Home Forums Hunting & Shooting Long Range Hunting Looking for input on rechambering to something 'new'.

I have a Kimber 8400 in 338 Win Mag that will need it's 3rd barrel in the near future. I regularly shoot the rifle out to 1000y but I know there are better long range options out there. The rifle will be used for some long range shooting and culling. I would still like to carry the rifle around, but it does not need to be 'light weight'.

I would like to rechamber to something .30 or 7mm. If I can keep the same mag box and case head diameter it would be a big plus. If I can get something with a 'reasonably' short case to enable me to seat bullets long it would also be great. I was thinking of a 308 Norma Mag but would like to weigh up all other options.

I would appreciate any info, thanks.

Pieter

I am pretty sure the Kimber 8400 has a long enough action that it could accommodate H&H length cartridges if you modify the action by removing the magazine box(?).

(I don't have one to look at. I know this can be done with a M70; not sure on Kimber).

Anyway if possible you could use a standard old 300 Win Mag or 7mm Rem Mag and seat bullets further out. With the 300 Win Mag you could seat (say) a 180 gr spitzer even with the base of the case neck. This should function through the magazine and still allow longer seating of the heat 30 caliber bullets without i trudug too much into the case below the neck.

You can do the same seating with the 7 Rem Mag.

Of course you could also chamber for something new like the 30 Nosler or 28 Nosler which I am thinking will fit if they feed OK. You will probably need a new barrel a bit sooner than with the 300 WM;and brass is one source far as I know. These may or may not be important issues for you.

If I were doing it I'd build a 7mm Mashburn Super, which keeps up pretty well with any modern 7mm and has favorable bullet seating in a H&H action with heavy 7mm bullets.It is formed from easily available 300 Win Mag cases.

Here is a picture from RCamuglia on here of (L-R) 7mm Rem Mag, 7mm Mashburn Super, and 300 Win Mag. with long OAL seating.I believe that's a 195 Berger in the Mashburn.

Rick built a 7mm Mashburn on a Browning action. He may chime in.The picture gives a comparison. Not sure if you want a wildcat but a Mashburn is as easy as it gets.

I'd be in 7WSM mode if you want to seat long bullets in a standard mag box. If you have room the 7RM would be a great choice as well, especially if brass availability is a challenge where you're at.

Nosler 28 or 30. About as new as it gets and no darn belted case. The 30 with the 200 accubooms or 212 eld would be a wicked SOB.

I assume the bolt face will need to be opened up? Will feeding be a problem from the current magazine?

Thanks

Pieter

I guess I might be able to remove the spacer in the rear of the magazine to create more space for the long 7mms. I was looking at the Nosler cartridges but seems like they might be a bit too long to allow for magazine feed while seating them long? I have brass and dies for the 7RM which is a plus but I do not want to make that my deciding factor. Thanks for the input, I appreciate it.

Pieter

Will they feed fine from the 8400 action? Will the oal not be too long?

Thanks

Pieter

Nope, and not likely. It'd be worth getting a dummy round or 3 to test feeding.

I recently built a 7WSM specifically for LR shooting using a Rem 700 long action, PTG 0.532" magnum bolt-face bolt, and AICS .338 LM mags. Feeds slicker than snot. Shoots a 195gr bullet with 0.755 BC at 2900 fps with 64gr of powder. Pretty good bang for buck, and can seat the longest bullets out into the lands in a standard long action.

They are the same'ish body OD as the wsm a good smith could tune the rails to feed with out much effort and removing the spacer would give the OAL desires. I have been on the fence about shoveling one into a old ruger m77 round top and running 175grn lrab.

It appears that the .338 win mag has served you well. For comparison, I had one with Douglas SS barrel, 29", throated for the Hornady 250 spire point at 3.48" COAL. 75 gr. Rel 22 gave it 2900 fpa.

Inasmuch as you live in South Africa, and components are not as readily available as they are here (and when they are available, they are sometimes very spendy,) my advice will be a tad different. I would build one of three chamberings: a .264 Win mag, a 7mm Rem mag, or a .30-338. The one I chose would be based on what I could procure in terms of a good bullet.

They would all fit seamlessly into your current action--just put on a new barrel and no action alterations would be needed. They all work off of a common case, so you could buy a bunch of 7 Rem mag brass and re-neck it into either of the others. The .264 would have the least recoil, which would be nice on culling trips, but would have the shortest barrel life. Any of them would be a better choice for long range work than a .338 Win.

A 7RM with 168s or 180s sure seems to make sense to me for your situation.

Agree with Utah. And a 300 Win. Not much you need to do the 7mag could not do. Or the Mashburn if you want something completly different just cause. If brass is of concern...

Good luck...

W

Thanks a lot for the info guys. If the WSM rounds can feed from the mag I think it would be a pretty good choice. If they do not, I might have a look at a 300WM or 7RM cut with a reamer that would leave me with some mag space.

Pieter

The 338 did serve me well but the bullets are just getting too expensive around here. 7mm and 30 cal bullets are quite a bit cheaper and would still get the job done. I still like the 338WM but think I will be better off with 7mm or 30 cal.

Pieter

What about a 26 Nosler.?

For many years the .30/338 was THE 1,000yd precision cartridge. More neck and better case performance than the straight .300win mag...

The .338/300win offers more flexibility than the straight .338 case. Have loaded 79gr of XMR 4350 with 250gr Sierra bullet as a max and started out with 65gr of same powder as beginning load... Gets you right there with .340wby and .33 Dakota... Much greater flexibility than the larger ctgs though.

Might be able to simply improve your present barrel to .338/300 and get a new throat, unless it is really shot out and crocodiled as happens with stainless.


Might get a new .476 bolt body, if Kimber would sell you one... The 6.5/284 will keep up with 7mm Rem and others. The 284win case is great for wildcatting up to .375 bore. .30-06 and .30/284 share same data for loading, so you got ballistic and handloading twin but shorter case, more room for seating longrange bullets.

.264win is also still a great performer. If looking to shoot 200gr bullets or heavier from a .30cal, the .30-06 AI will really deliver and give you 5rds in the magazine, also the .338-06AI is a great performer with heavier bullets.

Lot of guys were having problems finding 7 WSM brass. That would certainly not be my first choice where you are. 7 RSAUM is a better option for brass IMO.

I would go with straight 300 win or 7 rem mag with faster twist barrel to handle the new LR bullets.

You checked on an extended mag box from Wyatts I think,. Plus CDI also sells a conversion.

Listen to utah708. The .300 Win and 7mm Rem are "World" rounds that everyone makes ammo and brass for. From what I've read, you guys pay through the nose for you components as it is, why add availability issues to your troubles? Chances are, the action won't require any work either.

Either round can be loaded down some with one of the 4895s for smaller game, saving your barrel and shoulder a bit. Both rounds are accurate enough that they've been used for long-range match shooting and the .300 as a sniper round by the military.

My granddaughter shoots my 300 Win mag with the 60% load of H4895 And 150 bullets. It's fun to shoot.