7mmSTW or 6.5 creedmoor...

[Dust270WSM]

I have a 7mmSTW I use for deer hunting. It's a Remington 700 senderio. I have a Vortex PST 6X24X50 mounted on it. I am wanting to shoot long range with it. The question I have is "Why does everyone recommend 168 grain for it and not 140 grain". Reason I ask which one creedmoor or STW is because everyone shoots long range with 140 grain on the creedmoor but everyone says shoot 168 grain in the STW. 2ND question is"Why wouldn't u shoot the 140 grain faster outta the STW for less drop than the 168 grain". They should have the same wind drift with the 140 grainer on the creedmoor vs the STW. But get more speed outta the STW....

 

[benchracer]

You are making an invalid comparison between bullets of different diameters. A larger diameter bullet has to be heavier to equal the bc of a smaller diameter bullet of the same composition and form factor. Comparing sectional density will give you a rough idea of equivalent bullet weights for different diameters.

6.5mm 140 VLD Sectional Density = .287
G7 bc = .307

7mm 140 VLD Sectional Density = .248
G7 bc = .256

7mm 168 VLD Sectional Density = .298
G7 bc = .316

The Berger reloading manual shows the Creedmoor launching a 140 VLD at a maximum of 2700 fps from a 24" barrel. I have seen real world mv for the Creedmoor much higher than that, so let's say the Creedmoor can push the 140 VLD to 2800 from a 24" barrel and 2900 from a 26" barrel.

The same manual shows the 7STW launching a 180 VLD, with a G7 bc of .345, at a maximum of 2950ish from a 26" barrel. The 7mm 180 VLD has a MUCH higher bc than the 6.5mm 140 VLD and can be launched faster. It will shoot flatter and drift less than the 6.5mm at any range.

The bc comparison between the 7mm 140 VLD and 7mm 180 VLD is even less favorable. Despite a mv edge of 300+ fps for the lighter bullet, the 180 VLD will easily catch and surpass the 140 VLD at long range.

If you want to really see how these comparisons work, use the ballistic calculator on the Berger website or JBM Ballistics website.

Here is another reference that may help explain things:

http://www.appliedballisticsllc.com/Articles/ABDOC105_1_UndLongRangeBulletsP1.pdf

http://www.appliedballisticsllc.com/Articles/ABDOC105_2_UndLongRangeBulletsP2.pdf

 

[MudRunner2005]

I have a 7mmSTW I use for deer hunting. It's a Remington 700 senderio. I have a Vortex PST 6X24X50 mounted on it. I am wanting to shoot long range with it. The question I have is "Why does everyone recommend 168 grain for it and not 140 grain". Reason I ask which one creedmoor or STW is because everyone shoots long range with 140 grain on the creedmoor but everyone says shoot 168 grain in the STW. 2ND question is"Why wouldn't u shoot the 140 grain faster outta the STW for less drop than the 168 grain". They should have the same wind drift with the 140 grainer on the creedmoor vs the STW. But get more speed outta the STW....

There are SO many different questions and misconceptions that need addressing in this question/statement...

First off, let's start with the basics...

First, there, is this thing called a ballistic coefficient. It is a mathematical (numeric) representation of how low or high the bullet's drag coefficiency is. The higher the BC, the "slicker" the bullet is when traveling through the air. Which is VERY important to have a high BC when shooting long range.

Next...

6.5mm vs. 7mm... The 7mm is bigger, therefore, for long range, you will want to be shooting the heaviest bullet with the highest BC that your rifle's twist rate is capable of handling.

Next...

Different caliber (bullet diameter) bullets need different twist rates for optimal performance with their respect sized bullets. 6.5's are standard for a 1:8 twist, therefore a 140-160 grain 6.5mm bullet is optimal. The 7mm also needs a 1:8, but because of the larger diameter the optimal bullet weights are 180-200 grains.

Next....

Just because a bullet is traveling faster and flatter, does not mean that it won't drop faster and farther than a heavier slower moving bullet. Usually, the heavier the bullet, the higher the BC. Which means the more velocity and energy it will retain down range. This is why we prefer to shoot heavier bullets, to lighter bullets. This is the reason why you don't want to shoot deer with a .25-06 beyond 600 yards, but it's perfectly ok to shoot them to 850-1000 with a .30-06 with a heavier higher BC bullet.

So, in conclusion...

When shooting long range with a 7mm STW, I recommend a 180 or 195 Berger Hybrid...If your rifle has a 1:9 or faster twist.

For the 6.5mm, you will want to shoot the heaviest bullet for it.

 

[Dust270WSM]

Y'all are awesome...really appreciate all this info....exactly what I was hoping to get!!! Bought this rifle slightly used so not sure of its history on round count. But I've been trying to get it to shoot 168 bergers and haven't been able to get a group less than 3/4". Used H-1000 4831 and imr 78 but still not what I think it should be able to shoot. Barrel or just need to try more bullets.. would like to try to the hornadys just haven't got a chance to pick any up yet.

 

[benchracer]

Y'all are awesome...really appreciate all this info....exactly what I was hoping to get!!! Bought this rifle slightly used so not sure of its history on round count. But I've been trying to get it to shoot 168 bergers and haven't been able to get a group less than 3/4". Used H-1000 4831 and imr 78 but still not what I think it should be able to shoot. Barrel or just need to try more bullets.. would like to try to the hornadys just haven't got a chance to pick any up yet.

Have you done this?

https://www.longrangehunting.com/th...-from-berger-vld-bullets-in-your-rifle.40204/

If you haven't, back off to a starting load and follow the above...

 

[Frank in the Laurels]

You couldn't find two opposites to compare, unless you picked a straight walled fat boy cartridge. I wouldn't be shooting to harvest animals with a 6.5 CM at much beyond 350 yards, I could hit them much further but to humanely harvest that would be my limit...on the other hand I'd reach for the big 7 stw beginning about where this little pipsqueek ends and would use it to 800 without hesitation. Just not a normal two cartridges to compare for long distance HUNTING cartridge, there just not close enough to start..

 

[Rich Coyle]

tag

 

[howard3]

Last week in NE Utah I shot a nice 6x6 bull at 801 yards with my 7STW McWhorter Custom rifle, 180 Berger VLD Hunting bullets at 3100 fps. It was an uphill shot and my G7 BR2 rangefinder ranged at 801 with a shoot to of 741. I dialed and hit the bull square in the right shoulder with the first shot. He was dead but didn't know it, moved about 10 yards and turned around, and I hit him again behind the left shoulder, and he went down. It was a guided hunt, and the guide took iPhone videos of the shots through his Swaro spotting scope with one of those eyepiece adapters. The videos are a trophy in themselves. 7STW and heavy for caliber bullets are the way to go!

 

[atkinsinc]

I am looking at adding this caliber, so this helps a lot. Congratulations my friend.

 

[gohring3006]

The good thing is, you're in the right forum. Keep asking and reading. These guys will help you understand.

 

[Capt RB]

Check the twist rate of your barrel before you go any further/purchase anything. To do this wrap a tight fitting patch on your cleaning rod.mark the top at the handle and make a mark at the begining of where it enters your bore guide. Push it till the witness mark at the handle is in the same place, mark it. repeat it one more time then measure both sections you marked. If they are different the second must be less or it will never shoot right. Second match the twist of your rifle with the highest bc bullet for that twist.
Some stw's have 9.25 and some have 10tw. Both will not shoot the 180eldm's or 183 sierrias. The 10 is a 140gn tube and the 9.25 the 162-168 class of bullets.
If you post it here many can comment on your next move to save some components and barrel life

 

[atkinsinc]

Awesome! Many thanks guys. I am thankful to steal/learn from your experiences.