A word of caution to anyone about to start loading any of the new short mags.With little load data in the existing manuals the most accessable data can be pulled off of various web sites ie/ powder manufactures,bullet makers and a few daring souls have posted data.I have been loading the 7mmSAUM since last spring and have just purchased a 270 WSM.
When I started loading the 7mmSAUM I checked case capacity by completely filling the case level to the top of the neck with W760 powder.I wasn't concerned with the exact capacity in grs of water,I just wanted a comparison and W760 is a lot less messy than water.The following are those comparisons 7mmSaum 73.5grs w760
7x61 77 grs
7mm Rem 82.5 grs
7mm wby 84.5 grs
280 rem 72.5 grs
270 win 70 grs
270 WSM 78 grs
A quick check indeed showed that the max loads I had worked up for the 7mmSaum were only a grain or 2 above max 280 loads for a bolt action 280. When I started gathering load data for the 270WSM I had no trouble finding loads that listed a max of 67.4 grs of RL 19 and 70 grs of RL 22for 130 gr bullets. Am I ever glad I started at least 10% lower than those max loads. I found that the max in my rifle was 63 grs of Rl 19 and 67 grs of Rl22 with 130 gr bullets. I shutter the think what another 4.4 grs of RL 19 would do. Checking back in several loading manuals I found that in the Nosler # 4 manual they listed a max load of 70 grs RL 22 with the 130 gr bullet for the 270 Wby.That wby case held 6.5 grs more 760 than the 270 WSM case. If 70 grs of RL 22 was max in the Wby freebore and all just think where the pressure would be in the 6.5 gr smaller case of the 270 WSM. Just be carefull. I wouldn't want to see somebody hurt trying to prove those wild assed velocity claims from Win & Rem correct.

Another thing is that pressure seems to come on in a hurry. One load I was working up in my 223 WSSM went from sooted necks to flat primer in three grains (minimal headspace chamber -- it was pressure). Use a double dose of caution, and a large dose of common sense. JMO, Dutch.

Smowman, I totally agree with you. I had a 300 WSM Abolt stainless stalker and I still have a 270WSM composite stalker. I tried and tried to get near the velocities that were advertised without resorting to dangerous loads. I never did get close except for a 180 gr load in the 300. I was using 760 powder and I finally got 2975 fps for 10 shots. I gave up on it. In the 270, I'm using RL 19 and a 140gr Accubond. The load velocity is 3075 fps. and I'm satisfied with it because for 8 shots, I got a .768 group @100 yds. But I never got the claimed factory velocities or what some people were claiming. I even wondered about my chronograph until I checked it with several other rifles with known loads. IMHO, they're nice rifles, but not quite what I was expecting. BTW, I traded the 300 for a Abolt stainless stalker in 7mm-08. Now that's a sweet rifle. No recoil and with 43 gr Varget and 140gr Ballistic tips, the first group (5 shots) 5/8 in. @100 yds.

I have had a 7mm WSM in a M 70 for a year and a half and it's a normal rifle and cartridge. The loads it takes are just about what the data says. For a while my velocities were about 75 fps low and that was traced to a out of calibration chronograph.

I did have a Savage 12fvss in 270 WSM for a few weeks last summer. The factory 150 gr Power Point factory load was hot with some bolt lift difficulty. Also the velocity was 73 fps higher than the factory load velocities. The tops of the lands in this rifle were very dark and rough. I sent it back with a letter describing the problems and Savage did not understand what hard initial bolt lift might mean. They polished the chamber and replaced the extractor! Clearly they just don't understand.

I sold that rifle.

I see those two WSM's as satisfactory cartridges that are loaded hot. This has happened with many other new cartridges when they were introduced.

Hi guys, I have been looking over everything that i can find about the new shot mags, both Winchester and Remingtons. Have also been working with at 300 WSM that was built by HART. The rifle that HART put together on a Remington 700 Sendaro with a 26" barrel will come no where near the factory claimed velocitys, no mater what we do with it. I have come to look on the short mags as short fat copies of cartridges that have been in place for a long time. The 300s are not much more than a short fat 30-06, and that goes for the rest of them as well. The new 223 SM isn't anything more that the good old 22-250. Never forget that the gun companys are making gun for one reason "TO SELL THEM TO YOU". The one part that they did get right is in getting rid of that MAGNUM BELT. There is no need for the belt in a bolt action rifle. The take off on the PPC design was also a great idea, but both REM and WIN missed the boat! The RUM (long UMs) have too much case cap. and the short mage too little. They would have been far better off coming out with true magnum cartridges in a beltless design that were near the 300 Dakota cartridge,or a little less in case cap. The short mags are another flash in the pan like the 260 Rem. Did we really need that cartridge, or these short mags? Why not build cartridges that are designed for improvements in accuracy and performances, and not just to sell guns.

Sendaro

Perhaps an opposing view point to yours might be:

Most people probably consider the velocity that a 270 Winchester can deliver for a given sectional density is all that is ever "needed". The 300 WSM will do that as velocity potential with its 180 grainers is about like the 270 Win with 150s. Obvioulsy the 270 WSM and 7mm WSM do a bit better. In addition all this is obtained in a short action, for whatever that is worth.

Thus any improvement in performance probably falls into the "want" area and the Remington Ultras provide the maximum performance that is easily obtained from the Rem 700 and Model 70 actions. As you know the next step up is the 378 Wby based calibres and they are nor easily fitted to the Rem 700 and M70.

Having said all of that I do think if the there were no WSMs and no Rem Ultras but rather a bunch of calibres based on a 2.5" Ultra case chambered in in both R700 and M70 then Winchester and Remington would have sold more rifles.

Mike

Mike375, I agree that 2.5" UM case would be the way that they should have went. The big firearm companys are always behind the curve, and when they do make a move they just can't seem to get it right. Cases in point 244 Rem, 7MM express, 6.5 Rem Mag, 260 Rem, 225 Win, 300RUM, The short RUMs,the STWs, and so on. What are these people thinking!!!!!!

Well, just in case there's someone left in this place who hasn't yet heard me say this, what shoulda happened was Winchester - foreseeing that no one else would chamber their cartridges, took advantage of their 3.1" action, and made the WSM line on a 2.34" case instead of 2.1".
This would've given them 10g more case capacity to work with, and put the WSM pretty darn close to what the 2.5" Ultra would've been anyway.
Besides, neither of them makes a 2.34" action anymore, do they?
I'm still waiting for Winchester to pull out a 3.6" 416 cartridge on it's .555" casehead size, and blow the Remington off the market. (Since most of the 416 Rem's seems to be on M70's anyway.)

I would bet that if the Remington 700 in 300 Ultra was a bit more expensive, say between where it is and a Wby Mark V, and was given some distinctive name, then they would have sold almost as many and have made a heap more profit.

In my opinion Remington and Winchester should look at some of the things various car makers do and also a look at how Weatherby does things might be a reasonable idea.

Mike

Very good points above.The bottom line is to always start low and work up.I know with the WSM,WSSM,and RSAUM this can be hard to do as Good Data can be hard to come by.One good place to go for infomation and Data for these is at
www.shortmags.org

I have worked with 3 different 300 WSM all will SAFELY Match Factory Velocity Claims with Factory Loads,getting there with Handloads is a horse of a different color,It can be done but takes some real careful reloading to get there.Most of the loads are off the data by 100 to 200 fps low even at max, while the factory loads do as the ads claim
3275 with 150gr Ballistic Silver Tips.

I think this may be due to the use of "Mag" WLRM primers in the Reloading Data over the Std WLR that Win uses in thier factory loads.I can't prove it yet as I haven't used to many Std primers loads.Of all the Data I have seen for the 300 WSM no where will you find ??72-73grs.???of Win 760 with 150 gr Bullets.

From everything I've seen on the all the web pages is it seems be a Hit or Miss with the Short Mags,meaning one rifle will give it while another one won't.Also some of this could be due to alot 22" barrels instead of the 24" barrels that the data is based on.

I love the ones I have worked with and I'am working with,and wouldn't trade one for a Belted Mag.I can't and won't tell you they will be close to the Belted mags like the 300 Win Mag,7mm Rem or 270 WBY.But I will tell you I believe these to fill the liitle gap between the 3006 270 and 280 rem with 22 barrels and the Belteds with there 26",and I would bet this gap would be lower with the before with 24" barrels.

I'm to the point of not wanting to read threads like this one anymore. Shoulda, coulda, woulda is all hindsite babble.

There is a reason the WSM line was made as SHORT as it was, so it would fit in a short action! Making it 2.34 inches would have made it necessary to use a long action. Another point is that when Browning designed the WSSM line, they built an action from scratch that is a full .500 inch shorter than the standard short action. This all means the resulting rifles are lighter and stiffer actions which in theory means more accuraccy potential.

As for my 300 WSM, I have been able, in every bullet weight, to obtain factory velocities. I certainly didn't do it with WW760 powder! I tried it just after I got the rifle in May of 2001. It runs into pressure WAY before it gets to the desired velocity.

Like you, snowman, I extropolated loads by going halfway between 30-06 and 300 win mag. There was only the data put out by Winchester for 760 powder at the time I got the Browning a-bolt. I started with H4831 SC, AA XMR4350, and IMR 7828. I was able to get 3125 FPS from 165 SST's with the AA4350. Good .788 inch groups as well. The loads I came up with are close to max in the published data available right now.

The load I'm hunting with now is the 165 Hornady interbond using H4831Sc that is 2.0 grains over what Hornady considers max. Pressure ring measurements, chrongraph readings and accuracy all came together. At 3043 fps, it's about 100 fps under what the factory claims it's 165 does, but with a .467 goups I think I'll keep it. And with an extreme spread of 11.6 and a 5.3 SD It's consistant as well.

snowman,

In my 7WSM, I have found W760 good for the light bullets. For the heavy to medium bullets, the best powders have been WXR, RL-19, RL-22. Data for the short mags can be found in the Lyman 48th or the newest Hornady 6th loading manuals. BM