Forming 7mm STW Brass

[JakeWes]

There has been some commotion recently about the availability of 7mm stw brass. Most old timers still recommend using 8mm rem mag brass, which is great, but I'd argue that 8mm rem mag brass is harder to find than the stw. Others recommend 300 wby brass, which is another good option, but the overall length ends up a little short when fully formed.
For me, and others who've tried, I will attest to using 300 h&h and 375 h&h brass to easily form the stw. Both can be easily found online for less than half of Bertram or Nosler stw brass.

For the 300 h&h, a simple lube and resizing job in the stw FL die will get you to where you need to be. Then a fireforming charge will blow the taper out and mostly form the shoulder angle. A final full load will yield a perfect stw case.
For the 375 h&h you will need an extra die, for me it's the 8mm rem mag die. Lubing the case and running it in the 8mm rem mag FL die squeezes the neck down. If you run the case straight into the stw FL die you will crush the shoulder and neck. After the 8mm die, relube and run it into the stw die. Afterwards, prime and load a fireforming charge and repeat the steps mentioned above.

Cases from L to R: 375 h&h, resized in 8mm rem mag FL die, resized in 7mm stw FL die, 18gr of unique and a 154gr SP, 83gr of H1000 and a 140gr SP.

 

[LouisianaHunter]

There has been some commotion recently about the availability of 7mm stw brass. Most old timers still recommend using 8mm rem mag brass, which is great, but I'd argue that 8mm rem mag brass is harder to find than the stw. Others recommend 300 wby brass, which is another good option, but the overall length ends up a little short when fully formed.
For me, and others who've tried, I will attest to using 300 h&h and 375 h&h brass to easily form the stw. Both can be easily found online for less than half of Bertram or Nosler stw brass.
View attachment 526729View attachment 526732View attachment 526737
For the 300 h&h, a simple lube and resizing job in the stw FL die will get you to where you need to be. Then a fireforming charge will blow the taper out and mostly form the shoulder angle. A final full load will yield a perfect stw case.
For the 375 h&h you will need an extra die, for me it's the 8mm rem mag die. Lubing the case and running it in the 8mm rem mag FL die squeezes the neck down. If you run the case straight into the stw FL die you will crush the shoulder and neck. After the 8mm die, relube and run it into the stw die. Afterwards, prime and load a fireforming charge and repeat the steps mentioned above.

Cases from L to R: 375 h&h, resized in 8mm rem mag FL die, resized in 7mm stw FL die, 18gr of unique and a 154gr SP, 83gr of H1000 and a 140gr SP.
View attachment 526726

There has been some commotion recently about the availability of 7mm stw brass. Most old timers still recommend using 8mm rem mag brass, which is great, but I'd argue that 8mm rem mag brass is harder to find than the stw. Others recommend 300 wby brass, which is another good option, but the overall length ends up a little short when fully formed.
For me, and others who've tried, I will attest to using 300 h&h and 375 h&h brass to easily form the stw. Both can be easily found online for less than half of Bertram or Nosler stw brass.
View attachment 526729View attachment 526732View attachment 526737
For the 300 h&h, a simple lube and resizing job in the stw FL die will get you to where you need to be. Then a fireforming charge will blow the taper out and mostly form the shoulder angle. A final full load will yield a perfect stw case.
For the 375 h&h you will need an extra die, for me it's the 8mm rem mag die. Lubing the case and running it in the 8mm rem mag FL die squeezes the neck down. If you run the case straight into the stw FL die you will crush the shoulder and neck. After the 8mm die, relube and run it into the stw die. Afterwards, prime and load a fireforming charge and repeat the steps mentioned above.

Cases from L to R: 375 h&h, resized in 8mm rem mag FL die, resized in 7mm stw FL die, 18gr of unique and a 154gr SP, 83gr of H1000 and a 140gr SP.
View attachment 526726

There's quite a bit of 8mm rem mag brass on ammoseek . Not cheap though.

 

[8x68s]

Factory Overrun Brass 8mm Remington Mag Brass Bag of 50 (Bulk

This Factory Overrun Brass is manufactured to SAAMI specifications, but with visual imperfections that will not affect performance. This is not loaded...

www.midwayusa.com

HEADS UP!...375 H&H brass @ MidwayUSA

https://www.midwayusa.com/product/1026572891?pid=308105

www.longrangehunting.com

 

[JakeWes]

Factory Overrun Brass 8mm Remington Mag Brass Bag of 50 (Bulk

This Factory Overrun Brass is manufactured to SAAMI specifications, but with visual imperfections that will not affect performance. This is not loaded...

www.midwayusa.com

HEADS UP!...375 H&H brass @ MidwayUSA

https://www.midwayusa.com/product/1026572891?pid=308105

www.longrangehunting.com

That 8mm rem mag brass is the same price as new Bertram 7mm stw brass. Also, I am pretty sure that the factory seconds are Nosler.

 

[Charles De Salme]

Back in the day we used 8mm brass. Ran it thru a 7mm STW die. Put a bit of blue dot in it. Packed it 1/2 with corn meal and put cotton in the rest to hold everything in. Made a heck of a mess but worked.

 

[budlight]

I will attest to using 300 h&h and 375 h&h brass to easily form the stw.

Then a fireforming charge will blow the taper out and mostly form the shoulder angle. A final full load will yield a perfect stw case.

Cases from L to R: 375 h&h, resized in 8mm rem mag FL die, resized in 7mm stw FL die, 18gr of unique and a 154gr SP, 83gr of H1000 and a 140gr SP.

I've commented over the years about fire forming and all the concoctions that people come up with. I've been a wildcat and AI person from way back. Like my 7STW was a wildcat before the 7STW was comercially sold. It was made by a gun smith and is actualy more like a STW AI holding 3-4 grains more powder. Oh it was a 28 inch 8 twist that liked 175 - 190 vld's

But anyway when you get into rounds that have limited barrel life the dumbest thing you can do is waste precious barrel life Fire Forming. Oh my 30-378 also only had limited case life 120 grains of US869. So the AI guys always did full on FF. So I would load the un FF cases just how I loaded my proven rounds or determine some load from rounds of similar case volume from load tables for a new wild cat without load data.

I FF with a chronograph because of limited barrel life. FF and unfire formed with the exact same load always came within very close FPS. I've even gone trophy hunting fire forming rounds just so I had enough cases to bother reloading.

So my advice is to just skip the baby steps and just load up.

My latest gig is making 257 Roberts AI from 7mm Mauser cases full powered of course!

 

[nwmnbowhunter]

I've heard of guys just running a Mandrel through 6.5-300 wby peterson brass

 

[Bghunter338]

I've heard of guys just running a Mandrel through 6.5-300 wby peterson brass

That was me. Lol

 

[victor3ranger]

I'm going to have to come up with another chronograph, mine stopped reading speed all of a sudden. I need to get my stw clocked

 

[nwmnbowhunter]

I'm going to have to come up with another chronograph, mine stopped reading speed all of a sudden. I need to get my stw clocked

Probably just going too fast... haha

 

[victor3ranger]

Probably just going too fast... haha

lol

 

[VinceMule]

When Lane Simpson wrote the article for the 7 STW in 1988 or so, I ordered a reamer from PTG that month, been shooting it ever since. We formed brass from Remington 8 Rem mag brass, with fire forming load of the old 120g Nosler solid base lead tip at 3850 fps shooting 3/8" groups with R#22 on a 27" Hart 9 Twist. We shot those 120's for a long time.

 

[VinceMule]

Later on, when I started shooting winchester brass, I tried IMR 7828 with Federal 215s. The accuracy node with 120g Barnes TTSX is at 3900 fps, and three shot groups are less than 1/4" seated .050 off the lands. Very, very little load development.

My brother and I were both shocked how well the 120g Nosler ballistic tips performed on white tails using the same load. Rumors that the 120s are tougher than the 140 g ballistic tips are true.

 

[blkfrd]

When Lane Simpson wrote the article for the 7 STW in 1988 or so, I ordered a reamer from PTG that month, been shooting it ever since. We formed brass from Remington 8 Rem mag brass, with fire forming load of the old 120g Nosler solid base lead tip at 3850 fps shooting 3/8" groups with R#22 on a 27" Hart 9 Twist. We shot those 120's for a long time.

How did you get that much horsepower out of that STW? I started messing around with STWs in the early '90s and my go-to round for 120 grain bullets was 79 grains of H4831 which resulted in about 3,600 ft per second. I tried 81 grains of H4831 also and it might have been a little faster. I don't think Lane had any recipe for a 120 grain bullet that was near 3850 FPS. I used 8 mm mag cases back then. I rejoined a nearby range this year and took that gun to the range for the first time in many years. It still shoots the same 3/8-in groups like it used to even with my age-induced eyes. I knocked the scope several years ago and I had to adjust it slightly to get it back to my preferred point of impact.