Two of my 7x57s were made with the same actions and barrels of the same type and manufacture. The barrels were even bought at the same time.

All the cartridges used RP cases of the same lot, CCI magnum primers from the same container, and 42grs.7383 just slightly compressed.All the ammo was loaded at the same time.One batch had a 174gr.psp,one had a 154gr spire crimped and one had a 160gr. Sierra

The two barrels have .025" different throat lengths indicating they probably were cut with two different reamers ????????????. the bullets were seated out so they just touched on the 174gr and 160gr.

the 174 in rifle 1 =avg. velocity of 2329fps

the 174 in rifle 2 =avg. velocity of 2241fps.

the 154 in rifle 1 =avg. velovity of 2422fps.

the 154 in rifle 2 =avg. velocity of 2330fps.

the 160 in rifle 1 =avg. velocity of 2374fps.

the 160 in rifle 2 =avg. velocity of 2321fps

This is quite a different velocity response between 2 almost identical rifles.

This info was posted also for the 7383 aficianotos. These loads all appeared to be mild and all the powder burned. roger

Old age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone..

All it takes is a frog hair difference in the dimension of something (1/1000ths" difference) in chamber, bore, throat dimension to give you this kind of difference.

Or maybe the barrels were made up at the same time, but from blanks made of just a slightly different molecular make-up steel and you have another cause of something like this.

sounds like that longer throat wants a tad more powder.

quote:

This is quite a different velocity response between 2 almost identical rifles.

Hey Roger, Yes it is. Not many folks get to shoot two rifles that are so similar side-by-side and notice that.

You just Yanking the trigger harder on the first one or what?

Hey Roger, I saw in another post that you have Muzzle Brakes on some of your rifles. Do you have a Muzzle Brake on any of the Scout rifles?

If so, where does the rifle balance when you are carrying it in your hand?

I spend a good bit of time shooting Off-Hand and those Muzzle Heavy rifles sure do "Hang" well.

This isn't particularly unusual with the 7x57. I had one that went 2900 with 140's and 51.5 gr 4350, sold it and bought another one a couple of years later and the old ammo wouldn't go 2700 out of the new rifle, same box of ammo. I poured the powder to it and the long throated one will go 3000 fps, just takes more powder to do it. With the really long throated ones, you almost use .280 Remington loading data, there's a heck of a difference.

quote:

Originally posted by Hot Core:
Hey Roger, I saw in another post that you have Muzzle Brakes on some of your rifles. Do you have a Muzzle Brake on any of the Scout rifles?Yes on 4 of them

If so, where does the rifle balance when you are carrying it in your hand?

I spend a good bit of time shooting Off-Hand and those Muzzle Heavy rifles sure do "Hang" well.The muzzle brakes are super light and two of the barrels are 19" one 22" and one 23"

I also enjoy off hand shooting and for me these are just great. They get on the target fast. roger

quote:

Originally posted by Hot Core:

quote:

This is quite a different velocity response between 2 almost identical rifles.

Hey Roger, Yes it is. Not many folks get to shoot two rifles that are so similar side-by-side and notice that.

You just Yanking the trigger harder on the first one or what?

I have a Sauer double in 8X60RS- one chamber is slightly longer than the other (head to shoulder). There is about 40 FPS difference in the average veloicties between the two - the one with the larger chamber is slower using the same load.

If I can ever find an 8X60 reamer, I'll deepen the shorter chamber to match the other one.