P64 M70 375 H&H AI

SJB358

Ballistician
Dec 24, 2006
31,398
757
So, I had this rifle, bought it quite a danged while ago for the action to build my 7mm Mashburn off of. It was a rechambered to 300 Wby from 300 H&H. I didn't much care anyhow since the rifle was pretty nice and the metal was good, I didn't pay much for it, so I never paid too much attention to it honestly. The original wood stock was pretty nice, but it was refinished and shortened as well.

Anyhow, I found another action from my smith for about the same money, so I used it for the Mashburn. Well, I liked the rifle enough to stick it in a McM Legend and it was a sweetheart to handle.......

So I had this 300 Wby, tried a few times over the years to see how it would shoot and nothing I ever did could make it shoot. I tried Barnes, Nosler, Sierra, Hornady, Swift... 180's, 200's and 165's.. Tried IMR4350, 7828, RL26, etc. Nothin...

So I got to thinking, I'll just rebarrel it and make it right.. Then I got to thinking, I don't have a 375 so maybe a rebore would be fun, you know, just to try a 375 out. I called JES and he said a 375 Wby would be easy.. Well, I asked for him to do a 3 groove, 1-10 twist in 375 Weatherby.

I got the rifle back this past Saturday and the note said he couldn't do a 375 Wby for some reason and he made it into a 375 H&H Ackley. Don't know why, nor really care as the Wby and Ackley are the same really and I don't have to deal with Wby freebore, so it's all good there.

I had 36 Remington cases left over from when I loaded for a buddies 375 and just so happened to have the same amount of 260 Partitions.. So, I started loading them up. Pulled out the trusty Nosler manual, saw a top load of RL15 was 72 grains, so I backed up and loaded a couple with 71 grains, just to see how they'd form.





I said alright, this'll work.. So I leaded the rest of them up and started shooting 5 rounds at a clip..

I was shooting the rifle with the iron's that come on the gun and so far I was loving it.. Just a fun gun.



Was pretty surprised when I weighed it.. thought this might about right with a scope on it..

So, I had an old 6X Leupold and a set of Warne MountainTech 1" Low rings..



I thought, shoot, this is just about right for a portable 375...

So, I started zeroing it up the next 5.. Came right onto paper real easy. Praying the old 6X stays on point, if not, I am sure I can find something else..

I also was scrubbing the barrel down every 5 rounds to bare steel. JES's rebores have always shot well for me, but they grab up the copper.. After 5 rounds it looked like the bore was copper lined, so I attacked it with some JB's bore paste after every 5 rounds.



After 30 rounds the copper build up was WAY less so I scrubbed it down to bare steel again and coated the bore with Dyna Bore Coat this last time.







So, I have 6 rounds left and I'll use those to cure up the DBC.. I kinda wished I got the rifle a couple weeks ago, might have been handy in the timber country I am headed to on Wednesday for elk, but I'll sort out another use for it, maybe? HA!

I ordered 375 Wby dies, so I need to exchange those 375 H&H AI dies, so I am waiting patiently for them to get back to me.

I am pretty happy though, got to keep the old barrel with the factory sights on it, the rifle still looks like a P64 and so far, I think it'll work decently. Hopefully it is like all of the other 375's and shoots like crazy.
 

truck driver

Ammo Smith
Mar 11, 2013
6,971
335
I like it.
Don't understand why you would want to use 375Wby dies when you have a sharp 40 degree shoulder and not a radius shoulder like is on the Wby.
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
truck driver":vo03mg6z said:
I like it.
Don't understand why you would want to use 375Wby dies when you have a sharp 40 degree shoulder and not a radius shoulder like is on the Wby.

It was supposed to be a 375 Wby, so I ordered the dies before I got the rifle back...
 

truck driver

Ammo Smith
Mar 11, 2013
6,971
335
SJB358":2hqfu8jd said:
truck driver":2hqfu8jd said:
I like it.
Don't understand why you would want to use 375Wby dies when you have a sharp 40 degree shoulder and not a radius shoulder like is on the Wby.

It was supposed to be a 375 Wby, so I ordered the dies before I got the rifle back...
Okay I see where I misunderstood what you wrote and you are exchanging the 375Wby for 375 H&H AI dies.
Old Roy basically stole Ackley's design but changed the shoulder to a radius type and lots of free bore to hold the pressure down and then got a patent for it.
He was one of P.O.'s students and studied P.O.'s work in ballistics. One of the things that is never mentioned when Roy's cartridges are mentioned.
 

Europe

Handloader
Jun 18, 2014
1,123
94
Scotty, very nice. Well done!

My husband had a 375 h/h a.i. and remember he used 300 gr and rl-19, but this was over ten years ago. If you would like I can ask my son and see if he can find his fathers notes

Good luck on your elk hunt
 

truck driver

Ammo Smith
Mar 11, 2013
6,971
335
One thing is for sure and that is J.E.S knows how to chamber for the Ackely so you can shoot factory ammo in it if you should run out of reloads while on a trip and need to buy some.
My 35/AI shoots standard 35 Whelen ammo as well as the 35/AI with equal accuracy.
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
truck driver":3qedr3a9 said:
SJB358":3qedr3a9 said:
truck driver":3qedr3a9 said:
I like it.
Don't understand why you would want to use 375Wby dies when you have a sharp 40 degree shoulder and not a radius shoulder like is on the Wby.

It was supposed to be a 375 Wby, so I ordered the dies before I got the rifle back...
Okay I see where I misunderstood what you wrote and you are exchanging the 375Wby for 375 H&H AI dies.
Old Roy basically stole Ackley's design but changed the shoulder to a radius type and lots of free bore to hold the pressure down and then got a patent for it.
He was one of P.O.'s students and studied P.O.'s work in ballistics. One of the things that is never mentioned when Roy's cartridges are mentioned.

I heard through the rumor mill the radius shoulder was to make it look different for marketing and also to make sure that folks had to buy the reamers from Weatherby or something of that nature.

Europe":3qedr3a9 said:
Scotty, very nice. Well done!

My husband had a 375 h/h a.i. and remember he used 300 gr and rl-19, but this was over ten years ago. If you would like I can ask my son and see if he can find his fathers notes

Good luck on your elk hunt

April, thank you, I'll take any data you have for it. I kinda figured you'd give me a harder time with the Ackley vs the standard, but in this case it was the only way to utilize the factory barrel since it was already a 300 Wby.. I am good with it, still feeds like crazy, at least with empties.. Pretty sure it'll be good with loaded rounds as well.

truck driver":3qedr3a9 said:
One thing is for sure and that is J.E.S knows how to chamber for the Ackely so you can shoot factory ammo in it if you should run out of reloads while on a trip and need to buy some.
My 35/AI shoots standard 35 Whelen ammo as well as the 35/AI with equal accuracy.

So this gun will chamber the one 375 Wby round I have and of course 375 H&H.. Makes it sorta versatile and I'd imagine it'll be accurate enough with standard H&H to get thru a hunt if I needed to. Kind of a blessing to have the belt on this series..
 

truck driver

Ammo Smith
Mar 11, 2013
6,971
335
Hey Buddy from my experience with my 35/AI you can load both in the magazine and they will feed interchangeable.
I once fire formed and shot 50 rounds on one target and they just cut one nice hole with just a slight difference in elevation due to the velocity difference which one could expect since they weren't loaded with the same charge but still full loads for the standard so I could get the shoulder formed properly which is also an advantage over other wild cats where you have to use a reduced load and some type of filler to fire form the case.
 

Guy Miner

Master Loader
Apr 6, 2006
16,779
1,819
Well this is just plain OUTSTANDING! (y)

I guess I can take that sticky off my 375 Model 70 that read "Reserved for Scotty, someday." :grin:

Looking forward to seeing some photos of this rifle with some big ol' beasties; jackalopes, meese, bars, buffers... :wink:

Looks good Scotty. I don't see any downside to this "new" rifle of yours.

Guy
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
Guy Miner":13mnhd46 said:
Well this is just plain OUTSTANDING! (y)

I guess I can take that sticky off my 375 Model 70 that read "Reserved for Scotty, someday." :grin:

Looking forward to seeing some photos of this rifle with some big ol' beasties; jackalopes, meese, bars, buffers... :wink:

Looks good Scotty. I don't see any downside to this "new" rifle of yours.

Guy

Guy, I got tired of waiting for you to let up the grip on your 70!

I did think about what you said about putting it into a high quality synthetic stock though and I kinda kept the theme alive with the 6X on top. I don't feel too handicapped with that on the rifle though.

It was pretty pleasant to shoot from the sitting with the 260's around 2550 though. I know it has a ton more HP on tap..
 

mjcmichigan

Handloader
Dec 26, 2016
2,263
31
Very cool Project Scotty!

I have neither an Ackley or Wby and am sure I’d enjoy them.




Sent from my iPhone using Tapatalk
 

Europe

Handloader
Jun 18, 2014
1,123
94
Scotty. this is probably not much help

He wrote that it is ballistically the same as his 375 JRS ( which I think was on a Rem 700 donor )

His notes were more of a road map--ie weigh the standard and a.i. cases then weight them again filled with water. as an example, If it weighs 4 of water only use 3 of powder or approx 2/3 of the water weight He did not name the bullet but said the 300 gr ( if I had to guess, nosler or barnes ) he did write 88 gr RL-19

Scotty, my son said that these are old notes and that he would not automatically use RL 19, or 88 grs of it without more research. I dont think this is of any use to you but I told you I would ask.

neither the 375 A.I. or 375 jrs are still in our possession

I would bet that Fotis could give you exact data, and will as soon as he sees this thread
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
Europe":2rntei8n said:
Scotty. this is probably not much help

He wrote that it is ballistically the same as his 375 JRS ( which I think was on a Rem 700 donor )

His notes were more of a road map--ie weigh the standard and a.i. cases then weight them again filled with water. as an example, If it weighs 4 of water only use 3 of powder or approx 2/3 of the water weight He did not name the bullet but said the 300 gr ( if I had to guess, nosler or barnes ) he did write 88 gr RL-19

Scotty, my son said that these are old notes and that he would not automatically use RL 19, or 88 grs of it without more research. I dont think this is of any use to you but I told you I would ask.

neither the 375 A.I. or 375 jrs are still in our possession

I would bet that Fotis could give you exact data, and will as soon as he sees this thread

I would say it looks pretty close to me. That looks like an easy shooting load by the data here. Thank you April

David, thanks, I figured Guy, you and the others that like them would say a prayer it'll stand up to the 375... :mrgreen:
 

NYDAN

Handloader
Sep 17, 2013
1,345
404
What a great build, Scotty. I am looking forward to seeing targets from it.

Dan
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
So, I came home, after letting the DBC dry for about 12 hours or so, it only needs 4 but a guy has to work once in awhile. I took my last 6 rounds I had loaded and fired them from the sit on my 25 yard target out back. Pretty danged cool in and of itself as both grouped into a hole which I'd hope they would at 25, but you never know...

Anyhow, came back up and ran three CU2 soaked patches through the bore to knock out the carbon and peak at the rifling. Had MUCH less copper fouling than previous so I ran one more soaked patch through it and ran up to the UPS store to return the 375 Wby dies to Midway. Came back about 30-40 minutes later, put another CU2 soaked patch through it and it came out blue, but upon inspection of the muzzle it is dead clean! I am calling it a day. The DBC worked as it has on about 12 other rifles at this point. Pretty sure I have a winner...

Looking forward to getting it out at distance and seeing what it does.

NYDAN":1ynrg3pm said:
What a great build, Scotty. I am looking forward to seeing targets from it.

Dan

Thank you Dan! Me too buddy! Never had a 375, so this is new ground to me.
 

DrMike

Ballistician
Nov 8, 2006
35,490
2,288
Cool rifle. Meets the criterion of being different, so that is okay.
 

Elkman

Handloader
Apr 4, 2010
4,551
4
That is outstanding, are you bringing it with you???? You could hunt it later this week.
 
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