For those of you who shoot double rifles out there. How much does the point of impact change if you increase the muzzle velocity by 200 fps? I guess the question isn't really point of impact but rather how much does the spread change?

Eric

It will depend on the rifle in question. I've had ones that didn't change at all and other that would move by 3-5 inches. With doubles the only way to know is to do it.

Thanks 470Evans. I kinda figured that would be the response but figured I would check.

Eric

Eric,

If your double is already regulated, and you try to increase velocity by 200 fps, you are risking to increase pressure so much as to possibly damage your rifle.

Regards, Tim

quote:

Originally posted by ELeeton:
For those of you who shoot double rifles out there. How much does the point of impact change if you increase the muzzle velocity by 200 fps? I guess the question isn't really point of impact but rather how much does the spread change?

Eric

Mr. Leeton, first let me ask what is rifle chambered for? The reason I ask this is because uping the velocity by 200 fps in many NE rounds could very well damage your rifle, and totally destroy regulation.

quote:

Originally posted by 470Evans:
It will depend on the rifle in question. I've had ones that didn't change at all and other that would move by 3-5 inches. With doubles the only way to know is to do it.

470E, that could be a disastrous advice! Uping the velocity by 200 fps, in some cases, could raise the chamber pressures through the roof!

quote:

Originally posted by Tim Carney:
Eric,

If your double is already regulated, and you try to increase velocity by 200 fps, you are risking to increase pressure so much as to possibly damage your rifle.

Regards, Tim

AMEN! With some NE cartridges it might not make a lot of difference to the rifle, but with others it could be disastrous.

quote:

Originally posted by ELeeton:
Thanks 470Evans. I kinda figured that would be the response but figured I would check.

Eric

If this happens to be a round that 200 FPS is not a large percentage of the total velocity then it may not damage your rifle, but if it is a large percentage of the total velocity it is almost certain to run the pressures up drastically. In any event it will most effect regulation. If the rifle is shooting to the regulation built into the rifle then adding 200 fps will certainly cause the rifle to cross badly. You never want a double rifle to cross the centers of each barrel’s individual groups at ANY RANGE! But more importantly, you do not want to boost the chamber pressure too high.

............................................................................

Thanks for the thorough response MacD37. I've read about folks formulating reduced loads for practice and about other folks who have re-chambered various rifles. Also in the regulating process itself I figure the load can be changed in an effort to regulate as opposed to un-soldering the barrels and adjusting the wedge. I would suppose when working up a handload you would start a bit low and then work up hopefully reaching regulation before reaching high pressure. Having never done the later I am curious to know who much change in spread folks have encountered. I'm looking to the future when I finally get my gun.

Thanks to all who provided feedback.
Eric

Eric,
Please tell us about the rifle you are trying to load for. There are a lot of variables when trying to find a load that will regulate. Do you know what load it was regulated for?
Bill

As Bill said and as Mac said re Safety.



I have DR's that couldn't give a damn whether you load 2000 fps or 2150 fps, it shoots virtually the same (but note these loads were worked up over a Chrony from base loads so take head of what Mac said above).

I have other DR's that are VERY sensitive indeed to changes in fps.

Loads can be changed to regulate a DR but that doens't mean loads alone will make a DR regulate properly. If a DR has stuffed regulation, then in the majority of times re regulating and un-soldering the barrels and adjusting the wedge may be the only option.


Other things to try if having a problem regulating are (and don't forget that to drop 10% if changing a reloading component):-

- change of primers can make a difference (it did in one or two of my DR's)
- bullet seating depth - although this is more minor changes than major changes in regulation
- change of bullet - weight, shape, base etc/

.