Well fellas, Here are the results of the use of magnum primers in my 45/70, and a question also.

I took 5 factory PMC loads with 405 grain bullet and 10 handloads using Starline brass and Federal 9.5 Magnum primers in 5 loads with 45 grains of Re-7 and also 5 loads with Winchester large rifle primers with the same 45 grains of Re-7 and heres what I discovered.

I fired the factory PMC loads and the primers were normal, I then fired the 5 with the Winchester large rifle primers and they showed primers that were flattened with sharped edges but not totally flattened to fill the primer pocket, and I figured I'd really see pressure problems with the Federal 9.5 Magnum primers but,
when I fired them the showed very little signs of any pressure, only slightly if you look close but not like the large rifle primers. The only explanation I can think of is that the extra (nano-second) of burn time it takes to burn the powder created the noticible pressure and my question is why not the magnum unless my assumption above is right?
There wasn't any noticible difference in accuracy or recoil either, except on the factory loads, only on the large rifle primers. Anybody have any Ideas on this?
I will try this again, and if the results are the same, I'll probably stick with the Fed 9.5 Mag primers that showed less pressure signs.
Johnny Reb

The Winchester primers may have softer cups than the Federals, so they'd show pressure signs more readily.

Did you chronograph the loads?

George

George, I don't have a crono, so can only go on the velocities posted in reloading manuals and don't have a real good place to shoot either, I just hop in my cowboy cadilac and go out to one of the state management hunting areas and target practice if no one is around. Johnny Reb

Johnny I would love to know if you get better velocity with not much increase in pressure.

PC, so would I but at the present can't afford to get a good cronograph. Maybe Santa will bring me one.
I went back to my reloading bench to scratch my head and think and after checking,,,Found out that I grabbed my large pistol magnum primers instead of large rifle primers. I guess thats why the flattened primer, but not really that much, but I don't plan on doing it again. Live and learn. Johnny Reb

Johhny,

I would like santa to bring me a Dillon progressive press, actually a pair of them so I do not have to change calibers as much. As well as a .375 H&H in either an M70 or CZ 550, and a leupold to go on top.

But I have not been that good this year

PC, I have a Lee turret press and 4 extra turrets with my dies set in each one and a single stage Lee press that I use when I put my factory crimp die into it. I also have a Lee hand press and it works just dandy. The only problem with them is ME! when I get in a hurry and want to go to fast and go shoot and then that slows me down and I have to start over. I also reload my FA 475 Linebaugh and Taurus Raging Bull 454 Casull and Ruger Vaquero 44 Magnum and love the way they work. I wonder if I could use those Federal large rifle primers in that 475 cartridge. HMMMM ! I'll e-mail Freedom Arms and Alliant and see what they say about using magnum primers. Johnny Reb

PC, I e-mailed Alliant and Freedom Arms and Alliant said they didn't have any reload data for the 475 and suggested that I stick with the large pistol primers as suggested in the Hornady Manual and Freedom Arms said they didn't have any data but suggested that if I used a magnum primer, to use a reduced load. Do as the saying goes "If it ain't broke, don't fix it"! So I'll just stick with the large pistol primers and call it good for the 475. Johnny Reb

Johhny,

I though that was maybe how garret were getting there velcoities in there souped up 45/70 ammo.

I noticed both posts stating primers as not a reliable indicator of pressure in low pressure cartridges were deleted? Wonder Why? 28.000 Cup rates as low pressure compared to the vast majority of rifles that Large Rifle primers are designed for, as a matter af fact Large Pistol primers would be far more likely to show upper level pressures in the 45-70 than any Large Rifle primer.