need help with 40S&W--barrel leading

[10ses]

ok so i'm new to this casting stuff, and i'm having a hard time coming up with a boolit that won't lead the barrel of my Ruger SR40--i'm using the lee 175's that i've cast with some old .38 bullets a friend gave me. they have a BHN of 16-18, a charge of unique(i've tried everything from 4.0-5.0 grs.) and my lube is 1# beeswax,1# paraffin,and 1/2#petroleum jelly--any help would be greatly appreciated! i hope i didn't just buy the lee pro4-20, my molds and everything else for nothing!

[boltons75]

Keep playing, my Sr40c gave me some trouble, I went with the m expanding die, and it helped. Have you slugged the barrel yet? Mine needs a boolit sized to .402 at the min.

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[popper]

It'll work. Your lube is OK. I have the TC & SWC moulds, they're fine. You could go to 5.8 gr but probably won't enjoy it. You could also add some pure for a BHN 11 or so. Size matters, I have to size .401 for both my 40s or I'll get some leading (check size of sized CBs, my Lee pushthru was off by .0015 for all but really high Sb alloy). Yours may need to get bigger. With that BHN you are probably resizing the case when loading, make sure no shavings are at the mouth. Gear says some 40s have a sharp edge at the throat that can cause leading (shaving). He recommends a slight breaking of that edge to solve the problem.

[Lefty SRH]

Slug or barrel that will tell you what size your boolits need to be. Your lube sounds ok. Why are your boolits that hard? What alloy are you using?

[10ses]

ok here's what i've got so far--barrel slug is .402, mold is throwing boolits at .404 and the lee push through is doing them at .401-, i really liked the 4.0 grs of unique, i think i can drop down to 3.5 to 3.8 and still make power factor if i can get it to stop leading[smilie=b: thanks for the replies, keep them coming!

[10ses]

It'll work. Your lube is OK. I have the TC & SWC moulds, they're fine. You could go to 5.8 gr but probably won't enjoy it. You could also add some pure for a BHN 11 or so. Size matters, I have to size .401 for both my 40s or I'll get some leading (check size of sized CBs, my Lee pushthru was off by .0015 for all but really high Sb alloy). Yours may need to get bigger. With that BHN you are probably resizing the case when loading, make sure no shavings are at the mouth. Gear says some 40s have a sharp edge at the throat that can cause leading (shaving). He recommends a slight breaking of that edge to solve the problem.

if i polish the barrel with a barrel mop and some rubbing compound would it help this?

[popper]

Hone it to .403 but do it slowly. Can you get the .404 to load and chamber? Your hard alloy may alloy you to do that without the case resizing the CB, or at least keeping it > .402. It may work without sizing the case, just de-cap. Try with dummy loads. I don't lap my bbls. I'd work on the loading and wait on the bbl work. Gear has a different way of doing it, he may chime in here.

[gray wolf]

ok here's what i've got so far--barrel slug is .402,
If that's correct ? you may need a 403 bullet.

the lee push through is doing them at .401-
That's a .001 under bore already, [B]hows that posed to work ?[/B

i hope i didn't just buy the lee pro4-20, my molds and everything else for nothing!
No you didn't, you just gotta do it correctly.

[mpmarty]

Quit ruining good boolits with that undersize sizer. I shoot that 175gr LEE t/l boolit in my 10mm all the time at large loads of AA-9 at over 1300fps and have no leading whatsoever in three 10mms I definitely make major.

[boltons75]

ok here's what i've got so far--barrel slug is .402, mold is throwing boolits at .404 and the lee push through is doing them at .401-, i really liked the 4.0 grs of unique, i think i can drop down to 3.5 to 3.8 and still make power factor if i can get it to stop leading[smilie=b: thanks for the replies, keep them coming!

About what my Sr40c is, I ordered a .402, and a .403 die from buckshot for my lam2, and I have little leading now. Try to load some without sizing, good luck.

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[popper]

Did you slug it with pure lead or that hard alloy you are using? It will come out larger with the hard alloy due to spring back. If you decide to hone the sizer, I got a rod type diamond knife sharpener at Academy for $7 that worked real well. Took about 10 min. for ~ .0015". Remove the nut, oil the sharpener and roll on soft table top. Work up slowly, sizing and mic'ing a CB often. mpmarty - that SWC seems to run faster than the TC with the same powder load. I flat based mine but haven't used it much lately. boltons75 - is that the standard 40SW M? I'm thinking of getting the 41 plug and reworking it.

[10ses]

thanks for all the help guys, i'll try some without sizing, i don't have any other way to size-

[40Super]

My XDm is the only .40 I have that can get away with .401 bullets, all other I size to .403 or .404(Beretta's).The hardness will work if you get the size correct.

[prs]

About the slugging, use very soft lead such as a Hornady pure lead ball than measure with a micrometer instead of a caliper. Ruger is pretty generous with their chambers in my limited experience and your unsized boolits should be good to go as long as the transition of the chamber to rifling is not too sharp. Getting the boolits in the cases without an "M" die to prevent squashing them down could be a problem. Don't EVEN think about using a post sizing die!

prs

[cajun shooter]

I would most definitely slug the bore first. I would then use a softer alloy and see how things go.
What kind of sizing set up are you using? I have some of Lars BAC which may help you some also. You have a lot of variables going on all at once and to find the source of your problem you need to change one thing at a time.
If you make changes to everything at once, you will never know what the cause is.
Ruger has a reputation of making guns with the bores too large or the chambers of a revolver too small. I realize you are shooting a pistol but the problems with QC show up in that area also.
A very hard bullet which your alloy is approaching will have trouble with the obturation.
Find the book in the sticky section by Glen Fryxell and Ron Applegate named From Ingot to Target.
The book has a very good explanation on the subject starting on page 58. It will walk you through the things you may be seeing and the ways to correct them.
If you have not done so, then it may be a good idea to either down load it to your harddrive or print out all 178 pages and place them in a hard three ring binder for future reference.
I have been casting since 1970 and I refer to the book if I feel a need for extra information.It has a place on my book shelf.

[10ses]

Quit ruining good boolits with that undersize sizer. I shoot that 175gr LEE t/l boolit in my 10mm all the time at large loads of AA-9 at over 1300fps and have no leading whatsoever in three 10mms I definitely make major.

this isn't the t/l boolit, it's the 175 TC, i pan lube them-

[runfiverun]

he was refering to shooting 401 boolits in a 402 sized bbl.
it's easy to open a lee sizer a thou or two.

[10ses]

It'll work. Your lube is OK. I have the TC & SWC moulds, they're fine. You could go to 5.8 gr but probably won't enjoy it. You could also add some pure for a BHN 11 or so. Size matters, I have to size .401 for both my 40s or I'll get some leading (check size of sized CBs, my Lee pushthru was off by .0015 for all but really high Sb alloy). Yours may need to get bigger. With that BHN you are probably resizing the case when loading, make sure no shavings are at the mouth. Gear says some 40s have a sharp edge at the throat that can cause leading (shaving). He recommends a slight breaking of that edge to solve the problem.

what would be the best way to break this edge, mine is quite sharp?

[popper]

PM gearnasher, he has the fix. I didn't need to do it for XDm or PX4. I just TL the 40SW, works for me and is much faster and easier than pan lubing.

[10ses]

thanks!

[runfiverun]

it's called a throating reamer.
they have been using them on revolvers forever.
some of the new 40-45 pistols seem to have the same sharp square rifling start at the edge of the bbl and no leade in area.

[geargnasher]

One more time with the .40 and plastic pistols.

The brass is very thick and very hard to withstand the magnum pressures of this hot little round, and tooling is made for copper-jacketed bullets, which are WAY too small for cast.

Standard tooling both resizes the brass too much and fails to expand it enough, or expand DEEPLY enough to prevent boolit swage. UNDERSIZED BOOLITS LEAK GAS, WHICH ABRADES THEM AND LEADS THE BORE.

You're sizing the boolits too small to begin with as has been covered.

Even if you don't size them too small, often the CASE sizes them too small for you when you seat them.

Even if you don't size them too small and DO use a large enough expander so the brass doesn't crush the boolits, the boolit and case is often swaged undersized together by using the Lee Factory Crimp Die with the post-sizing carbide ring in the bottom, which is designed for jacketed dimensions, NOT cast boolits!!

So the boolit can be cast undersized, sized undersized, swaged by the case undersize when seated, and crimped undersized. Did I mention that undersized boolits lead the bore?

Even if all of THAT is right, and the boolit comes out of the case just a fuzz over barrel groove dimension as it should be, it can STILL scrape lead off on a SECOND sharp step ahead of the end of the chamber in some barrels. Two points can shave lead: The thoat entrance right at the end of the chamber if it isn't beveled to accept the size of boolit you shoot, and there is sometimes a second step at the origin of the rifling where the "cone" of the throat terminates, like the cutter is bigger than the bore diameter. This 90-degree step will shave lead like a potato peeler. This is what a throating reamer fixes, and often fixes undersized throat entrances as well.

Remember, these pistols were made for jacketed bullets which can tolerate these sloppy designs and sharp edges much better.

Often a custom-made expander spud is necessary to deal with the hard brass. I had one made with a spud that is .401" so I can load 15 BHN .402" boolits. The brass springs back to about .4005" or so after expanding, so it holds the boolits with nearly .002" tension, more than enough. I use a gentle taper crimp, just enough that the cartridge will fall .010" below flush with the barrel hood under the power of gravity, but is snug in the front. I seat the boolits out so that the cartridge headspaces on the boolit, not the case. Use the barrel for a case gauge, and makd a few "dummy" cartridges with no powder or primer and check your cycling from the magazine manually.

Use a good lube, yours is fine for this.

Balance the load to the alloy, you're doing fine with Unique is about perfect for the alloy you're using, don't be afraid to work them up, and expect accuracy, function, and chamber cleanliness to occur at the higher pressures because it takes a lot of pressure to make that brass expand and seal up.

This is NOT a .38 Special or .45 ACP, and like the 9mm, has a different set of rules to follow to get it to work right with cast.

Good luck,

Gear

[10ses]

wow, that is one nice chunk of info! thanks Gear!

[10ses]

ok everyone, thanks for all of the great info, i finally got it!--i polished the barrel with polishing compound, and are loading the boolits as cast. i broke the sharp edge of the chamber by hand. i only loaded 10 rounds, but the chamber was virtually spotless, the only thing i might do different is open up my push through to .4035 and try that as i did have 2 rounds that chambered a little hard, and i may drop the OAL back to 1.126 as i have them at 1.13 right now-- thanks again!

[10ses]

[smilie=w: