7mm STW Velocity

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by TMR, Jul 7, 2006.

  1. TMR

    TMR Well-Known Member

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    Was curious to see what guys were for velocity with a 28" barrel in the STW's. I am thinking about rebarreling mine, but would like to have some idea of velocity. I will be using 168 gr Bergers mainly.
     
  2. 300win

    300win Well-Known Member

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    Just started playing with the 7mm stw. I am getting 3850fps from 120 ballistic tips and 3675 from 140 BT. I shot some 162 a max at 3400. All max loads in my rifle (26" barrel). IMR 7828 and Reloader 22 work well. I have seen the 162 a max shot from a 7mm rem mag group at a measured mile. The heavy 7mm bullets have true long range potential.
     

  3. TMR

    TMR Well-Known Member

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    I have been shooting 168's over IMR7828 and getting right at 3100 fps. It doesn't seem to be max load, primers flatten out though, but case head and extraction is ok. I am going to try some H1000 tomorrow to see what I get with it. Thinking that it might be less temp sensitive. I was thinking about having Kirby build me a 7mm AM, but with the cost of brass, I am thinking maybe a 28" STW might be the way to go. The Barnes book shows some loads up around 3380 with H1000 and a 160 grain. I am thinking that I should be able to get around 3200 fps with the 168 Berger. Hopefully.
     
  4. TMR

    TMR Well-Known Member

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    300Win.......Is your barrel a factory barrel or a custom? I would be curious what your load is with the 7828 to get to 3400 fps. If you don't mind emailing me or PMing me with the info, that would be great.
     
  5. keithcandler

    keithcandler Well-Known Member

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    The 7 STW is one Hoss of a cartridge. One thing for sure, it pays big dividends to have your own reamer made to seal the gases behind the bullet instead of the gases blowing out around and in front of the bullet. Put those gases working for you instead of wasting the horse power. We have had fantastic results shooting the 140's at velocities that no one here would believe with extreme accuracy.

    We accomplish the extreme velocity and accuracy by doing the following:

    Pacific Grinding makes the reamer with minimal expansion over a loaded Winchester case which usually involves:

    .002 0ver Web dia
    .0005 over bullet dia in the throat
    .002 over loaded round neck thickness
    freebore to match the round that you want to shoot, with
    no bullet jump
    1 1/2* leade angle

    This is a sure enough long range cartridge when a gun is set up right.

    I do not believe that it is in the class of the AM rifles for shooting 1000 yards, but if you are shooting 600 and under, the 7 STW will fill the bill!

    email me at keithcandler REMOVETHIS at msn dot com and I will tell you what Our long barrels are doing with 140's.
     
  6. 300win

    300win Well-Known Member

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    TMR, I have two loads for the 162 a max. Both with federal premium brass neck sized and gold medal match mag primers. 81.5 gr of IMR 7828 or RE22 77 gr. The IMR load shows sighns of pressure but consider both loads hot and back off a little first. My barrel is a factory barrel. I have a Mc Millian on order and a 28" barrel. I started out years ago with the 7mm caliber and plan to revisit it again. I plan to try to get the max point blank range for fast shooting on deer and coyotes. With the 120 ballistic tip at 3850 fps I can hold on a deer at 400 yards if zeroed 3" high at 100. I prefer heavier bullets for deer hunting but out to 400 yards the 120's shoud make a mess out of a chest cavity at that velocity. I shot a few coyotes with it last winter useing 120 v max at 3775 fps. It was comparible to shooting a pd with a 308, all you hear is a pop and your partner giggle. Not a real fur saver but great for tournament hunting! Keep us posted.
     
  7. Roll-Yur-Own

    Roll-Yur-Own Well-Known Member

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    TMR, 80 gr of Retumbo or H1000 with a 160 Accubond it is a very accurate load. It is also about the max load of either powder, 80.2 Retumbo & 80.7 H1000, so be careful. You should get 3100+ with this load. That is a pretty flat shooter and a heavy hitter with a 160 bullet, plus a .550 BC as well.
    The STW in 9 twist (most STW's are 9 twist) will shoot the larger bullets better than the 140's. YMMV

    The key with the STW is not to worry so much about velocity. If that is super important to you, then rebarrel to 7 RUM.

    I think going to a 28" tube in STW is a better way to increase speed then lighter bullets.

    STW is a great round and if you get the 140's to shoot, that's great. But, If you rebarrel and go with a 10 twist to stabilize the 140's I feel that you are limiting yourself to the rounds potential. A 9 twist will shoot up to 180's with no problem. If I wanted to shoot 140's I still would get a 9 twist and take my chances. This way if I wanted to load up for Elk or Moose I'm confident I could find a good one for a heavy bullet.

    Best of luck with whatever you decide. STW is a fantastic round. Remember YMMV.

    Roll-Yur-Own
     
  8. TMR

    TMR Well-Known Member

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    I went out and shot some H1000 today. I have not hit max load yet, but 82.5 grains yields 3180 fps with the 168 gr Berger. I shot a 4 shot group that measured .384 at 100 yards. I will probably stick with this load. There is absolutely no pressure signs,ie....no case head expansion or sticky bolt. Barnes shows 83.5 grains for the 160 grain bullet....so I started at 77 grains and worked my way up. It is getting close to hunting season, so I will probably stay there.

    300Win....that is one hell of a charge of 7828 with the Amax. I might have to try that when I rebarrel to 28". Sounds like you are planning to do the same thing as me. I also ordered a McMillan A-5 Stock. After hunting season I will probably have it rebarreled and then start all over again. I think I might go a custom reamer with no freebore. I have to ask Kirby if he has any experience with that. Thanks for the advice and help.
     
  9. TMR

    TMR Well-Known Member

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    Oh, one other note.......I chrono'd my 7828 loads early in the year when it was down around 45*, they ran 3080-3090fps all day long. Today it was 85* and they ran 3040 fps. The load I was using is 76gr IMR7828 with a 168gr Berger. When I shot the H1000 I was pretty happy that I added another 140 fps. I did shoot the H1000 loads early this morning when it was 55*, so I know that it wasn't a heat factor. I will shoot the load some more, but it is very accurate. Figured I should add that information.
     
  10. Buckmaster

    Buckmaster Active Member

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    82.5 grains of H1000 with a 168 grain bullet /ubbthreads/images/graemlins/shocked.gif

    That's a hot load. It HAS to be past max...pressure sign or not.

    Was that new brass?
     
  11. TMR

    TMR Well-Known Member

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    [ QUOTE ]
    82.5 grains of H1000 with a 168 grain bullet /ubbthreads/images/graemlins/shocked.gif

    That's a hot load. It HAS to be past max...pressure sign or not.

    Was that new brass?

    [/ QUOTE ]

    It is with new Winchester brass. I also shot some with some fired Win brass. It is about 1 grain over max according to Barnes. I measured the cases before and after firing....no change. Primer pockets are still tight. I contacted a Hodgon tech last week and asked him about the load data they had.....I saw where some guys were running 83.5 grains with a 160 grain bullet, he said their data was pretty conservative. They show 80.7 grains H1000 = 51,500psi with a 160gr. The STW max is 65,000 psi. I imagine their are lots of variables between rifles. My rifle has .220" freebore. If the bullets could get to the lands, the 80.7 or less might be the max. I am very cautious when reloading. I have seen bolts come flying out and actions blowup(mainly on a homemade 50 cal by a local smith). In the reading I have done on this forum and others, if there is no case head expansion, the bolt lifts easily, and the primer pockets are tight, you should be ok. I am using Fed 215M primers, which flatten out easily. My minimum loads sometimes flatten them out. I put in some WLRM primers and they looked perfect. They are a little harder from what I have been told.

    The Load that 300Win listed above with IMR7828....IMR lists 76.0 grain max with 62,300 psi. I am not sure what a grain increase equates into psi gain. I think it is always best to start below the manufacturers max and work your way up. Every gun will be different. We have a Kimber 300wsm that reaches max before our Shilen barreled 300WSM. It also gets 100fps faster with a 2" shorter barrel and less powder. It comes down to the barrel and chamber.
     
  12. Buckmaster

    Buckmaster Active Member

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    It is true, Hodgdon does give conservative numbers. Retumbo & H1000 both gave me great accuracy. Almost Identical 1/2 MOA accuracy. I think I'm just a 1/2 MOA shooter. The load and gun are probably better than that.

    H1000 gives less pressure and slightly higher velocity than Retumbo.
     
  13. boomer

    boomer Active Member

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    The H-1000 has been the best powder for me, I quit load development before finding any high pressure signs on the brass (Rem.)or primers, I am past 85 gr. but I am using Molly coated 168gr bullets and they do help with pressure. I have found the rifle shoots best with lots of speed.
     
  14. Roll-Yur-Own

    Roll-Yur-Own Well-Known Member

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    Thw STW will does shoot great at high velocity. But, I find that the the 140's in a 9 twist rifle do not group well. I've never shot a 9.5 or 10 twist stw so I can't comment, but the 9 twist with 160+ bullets is does like those max load.