Rifle Project

[jbirdwell]

I just picked up a Winchester model 70 Super Grade Classic in 300 RUM. I looking to have my gunsmith rebarrel to either 404 Jeffery or possibly 400 H&H. Leaning more to the 404 since the donor rifle is a RUM. Can someone who’s done this conversion chime in as to what other work would have to take place besides the barrel being changed out?


Thanks.

 

[PHOENIX PHIL]

I just picked up a Winchester model 70 Super Grade Classic in 300 RUM. I looking to have my gunsmith rebarrel to either 404 Jeffery or possibly 400 H&H. Leaning more to the 404 since the donor rifle is a RUM. Can someone who’s done this conversion chime in as to what other work would have to take place besides the barrel being changed out?


Thanks.

I’d call Wayne at AHR, he’s done this before.

 

[WAB]

I’d call Wayne at AHR, he’s done this before.

If he won’t take it call LeRoy Barry at Canyon Creek.

 

[intj]

I just picked up a Winchester model 70 Super Grade Classic in 300 RUM. I looking to have my gunsmith rebarrel to either 404 Jeffery or possibly 400 H&H. Leaning more to the 404 since the donor rifle is a RUM. Can someone who’s done this conversion chime in as to what other work would have to take place besides the barrel being changed out?


Thanks.

I have opened up the magazine on a couple of my own M-70s and installed Wyatt's 3.825" magazine boxes. Before I had my mill and lathe, I had two other done.

If you want to lengthen to cartridge OAL, I really think it's better to use a non RUM action for these conversions. The M-70 RUM action has a cutout in the left feed rail. While they work great at the factory 3.6ish length, they can give problems when milling the receiver back .200ish" to fit a Wyatt's box.

Last year I did this mod to a 338 Win Mag action. I made a 33-28 Nosler and it came out great. The rifle feeds very well, though I did have to move the magazine spring aft on the floor plate and strake it into position.

I also did this mod to a 300 RUM action while making a 30-28 Nosler. It won't feed because when the round gets to the left rail cutout it pops up. I am still fussing with this one, and I think I might be able to get a center feed magazine box to work.

Anyway, an important thing to make sure of is that the 404 will feed in the RUM box. I suspect it will with the standard length box, but I am not sure it will work with the 3.825" inside length Wyatt's box.

I recommend whoever is working on your rifle isn't very aware of this issue.

 

[jbirdwell]

He is a gunsmith I trust and has done work for me in the past. I was asking the question more for my own education but plan on passing comments on things to watch for to him. I still have to decide between the 2 calibers but probably should have just bought a 375 H&H if I was going the 400 H&H route.

One question on mag length, I was reading that the coal on the RUM was longer than the 404. Am I mistaken?

 

[intj]

He is a gunsmith I trust and has done work for me in the past. I was asking the question more for my own education but plan on passing comments on things to watch for to him. I still have to decide between the 2 calibers but probably should have just bought a 375 H&H if I was going the 400 H&H route.

One question on mag length, I was reading that the coal on the RUM was longer than the 404. Am I mistaken?

The RUM has a listed COAL of 3.6, but the cartridge really wants to be close to 4" with 215 - 245 grain bullets. I am not sure of the listed COAL of the 404, but I would expect 400 grain bullets might do better at more than 3.6". It's when you open up a RUM M-70 magazine that that left rail cutout can be an issue for feeding. I am sure there is a solution, I just haven't found it.

My M-70 in 416 Rem only has a 3.62"
magazine box, and that was limiting. 400 grain SAFs slightly compress the Varget with the load it liked. I didn't have room in the case to run mono soft points with Varget, and this barrel REALLY likes Varget.

The 404 is a fatter case than the 416 Rem
so it may not run out of case capacity at 3.6".

 

[jbirdwell]

Thanks for the info

 

[jbirdwell]

A couple of references shows the 404 with a c.o.a.l of 3.530”

 

[375 Ruger Fan]

@jbirdwell I did the exact thing you are about to do. I started with a Mod 70 Super Grade in 300 RUM and sent it to Dennis Olson in Montana. The long lead time item was getting the barrel, but once that arrived it didn't take Dennis but a couple months.

Thread 'I joined the 404 Jeffery Club today'

Dec 17, 2018

For the last couple of years, anyone that's a regular on this site knows there has been a lot of positive comments and chatter on the 404 Jeffery. To be fair, that same statement can be made for..........pick a caliber. However, the 404 seemed to have a special place in African history and fills the spot in my gun battery for something bigger than my 375.

As many of you know, the two popular ways of achieving 404 nirvana is the CZ-550 or find a Winchester Model 70, preferably in one of the RUM cartridges, and have it re-barreled and a little other tweaking from a gunsmith.

I sent...

• 375 Ruger Fan
• Replies: 116
• Forum: .375 & up

• 

 

[Ontario Hunter]

The RUM has a listed COAL of 3.6, but the cartridge really wants to be close to 4" with 215 - 245 grain bullets. I am not sure of the listed COAL of the 404, but I would expect 400 grain bullets might do better at more than 3.6". It's when you open up a RUM M-70 magazine that that left rail cutout can be an issue for feeding. I am sure there is a solution, I just haven't found it.

My M-70 in 416 Rem only has a 3.62"
magazine box, and that was limiting. 400 grain SAFs slightly compress the Varget with the load it liked. I didn't have room in the case to run mono soft points with Varget, and this barrel REALLY likes Varget.

The 404 is a fatter case than the 416 Rem
so it may not run out of case capacity at 3.6".

I used 416 Rem bottom metal from Swift when I built 404J on Czech 98 Mauser. I expected I would have to open the shoulder area inside the box to meet Paul Mauser's cos 30 formula. I did not. It worked great as is. The shoulders of shells in the box are pinched a bit but that actually helps as the bullet tip for cartridge being loaded is pointed directly at center of the loading ramp instead off to the side of the ramp. Box length is also fine for SAMMI length 404J cartridges. I have a copy of Swift's blueprint with specs if interested. Might be useful for comparison to what's in your RUM M70.

I cannot see that there would be a huge problem with feeding rails. The RUM cartridges and 404J should be very close to same thickness at the base. Of course the point at which the rails release cartridges onto bolt face may need to be modified. Be careful to make the changes to feeding rails in correct order. Stack three cartridges in the box and modify the contacted rail so it will feed the top cartridge. Then stack two cartridges in the box and modify the other rail. Then you are finished with rails. One cartridge only in the box still MAY not feed properly. Not unexpected. Do NOT change the rails. Modify the follower to make the last shell cycle properly.

RUM and WSM do NOT have same diameter rim as 404J. Yes, everyone says those cartridges were built on 404J ... but not quite. Reloader shell holders for RUM and WSM will NOT hold 404J (I know because I tried them both when RCBS #41 was unavailable). As I recall, both have slightly smaller rims than 404J. I suspect the bolt face and extractor for your RUM may need to be modified to accept 404J, albeit only slightly.

 

[Ontario Hunter]

A couple of references shows the 404 with a c.o.a.l of 3.530”

That is correct. Your RUM mag box should be plenty long enough.

The 300 RUM actually has a narrower diameter shoulder than 404J (0.525" vs 0.530"). This tells me the feeding rails should have more than enough metal. However, the box MAY be a bit narrow in the shoulder. Or even overall slightly too narrow (the RUM rim is just slightly narrower than 404). However, a good gunsmith should be able to widen the box ... if it's even necessary. We are talking only 0.0025" difference on each side of the box! I have a feeling Winchester didn't make their magazine box tolerance terribly tight. Odds are very good your mag box and feeding rails will take 404J with little or no modification.

 

[jbirdwell]

Thanks for the info