Never had one before, but bought an unused Montana magnum long action receiver. I have a 300 Win mag reamer and a 300 Ultra mag reamer. I also have a 30 cal-11.25 twist Obermeyer barrel. I'm leaning strongly to the 300 Win. Mag.
What say you?

Boy, that's a tough one. How about a 26 Nosler?

Not a bad idea, but I don't really want to buy another barrel. I've had the Obermeyer for a long time.

Look at it this way, you can always load an Ultramag down but the Win mag will never perform like the Ultramag. The down side is that the Ultramag brass is more expensive but should outlast the belted cases with proper loading techniques.
I would be a little concerned with the 11.25 twist, it might not stabilize the heaviest VLD type bullets but would be great up the 180's or 190's.

I love the Ultra Mag and I have brass. I'm concerned about it feeding properly with the Ultra Mag.

I would think an ultramag follower would help a lot in the feeding department. In fact, I'm looking for one for the 26 Nosler I'm planning on building on a Rem 700 action. Of course, the Ultramag needs an Ultramag mag box for the wider case, doesn't it?

Bob

300 WM hands down.

I hope to have the receiver in my hands this weekend. I called Montana to see if they would give me the tenon dimensions and so forth. They said no. They sell receivers, but will not send a tenon print or give that info. My buddy said it appears not to need an extractor cut or cone on the bolt. Not like a pre64 Mod. 70.

Butch, with M-70's and M-700's, their RUM's have "windows" cut in a std. width 3.6" mag box to accommodate the wider case. If Montana chambers RUM's, see/ask how they handle that.

You may want to measure the box width and compare to M-70/M-700's.

Here's a M-70 .300 RUM donor used to build a .404J. The feeding ramp mod was for fatter .404 bullets, the OEM RUM box was not altered.

DF

Another thought, is that twist fast enough for heavy bullets?

IMO, the RUM would really show it's stuff with heavier bullets.

I'm more of a .300 WM guy. You could crank 150's, 165's out of that barrel, I'm thinking your twist would work with them.

Have you worked the spin formula for that twist to see what it will stabilize?

To me, if you're gonna use that tube, twist would be a major factor in round choice.

And, I know speed helps but IME, it's a POOR substitute for twist.

DF

300 winchester or 300 weatherby

I was told supper was ready and I better get out of the shop. I've used the 11.25 before with 190s. I will probably use 180s.

Thanks for that info on the twist.

If it will work 190's, you could go RUM or WM.

DF

My vote is for the 300WM. But then, what do I know? I've only owned one (Savage) and shot one other (Colt/Sauer). Both were great shooters.

Ed

I have a deer hunting bud who loves his .300 RUM, his Dad uses a .30-378. The both shoot 165 gr. Bergers, kill hogs and WT very well.

DF

I like the Win Mag, especially with that Obermeyer barrel, but in the end it is up to you.

Well, I'm about decided on the Win Mag. In the olden days Harold Broughton did a 700 for me in the Win Mag. It was a real shooter. The only real advantage that I see with the Ultra is the ability to launch larger bullets faster. My barrel limits me to the 190s. I do have a friend that has a bench at 800yds from his feeder. He is deadly with his 300 Ultra, but he also thinks in my case the Win Mag is better. I have brass for both rifles and an assortment of bullets. I think that I'm OK on powder, but haven't checked.
Supplies are not a problem for me, but it maybe for the person that I may sell it to at a later date.
I'll keep you in the loop.

Good choice.

DF

Yer leanin' in the correct direction IYAM..

My .308 Palma rifle with a 13" twist will stabilize 175gr Matchkings out past 1000 yards. Proven by high x-counts in competition and I'm not the only one using 175-180's. I haven't done the math but I would think the 11 twist would handle at least a 210gr 30 cal bullet at 300WM velocity.

A 300 Win. Mag. it will be. I'll keep you in the loop as I go.

Enjoy your 300 Win. Mag. It will work on all critters here in the U.S. and then some.

Butch,
Given any thought to the .308 Norma?
Randy

No I haven't Randy. I have reamers for the two mentioned. I don't need another reamer.May be a very good round, but haven't checked it.

While I had a 308Norma as a little brother to my 358Norma. Unless you just want to be different the 300Wmag makes far more sense.

Isn't there now or soon to be a 30 Nosler?

Here's the M-700 RUM box in my 26 Nosler covnersion from a 7RM action. Windows are a bit different than the M-70, both work well. View is from the bottom rather than from the top.

300 win mag

It's here.

DF