Steyr Throat Slug Pic - Mold Design

[MDF99]

http://www.castboolits.gunloads.com/picture.php?albumid=251&pictureid=4106

Here's a pic of the throat slug from my Steyr SBS rifle in 376 Steyr (0.375" caliber). As you can see, there's a continuous taper right into the rifling. The diameter above the case is 0.382", a quarter inch up at first line it's 0.378", another quarter inch further it's 0.377" and up in the rifling the bore/groove is around 0.375" and 0.367". The top black line is maximum C.O.A.L. of 3.110" to fit in magazine.

I'd like a gas checked hunting bullet of around 300-320 grains but am unsure of the best way to achieve this. Would I be better off designing a matching taper bore rider style bullet or going with a straight LFN around 0.378" or 0.379" that's long enough to give the weight I want and engrave the nose?

I would prefer to keep the gas check mostly inside the 0.36" length case neck.

Thanks for suggestions.

[geargnasher]

Can't see nuthin', no pic.

Gear

[MDF99]

attempt to show pic:

http://castboolits.gunloads.com/imagehosting/thum_5354e2b8bd6bd19f.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1565)

[MDF99]

another attempt to show pic:

[HORNET]

MDF99, You might want to read on this thread: http://castboolits.gunloads.com/showthread.php?t=122215 . If you PM 123.DieselBenz and ask real nice, he might be willing to send you a few of each to play with. Good luck with that thumper.

[Tom Myers]

Here's a pic of the throat slug from my Steyr SBS rifle in 376 Steyr (0.375" caliber). As you can see, there's a continuous taper right into the rifling. The diameter above the case is 0.382", a quarter inch up at first line it's 0.378", another quarter inch further it's 0.377" and up in the rifling the bore/groove is around 0.375" and 0.367". The top black line is maximum C.O.A.L. of 3.110" to fit in magazine.

I'd like a gas checked hunting bullet of around 300-320 grains but am unsure of the best way to achieve this. Would I be better off designing a matching taper bore rider style bullet or going with a straight LFN around 0.378" or 0.379" that's long enough to give the weight I want and engrave the nose?

I would prefer to keep the gas check mostly inside the 0.36" length case neck.

Thanks for suggestions.

This is something I worked up that maybe you can use.
The dimensions are all from the European C.I.P. Standard specs for the Styer Cartridge.

These links are to full size Chamber/Cartridge/Bullet superimposed drawings.

100% Throat Image (http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/376_Steyr_C.I.P_Standard_A_TMT_Design_Chamber-100%25.Jpg) 50% Chamber Image (http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/376_Steyr_C.I.P_Standard~A_TMT_Design_50%25.Jpg) 80%Throat Image (http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/376_Steyr_C.I.P_Standard~A_TMT_Design_.Jpg) 100% Chamber Image (http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/376_Steyr_C.I.P_Standard~A_TMT_Design_Full.Jpg)

Hope this helps.

http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/A_TMT_Design_.376_Styer_.Jpg


http://www.tmtpages.com/LinkSkyImages/forum_images/376%20Styer/A_TMT_Design_.376_Styer_301_gr_Sketch.Jpg

[Wayne Smith]

Tom, what's involved in translating those figures into Dan's (Mountain Molds) software? Looks to me like MDF could do it easily but I honestly don't know.

[MDF99]

Thanks Tom! I forwarded the drawing to Accurate Molds. Please let me know where to send the fifth of your preferred adult beverage!

[Tom Myers]

Tom, what's involved in translating those figures into Dan's (Mountain Molds) software? Looks to me like MDF could do it easily but I honestly don't know.

Wayne,

I tried the dimensions on the Mountain Molds design site but, in order for the design to work, the front band needs to be smaller than the main body bands with a grease groove in the front and I couldn't seem to manipulate the format to reproduce the configuration.

[Tom Myers]

Thanks Tom! I forwarded the drawing to Accurate Molds. Please let me know where to send the fifth of your preferred adult beverage!

You're welcome. Hope it works for you.

Thanks for the offer but I gave up the adult beverages about 40 years ago.

I already had the drawings on hand so there was no real effort but, if you feel it is appropriate, make a donation to the Cast Boolits website. If it were not for this site, I wouldn't have the data and knowledge to produce the software that made the drawings.

[turbo1889]

Here is my thoughts:

http://farm7.static.flickr.com/6015/5978941451_6cf4bd919d_b.jpg

The one on the right hand side is what you asked about (conventional lube groove, gas checked design to be cast and then run through a lubra-sizer to size, lube, and crimp the gas check on.

I would be tempted to go with a “tumble lube and shoot as cast” plain base design with a stop ring like on the left hand side.

In either case I would spec. the main body diameter to be fired case inside neck diameter -0.001” and put a taper on the nose that fit the throat that would give a “hand in glove” fit to the throat and put a row of DD engraving rings (like some of the old NEI molds that Walt made had) on the nose that were a couple thousandths of an inch over the minor bore diameter of the gun to just slightly engrave in the rifling.

That’s my$0.02 take it with a grain of salt ~ YMMV.

[MDF99]

Tom's design above is now listed in the Accurate Molds catalog #38-305S:

http://accuratemolds.com/bullet_detail.php?bullet=38-305S-D.png

The only change was to shorten the gas check shank and widen the bands a little to improve mold fill out.

I'll update this with a range report in a few weeks.

I've also contacted Veral @ LBT to make a mold to fit this throat slug and will provide a range report and photos of his product as well.

Turbo, your bullet designs are great, I especially like the minimal work, shoot as cast, tumble lube design. Makes sense to me!! Have you had any molds made for yourself in this style?

Thanks to all. I made a 20 dollar donation to the site since Tom is officially off the sauce!

[turbo1889]

. . . Turbo, your bullet designs are great, I especially like the minimal work, shoot as cast, tumble lube design. Makes sense to me!! Have you had any molds made for yourself in this style? . . .

Yes & No.

1. ~ I do have quite a few molds that I tumble lube only and shoot as cast with no sizing.

2. ~ I do have a custom cut stop-ring/healed boolit design for military throat 8x57 Mauser rifles that is very similar to what I drew up only without the engraving rings on the nose. The nose of the boolit that is outside the case neck being larger diameter then the body bands that are inside the case neck to fully fill up the cave cavern like throats some of those rifles have. It works exceptionally well in those guns that have trouble with most other conventional cast boolit designs.

3. ~ I do have several molds that feature nose engraving DD rings. One is an original Walt NEI mold (not to be confused with a post Walt NEI mold) as well as three designs from Accurate Molds. The AM#31-180B and AM#31-216T are both rifle boolit designs cut for me by Tom that are specifically designed with micro groove rings on the nose that engrave in the rifling. In addition the AM#36-210C when used in my single shot break action NEF carbine rifle engraves the first couple micro-bands on the tip of the nose in the rifling when I load them in the 357-max cartridge (I had the chamber re-cut from the original 357-mag chambering). The AM#31-180B and AM36-210C are proven designs at this point providing exceptional accuracy. With the 31-180B I can consistently hit a paper plate target at 300 yards range out of a Mosin-Nagant with a load that is pushing 1,800-fps muzzle velocity and printing groups in the 3”-4” range out of my SKS at 100 yards and the 36-210C is providing the same level of accuracy out of my 357-max carbine as the SKS. The jury is still out on the 31-216T since I haven’t had a chance to do a whole lot of shooting with it yet but initial results out of the 30-06 at 50-100 yards are promising; I still need to push the velocity up further into the 1,800-2,200 range and take it out further to the 300 yard target line as well as load it up in a few other 30 caliber cartridges other then the 30-06 both above and below in power (I also need to cast some up and send them to Gear as I promised him instead of shooting them all up myself).

Basically, when I saw that chamber cast of yours it looked like the perfect gun for throwing all three of those concepts together in the same boolit. I do not, however, myself have a single boolit that combines all three of those concepts – yet. :) :) :)