4000 fps in a 7mm STW w/140 Bullet?

[7stw]

WOW, that seems awfully fast, and WICKED hot if at all possible. Even if he had a 28-29 inch barrel, 4000 FPS is a little bit of a stretch. ( and then some). And the notion about a 270 not being adequate past 300 yards is insane. " There's your sign". I think I'd be looking for another " smith".
There's some great ones on this website!!!!!!

 

[barnesuser28]

tag

 

[varmintH8R]

Stop overreacting. I'll shoot that thing to prove it can be done!

 

[Lefty7mmstw]

tag

you're it...

 

[Trickymissfit]

one more time! You often can gain a hundred to a hundred fifty feet per second over many of the reloading manuals (Sierra, Hornaday right off the top). But your looking at 600 fps over the Hornaday manual, and at least 500fps over the older Hogdon manual. That's like trying to kiss and make up with your ex in court!

The 7STW is well into overbore, and just about anybody that shoots it a lot will confirm this. This means that you've entered into the relm of deminishing returns for what you add into the equation. Look at three magnum rounds with 139/140 grain bullets, and the .280 Remington:

a. The .280 will push a 139 grain bullet to about 3,000fps with a heavy charge of 55 grains of 4831.

b. the 7mm Rem. mag takes 63.5 grains to get to 3100fps, and 73 grains of Magpro to get another 100 fps. Ackley stated in his book that he felt the 7mm mag was about it for powder capacity with the 7mm bullet diameter, and works best with the heavier bullets. (he liked this round by the way)

c. The 7mm WBY mag is another to look at. It's got a slight larger case volume than the Remington, plus some other features that help it better with the bigger bullets. It takes almost two more grains of 4831 to get to 3100fps (first clue about overbore), and takes almost 71 grains of 4831 to get to 3400fps (I have to question the velocity that hornaday posted here)

d. now we move upto the big fellas! The 7STW needs a little over 71 grains of 4831 to get to 3300fps, and this should tell us right away that the case is in serious over bore. But 83 grains of H1000 will get you to 3400fps (Hornaday manual). Hogdons lists two loads with the 140 grain bullet that are almost 3500fps. One used IMR 7828 and the other was with H1000 (82 grains???) Compaired to the .280, we are seeing almost a 40% increase in the powder charge to gain 400fps! (4831)

e. (I know I said three) Then we come accross the 7mm Ultramag! Case looks like metal Montecristo cigar tubes! Takes 96 grains of H1000 to get to 3500fps! No wonder they have a short barrel life span! Hogdons must love this round! Yet the Winchester 7WSM with 76.3 grains of Magpro will do 3300fps! I seriously doubt this round with 115 grains of powder could do 3700 fps, let alone crack the 4000fps mark with the smaller 7STW
gary

 

[jakelly]

Stop the job. Get your rifle back. You just found out a pathological liar is cutting on your very expensive very precious firearm.

Next time use a reputable smith from here or other forums/places where serious shooters can vouch for a man's work.

Many of us on here have been burned before this isn't paid-for propaganda we know the price of precision. Use professional workmanship with proven components in the end you'll love the product and appreciate the savings.

 

[Fiftydriver]

My 7mm Allen Magnum which is based on an improved 338 Lapua parent case will outrun the 7mm RUM by 175 to 200 fps. It will out pace the STW by solid 225 to 250 fps and it will top out at right around 3700-3750 fps with the 140 gr Accubond.

This guy that is telling you he is getting 4K with a 140 gr bullet in the STW is, for lack of a better term, FULL OF IT!!! Maybe he was shooting a 100 gr bullet weight, even then I bet he would be blowing primer pockets if he got to 4000 fps.

 

[lloydsmale]

he wouldnt be even touching my guns!

 

[Trickymissfit]

My 7mm Allen Magnum which is based on an improved 338 Lapua parent case will outrun the 7mm RUM by 175 to 200 fps. It will out pace the STW by solid 225 to 250 fps and it will top out at right around 3700-3750 fps with the 140 gr Accubond.

This guy that is telling you he is getting 4K with a 140 gr bullet in the STW is, for lack of a better term, FULL OF IT!!! Maybe he was shooting a 100 gr bullet weight, even then I bet he would be blowing primer pockets if he got to 4000 fps.

honestly, I'd have never believed that you could have gotten 3700fps with a 140 grain bullet out of the Allen Mag as well. Do you have any problems with bullets holding together on impact? For sure you'd have to use a bullet with a heavy jacket thickness
gary

 

[J E Custom]

another major problem with driving most of the 7mm bullets that fast is that they'll probably explode after a couple inches of impact on something like a deer. Just not made for those kind of velocities
gary

+1

Years ago I built a rifle in 7 STW for velocity. It had a 31" barrel with a 1 in 10 twist.

I used the 140 grain bullets because at the time A Squair had a load that was advertised at 3550
ft/sec.(They later cooled it down to 3500 ft/sec).

I reached 3800 ft/sec but accuracy went to hell with anything over 3650 ft/sec. I did some very
close test on paper (10 yrds) because I suspected bullet problems, and found out that the bullets
were coming apart at somewhere around 3650 ft/sec (Shedding the jackets).

I tried the monolithic bullets and they gave problems at these velocities also so I decided to back
off and settled for 3600 ft/sec and was very pleased with accuracy and performance with the two
bullets I used (140gr partitions at 4 to 500 yards and in and the ballistic tip for shots over 500 yards).

I had to use a drop tub for the powder I used to keep from breaking the grains due to compressed
charges of very slow powder. (H 5010).

With less twist you might reach 3800 ft/sec with the right setup but it is doubtful. I recommend a
1 in 9 twist for the STW and it works well with any bullet up to 3550 ft/sec.

Velocity is like gas mileage, some like to exaggerate.

J E CUSTOM

 

[elktaxi1]

this guys not from texas is he? if so i had a 7stw from him and he says 4000 fbs and 3700 ft/sec and that is more than possiblie with one of there guns. he also builds a 257 stw that gets 4011 ft/sec with a 100 gr ttsx.oh and he does't think much of a 270 because of the bullets that are out there. not defending him but this is how he thinks of himself.

 

[BrentM]

Could you get 4000 fps with smooth bore or very loose bore? Wonder if he builds his own barrels or takes a good and ruins it. LOL

 

[J E Custom]

this guys not from texas is he? if so i had a 7stw from him and he says 4000 fbs and 3700 ft/sec and that is more than possible with one of there guns. he also builds a 257 stw that gets 4011 ft/sec with a 100 gr ttsx.oh and he does't think much of a 270 because of the bullets that are out there. not defending him but this is how he thinks of himself.

Anything is possible but the results may not be desirable for long range, And most large bullets will
not hold up at those velocities. (The larger the bullet, the more centrifugal force on the bullet jacket
and the more starting inertia because of the weight causing the rifling to engage poorly, effecting
accuracy.

Velocity is like gas mileage, some people like to stretch the truth about it.

J E CUSTOM

 

[Fiftydriver]

honestly, I'd have never believed that you could have gotten 3700fps with a 140 grain bullet out of the Allen Mag as well. Do you have any problems with bullets holding together on impact? For sure you'd have to use a bullet with a heavy jacket thickness
gary

it will do it no problem but yes bullet selection is an issue. Remember that I do not recomment the 7mm Allen Magnum for hunting under 400 yards. If someone wants a rifle for 0 to say 600 yards, there is no reason to use anything close to this range of performance. That said, when used on light medium game, the 140 gr Accubond works pretty well.

I recommend that the 7mm Allen Magnum be used with at least a 160 gr bullet weight (3450-3500 fps) or heavier which is where the 7mm AM really runs well at with these heavy bullets.

Of course proper bullet selection needs to be choosen for the job at hand. Bullet selection is far more important when using these ultra performance chamberings then it is with lesser chamberings.