reloads changing????

[BROWNT]

This may be a dumb question but it has me puzzled. February made a load for my 6.5x284 using hornady ELDX 143 with WIN. brass WIN. primers and H-1000 they ran 2946 fps. Verified drops and went on a test hunt taking 8 hogs and 1 coyote from 75 yds to 960 yds. Worked great. I have been reluctant to shoot any more ammo waiting on more bullets but couldn't stand it and had to shoot some steel. Well my come ups were off everything was going low. Verified 200 yd zero and today ran 2 over my magneto chrony and the same loads are now traveling 2907 fps. My tube is fairly clean and the loads are still accurate just slow. Any idea's?
Thanks

 

[Bwhittty]

This may be a dumb question but it has me puzzled. February made a load for my 6.5x284 using hornady ELDX 143 with WIN. brass WIN. primers and H-1000 they ran 2946 fps. Verified drops and went on a test hunt taking 8 hogs and 1 coyote from 75 yds to 960 yds. Worked great. I have been reluctant to shoot any more ammo waiting on more bullets but couldn't stand it and had to shoot some steel. Well my come ups were off everything was going low. Verified 200 yd zero and today ran 2 over my magneto chrony and the same loads are now traveling 2907 fps. My tube is fairly clean and the loads are still accurate just slow. Any idea's?
Thanks

Was the temperature or barometric pressure different from the 2946 to the 2907??

 

[BROWNT]

temp was a good bit warmer so I would have thought faster. psi was about the same I think.

 

[dok7mm]

I am having similar results. I suspect copper fouling is the culprit. I'm getting accuracy loss after 30-35 rounds in a 7mag 26" Kreiger that produced excellent and consistent results with 162 Amax during barrel break-in and load development. Then I received my 162 & 175 ELD-Xs. Accuracy was good, but fell off after thirty rounds in barrel that was squeaky clean to start with. I started cleaning powder out every 10 rds and it did not help. At the same time, a 280 Rem was going 100+rds. prior to needing a good cleaning. I was cleaning 7 mag with BoreTech and getting more copper than that barrel ever produced. I was aware of the longer bearing surface and that might explain the quicker copper fouling to some degree, but it's my guess Hornady is using a softer jacket material for better expansion. The 280 was on a diet of HBN coated bullets and did not suffer the same heavy coppering problem and cleaned up real fast. My intention is to run HBN coated 175s in the 7 mag. I have the barrel cleaned and pre-treated 162s and 175s coated and ready to test. Both barrels are 9 twist, 4 grove 26" Kreigers. I suppose the 7 mag version may not have been lapped properly or it hates the 175 ELD-X. Hoping the HBN will make a difference. JMO. I was borescoping both barrels before, during and after cleaning. if it continues, it's back to Bergers.