Magnum Primer Problem

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Qinzhou

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Hey guys

Newbee question here, do I need to decrease my powder measure if I am switching to magnum rifle primer?

I am reloading some 6.5 Jap, I am not using the maximum load, my powder measure is 1.2 gr away from the maximum.

Any advice would help!


Thank you, guys!
 
As per the other thread that you posted in, you could see that guy worked up his load with the components he used. Pretty standard practice in hand loading is to work up from start level loads to where you want to be - do not just pick a "random" load for somewhere. Any time that you change a component - bullet, brass, primer, lot of powder - then it is prudent to back up and start over with "working up".

Look at information in loading manuals - what brand brass did they use? What brand and type of primer? What brand and weight of bullet? If you change any one of those, no reason to expect that your load performs the same as their's did, and they were not testing in your rifle anyway - you are. If you are "forced" to change a component, then pretty much expect to back up and "work your way" up again. It might result in no change, or a change in desired accuracy, or a change in pressure levels.

And, as mentioned in that other post, is perhaps a difficult concept for a hand loader with 100 bullets, 100 primers and one pound of powder, who loads up 5 or 10 rounds and goes hunting. Had better follow the manuals pretty close, and start with Start loads. Once you have gone through a couple thousand primers, and kept records of each load, you probably gain some experience at which changes result in which results, but you are into "new territory" with a "new-to-you" rifle, bullet, case or primer... And therefore all of your previous "experience" may not apply to this "new-to-you" set-up.
 
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I shoot a lot of milsurps. I tend to stay well under book maximums (say 2 1/2 to 3 grains for 30 cal) for a number of reasons. Foremost is metallurgy flaws - today, we use NDT methods to detect these flaws in new rifles. If you are going to magnum primers, take the opportunity to back off the load a couple of grains more.
With this additional margin, component substitutions down the road are easily done.
 
One of the more extreme examples - Norma 7x61 Sharpe and Hart brass. There were two generations of it - see pictures below. The original - with the "+NORMA Re" headstamp is original. The other "NORMA SUPER 7x61" is the "improved" version. Both are correct brass for a 7x61 S&H chambered rifle. But the "super" version has over 5% more internal volume than the original. So, if a hand loader has developed a "good" load with the Super brass, he can probably expect difficulties inserting that same load into the original brass.

This 7x61 is one of the few that I know of with that much difference. But it does illustrate that simply dumping a random load into any case that says "7x61" will give unexpected results. To a lesser extent, the same thing happens among brass made by various manufactures for any cartridge - differing lots or differing makers may have differing head thicknesses, different wall thicknesses, etc. which result in different internal volumes. Changing primers without any "working up" can have similar results.

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You can probably use the magnum primer with no noticeably difference.

Note that I said "probably".

The Max in the book was in their rifle. Each rifle is different, and some are very different. If the book load was developed in a well-worn rifle, and yours is pristine, your pressure could be much higher.

That is why we say "Start with the START load and work up from there."

A magnum primer is never a wrong choice. But if your existing load is on the ragged edge of max pressure and you are using a ball powder (harder to ignite) the primer switch could be a big problem.
 
Ganderite said:
You can probably use the magnum primer with no noticeably difference.

Note that I said "probably".

The Max in the book was in their rifle. Each rifle is different, and some are very different. If the book load was developed in a well-worn rifle, and yours is pristine, your pressure could be much higher.

That is why we say "Start with the START load and work up from there."

A magnum primer is never a wrong choice. But if your existing load is on the ragged edge of max pressure and you are using a ball powder (harder to ignite) the primer switch could be a big problem.
Click to expand...

I guess I will just start with the minimum load and cut off 10% extra, just to be safe.
 
Potashminer said:
As per the other thread that you posted in, you could see that guy worked up his load with the components he used. Pretty standard practice in hand loading is to work up from start level loads to where you want to be - do not just pick a "random" load for somewhere. Any time that you change a component - bullet, brass, primer, lot of powder - then it is prudent to back up and start over with "working up".

Look at information in loading manuals - what brand brass did they use? What brand and type of primer? What brand and weight of bullet? If you change any one of those, no reason to expect that your load performs the same as their's did, and they were not testing in your rifle anyway - you are. If you are "forced" to change a component, then pretty much expect to back up and "work your way" up again. It might result in no change, or a change in desired accuracy, or a change in pressure levels.

And, as mentioned in that other post, is perhaps a difficult concept for a hand loader with 100 bullets, 100 primers and one pound of powder, who loads up 5 or 10 rounds and goes hunting. Had better follow the manuals pretty close, and start with Start loads. Once you have gone through a couple thousand primers, and kept records of each load, you probably gain some experience at which changes result in which results, but you are into "new territory" with a "new-to-you" rifle, bullet, case or primer... And therefore all of your previous "experience" may not apply to this "new-to-you" set-up.
Click to expand...

I guess I will just start with the minimum load and cut off 10% extra, just to be safe.
 
Moot point.

One manufacturers magnum is the others standard and vice versa.

Just do your load development like you normally would.

Primer make powder go boom, be sure to install primer.
 
Qinzhou said:
I guess I will just start with the minimum load and cut off 10% extra, just to be safe.
Click to expand...

don't do that. it could lead to other issues.

your japanese arisaka is considered to be the strongest action of its time.

the weakest part of the equation is the cartridge case.

imho, you can use your original load without much worry if it's in good or better condition.


the book loads for the 6.5 arisaka tend to be on the mild side
 
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