Home Forums Hunting & Shooting Ask The Gunwriters 9.3x62 Pressure

I have read that a factory 9.3x62 does not exceed 56,500 psi. I have also read that a modern fire arm is safe to ~65,000 psi. How many more grains of powder does it take to get to 65,000 psi? Thank you for any response.

An approximate rule-of-thumb with single-based powders is pressure increases twice as much as the added powder. This means a 7.5% increase in powder would increase pressure from 56,500 psi to 65,000.

With double-based powders pressure increases quicker, but varies depending on the amount of nitroglycerin content. In general it would probably be three times as fast as any increase in the powder charge.

I've pushed the 9.3x62 to around 60,000 psi (measured by strain gauge) in a 23.6" barrel, resulting around 2650 fps with 250-grain bullets with RL-15 and Varget, and around 2500 fps with 286's using Ramshot Big Game. That seemed to be plenty so I quit there.

Thanks you. I will look for 2600fps with the 250 Accubond.

John, is there any reason not to use Big Game with 250 g. bullets in the 9.3X62? (I'm asking because in the current panic have a lot of Big Game but no Varget and just a little RL15.)

I have loaded 250gr and 286gr bullets with RL 17, about 4% compressed. Check speed and accuracy tomorrow.

Very interested in your RL17 results.

CKW,

No reason not to use Big Game with 250's, though velocity probably won't be as high as with slightly faster-burning powders.

Thanks! That helps - as I am now well supplied with Big Game and IMR 7828 SSC and large rifle primers. My 9.3X62 and 30-06 both seem to like Big Game so I don't worry about the lack of H4350 or RL 15 for them.

Please let me know how it works! My guess would be fine accuracy and around 2500 fps, which of course is plenty.

Now if I could just find some 250 g. Accubonds to try out!

67 grains of Big Game behind the 270 g. Speer bullet just reaches 2500 fps in the 20.5"barrel on my rifle. So if I hunt elk this year I'll probably use the Speer.

(I would prefer the 250 g. Accubond because of your favorable reports on that bullet.)

RL-17 250gr NAB, 68gr=2577fps,69gr=2647fps.

RL-17 286gr Hdy, 65.5=2375fps,66.5=2444fps,68gr=2515fps

The rifle is a Sako M-85, 22.4" (570mm) barrel. Quickload predicts 63171psi with 66.6gr of RL-17 for 2599fps. Accuaracy is 1" for 3 shots.

Sounds like you're good to go to me!

There is a real shortage of RL-17 around here, it takes a big compressed load with Viht N550 (which I have many pounds ) to get similar results, these loads are only slightly compressed. Any suggestions on an alternate powder?

For 250's, any powder in the 4895 range will work, whether R15, Varget, TAC, H335, 4064, etc. Slightly slower powders that have small granules would also work, such as H414/W760.

The same powders will also work with 286's, but the slower-burners tend to get more velocity, such as Big Game, 4320, H414, etc. Big Game I what I normally use, but apparently it's hard to find right now.

Thanks, are there any issues compressing 'ball' powders or is there a need in this case?

There really isn't any issue with compressing ball powders--unless, like many did with the first .458 Winchester factory ammo, you're going to store it in hot places for quite a while.

You shouldn't have to compress any of the ball powders mentioned much. I've used 65-66 grains of Big Game with 286's for several years, and among the bullets has been the 286-grain Barnes TSX, probably the longest 9.3 286 made. Never had any problems.

Thank you, I have more confidence now with ball powders

Curious to know what powder charge you are using with VV550? It is the powder I settled on in 2000 when I started loading for the round.

Mule Deer, here are my results with Big Game and 250 G. Accubonds, also with 286 g. Partitions.

Rifle is a CZ 550 FS with a 20.5" long barrel, brass is new Hornady, primers are Winchester Large Rifle Magnum, OAL = 3.378". Temperature was 56 degrees F. Overcast skies so the ProChrono digital chronograph had favorable conditions. Two shots at each 1/2 g. increment of powder.

Results: Accubonds: 67 g.= 2564, 2564 fps.; 67.5 g. = 2578, 2588 fps.; 68g. = 2594, 2599 fps.

Results: Partitions: 64 g. = 2393, 2398 fps.; 64.5 g. = 2428, 2415 fps.; 65 g. = 2446, 2442 fps.; 65.5 = 2450, 2442 fps.; 66 g. = 2455, 2450 fps.

I'm going to stay with 67 g. of Big Game with the 250 g. Accubonds and 65 grains with the 286 g. Partitions.

All of the loads are compressed ! (Just my personal idiosyncrasy.)

Disclaimer: None of the above showed any overt - admittedly over-simplified - signs of high pressure in my rifle; i.e. stiff bolt lift and/or marks on brass. They appear safe in my rifle, but this does not indicate they are safe in any other rifle. As always work up gradually from below. I had already worked up to 67 g. with 270 g. bullets, hence my starting point with the 250 g. Accubonds.

Mule Deer, you were spot on on your estimate of velocity with Big Game and Accubonds, and the other loads are sourced from you also. I have you to thank for owning the 9.3X62. And all the money it has cost me! But dang, I like this rifle, it gives me a lot of enjoyment to fuss with in my retirement. THANKS!

(I have not tested the above bullets for accuracy yet; but the rifle has been accurate with the 65 g. load behind 285 g. PRVI, 286 g. Hornady and 270 g. Speer bullets so I anticipate it to shoot well with the Noslers.)

I have settled on 67 gr of VV N-550, 286gr Nosler Partition, for 2460 fps. 5 shot group at 100m is a little over one inch. This load has over 2000 ft/lb of energy at 450 yards.