magnum primer velocity change?

[rockrat]

Had been trying some loads in the 45-100 double rifle with 420 gr. boolits. Figured I would try some magnum primers with the AA MRP (4831eq). Velocity jumped 500fps.

Is this normal when using mag primers? Hardly ever use them, so not familiar with velocity changes.

Or is it because of such a long case, that the velocity changed so much, and maybe combined with the slow powder?

Thanks


WW brand both types

[mooman76]

Probably your other primers were not doing the job and burning the powder efficiantly so you need a mag primer to get the job done.

[fredj338]

I would check your chrono readings again. Sometimes you'll get an increase, depnds on bore dia. & powder choice, but I have never seen anything close to 500fps, not even 150fps in rifle rounds. I've run both std. & mag primers w/ 84gr of 4831 in my 404jeffery w/ 400gr bullets & the vel. deif is about 35fps + for the mag primer.

[beagle]

Maybe better ignition but that's a lot of increase for a mag primer although #2 son opened some .270 brass by swithching to mag primers once with a pretty hefty load of 4320 that shot all right with regular primers.

I've read that John Buhmiller used 4831 (probably Hodgdon's in those days) and he'd drop an additional primer in before he dumped the powder to get as much "spark" as possible. That was with (as well as I recall, a 105 grains of 4831) under a bullet made by casting a steel .45 ACP case full of lead and turning a nose profile on his lathe. Made for a bad "solid" and he killed a bunch of elephants with it.

The old 4831 was really hard to light as I used a bunch in my M1. The 20mm had a pretty large and probably hot primer in it and about a cup of 4831 in it as well as a pretty good sized projectile.

I'll be watching this thread to see what others have to say./beagle

[Frank46]

I use CCI 250 mag rifle primers in my '06 with 55 grs IMR 4350. Chrono's 2800 with 165 nosler ballistic tips. Not to get more velocity but consistency. However I'm kinda concerned that you may be treading into uncharted territory aka SEE. Or getting something like a flash over. Is the case full?. And wasn't there a formula for british cartridges using something like one of the reloader powders?. With the big powder capacity of your case it might work in your case. Not trying to preach here, just concerned. Frank

[Lead Fred]

According to CCI, unless you use more than 63 grains in your case, a magnum primer doesnt do much.

Well I launch 180 A-Max with 54 grains of H4350 at 2900 and change using Federal 210 match primers.

None others I use go much over 2800.

[rockrat]

Yup, over 63 grains, and the case is full. Only chrono'd one shot with the std primer, and two with the mag ( I don't have alot of brass). 35fps difference on the two mag primer shots. It liked the mag primer load as one barrel shot a group under 3/4" @50yds (open sights). You could tell the difference right away , in recoil, between the loads. Gun has a long throat, kind of like a Weatherby.

[HORNET]

Might have some hellacious velocity spreads going and hit one on the low side with the standard primer and a couple of the fast ones with the mag primer. I think you ought to chronograph LOTS more of both (that'll teach ya).....You'll probably get more consistant ignition with the hotter primer (or a heavier boolit).