338-416 Rigby Improved

[Long Time Long Ranger]

Anybody know who has reamers that will get the most powder capacity out of this case. Tons of 416 improved out there. Thanks for any help.

 

[Fiftydriver]

Don't know about a reamer but I will say that a 338 Kahn is the exact same thing but DRAMATICALLY easier to form cases. This is just a 338-378 Wby that is fireformed to a 35 degree conventional shoulder angle to replace the double radius Wby shoulder.

When Wby commericalized the 338-378, they pretty much made the 338-416 wildcats obsolete in my opinion, just to much fuss forming cases.

Kirby Allen(50)

 

[Long Time Long Ranger]

Thanks for the help. I'm starting another project and just trying to get the most case capacity out of a non-belted case. The Rigby case is about the largest I could find without a belt that I could easily get brass for. I thought if I could push the shoulder out a bit to reduce that long rigby neck I might get what I was looking for. I understand bringing that 416 down to 338 is a chore. I built my first 338-378 in the late 70's for long range elk and now have 5 or so of them. Just trying something new that I didn't have. I like headspacing off the shoulder on the big guns. I did a lot of stuff with that ultramag case when it first came out several years back and everything off it turned out super accurate. I really liked working with the non-belted case. I never heard of the Kahn. Will the 35 degree shoulder get an extra couple of grains of powder in there? The reason I ask is my favorite accuracy load for light 200 grain bullets is 132 grains of H-870 which is a chore to get in the case but shoots great. Shoots extremely flat at 3600 fps and just flattens game out to 600-700 yards. If I'm shooting beyond that I use the 300 matchkings. I have a 378 wby action and a 338 Lapua Sako action just sitting there right now. Just looking to experiment with something else.

 

[Fiftydriver]

Adds about 5-6 grains more volume over the 338-378.

How is your case life with a 200 gr @3600 fps?

Kirby Allen(50)

 

[Long Time Long Ranger]

Thanks for the info on the Kahn. I want to build something on those actions different from another 338-378. I like the idea of the 35 degree shoulder on that case. Do you know if that design has shown any improvements with accuracy or velocity? Where can I get info on it? Is there a barrel company who can chamber a barrel in the Kahn. I like that idea. I may just do one of those actions with it. I have been thinking about changing that shoulder for some time and figured somebody had just didn't know who.

The rifle I shoot the 3600 fps load in is a 28" Hart barrel on a MK 5 action. I had 1/2" freebore cut in it. It has a 1-12 twist for the light bullets. It was built particularly for the 200 ballistic tip to see what I could do with it. I call it my mid range gun for out to 700 or so yards. After that the light bullet starts falling off quite a lot. But out to there it is devastating on elk size critters. One time I did shoot a moose up in Alaska out of neccesity at a tad over 1100 yards with that bullet and one shot through the lungs put it down with no problem. Bullet performance was perfect under the off side hide. The gun was not designed with those ranges in mind though.

I started 50 new brass with that load and I have been through that box about 5 times but I would have to check to know exactly. I keep all my loads for each rifle in seperate 50 round boxes. It is not a super hot load in that rifle I just can't possibly get another drop of powder in the case. I use the fed 215 match primers. I suspect that if I shot that load in one of my guns with no freebore and a 1-10 twist it would be to hot. I have the gun zeroed at 650 yards for long range hunting and it averages 4 1/2" groups on zero.

 

[Long Time Long Ranger]

Forgot to add this about the 200 velocities. The one rifle did so well with the 200's I built another on a Ruger #1 with a 30" barrel. It is a Pac-Nor with 1/2" freebore and a 1-12" three groove barrel. I never had a chance to work with the gun so this year let a buddy work up some loads for an elk hunt with it. He found a sweet load of Retumbo that is getting 3750 fps with the 200 ballistic tip. I think he said 125 grains but whatever it was it was all the case would hold. It also was not a super hot load in that rifle. This has just happened over the last few weeks and he is in Alabama and me in Wyoming so I haven't shot it yet but looking forward to. I was looking to shorten the length down and cut some weight with the #1. I am a retired mathmatics/engineering and tinker a lot with a lot of projects.

 

[davewilson]

3750 with a 200 BT...this would make quite a varmint buster.

 

[sniper2]

Ltlr

Ask 'ol Kirby excuse me fiftydriver about some of his cartridges he is not in the alignment business he comes up with actual configurations of his own design most of which are very interesting to say the least...

 

[James Jones]

Woulden't a 338-416 Rigby improved be the same thing as a 338 Lapua improved?

 

[Stormrider]

Woulden't a 338-416 Rigby improved be the same thing as a 338 Lapua improved?

No, the 338 Lapua case is about 3/8 inch shorter.