Lower Velocities = better accuracy ??
Do the slower velocities allow the boolit to "grab" the rifling better than higher velocities? It seems in most cases with cast bullets that the slower velocities give better accuracy? What's the reason?
Shiloh
311299/314299 target load
Quote:
Originally Posted by
joeb33050
The put-the-nose-in-the-muzzle business doesn't do much for me. The chmber end of the rifling in a rifle wears or erodes or goes away, and it does so quickly. Then a bullet that is a tight fit in the muzzle is a loose fit in the chamber end. So the real test is to push the nose into the chamber-end rifling and see how it engraves. Now I have 311299 and 314299 molds and the '4 is slightly bigger than the'1. I've worked with 2 cavity 311 and 314 and 1 cavity 311, the 314's "engrave" more than the 311s, but I can't find the accuracy improvement due to more engraving. Back to "Cast Bullets", Col. Harrison tells us that bore rider are best in 2 groove barrels, as the groove/bore ratio increases, the "goodness" of bore riders decreases.
I get equal accuracy with 31141 and 308403, with no nose having anything to do with the rifling.
I'm starting to think that bore riding is a road best untraveled. That 311X99 gives good accuracy, 1 1/4" 5/100 yard 5 group averages in a M54 Win 30WCF and .85" samo in a Martini 30/30. But, 31141 at ~175 gr. is as good and Borton-Darr 185 gr. is better, breech seated. I'm starting to think that we like bore riders because they look nice, I know that the SS breech seaters in head-to-head competition with fixed ammo gas check guys DO hold their own or win. Maybe we should shoot a 200 grain 31141-style and forget the bore rider business.
It's clear to me that the SS breech seater vs Fixed ammo gas check business is about what happens to the bullet from the case to in-the-rifling. Everything else is about the same, except velocity, where the Fixed ammo guys center on high velocity to beat the wind. The SS guys don't worry about the wind, shoot at 1400 fps and beat the wind beaters a lot.
How about a .310" cylindrical long throat and gradual reduction to rifling, .3095" bullets aligned by the throat, and maybe 1:14" twist.
31141 or Loverin may be better solutions than 314299.
I know I must be flogged for this.
joe b.
Joe, My 03 2-groove sporter finally shot 0.85" 5-shot average of 5 groups at 100 yds in a match I won. MV was 1500 with 0 .011" neck turned match RP brass, also measured for consistent thickness at inside base, WLR, 14.5 gr AA2 (two) and I don't recommend experimenting with powders as gun parts will break injuring people but this powder load kept head space consistent. I cast with old WW and soft lead sheathing 1:1, taper to fit the throat with HGC seated, nose at 0.3015" from 0.3035" and entire bullet tapered in a taper reamer that was cut by the generosity of Glenn Latham of CBA. These were then heat treated from 450F, quenched in tap water and aged for 30-72 hrs before lubing in a 0.311" die, the die seating the GC tighter as HT/Q tends to loosen the GC. I used a Lee Collet NS die to NS the brass and only partial FLS when bolt pull indicates needing the FLS die, then annealing the necks and shoulders in propane torch flame, cherry red works for me.
There are other small details not necessary to explain this. The same powder load shot much better in my worn M-1 Garand and 3 Brit 303's with one custom mould for 2 of the Brits. I worked up hi-vel loads for the 03 to 2450 fps max with hunting accuracy to 300 yds and beyond.