Super-sensitive to powder charge?

[rg1911]

I was at the range Saturday, testing loads for three rifles, including my AK47. (I know, why bother with the AK? Basically, just curiosity.)

Shooting carefully off a solid bench and rest, the results were:

Load #1 put 5 into 4-5 inches at 100 yards.

Load #2 put 5 into a very nice 1.3-inch cluster.

Loads #3 and #4 went right back to the 4-5-inch spread.

Range conditions were the same. All charges (RL-7) were weighed. All brass was new 7.62X39 WW. The charges increased by .3-gr between loads. I let the barrel cool about a minute between shots.

Obviously, I need to test load #2 again.

Is it possible for a cartridge/rifle to be that sensitive? (I've never experienced anything that dramatic before.)

Thank you,
Richard

 

[rduckwor]

Yeah, retest #2. Awfully good group for a commie rifle.

Good Luck. And yes, rifles can be very touchy when it come to loads. If #2 holds up, stick with it. It's golden.

RMD

 

[MJY65]

I'm going to say #2 was almost certainly an anomaly.

 

[noylj]

The basis for the OCW/ladder test is to determine the range of charges that will put the bullets into almost the same hole. In MOST cases, no, a 0.3gn charge weight variation will not make a difference.
If you reshoot all three loads again, you may/probably will find that the "best" load this time is not the best load again. You really NEED five 5-five shot groups to really know if a load is accurate or if it was all the statistical "standard errors" simply stacked in your favor that one time.
Even psychological effects if you reviewed each target as you finished with it:
First group--getting used to the rifle/position and settling in, fouling the barrel, and getting all components settled in.
Second group--excitement
Third and fourth group--excitement ruins these groups or barrel is getting hot.

 

[4Quangs]

The basis for the OCW/ladder test is to determine the range of charges that will put the bullets into almost the same hole. In MOST cases, no, a 0.3gn charge weight variation will not make a difference.
If you reshoot all three loads again, you may/probably will find that the "best" load this time is not the best load again. You really NEED five 5-five shot groups to really know if a load is accurate or if it was all the statistical "standard errors" simply stacked in your favor that one time.
Even psychological effects if you reviewed each target as you finished with it:
First group--getting used to the rifle/position and settling in, fouling the barrel, and getting all components settled in.
Second group--excitement
Third and fourth group--excitement ruins these groups or barrel is getting hot.

I didn't write this, but it sure does sound as if I did.

 

[rg1911]

Appreciate the comments.

I rather (and sadly) figure Load #2 results are a fluke, but it did get me wondering if a .3-grain change could make such a difference. I will retest Load #2 and, if it gives the same results, will enshrine it in gold (and run out and buy a Lotto ticket).

Cheers,
Richard