-- How much more presure would it generate ? --

PaulT

PaulT

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Hi guys,

Ok, lets say I reload some 140gr Accubond .270win cal, with 56.5gr/58.5gr H4831 and use a CCI 250 mag primer instead of Win LR primer... how much more presure would a mag primer generate?

Would it be safe to shoot?

Just a question as I read in these reloading books and compare loads, many use Mag primers with .270win, .308win :confused: and not necessarely used only with a Magnum caliber so... yah, that's it,

Would slowly working a load up using Mag primers for a .270win/140gr/H4831 instead of reg WinLR primers be safe to do? " :confused:

I think it would be safe (as one examine the brass to detact any signs of pressure)
but what do you "experimented old timers" think?


Thanks
 
Yes, using a magnum primer in a load developed with a standard primer will raise pressures, sometimes dangerously.

If you want to try a magnum primer you MUST start load development all over again starting 10% below maximum book data. Changing to a magnum primer in a mid-sized case like the 270 however seldom results in improvements in accuracy. If you are looking to "tweak" a load you would be better served reworking you loads with different brands of standard primers.

BTW, the WLR primer you are presently using is the hottest of the standard primers and in fact is as warm as a few of the magnum offerings.

Anytime you change ANY component of a load - bullet, case, or primer - ALWAYS work up from 10% below book maximum.
 
It is not safe to change your primer without backing down on charge and working back up.

Commonly, primers use pieces of aluminum to ignite the powder. As the primer miture is detonated, the hot gases heat the aluminumm pieces red hot and shoot them through the flash hole. It is these red hot pieces of aluminum that ignite the powder, not the hot gas produced by the detonation of the primer mixture. Magnum primers of this type have larger pieces of aluminum than their regular primer counterparts. These larger pieces of red hot aluminum penetrate deeper into the powder column and start the near simultaneous ignition process on more kernals of powder than regular primers. Since the start of the powder burn happens over a larger surface area, the burn speed is increased. Since the burn speed is increased, pressure is increased.

Often, the same type of primer is used for many calibers simply because the reloader has no good reason not to. If a guy reloads for a 300 win mag, and a 338 win mag, there is a good chance he will load magnum primers for his 270.

Cheers
 
mmmm

lots of us shooters using ball powders in cold weather and especially when over 60 grains find that a magnum primer is a must for that combination and gives a very consistent speed.l use them with a lot less powder in my 308. l also use them in some extruded powder loads with very good results,but l also start lower and work up,l can only say in my experience that some loads with magnum primer might make a grain of powder difference in what l tried and l have tried lots and lots of different combo's,but that doesnt mean there isnt one load out there that might ending up doing something?so best beware,l guess this should have been brought up with the using of magnum primers in standard loads?
 
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When switching primer always start the load development all over again. Play safe as everyone's saying.

The only load I have switched from standard to magnum primer is my 45/70. It given the speed as if I have 5 more gr of H4198 powder. I was luck to have my chrono with me. Reading the pressure signs is not good enough.

Danny
 
The load you describe is the most aaccurate in my son's Tikka. 59 gr of H4831sc, 140 gr Accubond, CCI magnum primer, just over 3000 fps.
 
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