Home Forums Hunting & Shooting Custom Rifles & Wildcats 7MM to STW

I am considering rechambering my Rem 7MM Sendaro to the STW. Does anyone know if the action and mag will work or will I have to manually load the longer cartrige? Anyone done this to a heavy barrel and what result?

Done this a couple of times for myself and numerous times for customers.Action and mag work fine except you lose one round magazine capacity. If chambering job is up to snuff accuracy has always been acceptable. Rechambering a worn out barrel won't cure the wear problem but a rifle that shoots good in the original chambering usually shoots comparable when punched out to STW. Have done 4 or 5 stainless fluted Senderos wiyh nary a problem.

I have a rifle that Has been rechambered. I added a Vias brake and it shoots like a dream!

I had a reamer ground with a minimum spec chamber, short leade. Brother has two 7 STW's wtih rechambered stainless fluted Sendero barrels and one Pac Nor 27", I have the same.

We load IMR 7828, Fed 215's, Winchester Brass and the 140g Nosler Combined Technology bullet at a touch over 3600 fps and the 120g Tripple shocks at 3800+, accuracy is groups in the high .300's with the 140's and in the high .200's with the 120's.

Remington brass is a little soft, you will get about 3500 fps with the 140's Combined Technology bullet.

We have killed a lot of deer with the 140g Nosler Combined Tec bullet. It does not matter if they are near or far, they have never taken a step when shot with this bullet. I know folks think that this bullet will blow up, but it NEVER has!

The Naked 140g Bullets can not be driven as fast as the 140g Combined Tec bullets, they build pressure much faster.

The most accurate bullet that we have ever shot in our rifles has been the 120g Weight bullet in either the Nosler Solid base lead tip, Nosler ballistic tip, or the 120g Barnes Tripple shock. At 3800+, these bullets are so flat shooting out to 450 yards, it is simply hard to imagine.

The first STW we put together was about 1990, on a Savage action, a 27" Hart with a 1-10 twist. We necked down 8 Rem Mag brass and using Fed 215's, we started working up a load with the old 120g Nosler Solid Base lead tip spitzers. We started off using R#22 and kept increasing the powder charge. At the fireforming load at 3800 fps we started getting groups in the high .300's and at 3900, we were shooting groups where all the bullets were just opening up a single ragged hole, but at 3900 the primer pockets were getting loose. None of the groups went over 1" while fireforming the 120's. We were still shooting 1/2" groups at 200 yards.

We killed a bunch of deer with the 120g Nosler Solid base Sp, everyone a bang flop.

In summary, we have had two Pac Nor 10 twist three groove's, one 27" Hart 1-10 twist, and 4 Remington stainless fluted re-chambers in the 7 STW. Every one of these barrels produce very fast velocities with exceptional accuracy very quickly with little load development. The Hart and Pac Nor barrels took less than 40 rounds to dial in a load, while the Remington rechambers took about 60 rounds. Load development with the 120's is less than 20 rounds with all barrels.

Why would one lose any capacity when both rounds are the same diameter of case, i.e. belted H&H sized cases? Were you thinking 7mm Rum there? That one would cost some mag capacity.

To the OP.... ream it out and shoot it! Done.

don't waste your money...last summer I had a stainless fluted Sendero in 7mm Rem Mag and the exact same rifle in 7STW...the STW was faster by maybe 100fps at most...140 Accubonds and TSX's went 3300-3325 in the Rem Mag and a bit over 3400 in the STW...I ended up selling both and recently bought the 7mm Rem Mag back from the friend I had sold it to...he had a 150 Ballisitc Tip going 3175 and shooting in an inch and half at 300 meters...

..amd they both held three down in the mag....

..and you can't reach the lands in the STW and fit the mag box....

You will regret re-chambering to the 7STW. The Rem 700 only has a mag box of 3.60" and you will use all of it with the STW. A guy doesn't need to always reach the lands as there is usually a sweet spot close to the lands and another further away, but it still is nice to start there.

Meatlover,
The estimate of around 100 fps is probably right. The 7mm STW will really shine in a 28-30" barrel. Brass is getting a little harder to find also. All things to consider.
Having said all that, I had a Savage Tactical rechambered to STW back in the 90's. It remains one of the most accurate rifles I own and it has shot my smallest group ever, 0.14" for 3 shots at 100 yards.

Course a 7 RM with a 28-30" tube will really shine as well...grin

Dober

Nice thing about that long barrel is you can use it to pole vault over a rather wide stream and keep from getting your feet wet..

I left out in my post that Winchester brass is no longer available in the 7 STW, remington is soft, and Federal is junk soft.

Meatlover, have you ever tried R#25 in your 7 Mag? Cousins, and my another brother are shootng 72-73g of R#25 in their Browning A bolts and Remington's with a 154g Hornady Sp for deer and Interbond for Elk, accuracy is 3/4" at 100 and 4 1/2" at 550 yards with a muzzle velocity of 3250 fps and Win Mag primer is critical for accuracy.

The practical side of re chambering to a 7 STW is almost is almost nullified with the above load. Brother killed a nice bull in Colorado last year, one shot at 550 yards...bang flop with the above load in a 154g Interbond.

Since Winchester brass had disappeared for the 7 STW, you are at a serious disadvantage for getting the most out of this cartridge. In Rem brass, if you start off loading the STW with a Fed 215 the primer pocket will get loose within 2 shots, then go to a Win Mag primer and the primer pockets will be very tight again.

If I were starting over from scratch, I would go the Mashburn, necking down the 300 Win Mag...it's a no brainer for sure. With the avialability of Winchester brass, you would get some fantastic speeds with extreme accuracy out of the 140-150 Weight bullets. Also, Magazine length vs loaded over all cartridge length is somewhat better with the Mashburn. When trying to achieve maximum accuracy out of your rifle, there is a relationship where the load will demand to be a certain distance from the lands. With the 7 Mag and 7 STW, I found in all rifles, customs and factory that this caliber likes to be touching the lands or jammed by .003 to get groups in the 3/8" area or less, long range shooters have known this fact for a LONG time!

With the development of the Barnes tripple shock in 120g bullet, you have the equal of a 160g+ cup and core bullet in as far as weight retention. I would remind you that your 7 Mag will shoot these 120g Tripple shocks in a single ragged hole with R#22 with CCI250's at 3500-3600 fps if the rifle is bedded.

If the 120g Barnes at 3600 seems a little weak, think of how many head of game all over the world has been killed with a 257 Weatherby with the 117g bullet with a velocity of 3350! The nosler reloader manual has the accuracy load with R#22 that we all shoot in the 7 mags, be sure to use the CCI250 primer, hotter primer may work, but groups go to heck with std primers and the rem 9 1/2M is NO magnum primer.

Good luck!

I have an STW and had a 7 mag. You will not regret going to the STW.

I punched a Browning 85 28" in 7 rem mag to STW.
Not worth it and will never do it again.

Just shoot 120's out of the 7 rem at 3,500 mv and you'll match the STW for most applications.

I thought real hard about doing it too. Just couldn't justify it. Some can, I'll keep my 7 mag. I would have had to go buy another one if I had turned it to an STW. It's one of those rounds for me, I'll never be without a 7mag. Happen to have a soft spot for this one now anyway. It's the fourth...should have kept the first.

I was at the range tonight with Dad's 7mm Rem Mag I had built for him. It is a 1-9 24 1/2" barrel. 70gr RL25 CCI250 in a PMC case with a 160gr Partition was going over 3200 FPS with a nice little cloverleaf @ 100. Dang I think I'll have to keep it for myself. BTW I have had 140's running mid 3300's out of this rifle with the same accuracy. Must be Ted's fine barrel he makes.