This short excerpt was taken from the 3rd edition, vol. 1 of the "Cast Bullets for Beginners & Expert" by Joseph F. Brennen Jr. and published by the Cast Bullet Association.
4.3.2 HOW TO BUMP BULLETS IN THE LUBRICATOR/SIZER
I have only used the Lyman 45 and 450 Lubricator/Sizers, but understand that the Saeco and RCBS machines will also bump bullets. The problem with bumping bullets in a Lyman machine is that the handle, a flimsy proposition at best, will easily break.
Ken Mollohan: The warning that Lyman handles are too flimsy for bumping, and will break is correct in my experience also. But my remedy was to weld a reinforcing strip of steel across the top of the handle above the pivot holes, which is where the handles is thinnest, and the breaks occurred. These strips were the same size and thickness as the original handles, and perhaps an inch or an inch and a quarter long. Welding was completely across the surface. This simple alteration has prevented further problems for several decades.
4.3.2 HOW TO BUMP BULLETS IN THE LUBRICATOR/SIZER
I have only used the Lyman 45 and 450 Lubricator/Sizers, but understand that the Saeco and RCBS machines will also bump bullets. The problem with bumping bullets in a Lyman machine is that the handle, a flimsy proposition at best, will easily break.
Ken Mollohan: The warning that Lyman handles are too flimsy for bumping, and will break is correct in my experience also. But my remedy was to weld a reinforcing strip of steel across the top of the handle above the pivot holes, which is where the handles is thinnest, and the breaks occurred. These strips were the same size and thickness as the original handles, and perhaps an inch or an inch and a quarter long. Welding was completely across the surface. This simple alteration has prevented further problems for several decades.
Here's my Lyman 450. Note the repair/braze area where the handle broke-several times. The ADJUSTING SCREW adjusts how far
down the bullet can be pushed in the sizing die by the TOP PUNCH. Note that the TOP PUNCH fits into the sizing die and into the NUT. I use the
NUT; it fits inside the SIZING DIE LOCK NUT; to stop the downward motion of the ram and TOP PUNCH. Then I adjust the ADJUSTING SCREW to limit the downward movement of the bullet in the sizing die. When the bullet is all the way down, and there's space between the ram and NUT, further pressure on the handle mashes the bullet shorter and bigger in diameter. Other and better arrangements are made by those more mechanically inclined than I.
Bumping the nose. The example is the Lyman 311299 bullet, with a bore-riding nose that should be about .300", and a set of three bands over .308" in diameter. I'm assuming here a 30-caliber barrel of .300" bore and .308" groove.
My 311299 molds produce bullets with varying nose diameters and bands over .312" that are sized .312" in a Lyman 450.
In the process of sizing and lubing the bullets, with no undue pressure on the handle of the 450, bullet noses increase one thousandth of an inch minimum. They get bumped up. By fiddling with the lubricator/sizer and increasing the pressure on the handle, it is easy to increase the nose diameter of the bullet by three to four thousandths of an inch. Somewhere around four thousandths of an inch the nose starts to bend into a banana shape, and/or the handle of the machine breaks.
With bullets under .312" band diameter, sizing normally, without undue pressure on the handle increases band diameter at least one thousandth of an inch. All my 30 caliber molds make bullets that have the base bands "shined up" in the lubricator/sizer.
Bumping the nose. The example is the Lyman 311299 bullet, with a bore-riding nose that should be about .300", and a set of three bands over .308" in diameter. I'm assuming here a 30-caliber barrel of .300" bore and .308" groove.
My 311299 molds produce bullets with varying nose diameters and bands over .312" that are sized .312" in a Lyman 450.
In the process of sizing and lubing the bullets, with no undue pressure on the handle of the 450, bullet noses increase one thousandth of an inch minimum. They get bumped up. By fiddling with the lubricator/sizer and increasing the pressure on the handle, it is easy to increase the nose diameter of the bullet by three to four thousandths of an inch. Somewhere around four thousandths of an inch the nose starts to bend into a banana shape, and/or the handle of the machine breaks.
With bullets under .312" band diameter, sizing normally, without undue pressure on the handle increases band diameter at least one thousandth of an inch. All my 30 caliber molds make bullets that have the base bands "shined up" in the lubricator/sizer.
Bumping the bands This Lyman 319289 bullet has bands of constant diameter. Let's assume that the bullet is .321" in diameter, and we want it larger. Run it through a .323" sizing die, and make sure that all the lube grooves are filled. Then set
the lubricator/sizer and force the handle down to expand the bullet to sizer diameter, .323". Again, three to four thousandths of an inch is the maximum increase in diameter before the nose gets to looking funny or the handle breaks.
I have bumped many bullets using conventional sizing dies in the Lyman 450, calibers from 22 to 45, and never increased accuracy. Others have had great success. I like the Lyman 311299 and 314299 bullets, and have worked with them a lot. Here's a picture of the 311299, the 314299 looks exactly the same. This story is about the 314299. I have been working with a Winchester M54 rifle in 30/30, casting bullets in 25:1 lead: tin and linotype. The nose of the bullets measure .3032"-.3036", and cast in either of the alloys the nose is lightly engraved when the cartridge is chambered. With 25:1 and bullets sized .312", a cartridge overall length of 2.895" chambers in the gun, mashing that front band into the throat. With linotype and bullets sized .312", that front band stops the cartridge from chambering at an overall length greater than 2.865"-it won't be mashed in. So I sized bullets of both alloys down to .309" in search of a longer overall length for the linotype bullet, and for accuracy in general. The linotype bullets easily chambered at 2.895" overall length, but the 25:1 cartridges had the bullets pushed way back into the cases when I attempted to chamber a couple.
Now, after sizing to .312", the bullet noses grew from .3032"-.3036" to .3040"-.3045". But, after sizing to .309", the 25:1 soft bullet noses had bumped up to .306"-.3092", the bullet jammed in the rifling when chambered and was pushed back into the cartridge case. The linotype bullet noses were still about .305" and chambered with no problem.
I'm telling this story to illustrate the notion that sizing bullets can change dimensions of the nose enough to affect how the bullet fits in the gun, and the maximum overall length. And that alloys of different hardness are affected differently by sizing and bumping, and that hardness affects how easily the bullet is engraved by the rifling. Change the sizing diameter and other things change. I seated bullets of both alloys to 2.875" and crimped the case necks slightly to keep the bullets from being pushed into the cases, loaded them up and shot five 5 shot groups with each yesterday, 4/18/07. The 25:1 bullets averaged 1.32" groups at 100 yards; the linotype bullets averaged 1.1".
Now, after sizing to .312", the bullet noses grew from .3032"-.3036" to .3040"-.3045". But, after sizing to .309", the 25:1 soft bullet noses had bumped up to .306"-.3092", the bullet jammed in the rifling when chambered and was pushed back into the cartridge case. The linotype bullet noses were still about .305" and chambered with no problem.
I'm telling this story to illustrate the notion that sizing bullets can change dimensions of the nose enough to affect how the bullet fits in the gun, and the maximum overall length. And that alloys of different hardness are affected differently by sizing and bumping, and that hardness affects how easily the bullet is engraved by the rifling. Change the sizing diameter and other things change. I seated bullets of both alloys to 2.875" and crimped the case necks slightly to keep the bullets from being pushed into the cases, loaded them up and shot five 5 shot groups with each yesterday, 4/18/07. The 25:1 bullets averaged 1.32" groups at 100 yards; the linotype bullets averaged 1.1".