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Posted - 04/04/2007 : 2:19:22 PM
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My two 9,3x57s:

M146 c.1939;
6-groove barrel.
Lands .354"
Grooves .369"
Twist 15"

M46 1942;
4-groove barrel.
Lands .351"
Grooves .3675"
Twist 14"

Could the dimensions of my 146 be the reason why it demonstrates no pressure signs with seemingly-ridiculous charges that "should be" excessive? I wonder. Certainly bullets of .365/.366 are undersize.

Now, why did Dieter Sturm cite these rifles as possessing 1/16" twists?

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For God so loved the world that he gave his only Son, that whosoever believes in him should not perish but have everlasting life. Jn 3:16 Verbum Domini Manet in Aeternum.

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Edited by - LeeSpeed on 04/04/2007 9:57:01 PM

Smokepole50
Gunboards Premium Member



USA
151 Posts
Posted - 04/04/2007 : 6:35:55 PM
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Lee.......Which one of your rifles is more accurate, the M46 or the M146? My 1937 M146 also has 6 grooves and it appears to be very accurate with iron sights.

I too have filled the cases just short of compressed loads with several powders and 3 types of bullets and have yet to crack a case or iron out a primer.

I guess I should slug my bore also. Did you push some lead down you bore or just measure some of your fired PP bullets you recovered?

Regards, Smokepole50


LeeSpeed
Gunboards.Com Gold Star Member



USA
1024 Posts
Posted - 04/04/2007 : 6:49:06 PM
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Smokepole:

Somebody on the forum here recommended pointed fishing weights for slugging the bores. I have always used roundballs in the past but I will never use them again! The fishing weights are the Cat's Meow! First I lightly oiled the bore with Tri-Flow and I used a 1/4" brass rod to run them thru, driven with a brass hammer. It was so much easier than my old method.

If I get a cast bullet mold for these rifles I will have to size much differently between the rifles.

I really can't say about the accuracy, as my 146 is scoped and the 46 has the Jaktdiopter rear sight.

Really, I think a big warning is in order:

Assuming it is common for some rifles to be bored substantially differently than others, the old adage about not shooting max loads of one rifle in other rifles shooting be strictly adhered to.

I really have to wonder if shooting .366 or .365 bullets in that .369 barrel is giving me a pressure safety margin that wouldn't be there in a .366 rifle.

Each rifle is a law unto its own and loads should be tailored for the rifles.

By the way, my PP bullets go .366 while the Norma Vulkan I tested went .365.

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For God so loved the world that he gave his only Son, that whosoever believes in him should not perish but have everlasting life. Jn 3:16 Verbum Domini Manet in Aeternum.


Baribal
Gunboards Member



Canada
93 Posts
Posted - 04/04/2007 : 8:25:31 PM
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Hi LeeSpeed,

If you don't have it, CIP specifies for 9.3 cal.;

Barrel;
F = 9.00 (0.354)
Z = 9.28 (0.365)

Grooves;
b = 4.60 (grooves width) (0.181)
N = 4 (n grooves)
Q = 66.32 mm sq.

Leade;
G1 = 9.35 (free bore dia) (0.368)
G = 28 (lenght of leade)(1.102)

These are MINIMUM values

I ran some loads in Quickload with .369 and .366 grovve dia...
The loads are using 44 grains of IMR 3031.. I used the default cartridge lenght (81.99 mm) and 270 gr bullet.

Test 1 - .366 Dia
P = 36 610 PSI (2525 bar) (CIP's max 2600)
B.V. = 2165 fps

Test 2 - .369 Dia
P = 35 467 PSI (2445 bar) (CIP's max 2600)
B.V. = 2155 fps

I can send you these PDF files and/or can run one or two specific loads in it, if you want...


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Coagula / Solve


LeeSpeed
Gunboards.Com Gold Star Member



USA
1024 Posts
Posted - 04/04/2007 : 9:53:36 PM
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quote:
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Originally posted by Baribal
I ran some loads in Quickload with .369 and .366 grovve dia...
The loads are using 44 grains of IMR 3031.. I used the default cartridge lenght (81.99 mm) and 270 gr bullet.

Test 1 - .366 Dia
P = 36 610 PSI (2525 bar) (CIP's max 2600)
B.V. = 2165 fps

Test 2 - .369 Dia
P = 35 467 PSI (2445 bar) (CIP's max 2600)
B.V. = 2155 fps

I can send you these PDF files and/or can run one or two specific loads in it, if you want...


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Great stuff Baribal.

What bullet diameter do these tests assume? Wouldn't different bullet diameters and bearing surfaces {length} impact the pressures significantly?

I am really wondering about the varying pressures that may exist in the assortment of 9.3x57 rifles that are floating around.

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For God so loved the world that he gave his only Son, that whosoever believes in him should not perish but have everlasting life. Jn 3:16 Verbum Domini Manet in Aeternum.


Baribal
Gunboards Member



Canada
93 Posts
Posted - 04/04/2007 : 10:21:05 PM
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LeeSpeed,

These loads were assumed with 270 gr, Speer .366 Dia. There are plenty of bullet specs availlable in the Quickload program, and one can also incorporate his own datas for custom bullets...

And, Yes, each bullet have it's own friction coefficient.... Wich is took in account for the calculation... This program gives me very close datas from what I get with my chrony...
It also gave me some hints on some funny things that happened with some loads... Now these loads are fixed and aligned with what I got as a result with this program....

Give me you specs (load, bullet, brass capacities in gr of H2O, OAL)

and I can run it through the beast... I'm quite confident it will give something close to what you got.
The only times the load does not fit (lower velocity for a given load) the velocities are when the caliber uses a very long throat (leade), dropping the pressure a lot... I see this very often with the 8X57 Is....

Here what the document looks like

Download Attachment:
48.91 KB


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Coagula / Solve


Ordtech
Gunboards Premium Member



USA
150 Posts
Posted - 04/05/2007 : 12:04:13 AM
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Informative data again, gentleman, thank you.
I've yet to measure leade on my 1930 M46 but here's the sinker test:
lands .3565"
grooves .369

I used an oval sinker, hardwood dowel, small mallet, and Tetra gun oil. It was soooo easy. I had to tap the sinker to bump it up as someone suggested in another thread and just punched a well oiled patch on an 8mm jag down the bore to wet it.
Try it Smokepole, the sinker slid down soooooo easy and I don't have the shiniest bore around either.

I won't be doing any shooting until May; TDY and too much "necessary" stuff to do. I should have a new chronograph and Leespeeds favorite PPs by May, too.
 
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