Author Topic: Rolling Grease Grooves on P.P. slug?  (Read 761 times)

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Offline .22-5-40

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Rolling Grease Grooves on P.P. slug?
« on: February 14, 2011, 06:16:51 PM »
Hello, I have an idea I wonder if you guys could comment on?  I have an adjustable .40 paper-patch mould (Tom Ballard) with cup base.  It casts a bit large at .405" dia., which is no problem to size .  But I have another idea...I have a Corbin cannelure tool, with two sets of knurled wheels: .050" and .080" width.
I was wondering if I could roll some lube grooves on those smooth slugs & shoot them over Black?  They would only have to slug up .0015"/side to fit .408 groove dia. of .40-70 brl.  Alloy is soft.  If the .080" grooves seem too small..I could always use a grease cookie.  What do you guy's think of this wild idea?

Offline Nobade

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Re: Rolling Grease Grooves on P.P. slug?
« Reply #1 on: February 15, 2011, 02:24:00 AM »
Point #1 - no grease cookies or other wads used with cup base bullets.

Point #2 - with no lube grooves there is nothing to seal the gas blow by. Bore gets leaded very quickly.

Point #3 - unless you muzzle load those bullets over enough powder or powder and then filler to get them past the throat, they don't stand a chance when the big kick in the butt hits them and they slug up to fill the throat and space between the case and the end of the chamber and then get squeezed back down into the bore.

The question is, why not use it like it is designed to be used, with a paper patch?
"Give me a lever long enough, and a place to stand, and I'll break the lever."

Offline .22-5-40

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Re: Rolling Grease Grooves on P.P. slug?
« Reply #2 on: February 15, 2011, 05:26:45 PM »
Hello, Nobade.  And thanks for reply.  I guess I should have been more clear..Those .050" and .080" wide knurled wheels ...there are two in a set & can use two at a time.  Actually roll a conventional lube groove into the surface of the P.P. slug.  I got the idea when trying one..and it looks to be alot more streamlined ...that is..there should be less air turbulence with those shallower grooves..that could be a problem though..perhaps not carrying enough lube for B.P.?  I will try out this summer..maybe all I'll get is a bore full of lead?  I do use these as Paper-patch..though sparingly..those patched slugs sure do shine up a bore...I was worried at what point polished becomes...excessive wear?  Thanks again!

Offline Nobade

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Re: Rolling Grease Grooves on P.P. slug?
« Reply #3 on: February 17, 2011, 02:47:51 AM »
Ah, I see. OK, it likely would work if you can get the bullet into the bore and not let it go through the throat. Same thing that happens in a muzzle loader. Have to size them to bore dia. after they are lubed. Of course this all depends on the rules you are shooting under. Some matches require fixed ammunition, and others allow you to use a breech loading muzzle loader.  As for patch wear, use 100% cotton paper without whitening agents and the bore should last a long time. But I do hear you, and if it is an original rifle then grease groove bullets will be easier on it. One big question is what does the throat look like? Usually rifles are cut for either GG or paper patch bullets and don't give their best accuracy with the one they're not made for. And quite often a PP chamber won't let the case expand enough to seat a groove diameter bullet into the case mouth. Have you done a chamber cast to know exactly what you are dealing with?
"Give me a lever long enough, and a place to stand, and I'll break the lever."