You and I must be on the same wavelength as of late.
Since I have the facilities to do it, I have often thought of pushing the shoulder back on a regular 6PPC untill the capacity is in the full density charge range of 4198.
(GB)
Jackie, why go to the trouble when I've already done the work for you and even have custom, off-the-shelf dies for the 6Beggs? The case capacity is perfect, (26 grains H4198 Extreme) and you have already proven the cartridge easily delivers the same velocity and accuracy as the 6PPC. (3400 fps with 68 grain bullets) I think you already have a set of dies. If you are like some and don't like the name Beggs, call it whatever you wish; call it the 6Jackie Sackie or whatever. Dave Kiff at PTG has the reamers in stock with the latest dimensions, which he designates as the 6Beggs MkII. Diameter at the base is .4420 and at the shoulder, .401. It fits perfectly, the Hornady bushing type dies.
What keeps me from doing this? 4198 has it's own set of problems, mainly due to the manufacturer. Consistant burn rate, from one lot to another, is very inconsistant.
(GB)
Jackie, I have not found that to be a problem with the H4198 Extreme I have used, and I've tried several different lots.
We have found in our 30BR's that one Lot # to the next can vary as much as a whole 1.5 grn to achieve the exact same velocity in the same barrel. That is a lot when dealing with small capacity cases such as we use.
(GB)
Heck, if small variations in burning rate bother you, just buy 48 pounds of the same lot and forget about it. H4198 Extreme is the most underappreciated and versatile powder in the world. JMHO, mind you.
Of course, the 6BEGGS is exactly the case capacity we are looking for, I chambered a rail gun barrel up for it a year ago and it shot quite well. However, since the laws of physics have not been repealed, it did take a pretty stout load to achieve 6PPC performance in velocity, but perhaps it's upper end window is really in the 3250 range.
(GB)
Jackie, the upper window of the 6Beggs is exactly the same as the 6PPC, (3400 fps and it does this with two grains less powder; the perfect powder being H4198 Extreme. As a further advantage, it is not difficult to get 26 grains of H4198 in the case; you don't have to trickle it in slowly like you do 30+ grains of N133 in the 6PPC.
The lowered capacity 6PPC, (probably .150 short), would probably be a great option if you could score a good lot of 4198 and aquire enough to last a lifetime.
As a note, that might be why the old originol Lots of "T" worked so well at 3250 to 3300, the burn rate was very uniform. You could simply use the same powder, even the same charge, be willing to find barrels it liked, and shoot on a very consistant basis without worry that the Rifle's agging capability would just go down the toilet with certain weather changes.
In fact, that is what several very well known Shooters did for a long time........jackie