SmallCaliberCentral

I gotcha. I guess I'm just much simpler than most folks when it comes to this stuff. For what I do I only need a basic 3/4" at 200yd load which is what I've got. If I were out shooting like some of you folks with p-dogs & Skippy then I would probably have a different point of view. I'm only able to get a 400yd shot & I haven't seen any hogs out that far yet.

I've been thinking about my 700 trials & tribulations. This goes back to the bearing surface/bottail post. The 32gr V-Max shot so well that I was over come with the joy of shooting at paper. Not really but it did feel good to shoot those small groups. Then I decided the 204 wouls shine brighter with the heavier higher BC 40's around 3900fps. Well the 40gr V-Max wouldn't produce much under 1" at 100yds for me. Then the 39gr BK's came along & I can now shoot 1" groups at 200yds 95% of the time. With about 80% right at 3/4". Then I tried some 40gr Bergers a Good Friend of mine sent me. (Thanks skypilotbc ) What I found with these & 10X was they would group between 1/2" & 3/4" with 7 different loads but I didn't like the velocity. Then I lined up the above 4 bullets. The 32gr V-Max has no boattail. The 39gr BK & the 40gr Bergers had small boattails & the 40gr V-Max had the largest boattail. I deduced my rifle didn't like much of a boattail. Maybe I don't fully understand the intent of the original post or it got sidetracked. I would say it is me & the not understanding part honestly. I guess I took it as the 37gr bullet being the bullet for the 204's 12" twist instead of a discussion on how well it would perform ballistically. Sorry if I confused anybody with this long winded post.

Here's a handy calculater for figuring out barrel twist.
http://kwk.us/twist.html

Here's a quick explanation in regards to "boattail theory".
http://wildcatbullets.homestead.com/BulletTheory.html

Oh, by the way, Richard from Wildcat Bullets informed me that Corbin is working on the new dies and he should hopefully be in production by January.

Here is the data from Gube's calculater he posted.

2850 fps: .620" bullet lenght = 1-12.5" twist
.650" bullet lenght = 1-12" twist
.667" bullet lenght = 1-11.7" twist

2750 fps: .620" bullet lenght = 1-12.3" twist
.650" bullet lenght = 1-11.8" twist
.667" bullet lenght = 1-11.5" twist

The Sierra 39gr BK at 2850fps = 1-10.6" twist
The Nosler 40gr BT at 2850fps = 1-10.5" twist
The Hornady 40gr V-Max at 2850fps = 1-10.4" twist

All the ballistic calculaters we used so far say the same thing. The 1-12" twist is very marginal for 39-40gr bullets. A shorter and lighter bullet 37gr bullet should work and shoot very well in the all 1-12" rifles.

Hopefully this should generate some interest in a 37gr bullet for us to use and the bullet companys to make.

Grayfox

Grayfox wrote: .....All the ballistic calculaters we used so far say the same thing. The 1-12" twist is very marginal for 39-40gr bullets. A shorter and lighter bullet 37gr bullet should work and shoot very well in the all 1-12" rifles.

Hopefully this should generate some interest in a 37gr bullet for us to use and the bullet companys to make.

Grayfox

"All the ballistic calculaters" will show you that a shorter (your 0.620" length) and yet even heavier bullet than 37 grains...actually up to about 41 grains.... will "shoot very well in the all 1-12" rifles".

The weight - which again is not a factor - could be even heavier for any and all purposes, but you can only stuff a certain amount of lead in a given bullet jacket length - in this case 0.620".

-BCB

I wonder how long the new Barnes 26 gr varmint grenade will be. Because it is lead free the overall length of this new specimen may be to long to stabilize in a 1 in 12 twist even though the weight is only 26 gr. If it is longer than the 40 gr V-max, it aint gonna fly. Hopefully Barnes has done their homework in this regard.