Velocity loss

[Downwindtracker2]

This is interesting but means very little . Last Saturday at the range I brought my chrony along to do some load development. I chronyed a couple of my buddy's Winchester 180gr 30-06 Power Points.one out of my '80 M-700,the other out of his new M-760 carbine.Book 2700f/s,22" barrel 2674f/s,18 1/2" barrel 2534f/s

My buddy now can use 308 ballistic charts.

[Rocky Raab]

It is interesting, and you are right: it means very little.

What is equally interesting is that it MIGHT have gone the other way - the longer barrel may have been the slower one.

That 670 does seem to be awfully slow, though. If all were equal a 100+ fps loss for an inch and a half is a bunch. But all things aren't equal, are they? That 670 is newer and might not be as smooth as your 700. It may also be a bit looser in bore and/or chamber.

Put a few hundred rounds down that 670, and he might see the speeds coming up a bit. Or not. As you seemed to be saying, "Ya just never know, do ya?"

[Lone Star]

I'm confused here. There is a 3.5" difference in barrel length, and a 140 fps difference in velocity; that's 40 fps/inch loss, pretty close to standard for the '06 IME. That factory ammo is pretty right on in the M700, losing a theoretical 26 fps for 2" of barrel length, theoretical because we don't know the actual velocity in a 24" barrel.

Using the standard Remington rule of thumb of 20 fps/inch for 2500-3000 fps loads, you'd come up with 2660 fps out of the M700 and 2590 fps out of the M760. Pretty darned close it seems to me.

[Rocky Raab]

Sheesh. Math was never my long suit, huh?

Of course it's 3.5 inches and not 1.5. Thanks for slapping me upside the head, Lone Star.

[Downwindtracker2]

1980 was a good year for M-700s,the barrel is a bit fast. I also have a Winchester M-70,which is 10f/s slower.They both shoot the same loads.

On the other side I have a P-14 303, even with it's 26" barrel is going over 100f/s slow.Guess I need fatter bullets if I want that 100f/s.