Hi all,

 

I'm using a new combination of powder and bullets for my .357 Magnum. I want some load recommendations for the combination of Sierra 125 gr JSP and Accurate Arms #9 powder. My Sierra manual shows a range of 15.5 gr to 17.9 gr for AA#9 and 125 gr bullets. However, when I look at the Western Powder website, I see a range of 14.1 gr to 15.6 gr for a Nosler JHP bullet and AA#9.

 

So, what gives? I've never seen such a discrepancy before. I've been reloading for years, but the maximum of one manual is the minimum in another. ARGH!

Bullet weight is not the only determining factor on how much powder to use safely.  Length of bullet will have a factor also.  Longer bullets will have to be pushed into the case farther to achieve the the same OAL,  but increased pressure will result using  the same amount of powder as the shorter bullet.  Try to find a couple of bullets that are the same spec lengthwise.  I see this occurance loading Nosler 10mm 200grain JHP and Hornady XTP 10mm 200 grain JHP.  Bullets are way different in length.  

Published load data does have big differences between bullet and powder manufacturers.  Sometimes its a legal thing, sometimes different bullet shapes may use different loads.  What is published is what they found when when they use the brass, powder, primer, and bullet used in a particular gun.  Everything is open to interpretation. I have a published reference showing 11.9 to 14.5 for a 125 jacketed bullet with AA9.  YMMV.  Start low and work your way up, only way to go.

Well, I am using Sierra 125 gr JSP bullets. So, I guess I'm safe using 15.5 gr of AA#9 with these bullets as long as I set COL to the manual? I'm not looking for full power load, just something safe for target shooting.

Well, I am using Sierra 125 gr JSP bullets. So, I guess I'm safe using 15.5 gr of AA#9 with these bullets as long as I set COL to the manual? I'm not looking for full power load, just something safe for target shooting.

according to the Lee manual,  I see 125 grain Jacketed starting at 14.1 and never exceed 15.6 so it seems you are close to maximum load.  1.575 min oal.

> I've never seen such a discrepancy before. I've been reloading for years, but the maximum of one manual is the minimum in another. ARGH!

 

EVERY load manual can only show what they got using their gun, a particular lot of powder, a particular bullet (and lot number), particular cases, particular primers (and lot number), and COL.

No manual has the same mix of components as another manual and no manual has YOUR components.

Thus, load work up from the start load. I feel better checking several sources and starting at the lowest start load, as I don't know how my mix of components compares to any manual.

The Lee manual is a compilation of data from many sources and a valuable single source, but Lee has already adjusted to show the lowest MAX loads in most cases (it is also the only source that many times has the same load for the start and MAX load).

Again, start at the start load and work up and stop at the first sign of pressure, whether it agrees with the MAX load in a manual or not.

For a revolver, watch for primer flattening, primer flow/extrusion/piercing, excessive recoil, and difficulty extracting cases (particularly if more difficult than factory rounds). If possible, shoot some factory loads with the same bullet weight so you know how the recoil feels.

For a bit more, go to:

http://www.massreloading.com/reading_pressure_signs.html

 

For revolvers, COL is usually very easy—roll crimp in the bullet's cannelure or crimp groove.

Otherwise:

Per Ramshot:

"SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”

It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.

The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.

This parameter is determined by various dimensions such as

1) magazine length (space),

2) freebore-lead dimensions of the barrel,

3) ogive or profile of the projectile and

4) position of cannelure or crimp groove.

• Always begin loading at the minimum ‘Start Load.’"

 

Your COL (OAL) is determined by your barrel (chamber and throat dimensions) and your gun (feed ramp) and your magazine (COL that fits magazine and when the magazine lips release the round for feeding) and the PARTICULAR bullet you are using. What worked in a pressure barrel or the lab's gun or in my gun has very little to do with what will work best in your gun.

Take the barrel out of the gun. Create two inert dummy rounds (no powder or primer) at max COL and remove enough case mouth flare for rounds to chamber (you can achieve this by using a sized case—expand-and-flare it, and remove the flare just until the case "plunks" in the barrel).

Drop the inert rounds in and decrease the COL until they chamber completely. This will be your "max" effective COL. I prefer to have the case head flush with the barrel hood. After this, place the inert rounds in the magazine and be sure they fit the magazine and feed and chamber.

You can also do this for any chambering problems you have. Remove the barrel and drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop round in barrel (or gage) and rotate it back-and-forth.

Remove and inspect the round:

1) scratches on bullet--COL is too long

2) scratches on edge of the case mouth--insufficient crimp

3) scratches just below the case mouth--too much crimp, you're crushing the case

4) scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit

5) scratches on case just above extractor groove--case bulge not removed during sizing. May need a bulge buster.