Here's some loads I tried: Bertram cases, Ideal 25720 clone 85 gr. 10 gr XMP5744, WWSRP 11/4", 1482ft/sec; same powder&bullet, CCI Mag SRP 13/4", 1470 ft/sec. 50 yds. 100 yd CCI SRP 10.5 gr XMP5744 3"@100 yds, 1599ft/sec. 12 gr IMR4198 51/4"@100yd, 1648ft/sec. CCI Mag SRP, Rem 87gr JFP, 12.5gr IMR4198, 11/8"@100 yds. IMR4198 12.5 gr with Fed SPP, 257464GC, 25/8"@100 yd. CCI Mag SRP, 11.0 gr VVN133, 257464GC Sized 0.258" and weighed, 33/8"@100yd. (That session I got up to 16 gr, giving 2040ft/sec and a flyer through my Chrony. You can tell when a rifle/caliber really hates you.) CCI SRMP, 15 gr Reloder 7 Rem 87gr JFP, 11/4" vert string @ 100 yd. Other groups 25/8" range with same load. CCI SRMP, 18 gr VVN133, Rem 87gr JFP 11/8"@50 yd. 2540ft/sec. Put a throating reamer into the chamber and turned until the "bumps" stopped being felt. Bertram and UMC cases, CCI SRMP, 17.0 gr VVN133, Rem 87gr JSP seated way out. 11/4", 31/4"(4 in 11/4") 21/4" (4 in 11/4") 17/8” (4 in 1"). 100yd. Bertram brass, new throat, CCI SRMP, 12.5gr IMR4198, 100gr Cramer #55. 3" and 11/2" (4 in 3/4") 100 yds. 1613 ft/sec. Redid above: 3", 23/4", 23/4" 31/8". Bertram brass CCI SRMP, 10 gr XMP5744, Kapok tuft, RCBS 87 gr tumble lubed 2" to 51/5" @100yds. RMC cases, misc primers, 25 gr Swiss 11/2grease cookie between card wads, 100gr paper patched. Keyholes, tips and scattered 100 yd. 25gr olde Eynsford 11/2, 90gr 25720 90 gr 0.258" Lyman BP Gold, Rem 91/2, CCI400 and CCI450 51/2" to 81/2" verticals @ 50 yds. Same powder & bullet, 50 yds Rem 71/2 BRP OE 11/2, 26 gr 4 in 51/4"; 28 gr 91/2" (4 in 51/2"); 30 gr 61/4". CCI SRP best 26 gr 3", CCI450 SRMP best 30 gr 41/4". Fire lapped the barrel 60 shots. Before lapping, CCI SRP 12.4 gr 4198, 257464 sized 0.260" 33/8"@50 yds. After lapping, 6 shots in 25/8" @ 100 yd. Did above over, 3 groups @ 100 yds. 6 in 23/4", 5 in 23/4" (4 in 11/8") and 5 in 11/8". Throating and fire lapping seemed to help, but I ran out of steam. No further development since mid 2020. Haven't retried the blistering velocities with jacketed bullets after the barrel treatments. This is a Low Wall, relined by Redman, chambered by me. I chambered three more Redman .25 caliber relines in .2520 SS&WCF and .2521. All can give 21/4" groups @ 100 with no particular trouble. Some do better. Most Bertram cases are different lengths&heads and all are too short. Doesn't help accuracy much.
