Does temperature change POI?
 

I've got a scoped TC and had it sighted in dead on at 70yds, on a 80 deg day. I went out and shot the gun again on a 40 deg day and my point of impact was 2 in. high, it was dead center Left to Right just high. I resighted in to be dead on at 70yds again. Is this common? If it ends up being 20 deg. when season opens do you think I,ll have to sight in again. Thanks.

RE: Does temperature change POI?
 

Did you fire more than one shot to see if the next shot hit high? The first shot from a clean barrel will often hit high. I dont know about temperature change effecting POI because most of my shooting is done in colder weather. Check out page 4 of the forum under Dirty M/L shoot better. Cayugad gave some good info there and may be able to answer about temperature change effecting POI as well.


WV Mountaineer

RE: Does temperature change POI?
 

Temperatures I was under the impression, could effect the POI in places where there are large temperature differences. Even heating the barrel up by shooting too fast and not allowing it to cool down can effect where the bullet will hit.That is why I always double check my rifles this time of year to make sure they are ready for hunting. My Black Diamond XR was two inches high the other day when I shot it. I have not adjusted anything, I want to shoot it again to double check a different powder though.

RE: Does temperature change POI?
 

I don't shoot a lot in high heat for a couple reasons it is uncomfortable, longer cooling times requiredand it is essentially useless in regards to my hunting. Here high heat = higher humidity, it has been my experience this knocks down the POI(shoots lower). If I shoot at this time or conditions I don't do any fine tuning. All things being equal(no oil in the bore, proper cooling, seating pressureand same load/powder) 70 toa few degress below freezingF I have had very little variance in POI. In terms of inlines and sub powders such as T7 or pyrodex once the mercury drops to double digits on the minus side I have experienced some variances usually aknock down or slight delay fire that usually results in shooter errors.

Of course like mentioned if you never varified that it was indeed now grouping 2" higher it could be your ML needs to be fouled or oil in the bore creating a presure spike. Though I assume you fired more than 1 shot as you mentioned re-zeroing or adjusting your scope.

In any regard the only and best practice is shoot your setup as you were hunting, basically trail and error in simulated practice sessions for conditions. This will give you thescoop on whatyour setup does inthe temperature/conditions variances you'll seeduring hunting.

For meit means Isight in +1"/100for my average conditions/situationsI'll see in October's ML seasoncome Nov or even December I expect to be zero'd at 100 on those cold days. Through trail and error I feel no need to touch the scope caps after final sight in, unless a equipment problem arises or I need a different zero.

Good Luck

RE: Does temperature change POI?
 

If you sight in in temps over 75 the sabot is some what softer which changes the pressure build up on what it takes to start the bullet moving there for affects POI. Lee

RE: Does temperature change POI?
 

It sure will. A load worked up at 80 degrees will hit higher than the same load shot at - 20 degrees. It isn't that noticeable until your range gets beyond 100 yards, then it really exhibits the effect. Smokeless or blackpowder, same result for temp extremes.