Load DataTitan ReloadingRepackboxLee Precision
RotoMetals2Reloading EverythingMidSouth Shooters SupplyWideners
Inline Fabrication
Results 1 to 5 of 5

Thread: What Diameter and Length Slug to use for Bore Size?

  1. #1
    Boolit Buddy
    Join Date
    Jul 2022
    Location
    FL Panhandle
    Posts
    161

    What Diameter and Length Slug to use for Bore Size?

    As you can see by the number of my posts, I'm new to all of this. I need to slug several barrels but I'm deathly afraid of getting a slug stuck which I can't remove on my own. So far I've run slugs through two barrels, a 2 inch 32 cal revolver and a 20 inch Marlin 336 30-30.

    I have some pure soft lead from a plumbing fixture. I have cast the lead inside the 32 brass. I have some Lee Breechlock push through sizing dies in the following sizes: 0.314, 0.313, 0.312, 0.309. I've ordered but has not yet arrived a 0.311.

    For the Marlin, I sized the slug down to 0.309 and it was approximately 1/2 inch long. As I began pounding the slug into the barrel, the rod began to make a depression in the lead and the end of the lead began to mushroom. Once the entire slug was in the barrel, it easily went through the entire length without a problem. I can see the marks left by the rifling on the lead, but what have I learned?

    The starting diameter of the lead was 0.309, so if the grooves were deeper than that I'll never know. If I start with a larger diameter, I'm afraid it will mushroom to much before it is entirely within the barrel, get stuck, and I will not be able to push it through or pull it out.

    In relation to the stated bore size ( in this case 0.308) what diameter size should I use; 0.309, 0.310, 0.311? In other words how big above stated bore size should I be using?

    The issue of slug length. Is there a way to know how large the mushroom cap will become before it gets so large that I can't get it into the bore, thus becoming stuck? With this 1/2 slug I just used on the Marlin, it looks like the mushroom cap extended 5/16" beyond the original 1/2" length. If I used a 0.309 slug 3/4" long, I'd expect the mushroom to be longer. At what point will the starting slug length be to long and not compress to the bore size?

    I really don't want to get a slug stuck.

  2. #2
    Boolit Master


    Join Date
    Oct 2010
    Location
    Franklin, TN
    Posts
    1,629
    I can probably save you a bunch of time and trouble. Forget slugging a bore. In a rifle use the largest diameter bullet that will chamber. There are rare circumstances where this won't work but probably not in a rifle you have. Size for the Marlin either .310" or .311", whichever you have a sizer for. Either one should work, or at least does in the seven or eight examples I have. In my Winchester 30-30's I have to size to .3095" because they have tighter throats than the Marlins.
    On the handguns, revolvers, I'm not as well versed but would probably size to a little over the chamber throats. Contact Doug Guy on this forum for best advise there.
    Good luck to you!
    Rick

  3. #3
    Boolit Master

    Join Date
    Oct 2013
    Location
    JAX, FL
    Posts
    1,228
    I really don't want to get a slug stuck.
    If you are using pure/near pure lead it should be nearly impossible to get it stuck unless you are using the wrong tools or technique.

    Lube the barrel with a light oil, I use Kroil.

    I use barrel fishing weights just over your bore size work best (they well shave off the excess and give the lead a place to flow into when being compressed by the barrel). Set one over the muzzle and drive it into the barrel with a nice heavy brass hammer (or steel if you must, just stop as soon as the fattest portion of the barrel sinker has entered the bore). The bore will shave off the excess lead. We haven't used a rod yet, just a hammer.

    When driving the slug through the bore, DO NOT use wood dowels. Use a brass rod and a stout/heavy/large hammer. Bigger is better, I use a 4 pounder. Banging/tapping away with a light hammer is called peening and you will very likely peen that lead slug into the barrel and it WILL BE STUCK.

    I bought a section of 1/4" brass rod at Lowes or somewhere a number of years ago. It is too narrow for larger bores and I was worried that brass rod would be slapping the inside of the barrel of a larger bore when being smacked by the hammer, so I cover it with sections of heat-shrink of varying sizes to take up most of the slack. I drilled a small diameter hole into the end of the rod and drove in a metal nail or pin, cut it off to 1/4" and sharpened it. That point will keep the brass rod mostly centered in the slug. You do not want that brass rod driving in between the slug and barrel. A larger or correct diameter rod eliminates a whole lot of that, but available choices sometimes require innovation.

    That's about it, drive that slug through the barrel with a few sounds whacks and you are done.

    Pistols are a bit more complicated, especially if you are checking for choke/tight spots in the barrel to see if fire lapping is needed. I usually use minus pin gauges to measure revolver cylinders.

    If you are so inclined, PM me your phone number and I'll send photos of the appropriate pages out of a book on the whole subject of barrel slugging. I didn't invent this, guys like Veral Smith and Marshall Stanton did.
    Last edited by oley55; 08-15-2022 at 03:58 PM.
    “Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem.” Ronald Reagan


  4. #4
    Boolit Grand Master
    Mk42gunner's Avatar
    Join Date
    Aug 2005
    Location
    Butler, MO
    Posts
    9,021
    I use pure lead round balls. Once they are in the bore they are easy to push on through with a metal rod. Not very long, so it is obvious where to measure with a micrometer when you are done.

    I will second to use a metal rod, brass or aluminum work fine, you do not want a wooden dowel splitting and wedging in the bore.

    My technique is pretty simple: clean the barrel and leave a light coat of oil. place a RB on the muzzle, whack in with a soft faced mallet (a rawhide mallet works fine) then push it through.

    Robert

  5. #5
    Boolit Master
    Join Date
    May 2022
    Location
    MPLS
    Posts
    1,486
    Usr crosafe i believe that is what it is called low temp melt pore in after it cools follow instructings you can mike and have a true reading can get it at bronells or midway cheap safe accurate

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check