XMP 5744 Load. Heavier Charge Question

[Shiloh]

In both the Lyman 48th and 49th edition of the Reloading Handbook,
the starting load for a Lyman #311284 210 gr boolit is 28 gr of XMP 5744.
The MAX load is 38.5 gr. with this powder. This is for the .30-06 and from that lising in the load books.

The starting load for a Lyman #311299 200 gr boolit is 21 gr of XMP 5744.
Max load for this lighter boolit is 29.5 gr. with this powder.

The starting and MAX loads for a Lyman #311291 170 gr. are 26 gr and 35 gr respectively.

How can a boolit, the #311284, that is 40 gr heavier than the #311291, have both a Starting and MAX load that is a heavier charge than a lighter boolit??

The #311284 has a relief groove on the nose, but is still a much heavier boolit?
Is this a misprint?? Do any of you casters/shooters use this boolit with this powder at the listed charge weights?? Any pressure issues??

In the .30-40 Krag, the Start and MAX load for the Lyman #311291 are 20 gr.
and 26.5 gr. for this powder, and for the Lyman #311284, they are 18 gr. and 28 gr. respectively with this powder.

This makes sense. A heavier boolit gets a lighter charge. Any explanations folks??

Shiloh

[Vly]

You don't say what cartridge the data is for in the first part of your post, but in my experience the suggested start and max loads, when given for cast loads, are for the ideal velocity range for best accuracy, not pressure concerns.

I am looking through an Accurate Arms booklet with cast data for 5744, and all the loads max the velocity at 1800 - 1900 fps. So I think the vendors are steering people toward best accuracy and not necessarily highest possible velocity.

[Shiloh]

This is for the .30-06

That somehow got deleted when editing. There were lots of numbers. It's been replaced.

Shiloh

[BruceB]

"I am looking through an Accurate Arms booklet with cast data for 5744, and all the loads max the velocity at 1800 - 1900 fps. So I think the vendors are steering people toward best accuracy and not necessarily highest possible velocity."

Just a quick note, here:

In the .416 Rigby with the RCBS 416-350 (actual weight about 365) my standard 5744 load is 55 grains, which runs very nicely at just over 2000 fps. Accuracy is just fine.

This is not a maximum load, but I've never seen the need to find out just where that maximum load might be. The 55-grain load does NOT appear in any Accurate Arms publications, but then, neither do any other of my .416 or .404 loads. I reckon these cartridges are well outside the "normal" range, but so am I!

[Rocky Raab]

The accuracy velocity aspect might be spot on.

There are also other factors besides bullet weight, most notably the amount of bearing surface. A bullet with a narrow, bore-riding nose results in less friction (and thus pressure) than a bullet that is fully engraved, end-to-end. That might still be true even if the bore-rider is heavier.

Today's manuals contain almost all TESTED data, so I think I'd believe what the book says.

[Doc Highwall]

I know you are using a 30/06, but in my 308 Win I am using 20.5 grains with SAECO #315 cast 30:1 alloy and getting excellent accuracy, sub 1/2" at 100 yds.

[Shiloh]

Outstanding Doc!!

Shiloh

[rvpilot76]

Geez Doc, great shooting! What's that #315 weigh in at? I'm still in the quest for a good cast load for the M1A Loaded.

[Doc Highwall]

rvpilot76, the SAECO #315 with my 30:1 alloy weights 179.8 grains. The velocity I shot the target at was 1752 fps with 20.5 grains of AA5744. These are loaded at a over all length of 2.800" and with the soft alloy I can have them engraved into the lands.

[swheeler]

bRUCE B

This is not a maximum load, but I've never seen the need to find out just where that maximum load might be. The 55-grain load does NOT appear in any Accurate Arms publications, but then, neither do any other of my .416 or .404 loads. I reckon these cartridges are well outside the "normal" range, but so am I![/QUOTE]

Bruce I would like to bring to your attention Page 329 of Accurate #2 manual

416 Rifby-350Lead rn RCBS-5744 start 49.5-1912, max 55.0-2173fps 41.6k psi

[BABore]

I was seeing similar data when I was getting ready to use 5744 in my 338 with cast. Velocities were in the 1,800 fps neighborhood and pressures were quite low. I sent an email to AA and explained to them that I was looking for data that would take me into the 2,400 fps range and asked if this powder could do it safely. Got a reply right back that said sure, no problem, and they upped the max load by another 7-8 grains over book max. Worked great too. Give them a shout.