As the title states, I'm looking for some load data for the .41 magnum using 240 gr Keith LSWC bullets. Thanks.

I've loaded 44 mag for 35 years from mild to max with a variety of cast bullets. My data source for this post is Lyman # 48th Edition Reloading Handbook.

Comparing 44 mag data for different powders suggests that the starting loads are approximately the same within 1.0 grains of powder for bullets 210 gr or 240 gr. Unique has the same starting load of 10.0 gr for both bullets, IMR4227 is 21.8 gr (210 gr) and 21.5 gr (240 gr).

For 41 mag, 215 gr is the only listed cast bullet, jacketed bullets include 200 and 220 gr bullets. Comparing the data for 41 mag and 44 mag separately, suggests to me that reducing the starting charge for 215 gr 41 mag load by 0.5 gr will be a safe starting load for a 240 gr 41 mag bullet.

For cast lead or plated bullets, I have done this type of comparison with powders and burn rate charts or load data and different bullet weights for 20 years without any disasters. The results have been safe and succesful the first time for finding a safe starting load. Sometimes the test load is too "soft" and sometimes the test load was a little "brisk", but I never had a stuck bullet in the barrel, blown primer, or hard to eject case.

I've used my chronograph and found my test loads to be within 100 fps of expected results.

__________________
S&WHF 366

Check the actual weight(weigh a couple). The last 240s I got where only about 230. The lead alloy can change the weight on these heavier bullets. You can start around 6.0 grains of Unique and work up to 9.0, maybe a little more if they are for serious work. I usually stop in the 7.x range for range use. For heavy loads I always favored 2400. It can be loaded down where as 296 & H110 have a very narrow working range and only produce very heavy loads.

Hodgdon has the data on their web site:
Cartridge Loads - Hodgdon Reloading Data Center - data.hodgdon.com

Dale53

I use 240 grain Rim Rock .41 SCW Keith bullets all the time in my 57's and I use 7.5 grains of Unique. It has always worked fine for me.

__________________
SWCA #2421

Those are the bullets that I purchased. I've never tried that brand or weight before, but I'm looking forward to using them.

That sounds like a good load. 950 fps?

The 240gr Rim Rocks I got avg. ~242gr for their LSWC.

What are you loading them in?

I've used:
-Uniq/8.0gr @ ~970fps
-Uniq/8.5gr @ ~1030fps
-P-P / 8.8gr @ ~1125fps & was very accurate in my 657-5

Handloader #285 had some useful data too.

Rim Rock bullets


.



.

I'm using the Hogdon's data and H110. Seemed a bit over the top, but it's working great for me. Unfortunately, no deer has yet presented itself for terminal ballistics testing with this combo.

These are MAX with Lyman #410426 240gr : 18.5gr IMR4227 , 8.5 Unique , 17.5gr 2400 . H110 or W296 if full power is wanted . Above you can download some & still have a useful load .

My 41 Keith bullets weigh in at 233gr as cast and I push them with 9 grains of Unique and a winchester standard or magnum large pistol primer. Out of my 4 inch guns they are just under 1100fps. This is not a max load but is accurate, pleasant to shoot plus will probably fully penetrate ANY beastie you shoot with it.
These are my dead serious loads for when things are at their worst not my fun at the range loads.
Chip King

The old (1970) Lyman #45 manual includes data for a 240gr cast bullet: #410426, with their #2 alloy.

Recipes include:
Bullseye, 4.0gr start (684fps), 4.4gr max (749fps).
Unique, 6.0gr (780fps) to 8.5gr (1058fps).
2400, 14.0gr (928fps) to 17.5gr (1169fps).
Test firearm was a 6" model 57.

Please note that I'm just quoting from a book; I have never tried these loads.

-Mark

I've loaded these same rim rock 240g with 17.5g 2400. They are a handful in a model 58 with target grips. No signs of pressure, but they are all I want. I am going to try some Hogue monogrips I have around here somewhere to see if they make shooting these more comfortable.

Charlie

Thanks for the data. I have a 58 no dash 4", and a Ruger Blackhawk 4 5/8" circa 1978.

I appreciate everyones help with the load data.