Home Forums Hunting & Shooting Ask The Gunwriters Using Mule Deer's Rules with the 9.3x62

I'm looking to do some work with my newly rebored 9.3x62 with Power Pro 2000-MR, and I have been playing around with "The Rules" that John published in Appendix 1 of "Gack I" and thought I'd share it. I'll show the examples, and end up using about all the formulae.

Background. I have a 35 Whelen AI with a long throat in a commercial 98 Mauser. Speer has published some pretty game changing tested loads for the basic Whelen with their 250 HotCor and 2000-MR, specifically, a max of 66.2 gr for 2709 FPS. In my 35 WAI, the 250 HotCor and 250 partition are near perfect analogs, giving same velocities and groups with the same charges. In working up in my 35 WAI with the 250 Partition, I stopped at 65/2000-MR for 2645 FPS and sub MOA accuracy. This load in my 35 WAI produces only .0002" CHE on the first firing and then no further CHE on subsequent firings. Assuming Speer was pushing the SAMMI max of 62K PSI with their load, I figure I'm around 60K or less, the same target JB has used for his 9.3x62 loads. So I want to "derive" some 9.3x62 2000-MR loads for the 250 AB and the 286 Partition using The Rules.

My 9.3x62 has the same 23" barrel as my 35 WAI and also a long throat so both rifles are magazine limited, and I load to a 3.375" OAL in both for good feeding, and am around .200" off the lands in both.
My 35 WAI holds 65.7 grains of water underneath a 250 Partition seated to 3.375" in a once fired case.
My 9.3x63 holds 65.2 grains of water underneath a 250 Nosler AB seated to 3.375" in a once fired case.
SO, if they were both the same caliber, the 0.5 difference in case volume would cost the smaller case about 5 FPS
...65.7/65.2 = 1.00767. Divide the % difference by 4 to get the velocity gain/loss at the same pressure - .00767/4 = .0019. .0019 x 2645 FPS = 5.02 FPS (not even a standard dev of change but we'll play with it) so I'll take off the 5 FPS and call it 2640 FPS.
BUT, they are not the same caliber, the 9.3 has a greater cross-sectional area for the gas to push on. The cross-sectional areas are .1007 and .1052 respectively, so how much faster should the 9.3 go if loaded to the same pressure?
.1052/.1007 = 1.0447, or a 4.4% increase, but the 4:1 rule says we only get about 25% of the increase in actual velocity so 4.4% / 4 = 1.1% potential velocity gain (big whup, right?) so 2640 x 1.011 = about 2670 FPS.
But I need more powder to get that extra 1.1% in velocity, and the 4:1 rule says I need about 4.4% more powder, bumping the charge I'll probably need up to 67.8 grains of 2000-MR to get 2670 FPS with the 250 in my 9.3x62, and that ought to be at about the same pressure as my 65/2000-MR load for 2645 FPS in my 35 WAI.
But I want to shoot the 286 Partition with 2000-MR too. The 286 is actually .005" shorter than the 250 NAB so I will have about the same powder capacity when loading to the same 3.375" OAL. So using The Rules I add the 2 bullet weights and divide by 2: 250 + 286 = 536. 536/2 = 268. I divide that value by the new bullet weight of 286 grains. 268/286 = .93706 and use this conversion to calculate my potential velocity and powder charge.
67.8 gr x .93706 = 63.5 grains. Velocity ought to be: 2670 FPS x .93706 = 2502 FPS.

In summary, I ought to work up to ~67.8/2000-MR for ~2670 FPS with the 250 NAB, and ~63.5/2000-MR for ~2500 FPS with the 286 Partition.

How does that compare to the little bit of published data for 2000-MR? Speer's max for their 270 HotCor is 59.3 for 2439 FPS. Hornady's max for their 286 SP Interlock is 62.4 for 2400 FPS.
Now going back to Mule Deer's guidance for developing sub-60K PSI loads in the 9.3x62:
"All published 9,3x62 loading data is based on old, low-pressure standards. I have NEVER run into any sort of "pressure sign" by starting with published maximums and working up to around 2450-2500 fps with 286s and 2650-2700 fps with 250s, of whatever brand. That's with three different 9.3x62s that had 21-24 inch barrels."

Does that look about right, John?. That was kind of fun. Our local range is closed UFN due to the coronavirus but when I get a chance to shoot again over my chrono, I'll come back and update.
Thanks for "The Rules." I'm looking forward to Gack III.
Cheers,
Rex

Hi Rex,

That's about right! And is basically the same technique I used when working up modern loads for the 9.3x62 eighteen years ago.

John

Quick question: "This load in my 35 WAI produces only .0002" CHE on the first firing and then no further CHE on subsequent firings." What is CHE?

Cartridge head expansion?

I left out the last line of your quote in the post above, because I felt it was not relevant to my goal of staying around 60K PSI:

"All published 9,3x62 loading data is based on old, low-pressure standards. I have NEVER run into any sort of "pressure sign" by starting with published maximums and working up to around 2450-2500 fps with 286s and 2650-2700 fps with 250s, of whatever brand. That's with three different 9.3x62s that had 21-24 inch barrels.

No doubt it could be pushed even harder, but I have generally found 250s and 286s at those velocities kill big game VERY well."

But then I got to thinking about mainer_in_ak's excellent thread on his 13 years hunting Alaska with the 9.3x62, and his load of 64/2000-MR and the 300 grain Swift for 2460 FPS in his CZ carbine.
Based on the numbers I just ran shooting for about 60K PSI (63.5/2000-MR for 2500 FPS with the 286 PT), I'd guess mainer's load is probably right about the 62K PSI limit for the Whelen or the 63K limit for the 338-06. When I first read them it sounded pretty darn stiff, but after playing with The Rules it does not sound unreasonable.

AKA "Case head expansion"

Here's a link to Hodgdon's short description of the CHE technique. IMO, it should not be trusted as a stand alone method of pressure assessment but can be useful when combined with chronograph readings, load manuals, traditional pressure signs, and of course now, The Rules.
Hodgdon CHE description

Cheers,
Rex

Is this where I can find "The Rules"? https://www.riflesandrecipes.com/product/the-big-book-of-gun-gack/

Thanks for the link Rex. This is pretty interesting information in this thread.

Yes Sir.
And a fair bit of it is available open source here on the fire.
The Barsness 4 to 1 rule

Dang John, I might have just blown my commission.
Rex

I can make it a lot easier on you. Buy a bunch of Seller & Bellot factory loads with the 286 gr softpoint. That is all I shoot out of my 9.3 and they are super accurate. I can't beat them with a handload but I can get close to matching it. Very effective on game. Seller & Bellot isn't the ammo a lot of people go for right off the bat but I have 2 metrics (9.3x62 and 6.5x55) that shoot their ammo really well and it tends to be very reasonably priced. As a matter of fact several years ago Natchez had a sale on it and I bought 6.5x55 with the 131 gr softpoint for less than $9 a box. I laid in a huge supply and have been happily shooting my way through it ever since.

The S&B 286gr 9.3x62 factory load is also very accurate but clocks 2300 fps in my 24" barreled Mauser...quite a bit less than I think the OP is trying to achieve. But...it's cheap and accurate.

S&B bullets are a bit suspect, based on my shooting them a lot in 9.3X74R, 9.3X62, 8X57 Jrs, 8X57 JR, 7X57 R, 7X57, and 6.5X57R.

I've shot at least several big game animals with each round listed, and the bullet performance was..meh..adequate for the most part. Their bronze tipped spitzer is an absolute fiasco! I and another member here witnessed that bullet fail to penetrate the shoulder of an average sized doe in Oklahoma. She took several hits and still ran off with a big hole in her shoulder meat. This was with a less than rocket 8X57JR.

What I'm saying is, for the 9.3X62 and it's potential, re-load with good bullets. The standard S&B cup-n-core bullet is fine for deer, antelope, etc., but none of their own bullets are all that, especially the bronze pointed ones. They do some loading with Sierra bullets in some calibers.

Thanks for the suggestions on factory ammo but I'm good there. I scored 13 boxes of Lapua 285gr Mega for $10/box during a closeout from Williams Shooter's Supply. I have only fired a dozen rounds of them but they shoot very accurately but only at 2245 fps. And a test video I found on YouTube suggest they might not be terribly tough. They are also very blunt, though I don't know the actual BC. There are doubtless many applications for which they would be fine but I want to load the Accubonds and Partitions.

Cheers,
Rex

Lapua ammo @ $10/box...

I don't like you anymore.

I didn't believe it myself until the shipment actually arrived. Kept thinking there must have been some kind of mistake. There were all kinds of crazy deals going on at that closeout and I dropped a lot of coin on it, but boy did I make out like a bandit.

That's almost a steal just for the brass!

They had brass too.
Lapua 9.3x62 for $30 per 100. I bought 500.
Jamison .256 Newton for $50 per 100. I bought 400 (all they had).
And bullets. Got a few of these:
Lapua 9.3 285 Mega's, $10 per 100
Hornady 9.3 286 SP, $10 per 50
Hornady 9.3 250 GMX, $15 per 50
I figured they must have just decided to get out of the 9.3 business - who knows? But this score is what led me to build a 9.3x62, and will also spawn a .256 Newton. Are we having fun yet?

I saved the invoice as a souvenir of probably the best deals I'll ever see.

Some days you're the fire hydrant, and some days you're the dog.

Rex

Picked up 4 boxes of S&B off the reduced table at the old Gander Mtn store in Wichita Ks. In 2010. It is good ammo! I still have a few rounds left.

Nice rifle and fine looking critters, Kaywoodie! Mine is still a work in progress but I'll post some pics when it's finished.
Rex