Magnum vs Standard Large Pistol primers

powdergun

powdergun

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In the never ending quest for components I see that Large Pistol magnum primers are easier to find than Standard large Pistol primers.

My question is can the magnum version be used as a replacement for the Standard

cartridge 45 colt

7.0 gr of HP-38 under 200gr lead flatpoint ( i believe this is a relatively mild load )

Gun: new manufacture 1873 Win rifle


Or should I drop a grain in the powder ?

Thanks
 
You may or may not notice accuracy but unless you use a chronograph you won’t notice anything else. In 45 Colt with 8.5 grains of Unique under a 255 grain SWC the difference between a Federal standard and magnum primer out of a 7-1/2” barrel Blackhawk averaged under 20 fps difference. There was no noticeable difference in accuracy for me.
 
The lawyer-proof answer is to start again from the bottom with the new primers. Personally, I'd drop the charge a bit and run it through the chronograph.

It should generate more pressure, hard to say how much. Probably not significant. But possibly very bad news, and a chronograph will remove all doubt.
 
alpining said:
The lawyer-proof answer is to start again from the bottom with the new primers. Personally, I'd drop the charge a bit and run it through the chronograph.

It should generate more pressure, hard to say how much. Probably not significant. But possibly very bad news, and a chronograph will remove all doubt.
Click to expand...

This ^^^

However the ball powder may like the magnum primers??
 
My main worry is safety. Will they create a jump in pressure significant enough to worry about. As for velocity the range I will be shooting is not that long (under 100 yards) so there should not be any real practical difference if the speed changes.
 
Not sure if we're on the same page here - I use the chronograph to measure muzzle velocity, which is how you can indirectly determine chamber pressure for reloads in your particular firearm. Anything else is guesswork.
 
Questioning similiar but for rifles..
Soo i might of made another Boo boo an ive got a few hours of the nght to do something about it before heading off crack of dawn.

Now i replaced, LR primers with MAG primers so to speak, with the same charge of varget, in a 'mid' charge......... im sort of thinking this might not be ideal for accuracy ???
or am i over thinking?

will the pressure be dramatic changing to magnum primer??

edited- it got the better of me, i pulled / pliered out 24 projies an re charged them with proper amount of powder with the already seated LR primers.
 
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My friend did the same on his load last week and accuracy when to. Sxxt. He could not find large rifle primer….
My guess is, since you do not specify caliber, bullet , load , that you are playing with a much larger charge of powder and you can end up with an overpressure.
If this is the case with your load, you will have to redevelop the load again starting low with those primer.
 
Janeau said:
My friend did the same on his load last week and accuracy when to. Sxxt. He could not find large rifle primer….
My guess is, since you do not specify caliber, bullet , load , that you are playing with a much larger charge of powder and you can end up with an overpressure.
If this is the case with your load, you will have to redevelop the load again starting low with those primer.
Click to expand...

so its ina 3006 150gr, so i have them loaded with 'magnum' primers, il do a side by side test when it rains this coming weekend. im off for a few days hunting til then :)
will report back.
i read on another forum, these particular no34s, add around 2600psi to the load.... so i did some math, an was border line, which proberly ment #### accuracy, but i wwill confirm...
 
WhelanLad said:
...i read on another forum, these particular no34s, add around 2600psi to the load.... so i did some math, an was border line, which proberly ment #### accuracy, but i wwill confirm...
Click to expand...

If you're anywhere close to the upper part of the safe range, I wouldn't trust them. Actual gains in chamber pressure will depend on many factors, not least of which is the individual firearm. Some powders are much more "spike prone" than others at the upper end of the range, and can easily result in an overpressure load if you're operating up there.

The safe answer is that anytime you change a factor in an established "safe" load, start low and work it up again using a chronograph. Advanced reloaders may do otherwise, but they're probably not posting this type of question on CGN.
 
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