does this sound right?

[7.62_Reaper]

i have been doing load development on my 7mm Rem Mag and i have been having trouble with finding a load that gets me a good three round group at 100. what i have noticed is that the first two shots can be placed right on top of each other but the third shot lands about 1 inch low, +/-, i believe this is due to the barrel heating up and this has been very consistent. my question is that is it normal for the third round to have that much of i POI shift?

thanks for the help

 

[bjay]

Have you try playing with your seating depth?

 

[FCS]

Not nearly enough information to begin to answer your question(s).

Bullet used?
How much jump?
Powder used?

Barrel contour?
Factory or custom?

Scope? Tried a different scope?

 

[bjay]

Not nearly enough information to begin to answer your question(s).

Bullet used?
How much jump?
Powder used?

Barrel contour?
Factory or custom?

Scope? Tried a different scope?

When you say barrel contour? Do you mean thiner barrel it will heat up quicker? Wil it mater if shot taken only 3? On my varmint bardel does give me flyer sometimes

 

[FCS]

Contour because:

Mirage off barrel happens faster with lighter contour
More recoil, fatigue sets in faster....not 3 rds quick but quicker


Contour of barrel is part of the bigger system, define system so guys can give better suggestions to OP.

Stock type?
Bedded?

Scope mounting system?
Scope brand and model?

Custom or factory chamber?

I could go on but I'm sure idea has been conveyed.

 

[7.62_Reaper]

the rifle is a bone stock Remington 700 Sendero SFII, so i think that the barrel is their 26" fluted varmint.

the loads is:

168gr berger
66gr of h1000
fed mag No. 215 primer
MV is 2793 fps

i have played around with the amount of powder, seating depth etc. and each time when the barrel is cold the first two shot are even and the third will be around an inch low, give or take.

to be sure that this is what is going on i fired two shot with the cold barrel, i then felt the barrel and it was warm (odiously), i let the barrel cool so i will be another cold bore shot, fired my last shot and sure enough the last shot landed right on top of the first two. i repeated the process but with the third shot i didn't let the barrel cool and the shot hit low. to be sure that it wasn't me i placed the rifle in a vice so there was no movement.

so what do you guys think?

 

[Yakface]

Have you tried shooting more than a 3 shot group to see if rounds 4 and up are all consistently1" low?