Love some help with the 7mm US in a BF Pistol

[ihmsakiwi]

Hi, I am trying to help a mate to get his BF pistol sorted as he has not found a jacketed load that shoots worth a dam. I have just tried to seat both the RCBS 7mm 145gr & the NOE Hunter 145gr boolits and both do not engage the rifling even when half of the gas check is still visible. Is it worth persuing accuracy with these or should I go to the heavier and longer 160+ grainers? How much freebore is too much? Peter:|

[bobthenailer]

Allthough ive never owned a BF pistol , I have some experince with them as several friends have them.
What i do have are a 2, RPM XL's in 44 mag, 357 mag , 30/20 , 22lr in this pistol cast bullets shoot very accurate as good as jacketed . I also have a xp-100 in 7mm ihsma that also shoots cast bullets very accurate but not as accurate as jacketed as the jacketed will shoot under a inch at 200 yards. These guns do not have excessive free bore !
Next i have a TC in 32/20 and 7mm tcu after trying 2 for the 32/20 and 4 for the 7mm cast bullets designes and sizing diameters in each , and at least 5 different powders in each , i gave up trying to develope cast bullet loads for shooting as accuracy was sub par at best with any combo tried . With these 2 barrels however each barrel will shoot jacketed bullets with excellent accuracy. without requiring much load development.
IMO the 7mm & 32/20 had to much free bore for cast bullet shooting the bullet is almost out of the case before it engages the rifleing.

[Wayne S]

Peter,
E mail sent, try your jacketed loads at closer distances , 25, then 50 yds., shoot another known shooter [pistol] along side the BF as a test of the person doing the shooting, IF the BF shoots patterns at 50 Yds. check the crown.
Was the BF shooting good groups and just wend bad??

[stubshaft]

I had a BF in 7mmBR and the throat was near perfect for the RCBS 145, I've never heard of one with a throuat that was that deep. I have shot the 7mmIntlRimmed which is identical to the US in terms of case capacity, the primary difference is the length of the neck. I got my best accuracy with H335 and the 145RCBS I had to download the inside or I would get target damage. IIRC - I still have a couple of hundred new cases floating around as they were perfect to form 219 Wasp brass (the parent cartridge).

[mroliver77]

Why not do a chamber cast or hammer impression of the throat area? Then you know what is needed to fill that throat up or if it is messed up.

Loverin style or LBT cast boolits are not bore riders and can fill a long throat.

[44man]

I don't think you need to engage the rifling. Too many guns with long free bores shoot too good. 6.5 Swede, Weatherby rifles, 45-70 BFR and on and on.
More important to fit the boolit and case so they are in line with the bore.

[fourarmed]

Try shooting the ones you have with 8 or 9 grains of Unique. If it won't group, try to find a bigger bullet. I have an MOA and an XP in 7BR that have the same problem - eroded throats - and they won't shoot bore riders. I have some 180 grainers from an LBT mold cut for a military Mauser that show some promise, but I haven't gotten around to any serious load work yet.