How much do I download, when using a magnum primer?

[fatelvis]

I have 1K small pistol magnum primers that I want to use in my 9mms or 38spl loads using BE-86. Both charge weights are in the +P range. How much should I back off on the powder when switching from regular WSP primers? Thanks!

 

[jepp2]

How much should I back off on the powder when switching from regular WSP primers?

I always consider the 10% reduction to be the safe advice. May be more than you need to, but not knowing how high in the +P range you are.

 

[M W R]

Not only the 10% but do you have a chronograph?

 

[fatelvis]

Yes I have a chrono

 

[riflewoman]

Then load to the same velocity. It has been the experience of many bullseye shooters that magnum primers require about .1 to .2 grains less powder, but like all things your results will be YOUR results. Even though you match velocities, the accuracy will likely be different.

 

[Uncle Ed]

Do you have a Sierra reloading manual? The same manual below tells you any time you change any reloading component to reduce the load 10% and work up again.

I'm retired with nothing to do and all day to do it so I read my manuals again. I did this because I'm 70 years old and wasn't sure how much reload information had leaked out of my ears.

And sometimes I even forget why I'm reloading and have to fake it.

 

[fatelvis]

.5 gr. Are you shooting comp or just want to have ammo on hand for self protection. If the later I wouldn't worry about it. I don't shoot comp. I do want my ammo to function in my Pistols. Better to be a little warm then have a non-functioning Pistol because of a squib load. If across the living room I don't need a 1"

.5 gr. Are you shooting comp or just want to have ammo on hand for self protection. If the later I wouldn't worry about it. I don't shoot comp. I do want my ammo to function in my Pistols. Better to be a little warm then have a non-functioning Pistol because of a squib load. If across the living room I don't need a 1" group.

No competition,just practice and possible SD loads.

 

[fatelvis]

Then load to the same velocity. It has been the experience of many bullseye shooters that magnum primers require about .1 to .2 grains less powder, but like all things your results will be YOUR results. Even though you match velocities, the accuracy will likely be different.

Thank you Riflewoman, that's what I was looking for

 

[riflewoman]

Do you have a Sierra reloading manual? The same manual below tells you any time you change any reloading component to reduce the load 10% and work up again.

I'm retired with nothing to do and all day to do it so I read my manuals again. I did this because I'm 70 years old and wasn't sure how much reload information had leaked out of my ears.

And sometimes I even forget why I'm reloading and have to fake it.

While the results of the velocities and pressures tend to follow what is published, I’m not sure I’d drop 10% of the powder and work back up. Years ago the advice when changing primers only was drop a grain in 222 & 223 sized rounds, a full grain in cartridges using 50 “ish” grains of powder, and a grain and a half in magnums. Then work up to maximum again. A full 10% is going back to square one.

 

[Twicepop]

I have around here somewhere and article written by Brian Pierce about substituting magnum for standard pistol primers. In that he stated that in one of his tests, changing nothing but substituting magnum for standard primers, the pressure of the load was raised by 15,000lbs. I've experimented by switching from standard to magnum pistol primers, but I've always started at the bottom of the data or even less when using magnum primers.

 

[riflewoman]

If you find it, I’d appreciate reading it.

 

[fatelvis]

I just went to the range and tried a load workup with my 9mm, 115jhps, and HS-6, using magnum spp. The velocities were actually slower than with standard primers! Maybe it had something to do with the 14 ° outside temperature when I was testing. The other velocities were tested in 50-60 ° temperatures.

 

[sdean]

I just went to the range and tried a load workup with my 9mm, 115jhps, and HS-6, using magnum spp. The velocities were actually slower than with standard primers! Maybe it had something to do with the 14 ° outside temperature when I was testing. The other velocities were tested in 50-60 ° temperatures.

Whatever gets hit with the bullet probably can't tell the difference.

 

[fatelvis]

So really, there was no appreciable difference when substituting primers. At least with HS-6.