Bumping cast bullets on larger size


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Onty
May 18, 2006, 12:35 PM
I checked recently (started with this http://forums.accuratereloading.com/groupee/forums/a/tpc/f/1811043/m/856101974 ) several un-sized cast bullets and found that good number of them have the driving band in front of crimp groove smaller than groove dia for that specific calibre. Examples: 41 are .407-.0408, 357 are 355-356, 44 are .426-.428, etc. The rest of bullet has enough large dia-s so it could be sized to fit the cylinders. I remembered article in “Handgunner” about Keith bullets mentioning the same problem. It was done on purpose to make bullets fit all revolvers, regardless of cylinder bores. Author Brian Pierce (if I remembered his name correctly) pointed this as almost certain cause of inaccuracy, and, according to what I found so far, everything points that he is right on.

Now, the main issue with cast bullets is to fit hardness to the load so bullet will obturate properly; too hard, wouldn’t obturate/seal the bore under the pressure, too soft creates excessive leading. In that respect, straight wheel weight is just about right for velocities I am looking for; 1100-1200 fps so I can use plain base bullets, no gas check

If the proper obturation is desired and expected, how about mechanical obturation by some kind of die that will press the bullet and make all diameters uniform. The die should be designed to have adjustable stop so all bullets will be compressed on same height.

I found this locally available bullet for 40-65, see http://www.buffaloarms.com/browse.cfm/4,1547.htm , and looks as a good candidate to be bumped up to .411 dia, to be used in 41 Magnum revolver.

Anybody done this? Thanks, Onty.

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HSMITH
May 18, 2006, 09:21 PM
I have.

I made a punch that fit the nose of the bullet correctly that was a thousandth under the diameter of the bullet I wanted. I then made a bore in a block of steel that was exactly the size of the bullet I wanted. I set the block on another block of steel, dropped the bullet in base first, set the punch on the bullet nose, then whacked the punch with a hammer. Wallah!!! Bullets just exactly the size I wanted with no distortion. You DO have to calibrate how hard you are whacking them or you can compress the lube grooves or even eliminate them. Slightly different overall length of the bullet itself won't make enough difference to matter at all. After a few bullets I was able to keep the length within about 5 thousandths, it is more feel than anything to get them consistant.

Be aware that this DOES anneal the bullet and soften it somewhat, probably a couple or three points Brinnell. Bump them up RIGHT after they cool from casting, then size immediately and the annealing is minimized. A little aging and they are still plenty hard for what you want to do when cast from straight wheelweights.

I considered a press with an adjustable stop. Time to make it and time to use it stopped me. You would probably be best served using a lubrisizer since it will press the bullet back up out of the bump die, otherwise you will have to disassemble something to get the bullet out each time. I also didn't think my old Lyman lubrisizer would take bumping bullets for long, I don't think it is strong enough.

Nhsport
May 18, 2006, 10:16 PM
I see a couple of ways to go here,yours is down the right path but possibly not quite the best to get what you want.
First off, I would check some of the cast bullet semi custom guys,they many times have bullets available sized to several different sizes. They size (force raw cast bullet through a sizeing/lube die) anyhow and it is fairly easy to swap out the die for one a couple thousands smaller or larger. These bullets approach the cost of jacketed bullets but are the real deal.
A lyman or saeco (different brand,almost identical machine) luber/sizer is in the area of $100 with the dies $12-$15 each . Likely you could find a regular cheep .41 cast bullet and run it thru a couple times to expand it up a couple .001s.
The sure way to get just what you want is to cast your own bullets. Original outlay is to buy a pot (simple is fine,many think the simple pots better than the fancy bottom pour ) ,mould and handles,and the sizer and a couple of dies. Used casting equipment always seems to be laying around at gun clubs,gun stores and gun shows. Lyman's cast bullet handbook will teach you all you need to know and is a must have for the cast bullet loads if you don't ever cast a bullet.
Casting your own takes some time but once you find the gear or buy it used is dirt cheep. Casting your own is garanteed to get you what you want as you can adjust the alloy hardness,size and weight and style of the bullet.
Get the lyman catalog to find retail prices,Midway or the like will be 80% of that and used around half. Don't hold your breath on finding many .41 cal moulds used as most of the stuff out there is .30,.357,44,or 45.

One other thing to check out is your gun itself. For various weird reasons the cylinder,forceing cone ,and bore itself sometimes have weird,non matching sizes. I believe this problem was generally with the Colt single action army in .45 colt.
There are cutters that will reshape the angle and size of the forceing cone,some cases could need the cylinder to be drilled out. At any rate you should measure the cylinder at the front and back, the forceing cone ,and drive a pure lead slug or ball down the barrel ( "slug" the barrel) and measure the result. General wisdom requires a cast bullet several thousanths bigger than the barrel but you have to be able to stuff it into the brass case and thru the cylinder and forceing cone.
Good luck- likely more junk than you wanted to know.

ReloaderFred
May 18, 2006, 11:20 PM
I regularly bump bullets to other shapes using bullet swaging dies from CH-4D. They are relatively inexpensive at about $100 USD, and you can specify the nose shape you want when ordering from them.

As for the lube grooves collapsing, that is solved by lubing the bullets first. The lube will keep the groove from collapsing and helps to lubricate the bullet in the swaging die, both going in and coming out.

The Lyman and RCBS lube sizers are the same. The Saeco is completely different, as is the Star. I've got all four brands, and multiples of several of them.

As mentioned above, measure the mouths of the chambers to see what size they actually are. Also check for end shake, so make sure there isn't excessive play in the cylinder stop or cylinder pin. This can also cause problems with accuracy and shaving lead. Slugging the bore is also a good idea and then use a bullet that is .001" over the bore size.

Hope this helps.

Fred

Poodleshooter
May 19, 2006, 12:12 PM
It sounds like you already cast,so why not try altering your mold? You can artificially widen bullets by about .002" or so by putting a thin layer of aluminum foil between the mold blocks,then cutting away the excess that intrudes into the cavity itself. If you use too muchfoil,you get flashing. If you use a thin enough piece,it simply gives you a wider bullet that you can size down or shoot as is.
Make it large to start with,then swage down. It's easier than swaging up,IMHO.

Onty
May 21, 2006, 11:22 AM
Actually, Iíve got this bumping idea from Paco Kelly, see http://leverguns.com/store/acurizer.htm , http://gunblast.com/Paco.htm , http://gunblast.com/Paco_Scorpn.htm, http://gunblast.com/Paco.htm. (I made one from O1 tools steel, with modifications to adjust compression height. Waiting for friends with super-duper 22 LR to test validity of the tool).

I was thinking of increasing front band dia and length on two cavity Lyman 41032 and 410610, buy using specially modified cutter and milling machine. Lapping process to increase dia for few thousands could be OK in a single cavity mould, but I am afraid that in multicavity one there is always a chance that dimensions might be different from cavity to cavity. Thatís the reason why bumping up method looks to me as a more consistent. One whack and bullet is done. However, I agree that properly done mould is the best way to go.

If I make one tool, it will have threaded stop so I can regulate compression height and keep everything uniform.

Presently, I am thinking of making single cavity 41-220/230 SWC per my own design. Looking for 32 cal or smaller, they are next to impossible to find in my area.

I already made 44-315 SWC and 45-325 SWC, both with two grease grooves. Single cavity 38 moulds were used to make them on a lathe. Unfortunately, house renovation projects prevented me from proper testing. Hopefully, this summer I should be able to do that. Ransom Rest should exclude human error and save hands for the future.

Regards, Onty.

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