Impacts moving to the right of aim point

[koli]

This is the second time that I have noticed this.  Both times were extended shooting excursions (2-3 hours).  After shooting for about 2 hours, my shots are all drifting off to the right.  At first I thought that the barrel may be heating up ( I do take my time between shots to allow barrel to cool).  I tried a different rifle and the same thing happened so I do not believe it is the rifle.  I am shooting from a rest.  I am shooting a .243 so recoil is not a factor.  The only thing that I do notice is that I must bang the insides my right elbow off of the bench as I get a bruise there.  Any ideas as to what I am doing would be appreciated.
Thanks
Joe

[Mikey]

koli - if you are shooting with open sights you might be starting to flinch when your elbows start getting banged up.  I had a similar experience when shooting big bores from a bench so I started using a seat cushion from a deck chair - laid it on the shooting bench under my rest and let it hang over the edges so my elbows were not sitting directly on the bench and that seemed to help.  

Since this has happened with two different rifles and your shooting sessions are extended I would think more about your elbows than the rifles, especially since you let the barrel cool between shots.  HTH.  Mikey.  

ps - even though the rifles are in 243 caliber you can become recoil sensitive over time without realizing it.  You may wish to also use a recoil pad for your shoulder.

[beemanbeme]

You are getting tired.  And as posted, even the recoil of a .243 can make a cumlative impact.

[koli]

Thanks fellas.  I figured the answer would be something like that but I just wanted to hear it from someone else.  I will try to schedule more frequent, shorter duration range outings.

[elmer]

How many rounds are firing in that time period? How frequently are you cleaning the barrel? If I'm shooting for an extended time period, such as when sighting in for different distances, I clean every ten rounds.