Is there any issue using magnum primers for black powder loads?  I ask because that is what I have on hand, but also since I will be using a full case compressed load, I thought it might give more even ignition.  My concern though is pressure, might it create too much pressure?

For reference, I plan to be reloading .44-40 with Lyman 427098 bullets cast with pure lead (.427), over a pre compressed load of 40 grains by volume of 3f Swiss.  The cases I'll be using initially are Magtech.  Primer is CCI.

Revolver is a Pietta Californian.

I don't know if it's possible to get over-pressure in a BP load.  Magnums are fine.  Real BP doesn't "need" the magnum primers as it is quite easy to set off.  That's why brass shotshells use pistol primers to set off a big load of black.  But some people think they get some advantage with the magnums.  I believe Mike Venturino got a little better accuracy in his testing with magnums but those were his loads and his guns.  When I load BP, if I have magnums I use them.

Magnum primers will not create harmful pressures in a blackpowder load.

For CAS mainmatch distances you can safely use what you have on hand.

Wether or not magnum or standard primers give cleaner combustion and better accuracy at say 100 yards can really only be determined by the individual handloader.

I know that in the beginning the gospel was Large Rifle Magnum primers for .45-70 BP cartridge rifle silhouette loads, but then some shooters found that switching to standard Large Pistol primers (even adding a layer of tissue paper in the bottom of the primer-pocket to dampen the flame) gave better long-range accuracy in their rifles...
This refers to the crowd shooting steel silhouettes out to 500 meters.

Ive used both for 20 years, let us know if you get 40gr in them.

There won't be any issue arise from using magnum primers, but you may find better accuracy when using them by punching a wad from coffee filter and putting in the bottom of the case before dropping the powder in. Using magnum primers came about by the misguided attempt to "duplicate" the original trap door load and simulating the original berdan primers. But what the person that started that craze over looked was the primers of that time period were much weaker than the primers we have today, and the berdan cases had 4 flash holes from the primer pocket into the case.
 The biggest issue that may arise from you proposed load is unless that's an original gun, using a 427 bullet from pure lead may very well give you a good reason to develop lead mining technigue to get the leading out of the first few inches of the barrel.  Most modern produced rifles and handguns do better with 430 bullets.
 You might also find problems getting 40 grains of powder in the case without deforming the bullet when seating further exasperating the leading and accuracy problems.

   Oh Goody Goody 

I like this one.  To begin with, one cannot get "too much pressure" with BP.  You can get wonky ignition by "over compressing."  Beyond That:

Some Lustrum ago, one of our contributors used high speed film to document the difference in primers, both by manufacture and type.  There was a minor difference in Brisance(sp) between some standard primers and one or two "Magnum" primers.  A couple "magnum" primers exhibited a longer (further) flame travel than standard.  Other than that, ALL of the tested primers exhibited almost exactly the same flame travel.  SO:

As near as can be determined, with Black Powder, there is essentially no difference in ignition/burn between standard and magnum primers.  Black Powder goes BANG.  It's that simple.

Smokeless is a different story.  There actually exist powders that are resistant to ignition (no, I don't have a list) and Magnum primers give better ignition.  Then there is US.  Yep.  US.  Cowboy Action Players.  Always pushing for the smaller possible powder charge.  Small amounts of propellent in large volume cartridges can give some really spotty, wonky ignition.  In large volume cases with tiny little powder charges, Magnum primers can be beneficial.  Other than that, there is a whole lot of Old Wives Tales out there.  Don't believe everything you hear unless it's published by a reputable (Manufacture) ballistics house. 

IMO it's overkill!! Be similar to using magnum primers for a fast burning smokeless powder like Red Dot or Bullseye. Black powder doesn't need as 'hot of a flame' that a mag primer produces to ignite the powder. I'm sure the same ballistic laws and results that govern using to hot of a primer for fast burning smokeless powders pertains to using a mag primer to set off black powder exist, ie. higher pressures, erratic accuracy, etc. I have no need to use or own a coronagraph, accuracy and telltale signs of the need to use more/less powder, different primer works for me, has for 49 years of reloading and another dozen of shooting. Reloading for the 44-40 revolver round, a mag primer is unnecessary, a large volume rifle cartridge may be another story but that's another thread.  Going against the grain will sometimes result in a less 'harmonious outcome'. CC

Coffinmaker posted his post while I was typing, he posted his opinion, I mine. Some of what he wrote may have merit, but I'm skeptical. CC

Quote from: Ranch 13 on January 16, 2025, 07:08:05 AMThere won't be any issue arise from using magnum primers, but you may find better accuracy when using them by punching a wad from coffee filter and putting in the bottom of the case before dropping the powder in. Using magnum primers came about by the misguided attempt to "duplicate" the original trap door load and simulating the original berdan primers. But what the person that started that craze over looked was the primers of that time period were much weaker than the primers we have today, and the berdan cases had 4 flash holes from the primer pocket into the case.
 The biggest issue that may arise from you proposed load is unless that's an original gun, using a 427 bullet from pure lead may very well give you a good reason to develop lead mining technigue to get the leading out of the first few inches of the barrel.  Most modern produced rifles and handguns do better with 430 bullets.
 You might also find problems getting 40 grains of powder in the case without deforming the bullet when seating further exasperating the leading and accuracy problems.

Only reason I'm using .427 is because of the Lee dies, I read that they tend to not open the case mouth quite enough for anything else.

I'm using a compression die to avoid deforming the bullet.

I use Lee dies and .429 bullets with no problems. 

The original .44-40 cartridge used 40 grains of powder, but the balloon head cases used in those days had more case capacity than modern solid head cases. That is why people no longer use 40 grains powder charges. Even if you are able to compress 40 grains into the case without bulging it and making it hard to chamber, that much compression will negatively affect ignition/performance. There has been a lot written about this; be sure to learn from other people's lessons.

Griff

Many who use the Lee dies for 44-40, including me, use a 44 mag expander plug in the powder drop to be able to use larger diameter bullets. 

Don't care much for the Lee dies
Hornady,Lyman and Redding are my preferred
 Over compressing the powder can deform the cases
Looking forward to your results

One more thing to consider on you next set of dies the expander/m die in Luma Redding and RCBS dies can be adjusted to do powder compression and expanding at the same time

Hey Crow Choker

A little skepticism is actually a good thing.  The problem "WE" run into, is, without pressure test equipment (barrels) as possessed by the propellent manufacturers, we have no actually reliable way to determine the results.  It oft falls under the heading of Wild Ass'd Guess.  Although the differences experienced with over compressing BP are well documented by Ballistic Test processes by the BP manufacturers.  Most of this information is really scarce as BP isn't the most favored propellant at this point in time.  The primer test results I reference were not conducted by a Ballistics House.  They were amateur although very well done.  Of the various manufacturers, only TWO actually market "Magnum" primers.  Most call their primers as suitable for both standard and Magnum cartridges.  NONE of them address the problems inherent in igniting small powder charges in large volume cartridges, such as a 4Gr (or less) charge in a 45 Colt case.  Furthermore, ALL the powder manufacturers specify a "minimum recommended" load which indicates they experienced ignition problems with spotty pressure spikes and wide velocity variations.  Which has never stopped those gamers who want to know "how low can you go" and routinely shoot at sub-minimum load levels.

Lots of very knowledgeable BP shooters have reported strange performance with over compression in pistol cartridges.  Again, without adequate ballistic test equipment, which includes very accurate chronograph results.  I am also one of those long term shooters who have never owned a Chrono.  Don't need one.  So long as the bullet will make it from gun to target I'm fairly happy.  My own solution for reduced loads has been to utilize smaller volume cartridges.  Want to run lighter loads in a .45 caliber pistol??  Simple.  Use a smaller cartridge and it works very well.  Burma Shave