handloading for 350 Legend - projectile question

[AdamsT]

New to reloading. I have only loaded for pistol and 38/357 lever action rifle thus far following published load data closely. I am curious though about 350 Legend and I'm interested in purchasing a Winchester XPR in 350L. What intrigues me is the possibility of sharing the projectile I use for 38 special for my SW Model 10 revolver and Rossi R92 lever action, with the 350L for plinking...specifically Berry's 158 grain flat point .357. This projectile's max velocity is just 1250 FPS so loading it for higher velocity presents accuracy issues and potential core separation. There is published load data for 350L by Shooters World for a 158 grain .357 projectile starting at 1100 FPS, but this data is a different projectile, and a different rifle. This data provides COL but I assume that is tailored to the specific bullet used in the data (Sierra JHC .357 158 grain)

My question is, when working up a handload for a specific projectile that shares the same grain weight and caliber as a published data load, but has different projectile lengths and shape, how do you determine the best COL for this projectile? There are things to know and think about with respects to the distance from the projectile point to the lands and the specs of the chamber in between. With basic handloading for pistol plinking..it's generally just passing the plunk test. With rifle, it seems handloaders want more details for higher accuracy, and above all...safety, so you don't damage the rifle or yourself. For this reference...the Sierra JHC 158 grain .357 projectile looks to be very similar to the Berry's 158 grain .357 flat point. Perhaps the published COL for that published load data would be okay to follow for the Berry's substitute?

[mehavey]

When substituting a projectile for a high-pressure cartridge like the 350L, you need either an exact bullet
recipe, or access to both an internal ballistics program* and chronograph.

Magazine limits notwithstanding, the final OAL is dependent on fit to the chamber/rifling start, and
drives the available/remaining case space upon seating -- driving pressure.

The other challenge is that you'll necessarily have to size the 358 bullet down to 356 (or so) for jacketed.

Unless you've all the equipment and reasonable experience with the above, I'd hesitate to try it w/ with the 350L.



* Quickload and/or GRT.

[AdamsT]

Thanks mehavey, the published load data from Shooters World for 350 Legend using the Sierra 158 gr. JHC for 350 is a .357 diameter bullet normally used for 38/357 pistols and rifles, and is copper jacketed. Saami spec for 350 L is .357 bullets +0-0.03 so projectiles from .346 to .357 are recommended therefore sizing down the .357 projectile shouldn't be necessary. The published load data from Shooters World for 350 Legend uses .355 and .357 projectiles. The data for 158 grain uses 3 different Sierra projectiles..JSP, JHP, and JHC...these 3 bullets are identical in diameter and length. The data uses several different powders (all Shooters World brand) with minimum velocities from 1100 FPS all the way up to 2477 FPS. I'm wary of loading at high velocities because Sierra doesn't list maximum velocities for these projectiles, however Shooters World published the load data as if it is okay at velocities far higher than 38/357 pistol and rifle cartridges are normally charged. If I used the Berry's 158 gr projectile, I would not load it at higher velocities that Berry's publishes (1250 FPS), and this velocity is fine for my intended purposes (plinking/target). I realize that when handloading it is recommended to copy the bullet and powder, and work up from the lowest charge weight to test with your gun, but many will say it is okay to use a different projectile as long as it is the same grain weight, when referring to published load data. This is the point of my post. Because the Berry's 158 grain flat point .357 is nearly identical to the Sierra 158 grain .357 projectiles in shape, I wish to try the Berry's and I assume I should use the same COL (2.125") as the data publishes for the Sierra bullet. If the Berry's was a different projectile length by a significant margin, I would like to know how handloaders adjust the COL for the best fit in the chamber when projectile tip is a different distance from the chamber/rifling start.

[stagpanther]

the final OAL is dependent on fit to the chamber/rifling start, and
drives the available/remaining case space upon seating -- driving pressure.

This is a key aspect to loading for the 350 Legend. Mehavey is (I believe) suggesting that this would not be an ideal cartridge to experiment with unless you feel confident you know what the possibilities for "anomolies" are. These include "overly generous" headspace and (IMO) an unusual case design that makes the case vulnerable to failure even within rated pressure limitations if it does not seal to the chamber wall properly. I personally think it's one of the worst cartridge designs ever released and certified and regard loading for it the same as loading a wildcat.

[mehavey]

...suggesting...

+1

[Unclenick]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of [U][I][SIZE="3"]tested [/SIZE][/I][/U] data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

A few points:

The bullet diameters match well enough. The old military spec for 30-06 rifle barrels was 0.3065" to 0.3095" to accept a bullet with a 0.309" maximum diameter, or 0.0025" bigger than groove. Many 357 Mag pistol barrels are 0.355", same as a 9mm, so the shooting of slightly oversized bullets is not unusual. SAAMI's own drawings show bullets 0.001" over at the top of the nominal groove diameter, except target WCs, which it shows as 0.002" over.

One difference between the 350 Legend and 357 Mag is the former has a SAAMI standard 16" rifling pitch, while the latter has 18.75", so for the Berry's bullet to experience the same spin rate out of the legend, it will have to be fired at 1067 fps maximum.

For pressure, if you have a long enough freebore that the bullet stays at least 0.030" away from the throat, you can generally match pressures closely enough for same-weight, same-construction bullets by matching bullet seating depth. To get the correct COL from the seating depth, you have:

COL = Nominal Case Length + Bullet Length - Seating Depth

If you are trying to find the unknown seating depth of a bullet you have the right COL for, just switch COL and seating depth in the above equation to find seating depth. So:

Seating Depth = Nominal Case Length + Bullet Length - COL

The last complication, hinted at above, is that peak pressure depends on start pressure, and start pressure generally gets higher as the bullet construction gets harder. The pressures you have in your Shooter's World data for jacketed bullets will be too warm a load for a solid copper bullet, even if, by some miracle, it's greater length for weight still allowed you to have the same seating depth. Conversely, the softer Berry's at the same depth would let you run more powder, but the bullet will be going too fast if you do.

So, given the low maximum velocity, you are looking at making a reduced target load with pressures down in the teens and nowhere near 350 Legend normal running pressures. In your shoes, I would take a common target load powder like 231 (asa, HP38), Hodgdon Universal, or Tightgroup and load about 4 grains with a standard primer and measure velocity. Work up or down so yo stay within 1067 fps, and you should be good to go with that Berry's bullet.