highstandard40 wrote:I have an RCBS 145 mold and at one time had the 168 also. Both had a nose that measured .2805".,.....Both had body diameters of about .2845"
Sounds similar to my old NEI mold. The fat nose is designed for milsurp Mausers that have oversize dimensions. It's way too big for a modern 7mm barrel.
The 0.2845" as-cast diameter may or may not be a problem.
1. The nose on the NOE 150 is .2765"........it is a slightly loose slip fit in the muzzle of my XP. I would guess I could go to .277" and be OK.
K, that's good info. Ideally, then nose should engrave lightly, though easier said than done due to tolerances.
I have recently loaded cartridges with bullets sized .277" and they chamber without any undue effort.
I presume you meant 0.287" ? We still need to know the clearance at the chamber neck. I wouldn't ask if you were getting decent accuracy with normal bullet dimensions, but since you're not, we have to dig deeper.
Some chambers are very sloppy at the neck ID. This hurts both the gas seal and bullet alignment. Usually not a big deal with low velocity, low pressure loads but can rear its head as velocities and pressures rise.
I have slugged the bore and whereas I can assure the groove is .284" I don't know how to accurately measure the bore. I don't have any pin gauges.
Modern name brand barrels are almost always correct groove dimension or at worst 0.001" over, almost a waste of time to measure. Your slip fit test will suffice for measuring the bore.
-- you could invest in a 0.277" sizing die to nose-size the RCBS bullet
-- check out the chamber neck clearance and size the body of the bullet to result in 0.002" - 0.004" clearance in the chamber neck.
-- no telling whether you will be able to get the long, oversize freebore to shoot MOA with cast. Sometimes crappy throats shoot surprisingly well if you find the right combination. But it can be an uphill battle.
-- if you had a good chamber and throat, MOA should be easy with reduced loads. My old 10" TCU Contender barrel would shoot cast 2.5 MOA with a fairly warm load and the less-than-optimal NEI bullet. My 7/30 carbine is easily sub MOA at 1450 fps with the mis-fit NEI bullet.
-- I'm not familiar with 2015 powder. 4759 seems way to fast except for plinking loads. Assuming you want a warm load for knocking over rams, you'll likely find best results with a slower powder. The powder should match the velocity -- faster powders for low velocity plinking loads, slow powders for max loads.