I've been working with a 14" 7 TCU barrel and cast bullets for a year. I have an RCBS 7mm-168gr mold with the gas check shank milled off-now a plain base, and a Lyman 287641 GC bullet. In the Lyman 47th reloading handbook the starting loads for cb's is about 14 grains of SR4759 or IMR 4227.
After a year, here's the deal. Between 7 and 11 grains of either powder with a dacron wad shoot to the same point of impact at 50 yards, and shoot pretty good groups. Anything over 11 grains makes the groups expand-a lot.
Yesterday with the RCBS bullet; 10 in 1 3/4, 5 in 9/16, 1 1/16, 2 1/8; all with 7/IMR4227.
Lyman bullet, 7 gr, 5 shots in 3/4, 1 3/16, 2 1/4; 8 gr, 5 in 15/16, 1 1/2; 9 gr, 5 in 1 5/8, 1 3/16; 10 gr 5 in 1 3/8, 1 5/16.
The 7 grain load of IMR4227 leaves some unburned powder, but shoots maybe the best.
I use WSR primers and Darr lube. Unsized bullets, Gas checks put on before bullet seating, then the bullet is seated.
Having the bullet seated out too far so effort is required to close the gun screws up my concentration.
I find it hard to shoot the gun as consistently as I'd like, it has a Tasco 4-16 scope at 10X most of the time.
It's time to start separating bullets by cavity, turning case necks, and so on, as well as working on my shooting.
I've never had good luck without the dacron wad.
The gun shoots Hornaday 140 gr interlock into under an inch-frequently, for 5 shots at 100 yards. But where's the challenge?
joe b.
