404 Jeffery Reloading Help

[quaidwolfe8]

Good evening everyone! Long time member, first time poster. I’m reaching out in regards to reloading the 404 Jeffery.

A bit of background, my father and I have a buffalo hunt planned for September 2025 in Mozambique. I’m a novice reloader and have only been loading for a couple years and not for large cartridges except for 375H&H. I recently received my Pre 64 Model 70 custom 404 with a 25 inch barrel. I’ve started to reload for it to regulate my irons but I’ve run into an issue.

From my readings of the wealth of knowledge on the forum, everyone swears by the H4350 84.0 grain recipe at 2300+ with a Swift A Frame. However, I would rather load it to the classic 2150-2200 FPS. I’m currently working on a “inexpensive” load with hornady 400 grain softs and solids. Then I’ll move to the A Frames when I get a better idea of how my rifle performs.

The issue I am having is with the primers backing out after firing. I got the speed I wanted with the DGX and Solids but the primers are backing out. Not falling out but enough to make the case pivot on the primer if sat on a flat surface. This being a load of 82 grains of H4350. After trying different lower loads I’ve found that these are under pressure somehow and that is the reason the primers keep backing out. The lower the charge, the more it protrudes. I even called Hornady and they deemed this the same answer to the problem even though I’m over the max load at 78.9 grains. It’s also important to note I have no extraction issues, no brass bulging or anything like that. Factory loads perform excellent other than kicking like a mule in my rifle but all primers are fine.

My question is why is this the case and has anyone else experienced this problem at 2200 with H4350? I do have plenty of IMR 4350 on hand, and I get my speed I want with no protrusion of primers. Being a novice reloader I’m mainly concerned about the whole temperature sensitivity deal of the IMR versus the H4350 that ones talk about. Is this talk more of a drastic change in temperature from 90 degrees to 10 degrees or would a 30 degree difference even matter?

Any experience would greatly be appreciated! Thanks

 

[deewayne2003]

With 25years of loading under my belt, I personally believe the whole temperature sensitivity issue is blown way out of proportion.

I’ve used Reloader 22 in .257wby, .270win,
30-06, .300win, .300Wby, .375H&H; in temperatures ranging from -7F to 110F and had zero issues with pressure or point of impact change.

When I was in Zimbabwe this July my .300Win was loaded with Reloader 22 with .200gr Partitions and my .470ne was loaded with IMR3031 - another “temp sensitive” powder that people malign for having too fast of a burn rate and it preformed flawlessly.

Point being I would start by trying another powder and double checking your brass to make sure it’s trimmed to proper length.

 

[Bush Buck]

I'm not expert on this issue but this is what I'd do if it happened to me.

You may have a touch more head space than you need - shouldn't be an issue if you're not getting misfires - and factory ammo works well.

You might try backing out your full length resizing die a bit (maybe the thickness of a dime) so that you are only resizing the neck and not pushing back the shoulder. Chamber the resized brass to make sure it is resized enough to chamber before you load ammo.
For your low pressure loads you may also benefit from a faster powder like Varget or H4895 if you can sort out some load data.

 

[AimSmall]

When loading 3 grains more than Hornady max, I doubt you have low pressure. Have you checked the speeds over a chrono? When reloading big bores really watch the speeds.

Is this brass new, or used? Did the primers feel snug when pressed into the brass? Used brass could have swollen primer pockets.

As noted above, headspace could be an issue - normally high pressure flattens primers. Properly headspaced, there is not room for them to push out.

Keep us posted!