question about Rim Rock bullet 158gr LSWCHP load data

[rhodesengr]

Hi all. I am interested in playing around with this bullet for 38spl and/or 357mag

g/ch .38/.357 158 gr. SWC-HP per 100/ in a plastic ammo box

In-Stock g/ch .38/.357 158 gr. SWC-HP (sized .358) OAL 0.699, Meplat 0.260, Nose to crimp groove 0.305

rimrockbullets.com

I have an S&W 686 Competitor to run either case.

I can not find any actual load data for it that bullet. I also have some plain lead 158gr SWC bullets for comparison.

.38 SWC 158 gr. per 800

In-Stock .38 SWC 158 gr. per 800 (sized .358) OAL 0.693, Meplat 0.230, Nose to crimp groove 0.324

rimrockbullets.com

I am interested in a load ending up around 1000fps. Maybe 1100. I am working mostly with AA#5. I made up some rounds with each type bullet last night using 8.6gr of AA#5 which is about in the middle of the AA#5 load data for 158gr LSWC bullet in .357 cases. Here is my concern. The HP bullet is a bit longer from the crimp canellure to the base than the LSWC bullet. The volume in the loaded case will be less. Do I have to worry about overpressure? I have a chrono so I can measure actual speed but no way to measure pressure.

It would be nice to find some actual load data with the LSWCHP bullet.

 

[DGP4]

It is the same bullet used by Buffalo Bore Ammo for their 38spl +P ammo. On their site they have this info:

Item 20A: 158gr., very soft cast, semi wad cutter, (Keith) hollow cavity, with a gas check. This bullet will mushroom violently on impact and will penetrate roughly 14 inches in human flesh. Again, this bullet is gas checked and will not lead your barrel.

➤ 1,040 fps (379 ft. lbs.) -- S&W mod. 60, 2-inch
➤ 1,059 fps (393 ft. lbs.) -- S&W mod. 66, 2.5-inch
➤ 1,143 fps (458 ft. lbs.) -- Ruger SP101, 3-inch
➤ 1,162 fps (474 ft. lbs.) -- S&W Mt. Gun, 4-inch

I suspect you can just load to these velocities based on the powder company data.

 

[Surgeonwithagun]

The Buffalo Bore bullet is gas checked and deliberately soft cast. It can be driven harder without leading and will expand better than a hard cast bullet. I would love to know what powders Buffalo Bore uses for many of their loads but this is not shared information.

John

 

[rhodesengr]

I am worried about over-pressure due to the length from the crimp-groove to the gas check. It is longer than any other bullets I have load data for.

 

[Surgeonwithagun]

I am worried about over-pressure due to the length from the crimp-groove to the gas check. It is longer than any other bullets I have load data for.

Just start low on the powder charge and work up slowly looking for pressure signs. If you are looking for expansion from that bullet you may be disappointed.

John

 

[rhodesengr]

well at this point I don't have a way to test for expansion anyway so I have to go by velocity and whatever other expansion results are out there. That lean SWCHP is not much of an expander? I though it was the type used for the so-called FBI load with good expansion over 900 FPS

 

[wagonman]

I run the rimrock 158 gr lswchp gc in a mod 15 S&W 38spl 4in barrel with hs-6 @ 925fps expansion from this soft swaged HP is impressive no need to push this bullet past 1,100 fps in your 357 for a self defense load, your accurate #5 will work fine. On your load work up use a crony to verify your vel.