To slug or not for Cast bullets

Bigeclipse

Well-Known Member
Joined
Aug 10, 2012
Messages
1,944
How important is it to slug your gun to determine the proper size bullet? I would think it is really important to prevent leading and to assist with accuracy but for someone like me where I intend to reload cast bullets ONLY for my pistols to save some money does it really matter how perfect the fit? Penn bullets has .400, .401 and .402 for 40S&W. I know you are supposed to go like .001 over your boresize to prevent excess leading, so can I simply buy the .401s and call it a day or do I really need to go home and slug my pistols? I am not even sure the best way to go about this but from what I have seen it looks like you push some lead "fishing" weights through the bore with a rod of some sort and measure the "grooves" or the lands diameter I forget which one...id think it would be the groove? I have read a bit on this but wanted to come to you all before really diving into it. If it is ultra important to do this step, what is the best way? I have access to vice if that is needed...not sure how hard it will be to push the lead through. Guess it would depend how much bigger it is than the bore.
 

HARPERC

Well-Known Member
Joined
Jan 28, 2011
Messages
6,860
Location
Spokane, WA
I wouldn't bother. Buy a box of the .401's, and see if they perform to the level you desire.

If they don't try one of the others.
 

Gunpoor

Well-Known Member
Joined
Apr 28, 2007
Messages
436
Location
Fort Morgan, Colorado
Where groove diameter comes into play with bullet diameter is in revolvers. If there is a discrepancy between throat diameter and barrel groove diameter this will affect accuracy. Most of the problems with this issue has been corrected in the newer guns, so unless you are shooting older Colts or the early Rugers and some of the knockoffs you will probably never encounter this problem. I would recommend buy cast bullets .001" larger than listed groove diameter of your handguns and you will probably not have any size issues. This does not mean you won't see any leading in the bores because commercially cast bullets are usually cast to BHN (Brinnel hardness number) of at least 16 and sometimes as hard as 20. I think they cast them this hard to keep from suffering deformation from rough handling during shipping. I wish I could buy bullets cast to about 12-13 BHN but I just tolerate some barrel leading because I don't shoot enough of them to justify the expense and bother to cast my own. If you are serious about reducing barrel leading, cast bullets are readily available with a gas check base. A GC bullet has a copper buffer installed/crimped on the base of the bullet that greatly reduces lead melt off during ignition. I have used some of these type cast bullets and they do work but they are more expensive.
 

Kennibear

Well-Known Member
Joined
Jul 24, 2012
Messages
493
Location
Washington State
Hardness of the alloy and quality of the lube are more important than size for preventing leading. Slugging the bore uses a much larger bullet- 41cal in 40 cal, 40cal in 38 cal etc. But HarperC is correct as it doesn't matter much in pistols. Cast bullet benchrest sure. But if the first batch is squirrely then try one size up.

I have found commercial hard lubes less .than satisfactory. NRA formula has always worked best.


KB
 

Kennibear

Well-Known Member
Joined
Jul 24, 2012
Messages
493
Location
Washington State
BTW I use a binary utectic antimonial alloy inoculated with arsenic and containing trace amounts of gold and silver left over from the electrolytic refining of the antimony. The bullets are
dropped from mold into water, sized and double heat treated at 450 F. Then I lube them in another sizing die larger than the first. The 45/70 bullets drop correct diameter and are not sized just lubed in a die 0.002"larger.

All this said to point out you can really get lost in this. HarperC was right. With the 40 S&W, a pistol not revolver, it doesn't really matter. My revolvers shoot a very hard alloy best. The above triple chilled alloy makes linotype seem like cheese. The 45/70 tosses 20 consecutive shots under an inch.

There are no rules in cast bullets. Only guidelines.

KB
 

Bigeclipse

Well-Known Member
Joined
Aug 10, 2012
Messages
1,944
Hardness of the alloy and quality of the lube are more important than size for preventing leading. Slugging the bore uses a much larger bullet- 41cal in 40 cal, 40cal in 38 cal etc. But HarperC is correct as it doesn't matter much in pistols. Cast bullet benchrest sure. But if the first batch is squirrely then try one size up.

I have found commercial hard lubes less .than satisfactory. NRA formula has always worked best.


KB

from what I have read the penn bullets are decently lubed. how would I know if they were lubed well or not when I see them in person? if they are not lubed well...do I then go and lube them or simply shoot them knowing ill get some leading....
 

robert6715

Well-Known Member
Joined
Feb 7, 2012
Messages
122
Location
Afognak Island AK & Homer AK
I would suggest you do some research here Cast Boolits . Friendly bunch of folks who know there stuff about reloading cast bullets, and the Lyman cast bullet handbook is another good resource.


If your gun is copper fouled at all, it is much more likely to lead.

I would research what actually causes leading, you may be surprised. After you answer that question it will answer your question about sluging the bore.

Rob
 

Bigeclipse

Well-Known Member
Joined
Aug 10, 2012
Messages
1,944
I would suggest you do some research here Cast Boolits . Friendly bunch of folks who know there stuff about reloading cast bullets, and the Lyman cast bullet handbook is another good resource.


If your gun is copper fouled at all, it is much more likely to lead.

I would research what actually causes leading, you may be surprised. After you answer that question it will answer your question about sluging the bore.

Rob

thanks for the advice...I try not to joim new forums unless I absolutely can't find the answers...
 

robert6715

Well-Known Member
Joined
Feb 7, 2012
Messages
122
Location
Afognak Island AK & Homer AK
thanks for the advice...I try not to joim new forums unless I absolutely can't find the answers...

Not trying to recruit you, That forum is 32,000 strong:). Just use the search function, and all of your questions will be answered. Loading cast bullets is TOTALLY different then loading jacketed bullets.

Most guys that sell cast bullets will be more than happy to chat with you on the subject and answer questions, after all they want you to like their bullets, and buy more. Cast bullets get a "bad rap" from guys who load them improperly.

If you use the wrong kind of belling die, it wont matter if your bullets are the right diamater or not. Think of cast bullets as a bannana, and jacketed bullets as a brick. There is that much difference in hardness.

Just trying to get you pointed in the right direction. Rob
 

Kennibear

Well-Known Member
Joined
Jul 24, 2012
Messages
493
Location
Washington State
Lyman makes a 0.459" for sure and I believe a 0.460". Most manufacturers list 0.002" over nominal to cover oversized bores. Check the websites of Lyman and RCBS. They make custom sizes too but they ain't cheap.

KB
 

Lefty7mmstw

Well-Known Member
Joined
May 13, 2012
Messages
5,046
Location
Dakota del norte
A couple of things that haven't been covered here. Most cast bullets require you to load to a certain pressure level to get the bullet to obturate; ie. swell to bore diameter and fill the bore.
Bullets shot too slow or fast will lead much more than bullets loaded at correct velocity for the powder/ bullet combo. If you need to change your projectile speed, change to either a faster or slower powder depending on your needs. Faster powders will build to higher pressures at slower delivered speed and slower powders will give you more speed before you get to pressure.
You need to run your loads from just above squib and go up until you find/surpass the sweet spot and then settle on a safe charge within the sweet spot. This is much more critical in my rifles running cast pills where I want to get to 1-1.5 moa at worst, but I run the loads up in a pistol too.
Reloading for an auto pistol with lead bullets also has another issue that hasn't been touched on and is rather singular to autos. You need to keep your bullet within .001" or so of factory bullet diameter in an auto as your chamber likely won't allow chambering of oversized rounds. It headspaces on the lip of the case mouth, so they don't make that part of the chamber oversized. Try for more than a thou. over and you'll likely be jamming partially chambered rounds at worst and getting poor cycling and wacking the tail of the slide to seat the round at best.
 

Kennibear

Well-Known Member
Joined
Jul 24, 2012
Messages
493
Location
Washington State
Concerning obturation:

Everything posted by Lefty is correct in as far as it goes and expresses the current "best practice". I have yet to find a auto pistol with a chamber so tight it would not feed and function with a 0.002" larger bullet. One of the quirks of lead bullets is the seating process sizes them down from the force of neck tension. Try seating a measured bullet and pull it with a hammer style bullet puller and you will find it was sized down in diameter. Thus the recommendation that you use 0.001" over bullets. I have used 0.357" in 9mm (0.355" nominal) with no problem. Chambers are not so tight that 0.002" over won't work. I would start with 0.401" for the 40 S&W and if I could only buy 0.402"- no problem!

Bullets cast of the alloy I spoke of earlier are so strong they never swell up to obturate. They behave like the copper/gilding metal monolithic bullets we use everyday. The makers are adding over sized driving bands on those to help the gas seal as they are too sturdy to obturate effectively. I use 0.458" bullets in my 45/70 because of that. They are oversize enough to obturate the bore without having to be "bumped up" by powder pressure. Cup and core bullets are primarily lead surrounded by a thin patch of copper/gilding metal. The strongest lead core is not more than 3% Antimony and work softened by the forming process. Those bullets are bumped up ever so slightly by the chamber pressure especially at 60Kpsi. My alloy is 11.2% Antimony triple chilled and it is strong as hell. They see maybe 25Kpsi and using NRA Formula bullet lube they NEVER lead.

I reload 40 S&W for my two young ones still at home (his: Berretta PX4, hers: S&W M&P 40) and use plated bullets because all the local indoor ranges forbid cast bullets. You will find a good load if you use 180gr cast FN and a modest charge of powder. Any load that functions your pistol reliably has to be above a squib load. I use 7.5gr of Hodgdon's Longshot and it is listed as max but shows zero signs of pressure in either gun. 8gr of Longshot is max for 180 gr Hornady XTP. HP38/WW231 works very well. Unique is the cast bullet King. Do not use Bullseye as it is pretty dirty. Red Dot is very bulky and is a secret weapon of many cast bullet aficionados and is the substitute for Bullseye. Lots of other newer powders but this list is a good start. Use the heaviest standard weight for caliber you can find as the lower velocity is better for accuracy and leading.

Gas Checks eliminate the worry of obturating the bore as the base of the bullet is now acting like a jacketed bullet. I quit using them in revolvers and pistols as they were a waste of money at those velocities. Revolvers should be sized to the cylinder throat unless you use really hard bullets. I use Wheel Weight alloy as recovered with triple chilled processing and NRA Lube for GP shooting in handguns. The triple chill makes the surface as hard as Linotype and the bullets perform superbly at velocities up to 1500/1600 fps. Most of my bullets are plain base and they leave nothing on the table performance wise.

Cast bullets will allow you a lot of practice at affordable prices. It is another extremely enjoyable aspect of this hobby that is all consuming. Welcome !!!

KB
 
Top