I am having a hard time trying to decide on the muzzle diameter for my .510" .50 Alaskan barrel. I am having one built on a Siamese Mauser (1.410" front ring) and had a .510" groove diameter with 1-in-18" twist cut on a 1.75" diameter x 25.5" blank. I also had it milled to a tapered scalloped octagon leaving the top three flats stopped 12" short of the breech providing enough metal for an integral rib that could sit proud of the top of the front ring and be wider that .5". I worked out the math and wrote a Windows program (fun for me! :-) )to help arrive at a workable configuration. At present the barrel has had the breech section milled to 1.360" D exposing a nice integral rib which is presently .740" (too) wide and milled flat on top.

I had Jim Wisner make me some small BRNO dovetail (~.625") QR lever rings for an integral dovetails on the rib as I want to use a Burris "Scout" type scope in the "forward of the receiver" position on this rifle, thereby leaving the receiver area open.

I intend to have the barrel tapered to a round muzzle section and was wondering what muzzle diameter would be correct for something of this size - I am leaning towards something about .815" D as I would like it on the heavy side - 9.5 to 10 lbs and that is one of the sizes that Wisner makes his European Front banded ramps sights in. These are offered for .745, .770, .790, .815 & .845 diameter barrels.

PS: I have been tempted many times to abandon the .50 Alaskan part of this project and use the components to build up a .500 Jeffery (or .500 AHR = non-rebated rim and 1 diameter neck version of the .500 Jeffery) instead, but twist is probably a bit slow for that cartridge.

Would love to hear comments!

Thanks - Jeff Pfeifer

I would get .790 or .815. That should provide enough weight to be keep the recoil manageable.

Ooohh, sounds nice. I'd agree with the previous post about somewhere around .80" would be right. I'm using a ruger #1 front barrel band for my jeffrey, and I believe its .825". I was considering going all the way up to .875", but I figured I'd rather add lead to the forearm then have such a fat barrel.

As far as going with a 500 Jeffrey or AHR, if you are using the Siamese, stick with the Alaskan. I'd still like to build a 50 Alaskan on a ss Marlin lever gun action for a short barreled camp gun. As far as the 1-18 twist, it should be plenty for the 530 gr and lighter bullets, the 1-15 or faster is really only needed for the 600 gr and up bullets. What you really need is a nice 450 gr bullet mold, if I ever build the 50 Alaskan, thats all I'll shoot out of it, 450's at 2000 fps, not too much recoil, and plenty of whump!

I cannot address the barrel diameter question, but in my Encore .50 AK, I have shot from 450 to 750 gr. bullets. The 450 Barnes originals are outstanding performers, as are the 570 gr. Woodleighs, but both of those bullets need 2000 fps to expand-not that you need much expansion at .50 caliber. The bullets that I think are going to work out best are Beartooth's hard cast LBT LFNGC bullets at 475 grains. Expansion is not needed with the wide meplat, and even from my 12 inch barrel I should be able to get at least 1700 fps. Likewise, I have a 1895GS on order and it will got to Wild West Guns for rechambering/reworking/reboring to .50 AK just as soon as it comes in. In the lever, the 475 gr. bullet will be a natural. In your Mauser, you might want to give the 570 gr. X bullet a try. It will expand down to 1600 fps and it's shape will really help it's down range performance. Good luck.

All this talk of .510 bores has got me dreaming again. I am thinking of a 510 Nyati instead of the 585. I'm sure someone has done it before, probably someone named Wells.

The fellows are steering you straight on the muzzle diameter. A bare minimum flyweight would be 0.760" at the muzzle. Around 0.800" would be ideal for the muzzle of a sporty .510 bore. I have a 510 JAB/500 A-Square on a BRNO ZKK 602 that is 0.875" at the muzzle of its 23" barrel. My Ruger No. 1 with a 27" barrel has a muzzle diameter of 1.000", also a 510 JAB.

That said, I am now dreaming of a sporty 0.760" flyweight 510 Nyati...

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Good huntin' and shootin',
RAB

Big Bore,

Who did your Encore? Would you mind E-mailing me with specific load data?

Mr. Berry,

I would like any and all specific numbers relating to the .50 JAB's throat and OAL when loaded with various bullets intended for the BMG.

Thanks,

DOC

Nice to hear someone else calls the .50 Alaskan by ".50 AK"...I thought I was the only one that got tired of typing Alaskan!

My thoughts of jumping ship to the .500 Jeffery would include switching actions as well as that Siamese action is just too short for the jumbo Jeffery case. One really has to hold one of these .500 Jeffery or AHR in one's hand to appreciate the size of it! I've already sunk the $180 into the .50 (and .450 AK) die sets so I'll probably go forward with this at this point. Initially I ordered a 1-in-16" twist barrel but talked with the barrel maker the morning before he was going to pull the rifling and he said that the 1-in-18 should be more than adequate to stabilize the heavies and should yield better accuracy with a wider range of bullets. So the decision was made then to go to the 1-in-18" twist. I have two 50 cal bullets at the moment molds - the standard RCBS 50-450 FNPB and a custom LBT 510-330 FNPB. Also there is a used RCBS 50-545 FNPB mold at the gunshop that I'm contemplating picking up but not sure if it throws too wide of a diameter bullet to be of use, as it is being sold as a .50-70 mold which usually run .515" or so. With a Siamese Mauser the advantages of CRF, higher pressure handling abilities and the ability to use pointed bullets for a better BC all add up. This is why I had ABW (Kodiak Bullets) make me some "more pointy" bullets specifically for better feeding and BC in this rifle. These are designed with a .050" copper jacket, tapered at the nose and are good from 1400 to 2300 fps I believe...have it written down somewhere. Mike Murray said that the .50's like these create huge wound channels in the big bruins. If I remember correctly, he has taken somewhere on the order of 75 bears in his 30 or so years up in AK...so he knows what works and what doesn't work!

The gun magazine writer Brian Pearce also lives out here in the Boise ID area and is having a .50 AK built on an 1895 Marlin. We have talked several times about these. Apparently he is working with a group of folks to standardize this cartridge thus the recent announcement by Starline ( http://www.starlinebrass.com/ ) to produce .50 Alaskan brass???...I don't know for sure but speculate that they may have had something to do with this. BTW this brass is heavier webbed specifically to handle the higher pressure that the Siamese Mausers are capable of working safely with.

It looks like I'm on track with the .815" and .790" front sight selections then. I think I will probably order the .815" ramp sight shortly then as that works better with the way that my barrel is tapered. My friend has an original Shuler in 11.2x72 with a scalloped octagon integral full-rib roll-engraved barrel, that I was able to measure and reverse engineer before spec'ing this barrel. It turns out that the 11.2 Shuler barrel was built with a 1.500" barrel blank as that is what the measurements back out to be!...The critical dimension being the breech end of the rib, width and height determining the blank diameter. The critical dimension that I wanted to control was where to stop the mill such that I could place the "scallop" correctly in front of the tapered round section at the breech end of the barrel...It came out beautifully! ...Math and geometry ROCK!

In the .50 AK lever guns I've read and heard one has to be watchful of OAL due the the feed gate limitations on the 1895 and M71 rifles. I'll see if I can load a 570 grn bullet in the Siamese wrt magazine limits - I believe I can as I think Bill Thompkins had mentioned that they were shooting 600 grainers in some .50 AK Siamese conversions that Fred Wells had built years ago.

I have a picture of this barrel around somewhere in it's initial form. I'll see if I can get a current picture of it posted. May take a while though.

Regards,
Jeff Pfeifer

DOC,
When we speak of cartridge designations we must be accurate. I just realized, from reading a book by Ed Matunas, that when specifying the cartridge name it is not proper to include the decimal. Many cartridge names do not refer to the actual bore diameter. Some refer to the lands, some to the grooves, and some to neither. Include the decimal only when specifying an actual bullet diameter or a bore diameter. Even though a cartridge name may match the actual bullet diameter, we still should properly leave off the decimal.

Thus, it is the "375 H&H" and not the ".375 H&H." Or it is the "577 Tyrannosaur" and not the ".577 Tyrannosaur."

So you want to know about the 510 JAB?
Well, the 510 JAB is simply the 500 A-Square with a slightly different shoulder angle (though the shoulder is near negligible), a slightly different overall length (within 0.05"), and a variable throat.

The standard 500 A-Square has a throat of 0.400", as best I can tell.

My 510 JAB Ruger No. 1 has a throat of 0.588". This allows the 750 grain Hornady A-Max to be chambered with an overall length of 4.76".

My 510 JAB BRNO has a throat of only 0.300". This allows the milsurp 700 grain AP bullet to chamber when loaded single shot fashion and crimped on the cannelure. It is a very accurate bullet.

The Barnes XLC 570 grain bullet loaded in the 510 JAB has a COL of 3.60". There is room to spare in the magazine of the BRNO, or the CZ which is of identical magazine length.

Actually the 500 A-Square with a standard throat will easily handle most of the milsurp bullets. It won't handle the target bullets like the 750 to 850 grain Hornady, Barnes, and GS Custom HV. Some of these bullets are long and pointy and have secant ogives that just reguire that extra 3/16" freebore to seat them out enough to make use of the relatively limited case capacity of the 510 JAB.

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Good huntin' and shootin',
RAB

I have some additional info on the 500 Alaskan lever rifles. The one being built for Brian Pearce is being done by Reggie Nonneman of Maryville, Mo. (an old hunting partner of mine. He just received the Starline brass a couple of days ago and is testing now. He says he gets 1900-2000fps with a 525 grain bullet.

jstevens,
Curious as to which bullet they are using and whether they are able to get a bullet of that weight to feed through the loading gate easily...or were these loaded in some other manner? The Win M71 as I'm sure you've read has a OAL limitation due to the feed gate. This gun is an 1895 Marlin from what I remember in my talks with Brian, isn't it?

JP

I'll find out what bullet he is using in the 50 Alaskan leverguns. Reg is in Wyoming now shooting some big bores with John Linebaugh.They will give the new rifles a pretty good workout. When he gets back in Missouri, I'll give a report.

I talked to Reg last night about his 50 Alaskan lever rifles. The only bullet he's working with now is a 525 gr. cast bullet with a gas check. He has these going 2000 and says it will go faster if you can stay behind a 6 3/4 lb rifle with these loads. When I asked him about feeding the big rounds easily through the loading port, he said it was a real bitch making this happen and took a year to figure out how, but it works great now.

jstevens,
Thanks for the info. I'd love to know what bullet they've settled(?) on if that info is available...a custom or ???? Not to many gas-checked 50 cal bullet molds around! Sounds like I need to give ol' Brian a call again soon.

JP

Another thought I've had banging around in the back of my head was a 475 Alaskan! Way back when, I had my gunsmith make up a set of stepped expanders and this was an obvious step to include on the way up to .510" :-)

Has any one here ever heard of or built such a beast? With the 475 Linebaugh around some of the bullets should work for this too.

What would it look like though, as the .50 AK has no shoulder but the 450 AK does...so what is the criteria for a shoulder...enough case diameter beyond the neck diameter to form a decent shoulder? It's obviously a rimmed case so one doesn't really need it. I guess this is the same process John Linebaugh went through with his 500 Linebaugh and then his 475 Linebaugh...The old KO vs penetration tradeoff.

Jeff Pfeifer

Jeff, those 525gr cast bullets are from Cast Performance in Wyoming. I have a bunch here that I just got from Kelly about a month ago.They will be a "on the shelf item according to him."

I've had zero problems with feeding in my McGowen built 71. Hogdon Benchmark is the powder of choice so far for me. And at 2000+ fps, they rock.

Al,
Thanks for the info on the bullets. What kind of nose do these have - obviously an FN of some sort but like a WFN, LFN or something with more of an ogive? Does Cast Performance in Wyoming have a website with picts?

I haven't played with any Benchmark powder yet either, guess I will have to investigate when mine gets to a shootable stage! :-) I was at the shop yesterday going through Siamese Mauser parts and my gunsmith threatened me with..."I guess I should get to working on that soon shouldn't I?"...I love him for that remark! :-)

Jeff Pfeifer

Jeff, the bullets are a LFN gas check. I didn't see them listed on their site last time I was there but they have them. I'll see if I can scan one for you.

http://www.castperformance.com/

Thanks Al for the email with the 525 & 450 grn LBT - nice sharp pict!

JP