Separate names with a comma.
Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by casilva43, Aug 22, 2008.
what are the differences between the 7STW vs. 7MM REM MAG VS. 7 RUM??
Velocity! Power! Recoil! Muzzle Blast! Case Capacity! Barrel Life!....all personal preference.
The STW should out perform the Rem Mag by a couple hundred feet per second. The Ultra Mag should out perform the STW by MAYBE the same.
But with the added power comes the added recoil, muzzle blast, loss of barrel life and a little more cost to shoot.
I tend to focus on what the bottom line is as I know it.
If you reference a few of the guys from Best of the West (it really does not matter what a personal opinion is of the hunters or the show), they take game all the time at 1000 yards with a 7 Rem Mag and a 168 Berger VLD over a stiff charge of Retumbo.
It boils down to knowing your trajectory and velocity and the characteristics of the bullet in THAT rifle.
I was told that even John Burns went from using the modified 7STW back to the Rem Mag as it was less picky.
...very very little.
Except that the 7STW is older ctg and more lazer straight and dont really begin to drop till after 400 yrds or so. But the 7RUM ammo is probably more available. The 7RemMag is a great cal, the most popular mag in ammos sales annually, and most stores sell some kind of 7Remy ammo. It's really the best of the bunch in affordability. And I'd put my 7RemMag with Hornady Lite Mag Ammo up against most 7RUMs and 7STWs. Good luck on your hunt.
In my testing using the same barrel for each chambering and then rechambering it for the next larger round with same throat design, this is the results I got with the 160 gr Accubond loaded up until I just got a slight ejector mark on the case head.
This was out of a Lilja 1-9 6 groove barrel, 26" finish length
7mm Rem Mag.................3033 fps.......RL-22
7mm STW.......................3140 fps......H-1000
7mm RUM........................3264 fps......Retumbo
I am not saying these were top end loads. I just loaded 1/2 grain up at a time until I got an ejector mark on the case head using Rem cases in all to again try to keep the variables as close as possible even though some brass is harder or softer from lot to lot.
Again, I am not saying these are absolute max loads, that is not what I was after, I was looking to see what velocity each could when loaded to as close of chamber pressure as I could. I would say these were all good top end working loads in that barrel but there are some that are not opposed to a more noticable ejector mark and if the primer pockets hold up, so be it.
Basically, in this test you get 107 to 124 fps increase as you step up from the Rem Mag to the Ultra Mag.
This test is also not totally fair between all the cases, especially with the Rem Mag, why? We have to look at usible barrel length for each test. As the Rem Mag is roughly 3/8" shorter then the other two, it has a longer usible barrel length then the other two and will produce more velocity. How much more in 3/8" barrel, probably not enough to notice or pay attention to but for those purists, you know the type, this would not be a scientifically pure test.
Kind of like using bullet drop to estimate a BC number. Even though you can hit a target from 0 to 2000 yards, it does not matter to some, its still not a correct BC for that bullet no matter how accurately you can predict down range trajectory using that value.
Anyway, some will say the peak performance will be 200 fps over the smaller rounds. I will admit, I have seen some comparisions that were the same but when all are loaded to as similiar pressure as possible its not nearly that much. Still, 100-125 fps is a sizable increase in performance.
Some will also say the 7mm Rem Mag offers little over the 280 Rem..... Same story, about the same 100-150 fps difference in most comparisions. Is that worth it to you, that is your call.
What I generally look at is what the bigger cases can offer you over the smaller. Not comparing same weight bullets but what they can do with heaiver bullets.
In the 7mm Rem Mag, the 175 gr bullets can certainly be used but in my opinion, the 160 gr bullets are the best heavy weight bullet class for this chambering.
The STW really does well with the 175 to 180 gr class bullets as well as the 160. THe RUM really does its best, most consistant work with the 175 gr and heavier bullets such as the 180 gr Berger, 189 gr Caut. or 200 gr ULD RBBT. Thats what really makes these large cases run smoothly.
If you look at it this way, loaded to the same velocity level, you will have a 160 gr the Rem Mag, a 180 gr in the STW and a 200 gr bullet in the RUM. WHen you look at it that way, it shows you what the real difference is.
Not sure if Kirby has done any testing on these, but a couple of other 7mm cartridges are the 7mm WSM and 7mm Dakota. The WSM is advertised to get about 50 - 200 fps more than the Rem Mag, depending on load, and Dakota advertises it's 7mm to push a 160 gr bullet @ 3200 fps from a 25" barrel.
I have not done head to head comparisions between the 7mm WSM and 7mm Dakota but I can tell you from the couple dozen rifles of each I have built, in same length barrels, loaded to similiar pressures, the 7mm WSM WILL NOT outperform the old 7mm Rem Mag.
It will come within 50-75 fps with same length barrels but it will not outperform it on average and the heavier the bullet you use, the more advantage the Rem Mag has over the WSM. The problem today is that the 7mm Rem Mag is down loaded so severely to make the STW and RUM look better on paper.
If you look at factory load levels, yes the WSM outperforms the old Rem Mag but when you realize that in proper handloads, the 7mm Rem Mag will do anything the 7mm Wby Mag will get you, it clearly shows you why it outperforms the smaller WSM.
Its easy to manipulate numbers to make a smaller round look more impressive then a larger one, that is basically what has happened with the WSM hype. Do not get me wrong but most of what is told about them, even by their manufacturers is hype in one way or another.
While the WSMs are close enough to the standard belted magnums to combine them in the same performance class, they will not outperform the old rounds. Its just not sexy to say "The 7mm WSM comes close to the 7mm Rem Mag".
The 7mm Dakota, its a potent chambering. Its only limitation really was that the old brass was pretty soft. It is a ballistic twin to the 7mm STW, nearly fps for fps in same length barrels and with same weight bullets. Hornady is supposed to be making the new brass and I have heard its much harder and will take more firings per case. That is good news.
I cannot speak for the 7RUM,but I do have a 7mag and a 7mm STW.First off the 7mag is by far the most efficient and really makes the others step it up to beat it.IMR-4350 is my go to powder for the 7mag.I get ave. chronogragh velocities of 3250fps with the 140gr,3200fps with 150gr and 3150fps with 160gr. out of a 26" barrel.I recently aquired a 7mm STW with a 26" barrel and have been doing some load testing With H-1000,IMR-7828 and Winchester WXR powders using 150gr bullets.I am getting around 3250fps with my loads using H-1000 and IMR-7828 and could squeeze maybe a 100fps more out of her with these two powders which are very similar.The Wichester WXR gives me the highest velocity,I'm not sure how much more I can get out of it,but I'm satisfied,I'm getting 3450fps with the 150gr. bullets.The 7mm STW will out shoot the 7mag,but it takes about 15grs. more powder to do it.
Kirby or any one else out there have experience polishing throats every 200 to 300 rounds? I read some data on the 6mm Competion Match chambering and they were recommending polishing the throat every 200 to 300 rounds to extend barrel life and were using JB. I have a 7mm Dakota and I plan on shooting the barrel out either this season or next and it only has 30 rounds down the tube right now.
My 7 rum will shoot 180 hybrid at 3200, shot under 10" at. 1760y
Fifty driver is dead on on all accounts. The comparison and differences between the , 7 mag, 7 STW, and 7 RUM is a interesting discussion. Let me say, that right from the git go, I am a staunch supporter of the STW, and the 7 Mag as well. The 7 RUM really didn't catch on, as in anything else, you can have TOO much of a good thing, and the RUM is just that. It didnt shoot well for me, try as I may, and by the time I DID get it to shoot, the velocities weren't much over my STW's.
On average, I can get another 150-200 FPS over 7 mag speed, all else being equal, meaning bullet weight. The STW is SHOOTABLE, and accurate, and very hard hitting. The 7 mag, is a little slower, but not too slow, and recoil is very manageable. Actually, the recoil in the STW is also manageable.for extreme long range, go with the STW, and don't look back. But, the seven mag will not let you down either. TWO of the three you mentioned are excellent cartridges. IMHO.
Kirby knows more about this than me but Ammo guide shows that the difference in case capacities is less between the 7 RM and 7 WSM than the differences between the Dakota and the STW
7 WSM, 79.7
7 RM, 80.8
7 Dakota, 90.7
7 STW, 92.7
Maybe Ammo guides info is inaccurate?
With the advent of RL33, the 7 RUM could be a whole different animal.
Amen Bob on the 7mm STW!