357 Wadcutter Data Advise

[bluetopper]

I have developed a 357 load consisting of 5.5gr of N340 powder behind a plated 148gr wadcutter seated at the cannelure. It it the most accurate load I've ever shot benched at 25yds. out of my 586-8. I'd like to bump the power level up a bit, maybe a good bit. I just don't know how much I can safely do so. Can someone advise?

 

[ATLDave]

You've got both the limitations of plating (vs velocity) and the usual limitations of pressure to worry about.

Have you got data for a 158 grain jacketed SWC for N340?

 

[bluetopper]

Data for a 158gr jacketed HP is 7.7gr max.
For a 160gr lead flat nose is 7.4gr max.

 

[ATLDave]

Do you know how much of the case capacity the HP uses up?

Have you got access to a chronograph?

 

[Drail]

Swaged lead bullet or hard cast?

 

[bluetopper]

Swaged lead bullet or hard cast?

Xtreme brand copper plated 148gr wadcutter.

 

[bluetopper]

Do you know how much of the case capacity the HP uses up?

Have you got access to a chronograph?

Yes and yes.

 

[ATLDave]

NOT ADVICE, JUST DISCUSSION: PROCEED AT YOUR OWN RISK

If the case capacity under the 158 grain is equal to or greater than your 148 grain, I would think you'd be fairly safe from a pressure standpoint up to a similar charge weight (with the 10 grains difference in projectile weight giving you some safety margin).

The plating coming apart at higher velocities may be the more likely limiting factor. It appears that Xtreme advises a limit of 1200 fps for their non-heavy plated bullets (and 1500 for the heavy plate). http://www.xtremebullets.com/Bullet-Load-Info-s/1952.htm

 

[Walkalong]

I haven't pushed their 148 Gr WC more than about 750 FPS using a faster powder, but I have pushed their 158 Gr SWC a bit harder. I would recommend trying it for the stouter loads and then you won't be guessing so much on powder charges. It shoots great as well.

 

[cheygriz]

I've always used 2.8 Bullseye with wadcutters. That load has been winning matches forever.

 

[Skinnedknuckles]

Again, not advice but a thought process for evaluating load ideas. !. Do you have loads for that powder for a 146-150 gr jacketed bullet? If so, you can use the Berry's guide for using up to mid-range jacketed bullet data with plated bullets. Otherwise, basically any 158 gr load will be safe (pressure) for the lighter 148 gr bullet. 2. Based on the shape of a wadcutter, seating it at the cannelure will always take up more case volume than any other bullet shape, giving some additional margin. 3. The velocity of a plated bullet will usually be a bit faster than a jacketed bullet over the same powder charge, so you may need to be aware of the bullet manufacturer's maximum velocity.

 

[243winxb]

plated 148gr wadcutter seated at the cannelure. I

With the bullets base seated deeper, pressure has to be high. Why change

the most accurate load I've ever shot benched

 

[243winxb]

38 special data.

 

[243winxb]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

I have developed a 357 load consisting of 5.5gr of N340 powder behind a plated 148gr wadcutter seated at the cannelure. It it the most accurate load I've ever shot benched at 25yds. out of my 586-8. I'd like to bump the power level up a bit, maybe a good bit. I just don't know how much I can safely do so. Can someone advise?

6.3 gr maximun is my best guess. Good luck.

 

[rfwobbly]

I have developed a 357 load consisting of 5.5gr of N340 powder behind a plated 148gr wadcutter seated at the cannelure. It it the most accurate load I've ever shot benched at 25yds. out of my 586-8. I'd like to bump the power level up a bit, maybe a good bit. I just don't know how much I can safely do so. Can someone advise?

See the full VihtaVuori data here...
http://www.vihtavuori.com/en/reloading-data/handgun-reloading/-357-magnum-.html

• There is no plated 148gr bullet listed. IMHO you'd want to meld the 145gr lead (7.3gr max @ 1306fps) and the 140gr Speer jacketed (8.2gr @ 1325fps) data together. More toward the lower end for thin plated; more toward the top end for thick plated.

• It's the chamber pressure we're ultimately concerned with, and velocity is the best indicator we have. So IMHO the next step is to take the average speed of your present load to insure it's not over ~1320fps.

• IMHO you're already near the midpoint of the load, and powder burns the most efficiently in this range. Therefore any powder you add will need to be in 0.1gr increments until you find your goal or reach a maximum speed of ~1320fps.

Absolutely DO NOT exceed the max velocity, because above that point chamber pressure and velocity tend to part ways and loose any meaningful relationship.


Hope this helps, but I've been wrong before.

 

[Walkalong]

I seriously doubt you can push a 148 Gr WC seated to the normal depth of a WC and get to 1320 FPS with a fast powder without being over pressure. There is precious little space there when the powder first ignites, even in a .357 Mag case.

 

[243winxb]

velocity is the best indicator we have.

For pressure, i think not.