I am going to rechamber a rifle of mine to one of these calibers, which one should I go with 7mmSTW or 7mmRUM? The gun is a browning a bolt and it currently is a regular 7 mag with a 9 1/2 inch twist. Which caliber would you go to if you had the chance. And dont tell me to leave the gun alone because I already have a perfectly fine 7 mag and I want something else. I will handload for them, but to start I will be using factory ammo only. Ok now what would you do? Thanks guys

Bowman, I like both rounds, the first thing I would do though is to check the magazine length of your rifle to see if that factory ammo will fit. I`m thinking the Browning has a 3.4" magazine, and you need a rifle with a 3.7" or you will have a nice single shot, Tim.

Tim in Tn,

I called my gunsmith and he said he could just change out the magazine??? He said he would use a magazine for a .375 h&h and that would work? Does that sound right? I definately don't want a single shot. thanks

Boman,
First things first. Will the magazine even hold these cartridges. I won't comment on the rest because I wouldn't do either.

The 375 magazine will hold the 7mmstw But I can't tell you if it will hold the ultramag.

If you go out to www.hodgdon.com and look at the Case Overall Lenght the 7 RUM is longer but only by 35 thousands with a 160 grain bullet vs the STW. Another thing to consider is your gunsmith going to have to open the face of the bolt up for the 7 RUM and lengthen the mag well for the longer magazine. I think the case rim is bigger. Something to think about. Both are good cartridges, but you get about 120 fps faster with the RUM with a 160 grain bullet. Would be interesting to know.

Oh and the magazine should hold the cartridge but the magazine follower might have to be altered to hold the cases in the magazine right. You don't want to be out in the woods and pull the bolt back and the case pops out instead of staying in the magazine ready to chamber. Took a Ed Bround short action 308 and the cases popped out when the bolt was pulled back. Removed the follower and replaced it with a factory one and worked just fine.

The Browning A-bolt is the last rifle I'd personally do such(or ANY)conversion upon. It is a POS,in my not so humble opinion(there boys,I was the first to say it).

That before taking mag box constraints,barrel length issues and mag box/follower alterations,into consideration.

There are much better platforms,to base such a rifle upon. Hope you can appreciate an honest reply..............

The 375 box will work with the STW, and might work with the RUM. Your bolt face is the correct dia. for either case.

I have never performed a converson on a Browning A-bolt, I do know that Winchesters are easy to do a converson on and are very good actions. Weatherby actions are also very good actions to do conversions on. So are Sako. But if you already have a action, why not use it. You don't want to just throw it in a box and not use it. All actions are not near as good as they use to be. Everything is made cheaper as to keep cost down. If you really want to get wild, you can blow out the shoulder on the STW to a 40 degree. I have made several rifles using this chamber on Weatherby actions. Good rifle. Had CH-4D die company make the dies and Clymer made the reamer.

Deaddog1440-The 375 magazine will hold the 7mmstw with no modifications.The rim diameter is the same for both cartridges so the bolt face will not have to be opened up.I have rifles in both cartridges and have tested a couple others and the average velocity gain for handloads is in the 50fps to 75fps range.

I would have to agree with Bigstick on this one.
There are MUCH better platforms to do that on.
I personally would go with the RUM.

The .375 mag box on your Abolt will not work with the RUM. It would have to be modified to feed the fat rounds. It will work on the STW though.

Bolt face is the proper size.

But once again, I wouldnt do that on an Abolt.
Not alot of known accuracy smiths would take that one on. I know I wouldnt.

The Abolts are best left as is. The used to (not sure now) epoxy the barrels on, making it real tough to pull one for such a procedure.

The bolt design makes it very hard to true the bolt face, and the actions are probably the most prone to flex there is.

Get a Rem 700 from Walmart for $400.00 and convert it, or better yet, just build it for that round.
You will need all the accuracy you can get to take any advantage of either the STW or the RUM.
If the rifle won't shoot 1/2MOA, then the extra range you get will mean nothing.

No offence, just giving a well educated opinion.

Celt

To rechamber your A-bolt from 7mm Rem Mag, you simply recut the chamber and switch the box magazine to the 375 one. To rechamber to RUM, might be a little tougher, depends on whether the A- bolt is available from the factory in 300 RUM or not. If it is, it's the same story as the 7 STW, just rechamber and swap magazines. - Dan

Ditto what Dan just said.

As to which is the preferable cartridge, the STW has more case capacity than is generally practical, anyway. Any gains in velocity with the RUM over the STW will be marginal at best, and will come at the expense of several grains more powder, more muzzle blast, and more recoil (especially with your 24 inch barrel).

I'm sure it's not a big deal to get the .375 magazine to work with the RUM case, but your capacity will be only two rounds, as compared to 3 with the STW.

Added to the fact that brass will be more expensive for the RUM, I think that the STW is by some bit your better alternative.

Thanks to everybody who replied. I appreciate your honest replies. but If I may ask. I know a few of you said you don't like the Brownings can you elaborate more? examples? I admit I have had a problem with one Browning too. It was a .300 RUM in the Medallion model that I got for my dad. We could not get the damn thing to load from the top of the magazine!!!! I was told by browing that is should and I should take it to the authorized browning dealer I bought it from. well I did and they said that it can not be loaded from the top like most guns.. So i got rid of it. I've had a few other brownings and never had a problem.. So I ask you tell why you either would not do this to this Browning or why you don't like brownings. Also if I end up doing it I think I will go to the 7 mmSTW. Seems like more work and hastle to go to the RUM. Thanks to everyone.

Also I forgot to add that the a bolt has a 26" barrel.. Also for you guys that know what your doing do you know about what the cost would be.. Assuming I go with the 7mmSTW. Thanks guys

Well, the last time I had one of these types of projects done, it cost me $175. CDN, which is about $115 US. The 26" barrel is a good thing, in either of these calibers, and if the A-bolt comes in a 300 RUM, then a simple magazine change should suffice, same with the STW. You might have to do a little work on the feed ramp, for the RUM, but if you do it won't be much. - Dan

I think I will probably go with the STW, I've been looking at some ballistic info and Conley precision shows its barnes xlc loads at about 100 fps faster with the STW than the rum? Can that be right? Anyways now I have another problem..Over the weekend I went to a gunshop and accidently came accross a very nice Sako 75 stainless/synthetic.. In 7mm STW..Man was that rifle sweet! So now i've just got to decide what I should do? Should I go with the Browning and save a little $$ and get the Boss. Or do I spend a little more a get that fine Sako??So I am asking for your help again? what should I do? Thanks

SELL THE ABOLT and get the Sako!!!
You will be much much more happy with the Sako.

Sako=Sah Koe Seiko=Sae Koe
Sako builds rifles, Seiko makes watches.

Just a little pronounciation lessen taught to me by the gentlemen at Sako years ago.

Celt

Celt,

Thanks for the pronunciation lesson..seriously. Me and my brother were just talking about this.. Could you help with a couple more names?? how about Tikka?? is it Teeka or tika, Also what about Kahles, is it Kayless or Kohless, or Kohleese? Thanks again.

Boman, Barnes' info is a little suspect. They have made quite a few mistakes in their manual (check out their web site for corrections). I would expect a RUM to be a little faster than a STW. How much would depend on the guns involved. Why don't you buy the Sako, and convert the A-bolt. Then you can compare the two yourself, and report back to us. remember, "A man can never have enough red wine, books, or guns". - Dan

Dan,

While I completely agree with you and think I should get both the wife disagrees wholeheartedly!. So unfortunately I will have to go with one or the other. But I wish I could have both. maybe later but for now just one...On another note the information that I got those figures for were from Conley's precision ammo site. the address is www.cpcartridge.com check out the loads for the barnes xlc bullets. it shows the 7mmstw about 125fps faster than the 7mmrum with a 140gr bullet....So I dont' know what to think. I haven't had time to call them on it though. Thanks for the reply!

Boman-I have both calibers and can assure you that on average the larger case capacity of the ultra will provide slightly more velocity when loaded with the same bullets to the same pressures.A very fast stw may match a slow ultramag but on average the ultramag is a little bit faster.

[ 08-07-2002, 04:19: Message edited by: stubblejumper ]

Buy the Sako.....sell the A-Bolt to your brother-in-law.

Boman, thanks for the link. I don't know what to say about his data. The RUM has a larger case capacity, and all other things being equal, it will produce higher velocities. Perhaps, as Stubblejumper mentioned, it was a "fast" STW and a "slow" RUM. Curious. Well, if I has to choose between the two, I guess I would go with the Sako.

Celt, I just finished an article about a gunwriter touring the Kahles factory, and according to the article it is pronounced "Kaw-less". As long as we're on the subject, and one that's made me crazy for years, Porsche is "Por-sha". At least according to the surviving family members. - Dan

Thanks to all of you guys. I have to say even though I am fairly new to this site. It sure is a helpful one. Thanks again to everyone. I guess you have twisted my arm to get the Sako... Now to decide what scope to put on it... just kidding you guys have helped me enough. Thanks again and I hope everyone fills there tags!

Thanks Dan. I will now use the proper way of saying it.
It truely is important to me to pronounce these names correctly.
I may even gather a collection of mis-pronounced gunstuff items and put them up on my website.

H.D. Rifles

Hi Celt. Nice site. I especially like the flyweight rifles. Cool. - Dan