stagpanther
New member
7mm is one of my favorites--but I see very little talk of this cartridge.
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7mm STW--any thoughts/experience with?
- Thread starter stagpanther
- Start date
I have no personal experience with it, but it must be something. I once saw two men nearly come to blows over dibs on used one at the DE Cabela's. It was a "custom" stainless model, felt like it was about 6 lbs. It had a green Bells and Carlson stock, Mauser type action, and loooonnng fluted barrel. Price tag was $2799. They started there with a bidding war over who would walk out with it. I think the (very patient) old gent running the gun library that day was considering using it to paddle them both.
But if I ever wanted a 7mm/.284 faster than my 280AI, I would probably go STW. It has a certain, vintage authority over all other 7mms.
But if I ever wanted a 7mm/.284 faster than my 280AI, I would probably go STW. It has a certain, vintage authority over all other 7mms.
stagpanther
New member
What I like is that gets way up there in velocity but apparently is not the barrel burner that similar high-power 7's are--plus the parent case is the 8mm Rem Mag but can apparently also be sized from 300 Weatherby (otherwise the cases, if you can find them, are outrageously expensive!!).But if I ever wanted a 7mm/.284 faster than my 280AI, I would probably go STW. It has a certain, vintage authority over all other 7mms.
The 7mm STW burns more powder than any other 28 caliber cartridge so it wears out barrels faster. 700 rounds is about all it'll give best accuracy.What I like is that gets way up there in velocity but apparently is not the barrel burner that similar high-power 7's !!).
I am interested in in hearing the argument why it would not be a barrel burner.
I personally notice few 7mm Rem Mag loads exceed 85% load density.
IMO,cases larger than 7mm Rem offer diminishing returns. 7 MM rem does not gain much over 280 AI.
Greater overbore = less expansion ratio. Which means margin of error is more necessary .Pressure events will be more sudden and dramatic.
The mag box limitations of most rifles make bullets much over 140 gr less practical,especially those of more VLD ogive,
Many(myself included) prefer the higher BC's and wind bucking of the 160 gr + 7mm projectiles.
At long ranges,screaming whiffle bullets with the BC of a Cheeto are surpassed by the javelins that start at an initially lower velocity.
IMO,the 7x61 Sharpes and Hart was a better design than the 7mm Rem.
Bigger is not always better. There is a balance to achieve.
I personally notice few 7mm Rem Mag loads exceed 85% load density.
IMO,cases larger than 7mm Rem offer diminishing returns. 7 MM rem does not gain much over 280 AI.
Greater overbore = less expansion ratio. Which means margin of error is more necessary .Pressure events will be more sudden and dramatic.
The mag box limitations of most rifles make bullets much over 140 gr less practical,especially those of more VLD ogive,
Many(myself included) prefer the higher BC's and wind bucking of the 160 gr + 7mm projectiles.
At long ranges,screaming whiffle bullets with the BC of a Cheeto are surpassed by the javelins that start at an initially lower velocity.
IMO,the 7x61 Sharpes and Hart was a better design than the 7mm Rem.
Bigger is not always better. There is a balance to achieve.
Billygoat109
Inactive
Don’t shoot a 7mm STW, but do shoot a 7mm Weatherby Magnum. Also load a 175 gr Sierra SBT with 78gr of Hod-US869 using Lee Data. I like it!
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Billygoat109
Inactive
Oh, that load travels at 2751 FPS!
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Billygoat109
Inactive
7mm Weatherby Magnum 1 in 9 1/2"
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Do all 7mm barrels have the same bore capacity?Greater overbore = less expansion ratio. Which means margin of error is more necessary .Pressure events will be more sudden and dramatic.
.
If so, what is it?
7mm RUM is bigger if you must own the big kahana of 7mm's.
Here's a new one. 28 Nosler is nearly identical in case capacity but the guns chambered in the RUM tend to be less expensive.
https://www.gunbroker.com/item/890567124
Here's a new one. 28 Nosler is nearly identical in case capacity but the guns chambered in the RUM tend to be less expensive.
https://www.gunbroker.com/item/890567124
stagpanther
New member
Yes. Berger has a new high BC 190 gr 7mm uberbullet but I don't have any idea what additional throat I would need to seat it effectively.Are you thinking about 1/8 twist barrel?
I've used the 7mm RUM but it's a blast furnace after not many shots, so I'm not interested in it--and I suspect the 28 Nosler is similar (perfectly good for one-and-done hunting, assuming your projectile doesn't vaporize or laser right through the game without expanding). The 7mm STW and 7mm-300 wby, which is similar, seem to be a bit less likely to quickly self-imolate, but IDK.7mm RUM is bigger if you must own the big kahana of 7mm's.
Here's a new one. 28 Nosler is nearly identical in case capacity but the guns chambered in the RUM tend to be less expensive.
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Jim Watson
New member
Amusing story here.
Guy fell in love with the STW and rebarrelled or rechambered several rifles.
Problem was, his best accuracy was the fireforming shots. He never could get a full power load in fireformed brass to do as well.
Guy fell in love with the STW and rebarrelled or rechambered several rifles.
Problem was, his best accuracy was the fireforming shots. He never could get a full power load in fireformed brass to do as well.
stagpanther
New member
That is funny--what parent cartridge did he use? I wonder how important it is to adjust the freebore to get optimal results.Problem was, his best accuracy was the fireforming shots. He never could get a full power load in fireformed brass to do as well.
Txhillbilly
New member
The 7mm STW was all the craze back in the early 1980's. I don't think it has much of a fan base anymore.
Some Long Range Hunter's still shoot it, but in today's current offerings most shooter's consider it an obsolete cartridge.
Some Long Range Hunter's still shoot it, but in today's current offerings most shooter's consider it an obsolete cartridge.
Bart
My understanding,which could be wrong
A relatively balanced boiler room to bore ratio,like a 7mm08,might have the total volume of cartridge case and bore double when the bullet travels 8 in down the bore (a guess)
For the STW,doubling combustion chamber volume might take 16 in of barrel travel.
At the same time,the larger powder volume is turning to gas via doubling or quadrupling rapidly.
As the bullet travels down the bore,any 7mm bullet in any 7mm bore is increasing pure bore volume at the same rate, but pressure builds in the cartridge case before the bullet moves. The large pressure volume of the STW case is "diluted" less by the addition of bore volume via bullet travel.
Another way to llustrate what I am trying to say is with the absurd.
With a balanced design like the 308,its hard to blow one up using appropriate powder. The bullet can outrun the pressure.
Now lets neck a 50 BMG down to 17 caliber. It wants to be a bomb. Big production of gas, A very tiny hole . 30 inches bullet travel will proportionally increase chamber volume very little.
The cartridge will be a bit peaky.
I'm not into the 6.5 CM mystique so much,but there are reasons why it is far more successful than the 264 Win Mag.
Given the powder tech we have, there is an efficient sweet spot for a bore and projectiles.
We can hot rod beyond that,for some price. That price may be acceptable,but there will be diminishing returns
We don't need 3700 fps any more. We have learned to use adjustable sights.
My understanding,which could be wrong
A relatively balanced boiler room to bore ratio,like a 7mm08,might have the total volume of cartridge case and bore double when the bullet travels 8 in down the bore (a guess)
For the STW,doubling combustion chamber volume might take 16 in of barrel travel.
At the same time,the larger powder volume is turning to gas via doubling or quadrupling rapidly.
As the bullet travels down the bore,any 7mm bullet in any 7mm bore is increasing pure bore volume at the same rate, but pressure builds in the cartridge case before the bullet moves. The large pressure volume of the STW case is "diluted" less by the addition of bore volume via bullet travel.
Another way to llustrate what I am trying to say is with the absurd.
With a balanced design like the 308,its hard to blow one up using appropriate powder. The bullet can outrun the pressure.
Now lets neck a 50 BMG down to 17 caliber. It wants to be a bomb. Big production of gas, A very tiny hole . 30 inches bullet travel will proportionally increase chamber volume very little.
The cartridge will be a bit peaky.
I'm not into the 6.5 CM mystique so much,but there are reasons why it is far more successful than the 264 Win Mag.
Given the powder tech we have, there is an efficient sweet spot for a bore and projectiles.
We can hot rod beyond that,for some price. That price may be acceptable,but there will be diminishing returns
We don't need 3700 fps any more. We have learned to use adjustable sights.
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stagpanther said:Yes. Berger has a new high BC 190 gr 7mm uberbullet but I don't have any idea what additional throat I would need to seat it effectively.
In my limited experience shooting VLD bullets, you'll never get close to the lands in a SAAMI spec chamber. These two things can happen you seat the bullet out way too long to ever use the magazine making your rifle a single shot, the second is less likely but you dont have enough of the bulkets bearing surface in the case neck for proper neck tension. With VLD bullets the ogive is much closer to the base of the bullet than a traditional spitzer bullet, so a shallow throat is needed if you want very little jump to the lands.
Just read up on the Berger "making it shoot" seating depth test. I've had good luck with as much as .120-.130" jump for accuracy. If your rifle likes that much jump it's much easier to stay inside magazine length for reliable feeding.
stagpanther
New member
I'm not of the jam it the lands camp--I shoot lots of Bergers and yes they sometimes prefer like the long jump over the short one. I'm not worried about the magazine length rigamarole either--in the end, everything would be dictated by the bullet and the chamber. Problem is, no way for me to know that without getting a baseline barrel made and working my way up to the ideal combo you want as far as I can tell, sorta a "chicken before the egg" kinda thing.In my limited experience shooting VLD bullets, you'll never get close to the lands in a SAAMI spec chamber. These two things can happen you seat the bullet out way too long to ever use the magazine making your rifle a single shot, the second is less likely but you dont have enough of the bulkets bearing surface in the case neck for proper neck tension. With VLD bullets the ogive is much closer to the base of the bullet than a traditional spitzer bullet, so a shallow throat is needed if you want very little jump to the lands.
Just read up on the Berger "making it shoot" seating depth test. I've had good luck with as much as .120-.130" jump for accuracy. If your rifle likes that much jump it's much easier to stay inside magazine length for reliable feeding.
Good point Bart. I have a question for you--have you ever found that there is usefulness in using a treatment like moly plating on bullets to help increase barrel life and/or accuracy? I have quite a few "over bore" cartridges and was curious if the pros actually see benefits from it.The 7mm STW burns more powder than any other 28 caliber cartridge so it wears out barrels faster. 700 rounds is about all it'll give best accuracy.
HiBC, where does the force come from to push a 308 bullet ahead of the burning powder's pressure wave?Bart
My understanding,which could be wrong
A relatively balanced boiler room to bore ratio,like a 7mm08,might have the total volume of cartridge case and bore double when the bullet travels 8 in down the bore (a guess)
For the STW,doubling combustion chamber volume might take 16 in of barrel travel.
At the same time,the larger powder volume is turning to gas via doubling or quadrupling rapidly.
As the bullet travels down the bore,any 7mm bullet in any 7mm bore is increasing pure bore volume at the same rate, but pressure builds in the cartridge case before the bullet moves. The large pressure volume of the STW case is "diluted" less by the addition of bore volume via bullet travel.
Another way to llustrate what I am trying to say is with the absurd.
With a balanced design like the 308,its hard to blow one up using appropriate powder. The bullet can outrun the pressure.
Now lets neck a 50 BMG down to 17 caliber. It wants to be a bomb. Big production of gas, A very tiny hole . 30 inches bullet travel will proportionally increase chamber volume very little.
The cartridge will be a bit peaky.
I'm not into the 6.5 CM mystique so much,but there are reasons why it is far more successful than the 264 Win Mag.
Given the powder tech we have, there is an efficient sweet spot for a bore and projectiles.
We can hot rod beyond that,for some price. That price may be acceptable,but there will be diminishing returns
We don't need 3700 fps any more. We have learned to use adjustable sights.
Note that 7.62 NATO service ammo needs at least 60 pounds of force to start pushing bullets forward in the case neck. That is when pressure in the case is about 800 psi
No.Bart. I have a question for you--have you ever found that there is usefulness in using a treatment like moly plating on bullets to help increase barrel life and/or accuracy? I have quite a few "over bore" cartridges and was curious if the pros actually see benefits from it.