Gentlemen, the "Minimum Shoulder Requirement for Big Bores" is an excellent thread, so good that I printed all of it for my files.

Now, as the thread is getting rather lengthly, I started anew with 450 question:

Let's consider an "Ultimate 450". My first thinking is similar to the 450 Dakota, but do we need that much case capacity? And length? Consider the 460 Short A-Square, is it approaching ideal in case capacity vs bore size?

My thought is to use the 338 Lapua case, properly necked and shouldered to a 25 degree angle. And how about body taper: Need enough for good feeding, but not too much to diminish the difference of shoulder vs neck diameter. Case size dictates the use of a CZ550, Magnum Mauser, or similar.

Your comments, please. I will then take all consideratons, make a drawing, and have Dave Kiff grind a reamer.

PS, some shoulder angles from my reamer drawings:

416 Howell 25 degrees .515 shoulder .444 neck

404 Jeff 8 degrees 32 min 23 sec
.531 shoulder .456 neck

458 Ultra 30 degrees
.526 shoulder .490 neck

As I will be away from the computer Thursday Noon until Sunday Afternon, I look forward to your comments

Thanks!

John Ricks

I know John Lazzeroni was thinking about mecking his .30 Patriot up to .458 (case head is 0.580") but decided there wouldn't be enough of a shoulder for safety....the .416 on the short case is called the Maverick and I understand it has become very popular.

What is your max OAL on the proposed cartridge? I suggest 3.650" OAL so that it will fit in a M70.

I agree with your idea that the 450 Dakota is too big. Other than a CZ550, the actions that hold it are just too expensive.

By the way, isn't the 338 Lapua just .338 x 416 rigby with a different shoulder?

I still maintain that the "ultimate" 450 should be built around the 404 case. I would ask Andy to supply the dimensions of his 458/404imp and consider it done! A 25* shoulder on the 460 G&A will fix most if not all it's troubles, and with proper gunsmithing a M70 action can be used.
The 450 Dakota, as is, would/is my next choice. The case is not too big and the performance is anything you want it to be. I personally prefer a large action for this type rifle, they fit the part much better and add some weight, which is a comfort!

[QUOTE]Originally posted by John Ricks:
Hi John,
What about something along the line of an improved 338 Ultra mag necked up to .458. It should have enolugh case capacity to deliver the magic 2400 and still work in a 375 length action. I don't have a brass on hand to make sure that the case would produce enough shoulder. When I get back home I'll take a look at it. 470 Mbogo

John Ricks,
GREAT IDEA. The 338 Lapua is a great idea as a basis for the 450. The 338 Lapua, as you know, is a shortened 416 Rigby with a different shoulder, and the best quality Lapua head and wall construction.

To make it more universal in appeal and to allow a partial match of the barrel engraving to the head stamp of the great brass already available, you could call it the 450/338 Lapua John Ricks, or 458/338 Lapua John Ricks, or 460/338 Lapua Ricks, 450/338 Lapua Improved ala Ricks, etc.

This could be shortened in speaking/reference to:

450 JR
458 LJR
460 LR
450 LIAR etc.

Seriously, a great idea. Maybe with the proper case capacity RL-15 would be the perfect powder. Sniper brass and sniper powder in a "DGR" would have some merit for one shot kills on any critter imaginable.

------------------
RAB

/

John,

That is an excellent idea. I would recommend the Lapua shortened to 2.62" leave the shoulder were it is, but blow out the case to 0.565" @ the shoulder and use a 45 degree shoulder angle. I have a sketch drawn up, but alas I am too ingnorant to figure out how to paste it onto this post.

The above mentioned design should let you use a standard M70 (3.6") and get you the preferred 2400fps with a 500 grain pill.

If you would like to see the sketch let me know and I will e-mail it to you. I am done posting on this sight do to some flaming I have gotten on a long range shooting thread that has ticked me off.

Todd E

/

Todd-
Interesting idea but that 45* shoulder is something I'd avoid, just too steep and chances of bad feeding come into play.
Please re-consider your leave of this site. I know all about flaming, just check out the thread on the African forum that is addressed to me!
This is a great site and probably has the most knowledgeable group of posters anywhere on the net. Stick around and enjoy the fun!

Alf,

Some of these folks live for this stuff! Does it really matter whether one uses a belted basic case, 404 case, 416 case or belted 416 case, with whatever dimensions, just to push the same 500 gr bullet 2300-2400 fps? Of course not, but hey, we will not be deterred!

Alf,
Thanks for the interesting photos and information. Ditto Paul H, but there is a mystique to the Lapua Brass. It is of superb quality regarding strength and uniformity.

Todd E,
Don't go! Just don't waste your time responding to BS, from those who have had their panties twisted. Let it roll off your back. I am still here! They haven't banished me yet.

Back to the 450 Ricks, anyone?

------------------
RAB

I agree with John S on the 450/404 or 450 Ultra and for a couple of reasons.

Firstly as he has already said, they will go on an M70 or Rem 700 and so are easy to do.

Secondly, I don't think the 338 Lapua case will be much bigger than the Ultra case, remembering that it is a shortened 416 Rigby. Brass will also add to the difficulty.

Thirdly, unless you are prepared to have a KDF type brake or an extremely heavy rifle, a 500 grainer at about 2300 to 2400 is the end of the road for recoil, unless you have the gun as a stunt gun or similar and the 450 Ultra will have no problem getting that velocity.

However, to work in the Model 70 3.6" magazine the case needs to be shortened to 2.8" if bullets such as the Hornady are to be seated to the cannelure. That would be simple as just necking up 375 Ultras would shorten the case back to that length.

The only disadvantage I can see in a 450 Ultra as compared to a 458 Lott, is for very reduced loads, as the 450 Ultra being rimless and witha very small shoulder would increase its headpsace with each shot.

Mike

[This message has been edited by Mike375 (edited 10-27-2001).]

OK I'll stay I have cooled off.

John S,

The reason I recommended the 45 degree shoulder was to increase extrusion i.e. striker blow resistance. The 416 Rigby utilizes the 45 degree shoulder and at least with my rifle I have never had any feeding issues.

Actually from an accuracy standpoint I believe (this is just my opinion) that a
25 - 30 degree shoulder angle provides a better locating cone than the steeper angles while providing, with the Rigby size case anyway, adequate if not optimum striker resistance.

That said I still stand by my original recommendation of a 45 degree shoulder angle. I base this off of my personal experience with the 416 Rigby's feeding and the fact that this is a DGR cartridge and therefore, reliability not ultimate accuracy is of paramount importance.

Todd E

From my gunsmith's, mouth I have news that Powell River Laboratories (Oak Ridge, Tennessee) is planning to bring out a whole new line of cartridges based on the 338 Lapua. Up to and including a .458 bore. I don't know how small a bore size they will stoop to but there is yet another proprietary line of cartridges on the horizon.

As an aside, this will probably be in conjunction with some tunsten cored softpoint bullets. Rumor is that Federal might be interested in loading the tungsten bullets in their premium line. $200 dollars per box of 20??? The component bullets are not available to the public yet, but they are getting close, maybe to be sold through Midsouth Shooter's Supply, Clarksville, TN.

As to the shoulder angle of the 450 Ricks: one must balance this with the amount of body taper.

The Rigby with its 45 degree shoulder angle does work great, but it has quite a bit of body taper to the case. I think a balance can be made to maintain maximum shoulder diameter and a less than Rigby case taper with a less than 45 degree shoulder angle, for slick feeding, and no duds. This is a DGR concept after all.

I will have to go to the drawing board for this, or John Ricks will.

------------------
RAB

RAB,

That new line of proprietary cartridges sounds interesting indeed. Regarding the drawing board. I drew up a case like this a while back, but am not sure how to post the sketch. If someone would tell me how I would paste it here for conceptual reasons if nothing else.

Todd E

Todd E,
I am computer illiterate too, or at least pretend to be to get out of work, and let some one else do it. If you can scan it into a file and post it to a free site like www.tripod.com that might work. Then you could simply type in the link here and we could click on it. Surely one of the gentle men here who knows how to do it will offer to help.

I am at a hospital computer in Connecticut and can't be goofing off too long with their equipment. If I were at home in Kentucky I could get my wife to do it.

------------------
RAB

I agree the 404 case improved is the best route, specifically the 460 G & A....which I consider the best of design for 458 cal...I don't have the specs but I think the necking up the 338 ultra mag would be the same cartridge as its on the improved 404 case is it not (one of the new rounds is)

The 416 case being considerable fatter thus tougher to make feed and you will normally lose a round over the 404 case..

All that said, I think its just simplier to go with the 458 Lott, unless your a no belter...and that too may change with the new brass out there based on the 404 case.

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

Ray and .450 on the .404 case proponents,

After reading this thread and the privious one, I have been doing some research in the books I have available, and my files. My conclusion is the .404 Jeffery case will not provide enough shoulder to maintain positive headspace control if necked up to use .458" bullets.

I don't find any information on how much shoulder to neck step reduction is needed on a rimless case, but there are some data points.

The .400 Whelen on the .30-'06 case has a .462" shoulder and a .436" neck and ends up with about 13 thousandths per side; the Whelen is widely regarded as a failure because of headspace problems.

General Julian Hatcher describes some experiments in Hatcher's Notebook with the Springfield and Mauser rifles in the amount rimless cases are propelled in the chamber by firing pin thrust, and the consequent headspace problems that could result.

The .450 Howell (also based on the .404 Jeff case) has a .480" neck and .515" shoulder for a shoulder to neck step-down of about 17 thousandths per side.The other rimless factory cases at and above 9.3 for which I have case drawing or dimensions all have at least 60 thousandths step down per side and are known to maintain positive headspace (9.3X62, 9.3X64, .416 Rigby, .404 Jeffery, .450 Rigby, .505 Gibbs, .500 Jeffery). Shoulder angles run usually in the 17 degree to 45 degree range (except the .404 at 8.5 degrees), with sharper shoulders commonly being later developments. I don't have any drawings for the .460 G&A.

I also know of two factories (one American and one in Europe) who looked at loading .460 G&A ammunition, but decided against it.

Jeff Cooper told me in 1997 that CZ was going to bring out their 550 in a "Cooper Baby" commerative model; they had prototype rifles at the factory, but could not solve the factory ammunition problem.

jim

jim

------------------
"if you are to busy to
hunt, you are too busy."

The Remington 700 and Winchester 70 actions are not big enough for the Lapua case, which has a .580 head diameter. The UM cartridges have a .532 case head on a 404 body due to the smallness of the bolt. Remington built a 700 for the 338 Lapua, but it was deemed unsafe and the project was scrapped. I believe this article was in the first few issues of Tactical Shooter.
Todd

HunterJim,
Thanks for reviving this thread. Your post is about as authoritative as anything I have heard on this subject.

But you typoed on the step per side didn't you? You mean greater than 0.060" total shoulder or 0.030" per side.

404 Jeffery's Rimless Nitro Express:

shoulder diameter = 0.520"
neck diameter = 0.450"
shoulder angle = "approximate: 9 degrees" angle per side
shoulder step = 0.070"(total)/0.035"(per side)

416 Rigby:

shoulder diameter = 0.540"
neck diameter = 0.446"
shoulder angle = 45 degrees (44 degrees 53 minutes to be precise) angle per side
shoulder step = 0.094"(total)/0.047"(per side)

Surely both the step down and the angle at each side of the shoulder have a part to play in headspacing and dud prevention in a DGR.

It is amazing that the 404 Jeffery has an ~9
degree shoulder and the 416 Rigby has a 45 degree shoulder per side. They both are flawless in reputation. They both have >60 thousandths TOTAL shoulder, not per side. And the Rigby has way more shoulder and way more angle than the 404.

My gut feeling is that 30 thousandths per side plus at least 30 degrees angle per side is a minimum shoulder. We could call this the "thirty-thirty" rule.

If the angle is less than thirty degrees per side, better make the step bigger. But how much bigger? If the angle is greater than 30 degrees you still have to stay at 0.030" per side.

Several cartridges fail the 30-30 rule.
404 Jeffery
585 Nyati
400 Whelen

I think the 30-30 rule should be applied only to medium and large bores of 0.366" caliber and up, though it is a good rule for designing cartridges of any caliber.

The 35 Whelen has a 17.5 degree shoulder and 0.028" step per side (0.056" total). No problem.

The maximum shoulder angle for good extraction and feeding is 45 degrees. Yes, the 416 Rigby is max in many ways.

PS: This may be BS. Just like those blasted Letality Indexes.

------------------
RAB

[This message has been edited by DaggaRon (edited 12-10-2001).]

DaggaRon,

I'm sorry. I've damaged my 460 G&A papers beyond repair. Volvo went in a ditch in October and they were soaked. The folder I had them in stuck together - well you get the idea. Now, you have the best copy of what I had.

All,

Let's compare the 460 G&A shoulder with that of another very successful cartridge, the 35 Whelen. How do they compare? I know the answer - do the comparison. The 35 Whelen has even been chambered in a pump action rifle by Remington.

redleg

redlegg155,
sorry to hear about the car and the papers.
I will send you an email. See my BS comment added as a PS above. If it works, it works, eh? I never heard of any problems with the 460 G&A shoulder. They are imaginary, I imagine. There must be a threshold somewhere, but who knows where? The 30-30 BS is overly safe.

I will mail you a copy of the 460 G&A reamer specs. I only have that one page, filed on the bookshelf.

------------------
RAB

Gentlemen,

In Finland there exists at least two 458 wildcats which utilize 338 Lapua brass. The first one is called .458 Asepaja Helenius (.458 APH). Chambering for this cartridge is achieved by using a .338 Lapua for the chamber, and a .458 Win.Mag. reamer for the neck. The second one is called .458 Hannu Kamutta Short (.458 HK Short). This chambering is made with a 460 Weatherby reamer; when cutting the chamber, the reamer is not pushed in all the way, so it doesn't cut the belt recession.

The .458 HK Short works in standard length actions, while the .458 APH needs a magnum length action. The re-chamerings and re-barrel jobs I'm aware of have been done Brnos and Sako TRG-Ss.

Good thing about both of these cartridges is, that the chambers can be made with standard reamers, thus cutting down time and cost associated with wildcat projects.

And talking about minimal shoulders, there's also the .50 APH, which is 338 Lapua necked up to .50 caliber...

Regards,

Otto P.

[This message has been edited by OttoDude (edited 12-11-2001).]

OttoDude,
Can you tell us the shoulder and neck diameters, shoulder angle, and overall case length of the 50 APH?

Also is the bullet a .505 or .510 caliber.

MY-OH-MY! The 50 APH is "adventurous" sounding!

------------------
RAB

DaggaRon,
adventurous indeed

The specs for the 50APH are as follows:

neck diameter 13.55mm (.533 inches)
shoulder diameter 14.30mm (.563 inches)
shoulder angle 90 degrees
case length 66.20mm (2.61 inches)
bullet diameter .510

I talked with Mr. Helenius today about re-chambering/re-barreling a Brno to either 458APH or 50APH. He recommended the 50cal. version over the 458, and assured that headspacing is not a problem. Total cost to re-barrel, open up the boltface, reloading dies etc. is 2500FIM ($375). For an "effective" moose load Mr. Helenius suggested a 450gr bullet over 80 grains of Vihtavuori N133 giving 2345fps at the muzzle.

If I remember correctly, JD Jones offers a 510Whisper, which is a necked up 338 Lapua cut to 2 inches.

Regards,

Otto P.

OttoDude,
That shoulder angle is 90 degrees total or 45 degrees per side, I presume.

The shoulder step is 0.030" total or 0.015" per side.

Doesn't sound like a very good idea to me.
But what do I know?

I would say stick to the 500 A-Square or get a 505 Gibbs or 500 Jeffery.

------------------
RAB

I love new rifle projects. The excitement of it all. A cartridge with my name on it. You search scheme and plan. Except some guy you never heard of did the same thing in 1950. The ultimate 450 is already in existance. You just have to decide which is right for you.

Daggaron,
your presumption is correct, that would be 45 degrees "per side". And I think you might actually be on to something with that 30-30 rule of yours.

The reason I'm giving serious thought giving the 50APH a try, is that around my neck of the woods, getting hold of more "exotic" brass can be VERY difficult. Sometimes even trying to obtain brass for the 375H&H, seems next to impossible
338Lapua brass on the other hand is plentiful and cheap, so in my situation the decision is between the 458APH and the 50APH.

And hey, if it turns out the 50APH doesn't work, it can always be re-chambered...

Regards,

Otto P.

[This message has been edited by OttoDude (edited 12-13-2001).]

OttoDude,
That 458 APH sounds like the ultimate. As usual, the dream wildcat has already been done ... in Finland.

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RAB

this is an interesing old thread...