I have an Idea. I would like to neck up a 300 win mag to 9.3 Im sure someone has thought of it before...but I cant find any data so I'll call it mine till then. I digress.

Well I dont really know where to start as far as design and such...for reamers or dies...or anything. I have named this cartridge the .366 Dreadnought. My goal is to push 286 to about 2700 or more. I want to keep what little bit of taper the 300 case has..and the existing shoulder angle.

Thanks ahead of time for any help...

Djinn

DDjinn....the 7mm Rem Mag, the .300 Win Mag, the .338 Win Mag and the .458 Win Mag are basically the same case, with the same length as each other (except the .300 Win Mag has a little shorter neck) and this basic case (either the .338 necked up or the .458 necked down) has been necked to .375 (9.53) and called the .375 Taylor by the same fellow who developed the .416 Taylor it's much better known big brother. The .375 version basically duplicates the performance of the .375 H&H which is, what I assume, you are reaching for. It's already been done...if you want a rifle chambered for it, check with Chris at Pac-Nor as he has reamers.

why not try necking the 284 winchester case up to 9.3mm? that'd probably be a hot number...

Djinn,
Last year I built a .375 Taylor (.375/.338) and love it. It delivers .375 H&H ballistics with a little less powder. Incidentally, it has a Pac Nor barrel and is extremely accurate.

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Phil- Life Member NRA & SCI

Djinn,

The 300 Winchester case is not of the same family as the 264 Winchester, the 7.21mm Remington, the 338 Winchester, and the 458 Winchester. The 300 Winchester is 0.120 inches longer and holds more powder than any of the above mentioned cases.

The first thing that you need to do is come up with a legitimate case design that a reamer maker and a die maker can use for their work.
- If you decide that you want to do this you are probably looking at somewhere from $150 to $300 for a reamer and gauges.
- Next you will need a case forming die set - approximatley $125
- In addition to the case forming die set you will need a full length and seater die - approximately $150.
- I would also recommend that you purchase a neck sizer die - approximately $50 to $75.

I would recommend that you design the case so that it has a minimum of 0.006"/inch of body taper, a 30 degree shoulder, and a neck length of .330" to .360".

- Then you will need to purchase a new barrel - approximately $150 to $300.
- The barrel will need to be chambered - approximately $140 to $200.

- I can suggest that you call Dave Manson of Manson Precision Reamers for a reamer design (810) 953-0732.
- I can suggest that you call Mark Penrod of Penrod Precision for barrel purchase and chambering (219) 982-8385.
I can suggest that you call Stan Mayle of RCBS about forming, sizing, and seating dies (800) 533-5000.

Good Hunting !

Well you could just go with the 9.3x64 and get 2650 with the 286 gr. bullet and not have to worry with a wildcat....

Otherwise, you had best use the longer necked 338 Win case necked up to 9.3, that will get you 2650 to 2700 pretty easy and the longer neck will allow the use of 300 and 320 gr. bullets..My Lothar Walther barrels shoot ( 9.3x62 and 9.3x64 ) all bullet weights (250 to 320 gr.) into 1" or less at 100...I really like that!!

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Haven't seen the "Handloaders Digest" in a new version in a couple years but the last one (I believe) published has an article on wildcatting the 9.3 bore. It has specifically the cartridge you mention, a .338 necked up to .366 or 9.3mm. Matches the 9.3x64 Brenneke in performance.

redleg

Djinn. I kind of go along with D. B. Bill on the .375 Taylor, AKA .375x338 Mag. Wonderfully accurate, duplicates the .375 H&H powerwise, recoil appears to be about one third less than the H&H round in a much lighter rifle. (My .375 Taylor is built on a Ruger old version Model 77 with a Ramline stock. Weight, 7.5 pounds with scope, sling and fully loaded. My .375 H&H Ruger #1 weighs about two pounds more and kicks harder.) Wonderful elk gun. Probably would be a much less costly project as well. RCBS already has the dies. Loading data is available. The only thing my rifle does not have yet is a set of back up iron sights.
FWIW. Velocity extreme spread with my load with a 300 gr. Hornady RN was 6 FPS. With the Hornady 270 gr. spire point, 9 FPS. Three shots with each bullet at the same target grouped into two inched with the 270 gr. bullet a bit higher than the 300 gr. bullets.
Just my not too humble opinion, but that is one wildcat round I really believe should be legitimized by the ammo and gun companies.
FWIW, I find .458 Win. Mag. brass the easiest way to make brass. Just one pass through the full length sizer. You can fireform with a full load. Those of you who have one know where I'm coming from.
Paul B.

Djinn! If you find a cooperative riflesmith that has both a 300Win and any of the 9,3mm reamers he can make your chamber without you haveing to pay yourself sic on a completely new reamer. First he has to bush the 300Win reamer for 9,3mm. Then make the bodypart of the chamber with it. No neck or throat is cut since they are just .30 cal on this reamer. With a 9,3mm the chamber gets its neck and throat. Any of the 9,3 should do since the neck of the 300 is pretty short, shorter than any of the 9,3 (I think, dont have my cases at hand just now). Just do it, its pure fun. Just did it myself o) AKI

Ray,

Please explain what advantage the .3302" neck of the 338 Winchester would have over the .330" to .360" neck recommended above?

Also, please explain what advantage the .3302" neck of the 338 Winchester would have over the .264" neck of the 300 Winchester for the firing of 300 or 320 grain .366" diameter bullets?

Good Hunting !

[This message has been edited by Pumba (edited 07-25-2001).]

Djinn,

Redleg155 is correct. Norman G. Tonn has already wildcatted the .366 bullet and .338 Win Mag brass, and was quite happy with the combination. He was also happy with the 250 grain .366 Barnes-X and its effect on elk.

I don't remember which issue of Handloader's Digest it was, but if you can find that article, it should detail the reamer and die maker he used.

Interestingly, he also created a rimmed .366 on the improved .348 Winchester brass.

Djinn,
You will reach 2,800 fps IMHO. We did this in .375 caliber 10 years back and got 2,800+ fps with 300 grainers. The short neck did not present a problem and the forward set shoulder offers extra case capacity.
Go for it!

Nickudu.....I've gotten confused. What case did you use to get 2800 fps with a 300gr bullet in .375? What length barrel etc?