7MM WSM - LA or SA with an extended mag box ...?

[dwm]

So which would be better, building a new 7MM SAUM/WSM based on a 7MM RUM action or based on a 7MM SAUM/WSM action and then having the mods done to the stock and action to make it accept a Wyatt's magazine box? This would be intended to carry at least one round in the mag for a follow up shot if necessary.

Would a 7MM SAUM/WSM feed ok from a RUM long action? I like to seat the long 7MM bullets way long and in a short action they just don't fit in the mag well. Not sure if the Wyatt's box is worth the effort or cost. If one were to start from scratch which way would be best?

Rifle would have a 26 inch barrel with brake and at most a Sendero barrel contour, maybe even a bit lighter. Something that one would be able to carry in the field.

All comments welcome ...

[ 03-22-2004: Message edited by: dwm ]

 

[Guest]

The Wyatt's box gives you the ability to seat you bullets out to an OAL of 3.06"

If your rounds are longer than that and you want to feed from the mag then I guess that the long action would be the way to go

 

[dwm]

But what if your were starting from scratch, is the extra work and swith/machinist cost for the Wyatt box worth it?

If I could do the work myself it would be a no brainer, Wyatt box done deal.

 

[chris matthews]

Have to correct JD on this one. The outside of the extended box is 3.06", the inside is 2.85" to 2.9" Best way to determine which way to go is decide what bullet you want and at what length you want to seat it and then go from there.
Either action will work fine.

[ 03-23-2004: Message edited by: chris matthews ]

 

[dwm]

Thanks Chris,

Both the 7mm - 154 Interbond and 162 AMAX seated to optimum length in a RSAUM case are > 2.95. The 168 SMK is 2.852 OAL at optimim seating depth. Only the 139 Interbond and 160 Partition fit in the mag well with a decent OAL. This is with the top of the boat tail seated to the bottom of the neck.

The factory mag well in a REM700 SAUM will handle an OAL of 2.825 - SAMMI. So with the Wyatt box I would be gaining 0.025 to 0.075 inches, is that worth it? (I am still thinking about it, sure wish I could do it with a dremel.)

The 7mm WSM has a max SAMMI OAL length of 2.86. I guess the Winchesters and Savages must have a longer short action mag well than the REM700 to handle the WSM OAL.

7mm case length:
SAUM 1.724" base to bottom of neck - 75 GR water
WSM 1.858" base to bottom of neck - 83.2 GR water

Some 7mm bullet lengths:

1.280" 160 Partition
1.288" 139 Interbond
1.365" 175 Partition
1.366" 168 SMK
1.386" 154 Interbond
1.402" 160 Accubond
1.419" 162 AMAX
1.438" 168 Berger

[ 03-24-2004: Message edited by: dwm ]

 

[Brent]

Doug,

It's interesting that you list the WSM as being over .130" longer than the SAUM but the capacity is 8gr less?

Possibly a type-0??

The 176 Cauterucio is 1.485".

Just looking over the 7/270 wsm reamer plan and figuring a throat length for the 176, I can't see how you keep those bullets above the neck/shoulder junction in a Wyatt box, even with the lighter bullets.

The 700 rails for the Ultramag feed the WSM perfectly, that's the way I'd go, cheaper and plenty long in the box at 3.66".

 

[chris matthews]

dwm,
The Wyatt's gives you about 0.100" more than factory. With the lengths you mentioned I would put it in a long action and not look back.
The WSM's are longer than the RSAUM, and Winchester's SA is actually a medium action, being in between the SA Remmy and the LA.

By the way, you don't have to buy a RUM action to feed the WSM. Any mag action will work with a few minor changes. I think they are cheaper than the RUM actions is why I mentioned this.

[ 03-24-2004: Message edited by: chris matthews ]

 

[dwm]

Brent, your right, I had the two mixed up. I fixed it.

7mm water capacity:
SAUM - 75 GR water
WSM - 83.2 GR water

7mm case length - neck length:
SAUM 1.724" base to bottom of neck
WSM 1.858" base to bottom of neck

----------------

Chris,

The WSM's are longer than the RSAUM, and "Winchester's SA is actually a medium action, being in between the SA Remmy and the LA".

Thanks, I have been wanting to know this for quite some time. But are they long enough to seat bullets way long in a 7mm WSM case?

By the way, you don't have to buy a RUM action to feed the WSM. Any mag action will work with a few minor changes. I think they are cheaper than the RUM actions is why I mentioned this.

You mean like a 7mm Mag or 300 Win Mag REM 700 LA? What changes would have to be made?

I am now thinking buy a REM 700 BDL SS in 7MM/300 RUM, sell the barrel, toss the stock, add new stock, barrel and brake with 7MM WSM chamber. Ditch the J-Lock.

[ 03-24-2004: Message edited by: dwm ]

 

[chris matthews]

DWM
Using a 7 or 300 Mag action, you would have to change the magazine and open up the feed lips on the action a tiny bit.