Review of KS Arms Built Left Hand 338-378 Weatherby

[Dean2]

K.S. Arms built me a 338-378 Rifle on a Left Hand MKV Weatherby action. The rifle turned out beautiful. High gloss blued barrel, 3 Leaf express sights, Pearl Beaded Ramp front sight, glassed into the original Weatherby stock. The barrel is one of their Chrome Moly, cut rifle, hand lapped barrels that was custom contoured to be an exact fit to the old barrel. They also did the chambering and install. Chamber is a standard Weatherby 338-378 specification.

I took it out Oct 9th, 2023 for its first run. The target below is the first 16 rounds out of the new barrel. It is the first load I tried, going from 108 to 111 grains of H1000, Weatherby brass that was necked down from 460 Bee, Federal 215 primers and seated to 3.696 with a Hornady 225 Grain Interlock, Spire Point, Flat base. No crimp. I would consider the 111 grain load to be max as it shows slight ejector marks and a flatter primer than the lighter loads, but this is also the first fire forming shots on the resized 460 Bee brass..

The target was shot at 100 yards using a 2x8x33 Leupold VX3 scope, in Leupold QD rings, with a Gloss finish to match the rest of the gun.
I have shot a few other KS barrels, and all have been great shooters.They make barrels, brakes, actions and complete guns. The brake is custom built for the rifle. It does a great job of reducing recoil, shoots about the same as a 30-06, without making it unbearably loud for the shooter or producing serious side pressure at the muzzle. I was shooting alone so I put some stuff on the next bench over to check to see if it moved around at all from the muzzle blast, and it all stayed put. I also asked a couple of guys shooting about 5 benches over, and they said it didn't sound loud to them. Now to be fair, we were all wearing hearing protection, as no one should ever shoot a gun unprotected, let alone one with a brake on it.

Being priced in Canadian they are a VERY good deal compared to imported goods and are outstanding quality. For anyone in the States, and they will ship to the states, this means in U.S. dollars they are only paying about 70% of the published price.

I am very pleased with the build and the way it shoots. A little playing around with seating depth with the 109 grain load, I am sure will tighten the groups even more, However, under an inch for the first try is pretty darn good.

https://www.ksarms.com/

[Athabasca1]

Thanks for posting your review Dean. Looks like a very good custom build. Keep us posted on future load development.

[elkhunter11]

Other than that ridiculous brake, it looks like a very nice rifle. Hopefully you get to use it to hunt some very large animals, it is just too much cartridge for me, either too much recoil with no brake, or way too much noise for me with the brake. As for KS Arms, I have seen several of their rifles, and fired a couple, and they do excellent work, at a reasonable price.

[Mr.Piker]

Did KS do the bluing?

[Savage Bacon]

Nice rifle Dean. Those MKVs are beauties to begin with. How bad was the wait time? It's nice to have good quality that is also local. Like you said dealing in canadian makes a big difference. Like said above, keep us posted on load development. It doesn't look like you'll have a lot of searching by the look of the groups.

Sent from my SM-S901W using Tapatalk

[Smokinyotes]

Very nice Dean. Your a tough old bugger. I’m flinching just looking at it.

[Dean2]

Originally Posted by Mr.Piker

Did KS do the bluing?

Yes KS got the barrel and brake high gloss blued but I think they probably send it out. I am pretty sure they don't do bluing in-house.

Wait time was just over a year and a half, but sourcing the sights to go on the barrel took me some time and they didn't want to start till they had all the pieces together. I made up 4 dummy rounds as well, so there was a wait to get the Dies as they were not in stock anywhere in Canada. Karl did extensive work on the feed rails and ramp so that the cartridges feed like butter. I think had I had all the parts together to start with it would have been about 6 or 7 months to get it done.

As far as load development, pretty much going to stick with the 109 grain load, and just play a little with seating depth. Pretty sure I can get it to cloverleaf three doing that and for a big boomer hunting rifle that is plenty accurate enough. Even as the load sits, it is plenty good enough out to 500 yards.

[6MT]

Have you chrony’d that 109gr load? I would be interested in the speeds you’re getting.

[Pathfinder76]

That thing will be a decisive hammer.

[Moo Snukkle]

Beautiful gun. Excellent write up. She looks ready for Africa.

[MountainTi]

Now you just need the zama buff draw next year and you'll be set
Dandy elk gun till then anyways

[Dean2]

Originally Posted by 6MT

Have you chrony’d that 109gr load? I would be interested in the speeds you’re getting.

Haven't done that yet. I expected to have to do a bunch more development work, first trip was more for barrel breakin, so was saving the speed tests for the next go round. Book says they should be around 3000 FPS, so I would imagine it will be right in that ball park.

MountainTI, you are right it would make good elk medicine. If I was going to shoot a Buff I think I would probably use my 375 Ruger. Short 20" barrel, Stainless action and barrel, laminated stock. Would put up with riding around on a Snow Machine a bit better than the Weatherby and a lot handier in heavy bush if needed.

[roper1]

Beauty rifle right there, Dean. Something about high gloss blue & shining walnut. One to enjoy!

[Twisted Canuck]

Nice to see you finally got it out for the test drive Dean, and impressive results for break in. You're going to need to buy powder by the keg to feed that thing!

[waldedw]

Looks sweet, they are boomers for sure, about a ballistic twin to the 338 RUM that I had, I was pushing a 250 gr @ 2,950 with a case full of retumbo, it was a handful alright.

[leeelmer]

I am assuming this was a original 460?
Then with the ban on it you have decided to change her up?
Anyway beautiful work for sure.
I have always lusted after the big weatherby cals
Been searching for the right 416 or 378 or 340 in a deluxe for years
Just haven’t found the right one.
If you are looking for some correct head stamp brass I will ask a buddy I believe he has some.
KS does great work

[Dean2]

Originally Posted by leeelmer

I am assuming this was a original 460?
Then with the ban on it you have decided to change her up?
Anyway beautiful work for sure.
I have always lusted after the big weatherby cals
Been searching for the right 416 or 378 or 340 in a deluxe for years
Just haven’t found the right one.
If you are looking for some correct head stamp brass I will ask a buddy I believe he has some.
KS does great work

It was a 375 Bee but I also had the 375 Ruger with a 20" barrel, so decided to make this into something else as I didn't need two 375s. Brass head stamp is no big deal as it is really hard to confuse them, and I don't have a 378 or 460 anyhow. I have 378 and 460 factory brass I picked up so have lots of brass. Thanks for the offer though.

TwistedC

I have a few of these 100 grain powder eaters. You are right about a pound not going very far, 70 rounds a can.

[58thecat]

Wow now that’s a powder burning, snot knocking beautiful Dino slayer right there....when does T-Rex season open up in the badlands?

[6MT]

Karl and the boys do wonderful work. I’ve shot with Karl a couple of times. Very funny and entertaining guy. All of his rifles, he hand built himself. Nothing bought, all pieces manufactured himself.

[AlbertaAl]

as long as you're happy... appearance of rifle is fine.
I looked at the target a couple times and didn't see a good load based on holes being spread out

[Twisted Canuck]

Maybe look again.

[AlbertaAl]

still looks the same ...

[cowmanbob]

Originally Posted by Twisted Canuck

Maybe look again.

I’d be happy with that.

[Twisted Canuck]

Originally Posted by AlbertaAl

still looks the same ...

Ah, you're going to be That Guy. Carry on.

[Demonical]

Very cool.

I've had K&S do some simple smithing for me, great to hear they are still going strong!

[prarie_boy1]

I’ve been really impressed with the work they have been doing along with in house actions and barrels. Recently purchased the KS bottom metal for my wildcat stock and was happy with quality. Next barrel/re barrel job will be going there

[birdseye]

Your custom 338-378wby lokks very nice,I have always loved great wood stocks.Im curiois the FPS and hope you post when you find out.My son and are on tge fence trying to decide if we go the custom 338-378 wby or 338 Edge route.Have fun with your new build.You do realise the boot is bacwards haha

[dave99]

Great write up and congrats on the results. This is a worthy rifle to add to any collection and I’m sure it will see plenty of action. Thanks for taking the time to post, and we are lucky to have a smith like K&S available locally as they turn out some great smithing and rifles.

I went pretty much the opposite direction and had them put a 22 inch barrel chambered in 6.5 CM on a Finnlite 85 that had been a 7-08. The rifle is a beauty and a pleasure to carry.

As I side note, I did find that the K&S barrel ran about 60-80fps above book velocity for most loads. Anyone else find their barrels fast?

[Twisted Canuck]

I'm getting 25-30 fps more with my 22" in .338 Federal, then what is showing for 24" barrel. It's not a hot round mind you, but every bit helps I suppose.