cast bullet swaging/bumping/forming on the cheap

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  • Last Post 13 October 2015
Ken Campbell Iowa posted this 09 June 2014

with the recent deeper discussions on accuracy, i notice some interest in “  swaging ” .. lead bullets.  my interest would be to see if bumping/swaging either from scratch or from castings would result in less ” unacceptable “  or otherwise ” ooops “  fliers/outliars .

this not exactly new ground, but i think it needs a closer look.

i am thinking that a simple die set could be developed that could be made with an amatuer's lathe, .. in no more than a day, and for materials of no more than $10.

i have spent a few hours wading thru the 500 posts on swaging in cast boolets, and i can't think we need a $1500 super honed die set to IMPROVE our casting.  i aim for something LEE could sell for $29.95 ( g ).

with simple dies, we might get a simple bullet ... i am thinking a truncated cone might be a starting design.

i welcome any comments, including reasons not to continue this in this forum  (  g  ) .

ken, being squoze in iowa

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John Alexander posted this 09 June 2014

Ken, I think that is a great idea.  Actually doing something other than just arguing about it, how novel.

Put that feverish brain and all those skills honed by building toy racing cars and other incidental jobs to work and keep us informed. John

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joeb33050 posted this 09 June 2014

I have a mold for a no grease groove 30 caliber bullet that would make a good swage subject.

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armalite53 posted this 09 June 2014

I think it's a great idea also. It could be the hot set up for a 450/577 paperpatch bullet.

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joeb33050 posted this 10 June 2014

The 30 caliber bullet is ~.302” on the nose, ~.313” on the base band wirh a taper between the two. I will lend the mold, cataract surgery means no casting for a while.A swage die with the nose tapering from .302” to .306” and a base band of .310", with the 3 parts, a front/nose part, a middle part and a base part with a bleed hole would form it.Rather than a press, I've thought that a lever made from a 2X4 maybe 8' long bearing on the bottom part of the swage die? 12'long?And/or, a heated swage die would reduce swage force required.   The object to reduce cast bullet volume, eliminate voids and excess alloy goes out bleed hole and is cut off.I can make a sketch, but am a very poor drawer.

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muley posted this 10 June 2014

If , we swage our bullets , instead of casting, are we then going to be The Swage Bullet

Association ? or are we using the swaging process to enhance our cast bullets??

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joeb33050 posted this 10 June 2014

muley wrote: If , we swage our bullets , instead of casting, are we then going to be The Swage Bullet

Association ? or are we using the swaging process to enhance our cast bullets?? All kinds of CBA competitors were/are swaging bullets after casting. See John Ardito for example.

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LWesthoff posted this 10 June 2014

Okay. As long as we cast 'em first, then we can swage/bump/use any other method we can devise to alter their shape, and they're still cast bullets, right?

I'm gonna have to think about this for a while. Not real sure that sounds very good to me.

Wes

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RicinYakima posted this 10 June 2014

Running your bullet through the lube and sizer is swaging, and bumping bullets was the first advancement of the CBA back in the 1980's.

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delmarskid1 posted this 11 June 2014

The lug bolts on semi-tractor and trailer wheels are 7/8"X14 threads per inch. The same as our loading presses.

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mckg posted this 12 June 2014

LEE Loaders can be used to a certain extend; time and noise are limiting factors.

With a .44 Magnum one, I got an 11mm/.433 result. I don't remember any conicity.

.457 RB's would turn into smooth sided slugs; LEE's 190-SWC's would keep their nose.

I don't see LEE turning out threaded dies for operations that their presses couldn't handle.

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Ken Campbell Iowa posted this 12 June 2014

several bumpers on the ” booolets ” threads use the lee classic cast, single die press. i have one, it's pretty strong.

the limit of how hard an alloy could be bumped would be when the alloy crumbles and not flow. i have bumped 92-6-2 before, so that should be good enough to test a few with. 10b or 12b would be easier however.

ken

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joeb33050 posted this 12 June 2014

What is the purpose of bumping or swaging? Why do it? Is it to change shape; or squeeze out the voids; or ??

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armalite53 posted this 12 June 2014

There's lots of reasons, but for me it's just to be able to “tweak” the projectile just a bit. Examples: The noses of the bullets cast by my Lee 309-200 are just a teensy bit big for my K31's bore. For the Martini-Henry, my 457132 is too small.

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RicinYakima posted this 12 June 2014

Joe,

I do it to change shape, i.e. dimensions, for my Military Rifle chambers. They have very little standardization, as most are war-time production. At first it was just to increase or decrease the nose size, but now I am also tapering the front driving band to seal the throat.

Ric

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Ken Campbell Iowa posted this 13 June 2014

of the dozen or so reasons to bump bullets ( including just for the fun of it .. maybe the best reason ) .. my immediate reason would be to look at the ” void ” effect.

if indeed a thoroughly bumped bullet eliminates voids, giving us a perfect bullet ( g ) ... then we can compare perfect bullets to some we intentionally put voids into ..

thus we ... might ... know how important ” voids ” are ... do they really turn our 4 shot 2.5 moa groups into a 4 shot plus a flyer ... group that we are too familiar with.

i doubt that these perfect bullets will suddenly make a 2.5 moa deer rifle into a 1 moa tack driver ... but geepers wouldn't it be neat to be able to shoot 50 shots into that 2.5 in. without a radical outliar ?

it is most likely that that 1 moa ( and better ! ) accuracy will only come when we figure out to get our bullets down that first 2 inches of barrel without being distorted from the so far devastating birthing trauma .

i feel this bumping, or super-bumping , or swaging ... is just a 10 % way to get bullets good enough to go up against the monster that chews up our bullets in that first ... 1/4 ? ... 2? ... 3? inches ..

consider that cb pistols seem to shoot as well as cb rifles ... maybe because everything happens in the first part of the barrel, not the last half.. just interesting.

again, would appreciate more comments; for instance, how about lubing these things ? ken molly, our good friend, would probably be interested in this ... powder coating? oily sawdust filler ? or do they need lubed at all ?

hit me with your best shot ( pun intended ) .

ken

if your comments are really extra nasty, pm me .. i am so egotistical i am impervious to flame and strong acid ... ( g ) .

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John Alexander posted this 13 June 2014 

   Ken,

  I think we could investigate the effect of manufactured air voids now without having perfect (by bumping) bullets.  Normal bullets could serve as a control although not perfect.  This would find the difference in accuracy between the two.  I think Joe and perhaps others have done some of these tests and Mann certainly did.  I will have to look in Mann to refresh my memory.     Another interesting part of the question is how common and how big are air voids?  Bob Birmley clearly found a fair percentage of one type (air voids near but not quite on the surface) by tumbling. There may, or may not, be additional air voids further from the surface. I wonder how common Bob's situation of many air voids may be.  I have turned down and filed down a fair number of cast bullets without finding the first one.  What are your experiences?     Air voids at the surface we can see and we sometimes call them wrinkles.  A couple of years ago I had an article in the Fouling Shot reporting that even some pretty gnarly wrinkles (big air voids) didn't affect accuracy at the 1MOA level.  This doesn't prove that they don't have some effect at the .5MOA level but it does imply that they may not have as much effect as we might suppose and probably aren't the reason that some rifles won't shoot 2.5” groups.   John

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Tom Acheson posted this 13 June 2014

OK, couldn't resist.

From my limited experience, bumping offers four enhancements:

Makes the bullet “rounder” than the mould or lubrisizer.

Applies a consistent taper from bullet to bullet and that taper produces the condition of a taper being chambered in the similar tapered throat for optimum alignment before ignition.

Makes the base of the gas check square and sharp cornered (the change can really be dramatic).

Bump dies are adjustable to apply some or a lot of pressure and to move the location on the bullet where the taper starts.

As far as “squeezing out the air voids"...boy I don't know about that one. If the void is very far below the surface of the bullet it sure seems unlikely to be displaced by bumping. We might change the shape of the void but elimination seems to be a stretch, pardon the pun.

I've been bumping my .30 cal. bullets in a bump press/die made for me by Tom Gray since 1997 for .30 BR, .30 Kern, .30 PPC, .30 Silhouette (all of these in an XP-100 LRH) and .308 Winch. (Savage Model 12) and have proven to myself that bumped bullets are more accurate than unbumped bullets, more noticeably in the XP-100 with a custom chamber, than the factory chamber in the 308 Winch. rifle.

Tom

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billwnr posted this 14 June 2014

Tom Acheson wrote: OK, couldn't resist.

From my limited experience, bumping offers four enhancements:

Makes the bullet “rounder” than the mould or lubrisizer.

Applies a consistent taper from bullet to bullet and that taper produces the condition of a taper being chambered in the similar tapered throat for optimum alignment before ignition.

Makes the base of the gas check square and sharp cornered (the change can really be dramatic).

Bump dies are adjustable to apply some or a lot of pressure and to move the location on the bullet where the taper starts.

As far as “squeezing out the air voids"...boy I don't know about that one. If the void is very far below the surface of the bullet it sure seems unlikely to be displaced by bumping. We might change the shape of the void but elimination seems to be a stretch, pardon the pun.

I've been bumping my .30 cal. bullets in a bump press/die made for me by Tom Gray since 1997 for .30 BR, .30 Kern, .30 PPC, .30 Silhouette (all of these in an XP-100 LRH) and .308 Winch. (Savage Model 12) and have proven to myself that bumped bullets are more accurate than unbumped bullets, more noticeably in the XP-100 with a custom chamber, than the factory chamber in the 308 Winch. rifle.

Tom

Interesting comments Tom.   One thing I've been pondering is how to fix the effects of an off center nose punch on a lubesizer.   It might be that a full “bump” might just repair things.

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armalite53 posted this 14 June 2014

Small arbor press swage  set up for squishing nose diameters. “Die” is a scrap piece of inconel with a .3000 bore that I adapted. Gas checks are applied with an oversize die so the bullet diameter remains as cast. One could prowl the flea markets and duplicate this set up with an old ring gage.

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Tom Acheson posted this 14 June 2014

Bumping might correct the off center result from sizing but we'd have to experiment by shooting some before and after bullets to see if any improvement is seen. My RCBS sizer produces shiny scuffing on one side of the bullet. My Saeco unit produces much more uniform looking bullets.

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j35nut posted this 15 June 2014

My RCBS sizer was a pretty easy fix using six 6/32 nylon tipped set screws to center the ram.

---------J

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rbuck351 posted this 13 October 2015

I picked up an old Swag-o-matic not long ago for around $100 with a bunch of dies and I'm in the process for making a few more. It works really well for reforming cast bullets even wcwws. I just made a 312 die and am making a half jacket 85gr SWC in 312 for my 7.62 x 25. And I'm using 50BMG primer cups for the Half jackets. If you lube the cast bullets before swaging the lube keeps the grooves from collapsing and you end up with a very uniform cast bullet with very square sharp bases and a flat bottom. A die making company such as Lee could make dies that fit a loading press for swaging cast bullets that wouldn't have to cost any more than a normal die set and probably less.

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