Home Forums Reloading Big Game Rifles H4350, 7mm-08, 162 A-max load discrepancy?

I'm interested in working up a load with 162 A-max's and H-4350. I'm seeing a discrepancy in load data between Hodgdon's site and the Lee load manual:



Hodgdon

H4350, 45.0 grns max 2622fps, 50,500 CUP




Lee

H4350, 48.0 grns max 2714fps, 58,419 psi




3.0 grns seems like a wide discrepancy, the Lee starting data is Hodgdon's max. I'm inclined to trust data pressure checked in PSI more than CUP, but I'm still a little hesitant.

Am I missing something? Anybody have any insight?

Thanks,

David

I'd go with Hodgon's data and work up. It is there powder.

Nothing unusual.

If you look close you will probably notice they used different cases, or differnet primers ect...In addition, I image they were using different test barrels.

I would start with the lower of the two and work up, chronographing along the way.

^ And different pressure specifications

Jordan,

The difference in pressure specification was the primary reason I was thinking the higher charge listed in the Lee manual is probably the more trustworthy data. Agree? I'm shooting for 2600fps in 20" barrel model Seven's and won't load hotter if I can get that speed, even if that's only 45.0 grns.

I have no intention of loading 48.0 grains or even 45.0 grains and banging away. Work up is a given, particularly with the difference in load specifications. Having said that, as has been discussed to death, traditional pressure signs are not always a good gauge of safe loads. I'm not interested in shooting 48.0 grns with no pressure signs, but pressure is really 70,000psi - that's why I'm asking about the data discrepancy. I guess if I work up the loads with no pressure signs, I could reload a few cases multiple times to see if the primer pockets stayed tight, but even that is no guarantee.

David

If using identical components to the Lee load, and your chrono checks out with their velocity data, I wouldn't even blink at 58k psi data, and in fact, I'd not hesitate to run 65k psi in a modern, strong bolt gun. So if they're using a test barrel with SAAMI minimum chamber and throat, chances are that your pressure will be a little lower than theirs, assuming you use the same components that they use.

I'd work up to 48gr, watch the chrono, keep an eye out for traditional pressure signs, and try loading a couple of cases 5-6 times and see how the case head and primer pockets hold up.

Thanks!

David

My 162 Amax load is 48 grains of H4350 for 2725 fps. However, they are loaded way longer than magazine constraints in my SA M700.

Must be some new Hodgdon data.

The ADI/Thales book (they make the Extreme powders for Hodgdon) lists the following

AR2209 (H4350) min 45.0 2,570 - max 48.0C 2,715. I think this was developed with the 162 BTSP not the A-Max.

I suspect that the Lee manual is using the same data.

Very interesting! That may be the problem. The Lee manual just lists 162 grn Jacketed bullet, the Hodgdon web site load data is specifically for the A-Max. I guess maybe the A-MAX is longer and needs to be seated deeper?

David

You might be onto something with the seating depth. For its weight the 162 A-Max has quite a short bearing surface, so I don't think it would be a pressure issue.

I will check my printed Hodgdon magazine tonight.

Anyone with Quickload care to run a fairly generic 7mm-08/H4350/162 A-Max profile, seated to 2.820 and 3.000" overall to test the theory about seating depth and capacity?

I have the 2009 Hodgdon Annual manual. It lists the same data as the ADI book I posted earlier - 48.0C max for 2714fps and 49,800CUP. It lists the data as having been developed with the A-Max (not the BTSP as I thought earlier).

Hornady doesn't list a load for H4350 in its 7th edition, but predicts 2600-2700fps with max loads across the powders it does list.

Maximum modern SAAMI pressure for the 7mm-08 is 61,000 psi, so if you use the same brass and primers as whatever data you go with, you'll be fine.

Why are they loaded longer than magazine constraints?

David

Three reasons.... because Remington throats them waaay out there, and because I have a visceral dislike for combining max loads and heavy powder compression. And finally, during load workup the above load shot extremely well so given the other two considerations above I just stopped there.

It's at 2.970 COAL by the way, in case that has utility to someone figuring pressure on QL or something. So I'd be crunching .17" of powder column to fit the magazine. I don't like heavy compression without a crimp- seen it do not so funny things in other rifles- and I'm not crimping a long range load.

Since it's a long-range load, I don't mind single-loading them. If I get real sneaky I can actually have one in the chamber and one sorta catywhumpus in the magazine, anyway.

So to be clear, you have not tried compressing the load to magazine length?

Not judging what you're doing just trying to make sure I understand correctly...

My understanding is that COAL has no effect on pressure (excepting contact or very near contact with the lands). Theoretically it should not increase pressure to compress that load to COAL providing the chamber dimensions are unchanged. Keeping bullets seated in a heavily compressed load w/o a crimp can be difficult.

David

To be clear, I have not compressed it to mag length. No idea what happens.

Um... I've been wrong before <TM> but I was under the impression that seating depth DOES affect pressure.

Let me know what you see if you do choose to compress it to mag length (basically 2.820 for me). A cartridge I've done the powder compression wars with is .358 (which chronically runs out of space before hitting pressure, or at least did so with the "standard" .358 powders of a decade ago that I tried).... anyway heavy powder compression showed me enough potential for mayhem that I've been leery of it ever since- particularly with a precision load like my 162 AM load is.

I'm here to learn! The above is my thinking on things. Always ready to listen to other's experiences.

-jeff

Jeff,


I said " COAL has no effect on pressure (excepting contact or very near contact with the lands)."


There are certainly more knowledgeable hand loaders than me, hopefully some of them will chime in on the subject.

My understanding is that pressure does not begin to build to any appreciable amount until the bullet contacts the rifling. The pressure needed to push a bullet from the case is so minuscule that there is no ability to increase pressure regardless of how much powder compression takes place. Conversely, seating a bullet directly into the rifling or very close to the rifling may increase pressure as the bullet doesn't have a "running start" at the rifling and subsequently requires more pressure to get started.

Seating a bullet deeper in the case, compressing the powder charge results in more free bore in the chamber which generally helps to reduce pressures. Weatherby ammunition has always been loaded to SAAMI max as velocity is the Weatherby claim to fame. To increase the safety of pushing his magnums to max loads, Weatherby rifles typically have more freebore to keep pressures in check.

Most hand loaders work up there loads with bullets seated as far out as they might use (either max mag length and/or bullets touching the rifling - not always mutually exclusive). The reason for this, is because the bullets seated further out touching the rifling or nearly touching the rifling has the maximum potential for higher pressures. As they try to find ideal bullet seating depth (assuming it's not max length) and reduce COAL, pressures will not increase (and may decrease) so they don't have to work up a new set of pressure check loads every time they change the bullet seating depth.

Hopefully one of the more knowledgeable hand loaders will check in and comment.

Regards,

David

Yeah, I always find the lands then work back from there. Well, actually that's not true. On a few factory rifles I've owned or do own, the lands were far enough out that (once I measured this) I just focus on finding loads that will shoot and fit the magazine.

My custom-barreled rifles are all throated so that I can easily reach the lands if I want to from within mag constraints.

What you are saying about pressure not building until the bullet engraves makes sense. On the flipside, I've obviously created way more case capacity with it seated way out, and more case capacity means less pressure... That may not be relevant if what you say is 100% correct.

At any rate my reasons for leaving it long were that it shoots great and since I was up above the data that I'd seen up to that point, I didn't feel like trying to crunch it all the way down to 2.82 and introduce those variables. I've seen heavily compressed loads push bullets back out for instance, changing the COAL.

In the final analysis I suspect you are more right than I am, and that compressing it heavily has no significant pressure effects. An experiment for another day, eh? Preferable not a 29* freezing fog day like today!

Wow, 29 degrees, that's absolutely brutal!