Coated vs. Uncoated - WS2

[skunkriver]

Here are some results from shooting done 3/13/08 as the temps finally warmed this week and snow is leaving (for this winter, I hope). What trends do you notice???

• CZ 527 Varmint - .204 Ruger - 39 gr SBK - H-4895 - 28.0 grs. - WS2 Coated
  RD1 3798 3861 3864 3842 3893 3914
  RD2 3855 3871 3896 3874 3871 3930
  RD3 3795 3853 3899 3972 3949 3920
  RD4 3853 3860 3889 3899 3850 3893
  RD5 3776 3868 3879 3868 3862 3872
  RD6 ------------------------3917
  LO - 3776 3853 3864 3842 3850 3872
  HI -- 3855 3871 3899 3972 3949 3930
  AVG 3815 3862 3886 3891 3890 3906
  ES 78.18 17.25 34.87 129.9 99.24 57.83
  SD 36.23 7.07 14.21 49.60 37.30 23.23
  
  Same rifle, bullet , and powder, but uncoated at 27.7 grs of powder
  RD1 3872 3896 3837 3882 3902 3866
  RD2 3783 3807 3887 3935 3874 3816
  RD3 3817 3922 3822 3812 3877 3841
  RD4 3837 3814 3835 3831 3824 3899
  RD5 3841 ----- 3789 3898 3822 3846
  LO - 3783 3807 3789 3812 3822 3816
  HI -- 3872 3922 3887 3935 3902 3899
  AVG 3830 3860 3834 3872 3860 3854
  ES 88.37 114.7 97.36 122.7 88.09 83.61
  SD 32.83 57.92 35.30 50.05 35.31 31.00

The rifle was cleaned prior to each group of approximately 30 being fired and no foulers were shot beforehand.

[WrzWaldo]

I'm putting your numbers into Excel...

In the coated numbers, is the 5th string the one with 6 shots?


edit:

Looks like it took you .3 grains more powder to get your velocity back with the coated bullets.

How is the accuracy between the coated/uncoated?

Did you pre-treat the bore before shooting the coated bullets?

[acloco]

WS2 coated, round 4, shot 5....is 5000 fps slower than the rest, so, throw out round 4.

Throw out round 5 of the uncoated bullets.

3874.25 avg for 4 rds for WS2 coated bullets
38.97 avg std for 4 rounds of WS2 coated bullets

3853.66 avg for 4 rds
38.59 avg std for 4 rds


I do not see anything dramatic. Did I miss something?

[skunkriver]

WrzWaldo - Yes the 5th string has six shots ( a senior moment, forgot to reset chrony). I thought the coated was a tad more accurate just by looking at the various targets. I had a slight crossing wind so it was difficult to tell. The bore was pretreated before firing the coated bullets and not pretreated before the shooting of the uncoated bullets.

acloco - The table did not print out as good as it did when I was composing it. There are supposed to be six strings of 5 shots each, however, I had one string of 6 shots in the coated table and a string of 4 shots in the uncoated firings. That should have been 3850, not 3385. I'll edit and make the correction. Thanks, acloco. One thing to notice is the trend on the average speed of the coated bullets as you move from left( fired first) to right ( fired last) in the table. I wish I would have loaded more rounds to test to see how far the speed would have continued increasing. Carl

[acloco]

Post your raw data.

Makes sense now, but the posted data does not show 6 strings of 5 shots.

[WrzWaldo]

The table did not print out as good as it did when I was composing it.

Sometimes if you wrap your formatted text in {code} {/code} ( {} should be [] ) it will give you what your typed.

Code: Select all

      STR1   STR2   STR3   STR4   STR5   STR6

RD1   3798   3861   3864   3842   3893   3914
RD2   3855   3871   3896   3874   3871   3930
RD3   3795   3853   3899   3972   3949   3920
RD4   3853   3860   3889   3899   3850   3893
RD5   3776   3868   3879   3868   3862   3872
RD6                               3917

LO -  3776   3853   3864   3842   3850   3872
HI -- 3855   3871   3899   3972   3949   3930
AVG   3815   3862   3886   3891   3890   3906
ES    78.18  17.25  34.87  129.9  99.24  57.83
SD    36.23   7.07  14.21   49.60 37.30  23.23

[jo191145]

By pretreating your barrel (recommended) you are introducing surplus WS2 in the bore. Its quite natural for them to start slow and build speed as the barrel fouls.
Usually speeds stabilize at around 5 shots. Groups might require a few more than that to settle down fully.
Factory barrels offer a ton of variables that can change this along with differing powders.

I have a factory 308 Win tube thats so rough inside the velocity's climb through the roof as it collects copper and increases friction. I used moly in this tube in hopes it would build upon itself and smooth out a little. After four attempts it was retired, lifes to short to mess with cheesegraters

So far my use of moly or WS2 has been in the attempt to cure factory tubes that are found lacking in accuracy due to excessive coppering.
One of these days I need to try it in a good tube and relearn everything I think I know.