I quess what I'm trying to ask is if you reload for a rifle with a 24" barrel and then another rifle(same caliber) with a 26" barrel will it change you're chamber pressure? Or will it just effect velocity only? The reson I ask is I had one of my big bores rebarreled and went with a 2" longer barrel.

Thanks.

Steve

quote:

Does the length of a barrel change pressure???

No

You are far more likely to experience pressure changes due to differences in chamber dimensions, throat/leade, bore diameter, twist rate, and bore smoothness than might be measurable due to barrel length.

George

quote:

Originally posted by GeorgeS:
You are far more likely to experience pressure changes due to differences in chamber dimensions, throat/leade, bore diameter, twist rate, and bore smoothness than might be measurable due to barrel length.

George

All of that plus swings in ambient air temperature......

Look at it another way, if your rifle has a 26" barrel & you load a given cartridge to 3100 fps in it & then you dock that same barrel to 24" you might only see 3020 fps over the chronograph but docking that 2" will have done nothing at all to alter your initial chamber pressure all other factors being equal.. The difference in velocity will be entirely due to the shorter barrel giving less time the bullet is subjected to the pressure from the burning powder. All the other factors such as bore tightness, chamber size etc are eliminated by keeping the same barrel. Atmosheric pressure, temperature etc will affect velocity slightly from session to session regardless of physical factors in your rifle. So, go with Vapodog on this one. NO.
Steve.

A good reloading practice with a re-barreled rifle would be to back off a couple of grains of powder and work back up. If it was the same barrel and chamber the difference in length wouldn't make a difference. Since you've gone up in length and had to re-barrel and re-chamber to do it backing off and working up is the best and safest way.
Take good care,
Dave

I have to confess to having missed the point of the first post rather, so, new barrel, work up new load for it, as 470 Mbogo says.
Sorry for heading off in the wrong direction.
Steve.

Gentlemen

Thanks for you're suggestions and help.

A couple of years ago I worked up a awesome load in my .378 Weatherby Magnum. Then I made a terrible mistake and had a muzzle break installed.
As you can quess it helped the recoil however, it got alott louder and I wasen't real happy with the groups now.
So I had it rebarreled with a heavier contour and had a dead mule installed in the stock. Back to the subject the new barrel is 28" Shilen and that is why I was just wondering about the pressure. I went from a Hornaday 270 grain spire point to a 270 Barnes TSX bullet and I was planning on using the same load however, for starters I backed off three grains of powder(H-4831sc).

Thanks

Steve

quote:

Originally posted by Steve Lefforge:
I was planning on using the same load however, for starters I backed off three grains of powder(H-4831sc).

Thanks

Steve

Sounds like you've gone about it exactly the right way.
Steve.