even a boolit sized down to .428 by tight throats is larger than a .429 barrel when you consider all the lead displaced by the grooves and depending on alloy etc may seal just fine. I just think it works a bit better with a larger lead boolit entering the forcing cone.

[243winxb]

ww lead sized to .429 Wrong alloy, wrong Diameter.

[Master_Mechanic]

One more question that arose, the gun with the small throats is pretty much brand new, is this somthing I should be sending to smith to have corrected or just a local gunsmith?

[JonB_in_Glencoe]

One more question that arose, the gun with the small throats is pretty much brand new, is this somthing I should be sending to smith to have corrected or just a local gunsmith?
I would definately have the cylinder worked over on your 629 with a 4.2" barrel. I'd call S&W and see how you are treated, who pays for postage and such other details. If you know a local gunsmith who you know does this kind of work and is highly recommended, I'd surely pay him to do it and save the hassle.

edit: you said the 629 with a 4.2" barrel was like new...did you buy it from a dealer as "NEW", then maybe he'll deal with S&W for you ?

[Master_Mechanic]

Bought it from a semi-local online based store new in box, I should talk to them see what they say, I had an issue in the past with a 617 and emailed smith and wesson to see if there was any small tips I could try prior to sending it back and never got a reply. Being in canada makes it a little tougher to ship guns off to be repaired. I don't personally know any local gunsmiths, but I can ask around my club as I belive we have a gunsmith who does work for smith and wessons. Thanks for the tips.

[mdi]

Reaming cylinders isn't an insurmountable task. I have life long experience working with metal so it was a "walk in the park" for me, but with care, a home gun fiddler should be able to ream a few thousandth out of a cylinder's throats. I got my chambering reamer from Brownell's. Just make sure the cylinder is fixed solid, to a jig or table and the reamer is inserted straight...

[geargnasher]

Many bought boolits are just too small with bad lubes.
But the gun with smaller throats needs fixed.
Get a good mike too.

+ 1. I've reamed many a Smith cylinder. Rugers too. All it needs to be is groove diameter or a fuzz larger. Boolits don't usually need to be larger than the throats, but like MtGun44 mentioned, let Mister Revolver and Professor Target be the judge.

Gear

[thumper,eh?]

Master Mechanic, if you get leading at the throat you are using an alloy that is too hard for the pressure / velocity you are working with. Using undersized bullets will only make it worse. Larger bullets may fix the problem. If using a larger bullet does not solve the problem, go with a softer alloy.
I use two different alloys for my 629. Soft bullets ( approx 9-10 bhn ) for light / medium loads. These are used to just punch holes in paper or introducing new shooters to big caliber thumpers. And a harder alloy ( approx 12 bhn ) for approximating factory equivalent loads.
Use the softer alloy and work up the load to get it to where you want. If you start getting leading toward the muzzle, then its time to harden up the mix you are using. This all assumes you haven't hit max pressure. My cast are either .430 or .431, can't remember which.
Good luck.

[Mal Paso]

One more question that arose, the gun with the small throats is pretty much brand new, is this somthing I should be sending to smith to have corrected or just a local gunsmith?

S&W has admitted they cut the throats for jackets now. I think you will find the throats are within S&W specification although SAAMI Spec is .4325". I'm not saying SAAMI Spec is ideal but the late 629s I measured were .428"-.4285". I like throats .430" to .431" over a .429 groove and the boolit to just push through but all I shoot is lead.

[Master_Mechanic]

I don't think any of the leading is alloy related, I ran harder commercial cast and then ww alloy and had the same results, I believe the one with the small throats isi sizing the boolits down too small. And I believe that the other is just a boolit sized too small. I ran the same alloy and lube in 357 at simmilar pressures with no issues. I don't believe I have any throat leading and the leading I do have is in the first inch and a half of the barrel.