What caliber for the new build

[ajj]

The 4" thick target at Zwolle is a chicken, I think. You couldn't lift a 4" thick pig without a crane.

[Evelio Mc Donald]

They do have a 3" or 4" thick pig, it does take two guys to set it up.
Evelio.

[dwl]

Evelio;

Thank you for the technical turn of the discussion. You and everyone else will have to excuse my technical obsessiveness but then again aren't all shooters somewhat technically obsessive?

I recognized the formula you provided but I seem to recall that the gas velocity for small arms was 4000 fps instead of 4700 fps. As I recall the 4700 fps velocity was for larger calibers such as cannons and howitzers. Unfortunately I can't seem to find the reference in my texts.

The velocity of the free gas escaping from the muzzle is never constant. The gas is constrained by the bullet prior to the bullet exiting the muzzle. After the bullet exists the hot gases begin jetting out of the muzzle at greater than the muzzle velocity of the bullet, up to 2 or 3 times greater. In fact, the escaping gases blow past the bullet so that the newly fired bullet is in a tail wind when it is still close to the muzzle! Quite rapidly the gas pressure in the barrel subsides and the velocity of the escaping gas drops off, eventually to zero.

Since making energy calculations would be annoyingly difficult with a gas velocity as a variable, a constant number usually substituted to simplify the calculation and get reasonable predictive results. Changing the gas velocity in the equation from 4700 fps to 4000 fps should change the recoil calculation only a very little. So little in fact, that you could easily ignore my remarks. It's just an obsessive/compulsive out burst on my part.

BTW, you might want to consider an addition to your list of 6.5mm cartridges - the 6.5-250, aka the 260 Bobcat. Think of it as a 6.5X. It is easy to make and economic, just run 250 Savage cases through a 260 Bobcat die. No extra reloading steps. It is very close to the 6.5X47 in capacity. It costs less than the Lapua. It feeds slick from an unmodified Rem 700 short action and it will take down the 500m/50lb rams with low belly shots. It did at Landy, WY. And it's accurate, .298 to .5 at 100 yards with Sierra 142MKs, in my gun. There's at least two others out there shooting so mines not the only one performing well.

I'll be developing some velocity numbers with the chronograph JerryG so generously provided. I'll post them when I'm done and everyone can compare recoil and momentum.

dwl

[ajj]

I didn't see the thick pig at Zwolle but I did ring a normal one. There were at least three pig ringers. Wind was right in the shooters' faces. A tough course, at least for some of us.

[stsbuyer]

For what its worth my 2 cents

Here is what I get from my ballistic calculator. I have not included powder charges but all are from guns that I used in the past or my current rifles. I could switch to faster powder in the 6.5 x 55 and maybe end up with the same recoil on the 142. But my experience has been that the faster powder gives more pressure before velocity in the bigger case. The added recoil of the 107 between the two rounds happens because the 6.5 x 55 need more of the same powder to get the exact same velocity.
I think it is pretty obvious why I quit the 308 15 years ago. Now you can see why I like my new 6.5 x 47 Lapua.


Paul Freeman

308 Win.
150 Gr @2550 8.95# gun 10.1 Ft. Lbs recoil
168 Gr @2650 8.95# gun 13.3 Ft. Lbs recoil
180 Gr @2550 8.95# gun 14.5 Ft. Lbs recoil

7mm-08
130 Gr @2650 8.95# gun 8.4 Ft. Lbs. recoil
168 Gr @2625 8.95# gun 13.1 Ft. Lbs. recoil

6.5 x 47 Lapua
107 Gr. @2750 8.95# gun 6.8 Ft. Lbs. recoil
142 Gr @2740 8.95# gun 9.9 Ft. Lbs. recoil

6.5 x 55 SM
107 Gr @2750 8.95# gun 6.9 Ft. Lbs. recoil
142 Gr @2780 8.95# gun 11.9 Ft. Lbs. recoil

[Bob259]

After input from many sources and discusions with many people I've decided to go with the 6.5x47.

THANKS to all who helped me with my decision!

Still have time to decide single actiom or repeater... thinking repeater as of right now

[carl425]

Still have time to decide single actiom or repeater... thinking repeater as of right now

Why would you want a repeater? Besides, of the 3 rounds you were considering, the 6.5x47 is the least repeater friendly.

[jneihouse]

of the 3 rounds you were considering, the 6.5x47 is the least repeater friendly

Explain please???

Kitty

[Bob259]

I went with the single shot

[jneihouse]

When can we start powdercoating

[carl425]

of the 3 rounds you were considering, the 6.5x47 is the least repeater friendly

Explain please???

Kitty

The gunsmiths I've talked to all tell me that the more squat cartridges with less taper to the sides are the hardest to get to feed properly from a magazine. The BR cartridges are the worst. The 6.5x47 Lapua shouldn't be as difficult as a BR, but it won't be as easy as a 260 or a 6.5x55.

Take a look at Remington's 40x options. They only offer single shot actions for the BR's.

[BlauBear]

In looking back at this thread, is it instructive to ask if anything besides the 6.5mm is a solid candidate, or is everyone gravitating to that caliber?

[Evelio Mc Donald]

The 6.5x55 will feed great out of the long action, so will the 7.08 or 260 out of the short action. For some unknown reason, my 6.5x47 won't feed worth a shit out of the short action. I WILL BE GOING TO A SINGLE SHOT ACTION FOR THAT BABY AS SOON AS I FIND THE TIME TO DO IT.
Evelio.

[BlauBear]

The more I look at all this, the happier I am with the .260 irregardless of the expensive brass! On average, how much of your spent brass are y'all able to recover for reloading?

[Evelio Mc Donald]

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