The .375 x 55 Swiss (AKA .375 x .284 Win)

Started by gitano, July 06, 2008, 02:04:57 PM

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gitano

I got the NEW reamer yeterday, and recut the chamber. Some of you may recall that the first reamer I got was very tight. In fact it was so tight, I am using it as the reamer for making the reloading dies (done :)). I am very pleased with the new chamber. I sized (in the new die) 22 .284 Win cases (.284 cases instead of 7.5x55 Swiss cases so I wouldn't have to modify the bolt face/extractor of the Turk action). I fire-formed 5 cases (Bullseye and Cream-of-Wheat) and fired 2 with full charges behind Nosler Accubond 260s. Those 7 cases were used to get precise measurements for QuickLoad (QL).
 
Based on the QL calculations from the measurements of the fired cases when applying Optimal Barrel Timing theory, I get the following numbers:
 
Barrel length = 26.0"
Case capacity = 68.86 grains of water
Case capacity with 260-grain Accubond seated 0.637" deep = 51.66 grains of water
Overall Cartridge Length = 2.895"
 
Optimal Barrel Timing Charge (node #6) = 47.38 grains of Accurate 2495 (100.5% of case capacity)
Estimated Muzzle Velocity = 2388 f/s
Muzzle Energy @ 2388 f/s = 3291 ft-lbs
Estimated Chamber Pressure = 46,985 PSI
 
Trajectory when sighted in for a 6" target:
.....................................Impact ...... Retained
Range . . . Elevation . . . Velocity . . . . Energy
100 yds . . . 2.9" . . . . . . 2225 f/s . . . 2858 ft-lbs
125 yds . . . 3.0" . . . . . . 2186 f/s . . . 2757 ft-lbs
150 yds . . . 2.6" . . . . . . 2146 f/s . . . 2659 ft-lbs
200 yds . . . 0.3" . . . . . . 2069 f/s . . . 2471 ft-lbs
205 yds . . . 0.0" . . . . . . 2225 f/s . . . 2452 ft-lbs
241 yds . . .-3.0" . . . . . . 2006 f/s . . . 2324 ft-lbs
250 yds . . .-3.9" . . . . . . 1993 f/s . . . 2292 ft-lbs
300 yds . . . 10.1". . . . . . 1918 f/s . . . 2124 ft-lbs
 
I'm very pleased with these numbers, and based on previous experience, I think QL's numbers will be close. While I'd prefer the 300-yd drop to be 9" or less, for those rare occassions I feel I must take a 300-yds shot, I can add an inch to my hold-over if necessary. Most important to me is the muzzle energy of 3291 ft-lbs, (translates directly to felt recoil), the 300 yd retained energy of 2124 ft-lbs, and the very modest chamber pressure of 47 kPSI - all for something like 47.4 grains of power. 2100+ ft-lbs of energy behind a .375" bullet is gonna take care of anything in NA... without beating me up on my end of the bullet.
 
Since this is a brand new barrel, and inspection of the fired cases shows that the chamber is as round as I can measure, (zero runout to less than 0.0005"), I am expecting it to shoot pretty straight.
 
This rifle is built around a Turk .38 action, but once this prokect is complete, (sights, stock, and sighting in), I'm going to make one of my K-31's into a K-31/.375x55. That'll be a sweet rifle if I can figure out how to make the K-31 bolt handle "pretty".
 
I think I'm going to drill & tap this receiver for 'scope bases. I haven't made up my mind whether I retain a 'scope in the final configuration. I like the looks of open sights, but maybe that 'look' can be for the K-31 version.
 
Paul
Be nicer than necessary.

recoil junky

Sounds pretty cool Paul. Now punch some holes in some paper so's we can see it for reals.

The .338X284 sound VERY interestin' to this old boy!

RJ
When you go afield, take the kids and please......................................wear your seatbelts.
Northwest Colorado.............Where the wapiti roam and deer and antelope run amuck. :undecided:  
Proud father of a soldier medic in The 82nd Airborne 325th AIR White Falcons :army:

gitano

#2
Thanks RJ. If I get everything, (mainly sights and loads), together in time, this rifle will be coming to CO this fall.
 
I considered the .338, especially for the K-31, but... 1) It's tough to beat the .338 WM, and 2) The .375 is so much bigger than the .338. Ida thought you woulda been more interested in the .358x.284. It should compete very favorably with the Whelen when the criteria are not simply "maxes".
 
I also got a new barrel chambered in the .323 SST (Steyr Short-Throat). It's 28" long and should drive a 125-grainer 3400 f/s at only 50,000 PSI. I've got a special barrel (23 & 3/8ths inches long) for the .323 SLT (Steyr Long Throat), but I haven't got it chambered yet. It will be shooting the Hornady 195 FB and the Sierra 220 BTSP. The best shooter of the two will get the nod. I wouldn't consider the BTSP, but its BC is .515. If it shoots straight, it's got about the same trajectory as the 195 but carries more energy farther.
 
Since my lathe has remained operational, and I have been able to get the barrels and reamers, I have been able to complete - or at least get moving along significantly - several projects. As soon as I get the .323 SLT chambered and mounted on an action and the SST mounted on an action, I'll be finishing the .58 cal muzzle loader I started 2 & 1/2 years ago. That should complete the Colorado battery. :) Unfortunately, I may actually have to do some work starting in August, and that will definitely cut into my 'project' time.
 
Paul
Be nicer than necessary.

recoil junky

I hear the "work cutting into progect" time. I haven't got to go shooting for 3 WEEKS :stare: Had to work the 6th and 12 hrs today makes 22 hrs for the week already. Plus a summer class at CNCC. That's what I'm supposed to be doing right now is studying :greentongue:

I've toyed with gettin a 375 caliber something. I'd like to have a 375 H&H but I don't know what I'd do with it :undecided:. Shoot prairie dogs I suppose.

RJ
When you go afield, take the kids and please......................................wear your seatbelts.
Northwest Colorado.............Where the wapiti roam and deer and antelope run amuck. :undecided:  
Proud father of a soldier medic in The 82nd Airborne 325th AIR White Falcons :army:

Steve D

This project sounds like something I've been interested in for a while.  Since I'm such a fan of the 308 cartridge, I've wondered how big one can open it up.  I suspect someone has come up with a 375-08, or something similar.  I wonder if something even bigger is reasonableor possible, say 416.  I'm interested in something short range, but with a punch for that short range.  While the 375x55 is very appealing, I really don't want to deal with different rim sizes, etc.  I suppose I could get excited about a 375x57.
You\'re just jealous because the voices only talk to me.  :yes:

gitano

QuoteSince I'm such a fan of the 308 cartridge,

I assume you're referring to the .308 Win case, and if so then it's "you and me brother", as I doubt you'll find a greater "fan" of the .308 Win. here at THL than me. :D
 
If you back out of this thread to the site root (Factory Ammo and Reloading), sort the threads by the thread starter's name, and look back at some of my (gitano) threads, you'll see a few about the .308 Win. as well as some about cartridges derived from it. I'll go back myself and bring a few of the relevant URLs here.
 
With respect to a .375-08:
Personally I've stopped at .358". Primarily due to the case capacity of the .308 Win with respect to the bullet weights of .375" and bigger calibers. Just not enough 'oomph" for me. Of course your standards/desires/needs are very likely different from mine. I think a GREAT deal of the .358 Win. cartridge.
 
While mine is a personal choice, the fact is, once you get much above .375", you essentially have a straight case, and I hesitate to call such a cartridge ".308 Win.-based". To me, it's just a .473" headed case that's about 2" long. It could just as easily be made from an '06 or x57 case as a .308 Win case. Of course I realize that's true even for bottle-necked cases, but "straight-walled" means generic to me.
 
In answer to your
QuoteI wonder if something even bigger is reasonableor possible, say 416.

I offer this numerical consideration: The shoulder on the .308 Win case is nominally 0.454". If the neck wall thickness of your .416-08 was to be 0.012", (commonly, the neck wall thickness on factory ammo is 0.015"), then the loaded cartridge's neck diameter would be ~.440". While "do-able", it most certainly would be a "straight-walled cartridge". Of course, you could blow out the shoulder to almost head diameter - 0.473" - and have some 0.030" to play wiht to make a "shoulder". I'd submit that it'd be more like 'snake hips' than "shoulder" though. :D
 
I'm sure it'd be a fine deer cartridge inside 200 yds though. A .416 bullet is a 'hammer', no doubt.
 
Paul
Be nicer than necessary.

Steve D

Thanks.  I very much appreciate your response to my interest.  I actually think as large as I'm really interested is about .375.  I suppose there would be little difference between a 375-08 and the 375 Win.  I just think I would be interested in a rimless 375 Win for a bolt gun.  Couldn't give you the slightest justification or need.  Just interested in what would happen.:smiley:
You\'re just jealous because the voices only talk to me.  :yes:

gitano

QuoteCouldn't give you the slightest justification or need.

You'll never find me requesting either of the above. :D
 
Actually, there's a surprising bit of difference between the .375-08 and the .375 Win - at least to me. According to SAAMI, the case capacity of the .375 Win. is 48 grains of water. For the .375-08 it's 60 grains of water. That's a pretty big difference. Another surprize - in the opposite direction - was that (again according to SAAMI), the .375 Win can be loaded to a max chamber pressure of 63,817 PSI.:eek:  The .308 case's max is listed as 60,191 PSI.
 
Anyway, if I was interested in a .375 cartridge other than the .375x55 Swiss/.375x.284 Win or the .375 Steyr, I'd prolly go with the rimmed Winchester case in a SxS double. Or better yet, a .375 Win x 16 ga Cape gun. The Swiss or .284 cases satisfy my bolt-gun 'itch' in .375.
 
Paul
Be nicer than necessary.

Gmoney

Paul,
 
In case you didn't know I'm also a huge closet .308 case fan...grin...
 
Don't tell anyone...
-Greg
 
Personal field testing trumps everything no matter what Field and Stream says, what your degree of perceived manhood is, or what your buddies think.

Steve D

#9
Actually, my need is for something of that approximate performance that doesn't require a lot of changes to the rifle. Using either the 308 (or 30-06), most bolt guns require only a barrel swich (no bolt face changes, the shells fit in the magazine, etc). Now, if you had a K31 (or even a K11, to a lesser extent) that you just had to do a barrel switch, then it makes perfect sense. I just can't see myself switching a barrel on a Swiss in the near future. Of couse, my K11 is not in original condition, either. Someone "sporterized" the stock before I got it. It still shoots fine, but it's not original. Just wish I could use a scope on it. I think it would make a fine deer (or elk, or caribou......) rifle as it is with a scope. Are you aware of any sources for a short magazine (limit 5 rounds or less)? I have several rifles that have magazines that hold over 5 rounds and they don't see any humor in that in some of the states where I hunt.
Back to the point, I should just go with the 375 JDJ in a TC Encore, I suppose. Also, are you familiar with the Scoville wildcats? They are sometimes listed as Hawk-Scoville. They are usually off the -06 case, I believe. They have a 338 Scoville that pushes the 338 Win Mag pretty hard. They also have the 378 Scoville which is also impressive. The Barnes reloading manual lists them and a write-up by some fellows that use at least one of them in a lever action, an 1895 Win. A "simple" barrel switch and ready to go. :smiley:  It is sometimes called the Scoville-Hawk as well.
You\'re just jealous because the voices only talk to me.  :yes:

gitano

QuotePaul,
 
In case you didn't know I'm also a huge closet .308 case fan...grin...
 
Don't tell anyone...

I won't... ;)
 
There are a couple more. Without "outing" anyone, I'm pretty sure RBH is one too...
 
Steve,
 
I am aware of the "Hawk" line of cartridges. Good performers, all, or so I read.
 
As for the rim size issue, that's precisely why I used the .284 Win case. Head size is same as k-31 and Steyr, rim size (0.473") same as .308 Win, .30-06, etc.
 
By the way, there are 'scope mounts available for the k-31 that fit on the rear sight and require no permanent modifications. I have two of them. You do need either a LER (Long Eye Relief) or IER (Intermediate Eye Relief) 'scope for the "scout-type" mount.
 
As for switching bbls on a k-31, I have a few k-31s, so I can keep all but one in original, as-issued form. Switching back to as-issued would only require returning the original barrel to the receiver. If I wanted a "sporter" stock, (which I wouldn't), I wouldn't modify the milsurp stock, I'd just put a new "sporter" one on. Again with the mind that returning to as-issued would only require reinstalling the milsurp stock. My biggest "problem" with converting the k-31 to "sport" use is the genuinely ugly bolt handle. Tough to make that thing look 'svelt'. At least I haven't figured out how to yet.
 
QuoteBack to the point, I should just go with the 375 JDJ in a TC Encore, I suppose.

That's certainly "easy", but probably not as much "fun". ;)
 
Paul
Be nicer than necessary.

Steve D

That's certainly "easy", but probably not as much "fun". ;)
 
Paul[/quote]
 
I won't argue that.  I didn't modify the stock.  That was done before I got it.  It is rather handsome, but is obviously not a conventional stock.  I would love to find one of the scout scope mounts.  I tried to mount a side scope mount, but the one that was suggested put the scope on the right side of the barrel, which made aiming a real challenge.  I would be happy as could be with an LER scope.  
 
I figured that was the issue with rim sizes.  I only have one swiss, and I don't want to change it much.  I'ld love to get a 31.  Mine is an 11, which is OK, but the 31 is better.  I have three 98's waiting for work (and the $ to get it done).   I want one in 25-06, one in 280 Rem and the other is open to options.  I thought about just rechanbering to 8mm-06, or something with more teeth, like a 35 Whelan or even a Scoville.  That's down the road. :smiley:
You\'re just jealous because the voices only talk to me.  :yes:

gitano

I know of a couple of places selling k-31s with beech stocks for $130 before shipping. If I remember correctly, the walnut-stocked ones are $160 before S&H.
 
Paul
Be nicer than necessary.

Steve D

I'm gonna have to get hooked up with one of those.  :)
You\'re just jealous because the voices only talk to me.  :yes:

Steve D

I looked up those mounts for the k31.  Some of them specific ONLY for the K31.  I wonder if the others will work on th K11?  
 
Just want to let you know, after about 4 PM Central, I'll be out of touch for a week or so.  So, if I don't get back to you, that's why.
You\'re just jealous because the voices only talk to me.  :yes:

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