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!

 

[Ontario Hunter]

Your scale is probably pooched. Find another balance scale with instructions (or download instructions for it) and check your scale. I had the same problem. 83 grains of Accurate 4350 was too much recoil and presumably a lot more velocity than needed. Group also wasn't great (but barrel was brand new). So I dropped down to 78 gr and primers popped out like yours. Not enough gas. I bumped up to 80.5 gr (for 400 gr Barnes X bullets) and got a good group (shooting in the same hole at 50 yards) with manageable recoil. Winchester primers stayed in the pocket. I don't have a chrono but estimate it's shooting about 2200 fps which is plenty fast enough to kill buffalo. Accurate 4350 has a slightly different burn rate but all loading data I have found for it suggests almost the same as Hodgon 4350. I started with A 4350 because it was what I could get my hands on when building my rifle during the pandemic.

 

[Ontario Hunter]

Your scale is probably pooched. Find another balance scale with instructions (or download instructions for it) and check your scale. I had the same problem. 83 grains of Accurate 4350 was too much recoil and presumably a lot more velocity than needed. Group also wasn't great (but barrel was brand new). So I dropped down to 78 gr and primers popped out like yours. Not enough gas. I bumped up to 80.5 gr (for 400 gr Barnes X bullets) and got a good group (shooting in the same hole at 50 yards) with manageable recoil. Winchester primers stayed in the pocket. I don't have a chrono but estimate it's shooting about 2200 fps which is plenty fast enough to kill buffalo. Accurate 4350 has a slightly different burn rate but all loading data I have found for it suggests almost the same as Hodgon 4350. I started with A 4350 because it was what I could get my hands on when building my rifle during the pandemic.

Edit: I loaded with Winchester MAGNUM primers. Don't want to mislead anyone into thinking it's okay to use standard primers in thumper cartridges.

 

[quaidwolfe8]

I’m using a Hornady digital scale that auto measures, I always recalibrate it before each use.
I should also note I’m using Federal Large Rifle Magnum Primers.
All these speeds are from over the chronograph, factory rounds being 2388 my hand load of H4350 being 2230. This is once fired factory brass.
When primers are seated they are perfectly flush and snug. I’ll double check the primer pockets but everything else case wise is within spec. I do have some brand new 404 cases but being they are valued as gold I don’t really care to do load testing with them. I’ll try y'all's suggestions and see what happens, I may have to settle for the IMR and just learn to trust with the temperature deal, if it does even matter.
Thanks!

 

[Wyatt Smith]

Are the primers past flush after firing, meaning are they protruding past the base of the case? How does the primer look, is it flattening or cratering? Are the cases stretching a lot during firing? Do the primer pockets feel tight?
I’m just going to guess that you have a headspace issue with either the rifle or the brass, I can’t think of another way for a primer to back out, there shouldn’t be room for that to happen.

 

[cmk]

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.

I agree with this. If the primers are protruding, they must have had the room to do so when the bolt was closed. To me, this signifies that you may be calibrating the brass too much, thereby getting excessive headspace.

 

[Ontario Hunter]

Yep. Headspace can be particularly ticklish with 404 due to its gently sloping shoulder. I forgot that I initially loaded with RWS brass that came with my dies. That crap really set me back. For starters the brass overall length was short. When I set my brass up for the short case, it pushed the shoulder back. First indication that something was wrong occurred when I could not get the reloaded cartridges to "snap over" ( = extract loaded cartridges dropped into the chamber). Then primers were jumping out of the pocket. Finally I checked OAL length and discovered cases were short. Then I found a box of new Hornady brass at auction and picked it up for $80 Canadian (about $65 US). All cases were proper OAL. I loaded up a few and no more issues with either snap over or protruding primers. Then I used the new brass to set my dies up to neck size only. Many think neck sizing only is suicide for dangerous game rifles but don't believe it. Just make sure to cycle test every reloaded round and only load brass fired from YOUR gun. If your gun goes haywire on safari and you have to use a camp rifle, do NOT use your neck sized reloads without test cycling them in the loaner first. Anyway, Hornady brass was the fix. I fireformed a few of the RWS cases and reloaded those. Still had problems snapping over. On closer inspection I see the rim thickness on those is very inconsistent. The problem is 404's gently sloping shoulder. It's too easy for a cartridge dropped in the chamber to be pushed ahead too far in the chamber if the extractor can't jump over the rim easily. Not a problem with belted or sharp shouldered cartridges. Who says German components are best? Pfft!

I would NOT put too much faith in Hornady digital scale. My brother had one that was crap. Borrow a balance scale and check it. Personally, I would knock the bullets out of the Hornady factory ammo and start over. Put their powder in the garden. They load 404 way too hot. You'll just get beat up for no good reason. 2200 fps is plenty fast enough for 50-70 yard shots.

Don't be afraid to reuse the new primers pushed out of Hornady cases by your sizing die. Everyone does it and I've yet to hear of a misfire or mishap when loading.

 

[gillettehunter]

A Hornady scale like you describe often will vary loads by a grain of powder or more . Usually not a big deal in the bigger thumper calibers. It’s a big deal in a long range smaller caliber rifle. I also wondered about your headspace and case length. I don’t like the sounds of a primer backing out.
Bruce

 

[Shootist43]

I got the "Accuracy Load" i.e. 84 Gr of H4350 behind a 400 gr. pill and LRM Primers, for the 404 Jeffery from a former AH Member. He used a Woodleigh while I used the SAF. I've used that load since 2016 without any issues. I also use NORMA brass exclusively. Like others have said check your headspace and try factory ammo. You might also check with your gunsmith. Randy Selby did the conversion work on my 375 Win. Mod 70 and I know that Dennis Olsen has built similar rifles. None of these have had the primer issues you mentioned.

 

[quaidwolfe8]

After trying different solutions I believe I got everything fixed. I reset my die and I haven’t had any issues, with lower loads or higher. Apparently it was a headspace problem on my end of resizing. Thanks everyone for your suggestions and help.

 

[Nevada Mike]

I've seen this with my initial loads for my 404. Headspace is usually the problem. Try your once fired brass in the rifle before resizing... it should fit fine - then just size enough to bump the shoulder .005" - .008" while resizing the neck. TRY ALL THE LOADED ROUNDS in the magazine. and feed into the chamber. Done correctly they will feed like butter. You can do this safely if you have a three position safety.

For modest FPS you can get about 2200 fps with 74 grains of VV N-150.

 

[cajunchefray]

After trying different solutions I believe I got everything fixed. I reset my die and I haven’t had any issues, with lower loads or higher. Apparently it was a headspace problem on my end of resizing. Thanks everyone for your suggestions and help.

Glad you got this sorted out. Every rifle is individual with regards to setting dies.
Now show us pictures of your Pre-64 and groups.

 

[Ontario Hunter]

After trying different solutions I believe I got everything fixed. I reset my die and I haven’t had any issues, with lower loads or higher. Apparently it was a headspace problem on my end of resizing. Thanks everyone for your suggestions and help.

Have you checked your case lengths?

 

[Wyatt Smith]

That’s my biggest issue with the 404, headspace. The sharp shoulder of the 416 Rigby or the belt of an H&H is much more positive.
I am prepared to get stoned by crowd of the cult chanting, “404, magic bore” for saying this but I don’t see the hype.