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7mm STW Reloading Thread

 
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  #246  
Old 12-20-2013, 06:25 PM
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Re: 7mm STW Reloading Thread

Quote:
Originally Posted by joeycoates View Post
Afternoon gentlemen, I have a few questions for you guys if you have a minute. I have a 700 (I believe it might be an Alaskan, it is stainless with a 24" barrel and synthetic stock) that is currently chambered in 7RM, but I am going to use it as a base for my first semi-custom rifle. I have been doing a lot of reading and to me the 7 STW really looks like a great choice as I do know that I want to stick with the 7mm round, I guess I just like it!

Anyway, I am probably going to jump on the Benchmark group buy to get the barrel. I have been shooting the 168gr Berger VLD Hunting out of the 7RM with very good results, but in the 7 STW I would like to step up to the 180gr VLD's, and perhaps the mythical 195gr VLD's if they should ever appear. My question has to do with twist rate. As I am going to be ordering the barrel I can go with whatever twist I would like within reason. Is there any reason not to do a 1:8 or 1:8.5 as compared to the given 1:9 that kind of seems to be the standard? The lightest bullet that I would ever use would maybe be 140gr, but to be honest I do not know that I would ever even do that. I am kind of the type of person that will find a couple of rounds that work well, develop good loads, and then just use them. If the 195's ever appear it would probably be 168 VLD's and 195 VLD's, but to shoot the 195's Berger is saying that a 1:8.5 will be the minimum needed. I am in Texas so unless I go somewhere to hunt I will not be at a very high altitude for the most part. If I go with the 1:8 or 1:8.5 to be able to shoot the 195's I would probably have the smith put the Wyatt's extended box on it just to have the room for longer OAL's should I need it even though I have read where the STW likes a jump.

The second question is whether or not you think a brake is worth while on the 7 STW? I have never had a brake on a rifle, but other than being careful with the loud report the people who use them do seem to like having them. I just do not know if there is as much of a benefit on the STW as there is on one of the larger 300's or 338's.

I already have a Timney trigger on the 7RM that I will continue to use as I do like it, and I have a Viper FFP 6-24x50 PST that I will also use as I really like the scope as well. I am looking at different stocks right now, my goal is to have all of the components ready to send to the smith (whoever that will be, undecided right now) so that they will have all of the parts and not have to wait on ordering anything. While the rifle is being built I will try to get some brass and buy some dies. If push comes to shove I will just re-size some 8mm brass all though I have never re-sized before. I am looking forward to having the rifle built, it will be something that I will always keep until I hand it down to my son some day.

Thanks for your help!
To me personally, the STW is fairly mild mannered in the recoil department so unless you're spending a lot of time at the range shooting I wouldn't think you really need a brake. If you do get one, I would recommend having a threaded brake that you can replace with a thread protector for hunting use because the blast can be horrendous on the ears. I have shot my STW (no brake) a handful of times without hearing protection and have had no ear ringing - perhaps due to the 26" barrel. I think the recoil is muted in part because of the slow burning powders used for this overbore magnum. Only after about 15 rounds do I start thinking about it.

I think you're on the right track with 1:8.5 ish twist rate for 180 - 195 weight bullets. There are some stability calculators out there (online) that can help you nail it down a bit for your intended atmospheric conditions and bullet as temperature and altitude factor in. Use the length difference between the 168 and 180 VLD to guide you on the length of the theoretical 195 as you'll need length for the calculators. Whatever the length change is for the 168 to 180, multiply it by 1.25 and add that to the length of the 180 to get the theoretical length of a 195 VLD.

I've read that theoretically over-spinning a bullet of a given weight can magnify concentricity issues and balance issues with lighter bullets, but I have not seen any empirical data to back that theory up. I don't think it would pose much of an issue with a high quality bullet as long as you're loading good concentric rounds that feed into the bore nice and straight.

STW's seem to shoot well with Jump, but the main reason they like it is to keep pressures under control. Giving the bullet a running start at the lands minimizes the pressure spike compared to loading them close to the lands or jammed. Those conditions can create dangerous pressures and will require much reduced loads for safe operation.
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  #247  
Old 12-21-2013, 12:34 AM
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Join Date: Oct 2013
Location: Texas
Posts: 99
Re: 7mm STW Reloading Thread

Good deal Coop, I actually found length of the berger 195, it is 1.637 according to those who are in the fold. According to Berger's calculator 1:8.5 would probably work well as it shows over 1.4 at 2700fps (which I think is conservative) at sea level and 59 degree's. It does drop below 1.4 at 30 degree's even moving velocity to 2800fps, but I think that fps would be conservative as well. A 1:8 twist would probably cover everything so long as it is not too aggressive for the 140gr range bullets.

One thing I looked for on this thread but do not remember seeing is if anyone has loaded the Matrix 190gr bullets in the 7stw. I would be curious to see how they performed out of a 1:9 just to know, and what velocity they produced. I have plenty of time to nail down my exact combination, but I would rather do it once and do it right. I am pretty sure a 1:8.5 would be safe, but would probably go with a 1:8 5c barrel so long as it would not be too much. That is one great thing about building a rifle though, you get to pick what you want.
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  #248  
Old 12-23-2013, 03:31 PM
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Join Date: Aug 2011
Location: Houston Tx
Posts: 5
Re: 7mm STW Reloading Thread

I'am the owner of a 7mmSTW Rem 700 SS DM 24" with factory brake, but am reloading for my cousin's new McMillan 7mmSTW, he wants to shoot the 150 Sierra SMK and I've some Retumbo, I think is a good powder for this combo, but I don't see many shooters using it.........

G.
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  #249  
Old 12-23-2013, 06:30 PM
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Join Date: Oct 2013
Posts: 19
Re: 7mm STW Reloading Thread

Quote:
Originally Posted by joeycoates View Post
Good deal Coop, I actually found length of the berger 195, it is 1.637 according to those who are in the fold. According to Berger's calculator 1:8.5 would probably work well as it shows over 1.4 at 2700fps (which I think is conservative) at sea level and 59 degree's. It does drop below 1.4 at 30 degree's even moving velocity to 2800fps, but I think that fps would be conservative as well. A 1:8 twist would probably cover everything so long as it is not too aggressive for the 140gr range bullets.

One thing I looked for on this thread but do not remember seeing is if anyone has loaded the Matrix 190gr bullets in the 7stw. I would be curious to see how they performed out of a 1:9 just to know, and what velocity they produced. I have plenty of time to nail down my exact combination, but I would rather do it once and do it right. I am pretty sure a 1:8.5 would be safe, but would probably go with a 1:8 5c barrel so long as it would not be too much. That is one great thing about building a rifle though, you get to pick what you want.
Joey,

Might do some research on or talk with Kirby Allen. He's built some radical wildcats in 7mm around the premise of ultra high BC bullets including a 200 grain ULRBT. I don't believe the bullet is available anymore, but he has a fair bit of experience launching and stabilizing them. I think he builds the 7mm Allen Magnums with 1:8.5 twist for that bullet, but also claims they don't stabilize all the way until they're well down range. I spoke to him about it some time ago so don't quote me on my figures, it's just what I recall. He's forgot more about long range guns than I've ever been exposed to probably.
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  #250  
Old 01-05-2014, 08:40 PM
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Join Date: Jan 2011
Posts: 39
Re: 7mm STW Reloading Thread

Quote:
Originally Posted by villarreal View Post
I'am the owner of a 7mmSTW Rem 700 SS DM 24" with factory brake, but am reloading for my cousin's new McMillan 7mmSTW, he wants to shoot the 150 Sierra SMK and I've some Retumbo, I think is a good powder for this combo, but I don't see many shooters using it.........

G.
Have had excellent results with Hornady 139 SSTs, 162 A Max, as well as Sierra's 150 SMK, and168 SMK out of my Sendero SF. Looking to try the new Nosler ABLR in 150. Load data seems a bit scarce.

Bill
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  #251  
Old 01-06-2014, 07:26 PM
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Join Date: Oct 2013
Posts: 19
Re: 7mm STW Reloading Thread

Quote:
Originally Posted by wiiicgun View Post
Have had excellent results with Hornady 139 SSTs, 162 A Max, as well as Sierra's 150 SMK, and168 SMK out of my Sendero SF. Looking to try the new Nosler ABLR in 150. Load data seems a bit scarce.

Bill
I wrote down a load somebody was getting 1-hole groups with using the Accubond Long Range 150's with. It is a pretty stout load, so work up to it starting about 4 grains less...

In Rem Brass, COAL 3.645", Fed 215Match primer, 84.3 grains H1000, 3315 fps

Let us know where you end up and how she shoots!
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  #252  
Old 01-07-2014, 01:28 AM
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Join Date: May 2012
Location: N.D.
Posts: 2,815
Re: 7mm STW Reloading Thread

Quote:
Originally Posted by wiiicgun View Post
Have had excellent results with Hornady 139 SSTs, 162 A Max, as well as Sierra's 150 SMK, and168 SMK out of my Sendero SF. Looking to try the new Nosler ABLR in 150. Load data seems a bit scarce.

Bill
80.0 rl25 in rp brass, 215, 150 rlab... 1/2 moa at 200 with both my and my pops stw's.
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