what is the proper way to slug my bore/throat?

[sirAIG]

I am having leading issues in my sig 2022 in 40sw. I am using a fairly small powder charge, some missouri bullet co SWC's that are claimed 18bhn, and a lyman M expander. I need to get a bullet puller so I can pull some rounds to see if they are getting swaged down. But I also know I need to slug my bore - and quite frankly, im not sure how to do this properly. Any help is much appreciated...

[GP100man]

First clean the bore ,leading is removed in short order by wrapping copper pot scrubber strips around an old brush.

So it looks like this:

http://i746.photobucket.com/albums/xx110/GP100man/choreboyscrubber.jpg (http://s746.photobucket.com/user/GP100man/media/choreboyscrubber.jpg.html)

I generally lube the bore & push a tite fitting (as close to pure lead) ball thru , you can usually find Cap&Ball round balls close enuff to fit tite& the extra will shave off , if tempted to drive it thru overcomes ya get a brass rod, wood will break!

Measure with a quality micrometer.

Do all this with the barrel out of frame .

Revolvers are a bit different as ya have multiple throats to slug!

18bhn is a hard boolit for handgun pressures ,ya mite benefit from more pressure???
I rarely cast a handgun boolit over 12bhn.

Shoot em in 38/357 & 44s run em up to 11-1200 fps with just a bit of tin wash left behind .

Do you taper crimp ??? I`ve had problems with 45s being "resized" using the taper crimp.

[sirAIG]

I do taper crimp - I played around with the crimp to get it as minimal as possible so the gun would still cycle.

Thanks for the info - I thought that was what I needed to do, But I didnt want to hammer anything through my barrel before knowing for sure. Now - that will give me my bore diameter. What exactly IS the throat? And how does its size effect leading?

How do you know it is tin left in the barrel and not lead?

[leeggen]

AG I also shoot a 40 S&W, only mine is the PX4 Storm, After slugging my barrel it is .4003 I size my bullets 2 thousandth larger .402 and they are cast from coww air cool lead. I tumble lube with FWL or Lee alox lube. Use the search engine on here and look for tumble lube and slugging barrels. Also there is a few threads on here for great informationabout loads and casting for the 40 S&W. You shouldn't need a hard bollit. I use 7.4 grs of AA5 and I get little to no leading. There is a free book "From Ingot To Target" look in the search eng. for the download. READ THIS BOOK TWICE!! Then look for the problems you are having inthe book, also has great answers. Real good reference book. You are asking the right answers and you will get help here but you also need to help yourself by reading different threads and searchs to get the information you need for yourself. Makes you feel real good when you find the answer to your own questions. We all will help, someone stated one time that there must be 10,000 years experience in this membership.
Hope I have helped and good luck, don't give up and don't over think things. 99.9% of us here have done that and don't want to go there again, and still have the teeshirts from it.
CD in TN

[leeggen]

AG I also shoot a 40 S&W, only mine is the PX4 Storm, After slugging my barrel it is .4003 I size my bullets 2 thousandth larger .402 and they are cast from coww air cool lead. I tumble lube with FWL or Lee alox lube. Use the search engine on here and look for tumble lube and slugging barrels. Also there is a few threads on here for great informationabout loads and casting for the 40 S&W. You shouldn't need a hard bollit. I use 7.4 grs of AA5 and I get little to no leading. There is a free book "From Ingot To Target" look in the search eng. for the download. READ THIS BOOK TWICE!! Then look for the problems you are having inthe book, also has great answers. Real good reference book. You are asking the right answers and you will get help here but you also need to help yourself by reading different threads and searchs to get the information you need for yourself. Makes you feel real good when you find the answer to your own questions. We all will help, someone stated one time that there must be 10,000 years experience in this membership, I would like to know for real how many years of casting technoligycombined the membership realy does have. Bet 2 to1 this sight is way ahead of others. Just ask nicly and the answers will come.
Hope I have helped and good luck, don't give up and don't over think things. 99.9% of us here have done that and don't want to go there again, and still have the teeshirts from it.
CD in TN

[gray wolf]

M-dies are not a cure all, Most if not all that come from Lyman are for
jacketed bullets.

[popper]

I've shot a couple boxes of MBC 40SW. They work fine but the lube isn't the best and the alloy is harder than needed. Try Recluse lube ( or thinned LLA) and up your charge to near max for your powder. I doubt they are getting swaged smaller, mic the loaded case neck to see if they don't bulge the case mouth. Mine did. I think they use hardball alloy, 94/4/2. A 40SW M die is still sized for jacketed bullets (0.397 IIRC). I never did completely get rid of the leading with MBC, but it wasn't too bad.

[williamwaco]

I am having leading issues in my sig 2022 in 40sw. I am using a fairly small powder charge, some missouri bullet co SWC's that are claimed 18bhn, and a lyman M expander. I need to get a bullet puller so I can pull some rounds to see if they are getting swaged down. But I also know I need to slug my bore - and quite frankly, im not sure how to do this properly. Any help is much appreciated...


This is a leading disaster waiting to happen.

If you are using light loads, you need soft, preferably slightly oversized bullets.

Nothing leads like hard cast undersized bullets with hard lube and light powder charges.

PS: you can pull those bullets with some side cutter pliers and your loading press.
It will ruin the tip but will not damage the base you need to measure.

[sirAIG]

Hmm.. can you explain exactly why that is? I figured it would only help due to pushing a lower velocity


Does it have to do with the fact that there isn't enough pressure to "seal" a hard cast bullet with a light load?

[Iron Mike Golf]

You are on the right track. To prevent size related leading, you need to cause the boolit to "seal" (i.e. completely fill the grooves). We call this "obturation". There's basically 2 ways to accomplish this:

1. Use a boolit that is .001 to .002 larger that groove diameter.
2. Take advantage of the peak pressure of the propellant gas. If the pressure is high enough, the boolit alloy weak enough, and max pressure is reached quickly enough, the boolit will deform a bit and, even if a tad undersized, "bump up" to fill the grooves.

Missouri Bullet Co lists the size as 0.401 inch. My and my son's 40 cal pistols slugged 0.402 inch. One size fits all works for jacketed. Not so for cast. As you read threads around here, you will see many, many people working hard to cast boolits that fit a particular gun. That's approach #1 above. You'll read about people shooting plain base cast boolits using full power loads. I do - 9mm, 357 Mag, 41 Mag, 44 Mag, 45 Colt Ruger-only loads. If your boolits fit, then you have the latitude to tweak the alloy and hardness to get what you want in terms of accuracy and terminal effect.

Read the Technical section of MBC's web site. They subscribe to approach #2 above - use the pressure to bump up. If your boolits are undersized for your bore, a light charge will not bump those boolits up. Boolits too hard and charge too light. That's what WilliamWaco was referring to.

Having said all that, in addition to measuring your goove diameter, you also need to verify your don't have any conditions that cause "mechanical" leading. By that, I mean defects in the machining of the barrel that will cause lead to be shaved or scraped off the boolit as it passes by. Look real hard at the throat (the area from the end of the chamber to the point where the lands are full height). I have seen many barrels with tool marks on the lands where they ramp up. I have also seen "steps" right where the land begins to rise from the groove floor. These sorts of things act like a cheese grater and peel slivers of lead off the boolit. Gases blow these down the bore and the next round presses the shavings into the grooves. A camera that has a macro mode can be very helpful here. A borescope is better, but those are pretty spendy (around $800).

[williamwaco]

Iron Mike + 1


.