A few years back I saw an ad in Gunlist for a Valmet 412 9.3x74R combo gun (might have been a double rifle but then I'd be posting on the wrong list) that had been rechambered for an improved version of the cartridge. I recall the seller claimed a performance level something like that of the 9.3x64. Seems to me a long tapered case like this would derive maximum benefit from the improved treatment and the tip up action might appreciate the reduced head thrust. Anyone ever seen such a beast? Can anyone here run the numbers through their Quickload? Good hunting!

mb,

I have not seen an Improved 9.3x74R. There are though a couple of modern cartidges based on the 9.3x74R case like the 8x75R that have improved configurations and operate on higher pressures. I know there are a couple others (a 6.5mm as well?) but they fail my feable memory at the moment.

Like yourself would consider it more reloader friendly if for nothing else than making the correct neck/die adjustment easier. The neck position can be somewhat difficult to locate exactly and adjust the dies accordingly on the standard 9.3x74R.

The 9.3x74R's case is actually smaller in diameter than standard .473" based cartidges but the length helps assist in volume increase. I'm sure there would be performance benefits from an improved version but somehow have difficulties imagining that 9.3x64 performance could be attained since that case is already siginificantly larger (surprize me!).

I remember reading an article in Gun Digest where Elmer Kieth had a Ruger No1 in a .338x74R Improved - it looked like a really spiffy cartridge so the concept has been touched on beore.

Opening the shoulder to a rather optimistic 0.447" and blowing it forward to leave only a 0.32" neck will increase the case capacity from about 82 gn to about 92 gn. The "improved" x74R case will have a bit more volume than the x64 case.

Seating a 286 gn bullet a scant .32" deep (using a longer throat), these capacities change the net case volume (under the bullet) from about 71 gn in the standard chamber to about 83 gn, an increase of 17%.

A good rule of thumb is every 4% increase in net case volume gets you about a 1% increase in fps, at the same max. pressure. Your increase in case volume will get you, then, about a 4.5% increase in fps. This will be about 100 fps (to 2450 fps) with a 24" barrel. The x64 runs at much higher pressures and will continue to outperform the x74R.

The taper in the standard case should ensure reliable ejection, if that gun has an ejector. That may be affected by going to minimal taper.

If you want a hot 9.3 rimmed then the 500/416 NE case necked to 9.3 would give the volume you want without sacrificing neck length or taper for easy extraction. You would also get both lower operating pressures and much stronger parent brass.

quote:

If you want a hot 9.3 rimmed then the 500/416 NE case necked to 9.3 would give the volume you want without sacrificing neck length or taper for easy extraction.

Thanks. I'm interested in the 9.3x74R because I have a Valmet 412 (12/223) that I might like to make into a medium some day. I understand the advantage of the long skinny 9.3 is that it fits into a smaller more slender action than some larger cases. It's reputation as a medium speaks for itself but an improved version might give it a useful boost without incurring significant downsides. But if I were building a single-shot, double rifle, or combination gun from scratch I wouldn't bother with it at all. Good hunting!

mb, remember, those long, skinny, tapered cases ensure good extraction, in guns not noted for their powerful camming action. If you start to go towards a straight walled case, you may encounter extraction problems.
Just a thought.

Cheers, Dave.
Non Illegitium Carborundum

Mb: It took me a while to find this but I think that it is smoething that you may find interesting. specialtypistols.infopop.cc/groupee/forums/a/tpc/f/8246077864/m/506107466

Enjoy, Rusty

quote:

Originally posted by Sambar 9.3:
mb, remember, those long, skinny, tapered cases ensure good extraction, in guns not noted for their powerful camming action. If you start to go towards a straight walled case, you may encounter extraction problems.
Just a thought.

Cheers, Dave.

Non Illegitium Carborundum

The other thing that occcured to me was the reports of short brass life with the parent case. If you blow it out I assume you will develop some degree of shoulder which may help that condition if you have enough to headspace upon.

My experiences have been with Contender and Encore TC handguns on improved cases, 40 and 60 degree shoulders with minimum case taper, not exactly drillings but close enough for all practical purposes because they are still break actions. When things begin to become sitcky, problems in opening the action and extraction, back off the powder charge a little and the cases will fall out of the gun even though they are very straight sided. These guns do not have ejectors but they would easily function with ejectors if the pressures were not run up too high.

A summary of the above given thread covering 3 pages of information is that the 9.3 x 74R based wildcats exceed 3006 based wildcats of the same caliber by 200 to 300 fps, with the rimmed case always providing superior accuracy. This was considered too much capacity for pistol length barrels but provided the additional velocity in rifle lenth tubes. Although 2000 fps was never reached in 14 and 15 inch barrels of the stock 9.3 x 74R, in a rifle length barrel improving the 9.3 x 74R would give a considerable velocity boost with out increasing pressures, plus much better brass life and enhanced accuracy...Rusty.

I would also consider rifle action strength before hotloading these rounds. Once you shoot afew 9.3 loads in your break action gun, you will realize it does all it needs to unless your combo double is over 8.5 or 9 pounds.

You can load a 9.3 hotter, but case life is short, and your action will come off the face.

I would second the question of need for a 9,3x74R Improved. With good bullets like Noslers or Woodleighs the caliber kills beyond what one would expect from the calculated energy delivered. (And has more than enough recoil energy for an 8 pound rifle.)

In that respect it is a lot like the 9,3x62 ... which also "just works!"

quote:

Originally posted by tiggertate:
If you want a hot 9.3 rimmed then the 500/416 NE case necked to 9.3 would give the volume you want without sacrificing neck length or taper for easy extraction. You would also get both lower operating pressures and much stronger parent brass.

9,3X65R Brenneke would be my choice. A fine caliber

Cheers
/JOHAN

Why not a straight 9.3x74R Un-"improved"?

To me IMO making the case straight walled for a few extra fps is NOT an improvement at all, rather the opposite. Especially in a double or combo.

If you want bolt action performance a 9.3x64 in a M98 is the way to go.

The primary reasons for using improved cases in a break action isn't to gain increased velocity as is commonly believed, but to eliminate most of the backthrust transmitted to the action.

In the old days it was believed that tapered cases were necessary for extraction. Modern experience has proven that not to be the case. Granted, some taper in a case helps in feeding with repeating actions. But that is not much of a concern with break actions.

David White did some experiments in TC type barrels with improved cartridges comparing them to the same unimproved cartridges and others with tapered cases with no breach block in place to contain the case heads. The improved cases were driven .004 deeper into the chambers by the "flapper" he used to fire the primed and held there by the expanded brass with out a closed breach.

Fire forming loads protruded from 1/2 to 3/4s of an inch from the barrel but the cases were gripped sufficiently to prevent them from being ejected from the respective barrels they were fired in.

Four 35 Renington rounds were fired. The first ended up being deeply imbeded in an oak tree 8 feet behind the vise holding the barrel. David set up a chronograph to measure the velocity of the casings exiting the barrel. The first reached 1200 fps. The second 800 and the finalcase 1300 fps. Tapered cases exert considerable backthrust on any action type they are fired in.

If you would like to read the experiment and related information for yourself, click on the following, Rusty.

http://www.bellmtcs.com/forum/index.php?act=ST&f=24&t=1...aa10400c3db7c23ba23g

Another thing to consider is the opening of the action after firing. Valmet/Tikka 412 system guns are not famous for being easy to open if firing cartridges which are loaded at all warmly.

I personally think it has something to do with the lack of a reliable firing pin retractor in those rifles, but my experience with them does confirm that hot cartridges do make the action a "beach" to get open after firing.