Maven
04-21-2014, 04:34 PM
I have been experimenting with PB (plain base) CB's since I took advantage of a group buy 6 cav. Lee 30-150-TL (tumble lube) mold several years ago. Results have been quite satisfying given their accuracy, ease of preparation (cull, swish in liquid alox, dry, and load), and economy (small powder charges, no gas checks). Ben, another PB shooter,bless his heart, sent me a sample of a different Lee CB, the .30cal. 114gr. GC'ed "soupcan" (looks almost like a wadcutter) cast from the mold which he converted to PB. (For Xmas, he sent me the mold itself!)
Since then, I've been trying to refine the loading technique and load for the soupcan so that I can achieve at least 2 m.o.a. accuracy @ 50 yds. Today, I came closer to that goal than in past trials (ordeals?). I also learned that max. accuracy isn't always achieved by forcing the CB into the rifling: My Marlin #336 (Microgroove) in .45-70 doesn't especially care if the PB CB's are engraved by the rifling or not. Apparently my Win. Mod. 70 .30-06, with the plain based CB's, is of the same opinion.
Loading technique: Nothing earth shaking here except to say that when using PB CB's, you have to expand or flare the case necks a bit more than you would with a GC'd CB so as not to shave lead, which ain't so good for accuracy. I use the Lyman M-die. Even if I use the Lee .30-06 Collet Die, I still need to use the M-die with PB CB's. The rest of the loading procedure is straightforward. I initially was loading the soupcan to 2.95" OAL, which heavily engraves the 1/4" or so which protrudes from the .30-06 case. The force to close the bolt was a bit greater than I liked, so I decided to tap the rest of them into the case (while at the range) so that all lube grooves were contained by the case neck: Accuracy wasn't degraded and may actually have improved, but I'll have to retest this.
Powder and powder charges: Since the Lee 30-150-TL does well with small charges of pistol powder: Clays, Unique, and Blue Dot work, I thought I'd start with the fastest powder, i.e. Clays, with the lighter (~116gr.) soupcan. I've tried 4.5 grs. -> 6.5grs. in the past, but today I settled on 5.5grs. and 6.0grs. of Clays. Btw, I throw all my powder charges with a Lyman pistol powder measure after having calibrated each rotor for the powders I use most.
Results: Close to 2 m.o.a. from a rest @ 50 yds. in my .30-06 with 6.0grs. Clays and the soupcans seated with all lube grooves contained by the case neck. I'll retest with 5.5grs. v. 6.0grs. in the near future to see if I can improve this. (There was very little bore leading with either load, but it was easily removed with a few dry patches and a bore brush.) To wit, although not a tumble lube design, I want to see how the soupcans perform "as cast" and tumbled in liquid alox or a reasonable facsimile* to see if I can get any improvement in accuracy.
Tumble Lubing: I've tried the sizing and lubing TL CB's both normally and via swishing in liquid alox or something similar and haven't seen a marked difference in accuracy. The little soupcans will next be fired as cast and TL'd to see whether a conventional design will behave as predictably as the other type.
*I used the grease remaining in my grease gun + bees wax to make a vile smelling, and worse looking bullet lube that I call Maven's Mess.
Since then, I've been trying to refine the loading technique and load for the soupcan so that I can achieve at least 2 m.o.a. accuracy @ 50 yds. Today, I came closer to that goal than in past trials (ordeals?). I also learned that max. accuracy isn't always achieved by forcing the CB into the rifling: My Marlin #336 (Microgroove) in .45-70 doesn't especially care if the PB CB's are engraved by the rifling or not. Apparently my Win. Mod. 70 .30-06, with the plain based CB's, is of the same opinion.
Loading technique: Nothing earth shaking here except to say that when using PB CB's, you have to expand or flare the case necks a bit more than you would with a GC'd CB so as not to shave lead, which ain't so good for accuracy. I use the Lyman M-die. Even if I use the Lee .30-06 Collet Die, I still need to use the M-die with PB CB's. The rest of the loading procedure is straightforward. I initially was loading the soupcan to 2.95" OAL, which heavily engraves the 1/4" or so which protrudes from the .30-06 case. The force to close the bolt was a bit greater than I liked, so I decided to tap the rest of them into the case (while at the range) so that all lube grooves were contained by the case neck: Accuracy wasn't degraded and may actually have improved, but I'll have to retest this.
Powder and powder charges: Since the Lee 30-150-TL does well with small charges of pistol powder: Clays, Unique, and Blue Dot work, I thought I'd start with the fastest powder, i.e. Clays, with the lighter (~116gr.) soupcan. I've tried 4.5 grs. -> 6.5grs. in the past, but today I settled on 5.5grs. and 6.0grs. of Clays. Btw, I throw all my powder charges with a Lyman pistol powder measure after having calibrated each rotor for the powders I use most.
Results: Close to 2 m.o.a. from a rest @ 50 yds. in my .30-06 with 6.0grs. Clays and the soupcans seated with all lube grooves contained by the case neck. I'll retest with 5.5grs. v. 6.0grs. in the near future to see if I can improve this. (There was very little bore leading with either load, but it was easily removed with a few dry patches and a bore brush.) To wit, although not a tumble lube design, I want to see how the soupcans perform "as cast" and tumbled in liquid alox or a reasonable facsimile* to see if I can get any improvement in accuracy.
Tumble Lubing: I've tried the sizing and lubing TL CB's both normally and via swishing in liquid alox or something similar and haven't seen a marked difference in accuracy. The little soupcans will next be fired as cast and TL'd to see whether a conventional design will behave as predictably as the other type.
*I used the grease remaining in my grease gun + bees wax to make a vile smelling, and worse looking bullet lube that I call Maven's Mess.