Best primer for .375 H&H

[IvW]

Fed 215

 

[fourfive8]

You made my day, I had got a brick of this out of a whim,,,but was unsure what to do...

I have talked to some of the R&D folks in the ammo industry specifically about the CCI #34 primer. I did this because I had built some anecdotal evidence indicating the #34 was more consistent in ignition reliability than some of the other major brand primers. My results seemed counter intuitive because the original purpose of the #34 was to help prevent slam fires in some auto loaders- specifically rifles like the M14, M1A, M1 Garand and similar. It seemed counter intuitive because I thought, if anything, the #34 would be less reliable for ignition because of it's thicker, tougher cup. But!!!! it turns out many or most of the reported primer ignition issues are not related to the thickness or softness of the cup at all but are directly related to the consistency of the dimensions of the primer itself.... where a slightly oversized primer or a primer with variability in anvil orientation or internal clearance may in fact be a major cause of misfires.

The occasional oversized or out of spec primer found in any batch of most brands may not seat fully bottomed out. The firing pin energy is then absorbed by the primer and not used for deforming the cup and compressing the compound against the anvil. Or if the clearance between the cup and the anvil is out or spec, the compound may not be adequately compressed to fire even though the cup appears to be adequately deformed by the firing pin strike. Turns out the #34 primer may be one of the most consistent in dimensions and tolerances both internally and externally. It is this consistency that yields the most reliable ignition. This points out the importance of making sure the fit between the primer and primer pocket is correct, no matter the type of primer. Some brass cases have variations in primer pocket dimensions which will have the same effect as a primer out of spec. I always use a tool on new brass to make sure the primer pockets are consistent and of correct dimensions. I use a hand tool to feel the primer seat with insistent tension and feel it bottom out with a tad of pressure to very slightly compress the anvil against the bottom of the pocket during primer seating. I also make sure the primer is seated to just below level of case base up to about .004" below.

Additionally, the #34 primer has a magnum quantity of compound so it is a magnum primer. For non magnum and magnum loads simply reduce the start load by the normal 10% and work up. It is the recommended method working up a load no matter what type. Use a chronograph and work up to your velocity objective while watching for excess pressure and monitory accuracy. I have never had an issue using the #34 for both regular and magnum type loads.

 

[Inline6]

@fourfive8 what tool are you seating your primers with?

 

[358GWB]

Best what? Highest velocity potential, lowest ES potential, accuracy, chance of actually cooking off when struck by the firing pin?

I am a competitive1000-yard benchrester that uniforms primer pockets and seats all primers by hand for over-travel to obtain consistent ignition. The 250's I tried in various configurations of Norma brass had a misfire rate on the order of 1 in 50. Have no definitive technical reason why. (replacing a firing pin spring had no effect) The Ballistic Gods may have simply given me the "stink eye". I've never had a misfire with a 215, 215M, 210, 210M or BR-2 using the same reloading methodology.

I am primarily concerned with accuracy, regardless of target or hunting loads. The resultant velocity is what it is. My accuracy criterion for non-dangerous, big game hunting loads is 3 shots less than 3/4 inches (19 mm), on centers, at 200 yards (183 m), shot from a bench with a bipod as a front rest. With the 375 H&H case, I have comfortably achieved that criterion with BR-2's using RL 17 pushing a 270 Speer @ 2780 fps (847 mps) and H 4895 pushing a 300 SGK @ 2615 fps (797 mps). Both from a 24-inch (61 cm) barrel. No delayed ignition with the accompanying "snap, crackle, and pop" at temperatures as low as 40 F (4 C).

Each system is unique, so no powder charges or seating depths for the above loads will be furnished.

When components were available and "cheap", you could tinker with primers and a chrono to do applied and effective "mad science" to figure out "best" on your terms. Tough to do these days. One thing is for sure: my personal experience with the 250's I tried eliminates them from consideration for use in a personal dangerous game load.

I hope the above helps in making a strategic plan of action/decision.

 

[jlb1036]

BEST EVER FOR MAGNUM AND LARGE CALIBER CASES CANNOT GO WRONG WITH
THE ULTIMATE PRIMER 215 FED

 

[Silvine]

RL 15 started by Federal 215 primers would be a good place to begin.

 

[fourfive8]

@fourfive8 what tool are you seating your primers with?

The only primer seating tool I use is an old prototype Sinclair I've had for 25 years or so. All steel construction and uses the Lee type, smooth sided shellholder.

 

[Joker12]

The only primer seating tool I use is an old prototype Sinclair I've had for 25 years or so. All steel construction and uses the Lee type, smooth sided shellholder.

View attachment 509314

That's A very well made tool!