New to me 338-06 wildcat, looking for some help please

[Coyoteee]

it's in a rem700 bdl. Custom barrel and its stamped 338-06 rcbs improved. I called rcbs and they know nothing about that stamp. I did some measuring and the shoulder is .050" further ahead than an AI. The body taper is the same as an AI. I have no way to measure the shoulder angle but it's not as steep as an AI. Case capacity is 73.5gr H2O. 23.5" barrel measured from the point where the barrel meets the receiver.

i got it with some fire formed cases from a 35Whelan. And a few 30-06. I was able to neck size the cases in a 338WM die and seated some 200gr Hot Cor bullets at .040 off the lands. LR primers. I went with load info from Hodgdon and Nosler 338-06AI. Came up with RL15 and Staball6.5. Worked up to 58gr of the rl15, pressure signs after that. The only powder I tried. About a 2" group. Also got a reading and the 58gr were doing 2949fps.

Since this is a different CC than any saami spec cartridge, I'm wondering if someone could give me some suggestions, maybe run the data on quick load if you'd be so kind, as to different powders and charge weights I could try.

Thank you in advance!

 

[Budget'06]

Nosler has 338-06 (a-square) load data for the rl15. Hornady has 65 he as the listed max for staball 6.5. I've never played around with the cartridge but thats where I'd start. Maybe 2 grains under max and work up slow.

If I had to guess, something a bit slower might work. I've heard some crazy velocity numbers with it and Ramshot Big Game. Maybe something around IMR4831 would work?

Id like to have one some day so I'm very curious what you come up with.

 

[Cornbinder57]

In my 338-06AI I have had great accuracy and velocity with Staball 6.5. Mine is a Pre-64 Model 70 with 24" barrel. 62 grains behind Nosler 200 grain BT for fire forming 338-06 brass. 2730 fps and .45" groups at 100. 64 grains on the Formed brass and 2825 fps sub 1/2 MOA out to 300.
Maybe give 6.5 Staball a try and work up.

 

[dgp3006]

I have a rifle chambered in a similar cartridge that I have played with off and on for about 20 years. It is a .338/.280 Remington Ackley Improved and has a 23 inch Kreiger barrel. I have used data on loads from the Barnes number 3 manual for the .338 Scovill and a separate article he wrote years ago that might still be on the internet. I also have a poor copy of an article written by Chris Ross for Precision Shooting magazine in 1994 on my cartridge. Additionally, I also have several manuals with standard .338/.06 A Square data that I refer to as well. There seems to be a consensus that powders with burn rates similar to RL15, ww760, H414, Varget, etc. are best for the light for caliber bullets I like to use. Slower powders as the weight of the bullet increases. The water capacity of my case is around 75 grains depending on the weight of the particular piece of Remington brass I use.
one example of my original work up loads is 60 grains of RL15 with a 210 Nosler Partition. Velocity was 2900 fps and was considered MAX and not to repeated! This was also with Norma brass which is lighter by about 15 grains compared to Remington brass. My original hunting load I settled on was 68.9 grains of H414(discontinued) with a Barnes 185 gr. XLC blue coated bullet was running 2995 fps. However, all load data for the Barnes XLC bullet should not be used for non-coated bullets. I have recently found a load with BLC2 and 175 Cutting Edge and 175 Hammer Hunter's that looks promising. So, not much help but at least some experience with a similar cartridge.

 

[Reemty J]

I have a Bansner rifle 21.5" barrel in 338-06 AI, I shoot a 175 HH with 59 grains IMR 3031 @ 3127 fps, it will shoot 3/8" group at 100 yards and 3.315 OAL with a 1/4 turn crimp.

 

[jglenn]

Win 760 is H414 BTW

 

[dgp3006]

Yes, I've heard that as well. Also, Norma 203-B. I've got a few pounds but haven't used it yet.
edit: Actually 203-B is the same as RL15.

 

[sable tireur]

From your previous post:

https://www.longrangehunting.com/threads/anybody-ever-heard-of-a-338-06-rcbs.346599/

 

[TRexF16]

I did some measuring and the shoulder is .050" further ahead than an AI. The body taper is the same as an AI.

Thank you in advance!

It really sounds like your case may be based of the 280 or 280 AI vs the basic 30-06 case. That .050" difference at the shoulder is spot-on for the difference between the 30-06/.270 Win and the .280 Rem shoulders. I bet you'd get a good fit with a factory 280 AI case, and could either do the Cream of Wheat fireform method, or just neck up to .338.
Let us know if that works.

Rex

 

[FarmerMatt]

This is from my old Sierra book from the 70s. I can send you all the load data if you want, if this is the right cartridge.

 

[Rusty85]

My main Missouri deer rifle is a custom 338-06 A-square with 22" barrel and it loves 186 hammers and CFE223 at right around 2850 fps. Its sounds though like yours is more than likely based off a 280 rem. Going off the measurements you gave.

 

[sable tireur]

View attachment 531884
This is from my old Sierra book from the 70s. I can send you all the load data if you want, if this is the right cartridge.

Not even close.

 

[Shane Lindsey]

What is your fired case length? As stated, 280/AI cases may be the ticket for fireforming to give you more room.

I have a 338 Sherman (similar to yours but with 2.485" case length). Don't overlook Varget.

175gr Hammer Hunter with 64.5gr Varget = 3207 FPS
213gr Hammer Hunter with 66.5gr Stabal 6.5 =2843 FPS
213gr Hammer Hunter with 57gr Varget =2763 FPS

 

[Reemty J]

Shane what length barrel do you have, mine is 21.5" iwould guess your is 22-24 getting those velocities