Standard deviation.

[nf1e]

As of late, I have been loading .223 ammunition for precision shooting. Never paid any particular attention to SD. Well, over the last couple of weeks I have been doing a bit of checking on the results of differing variables. Powder is loaded to within .02 gn which is the size of a kernal. Bullets used are Berger 73 gn bt target and have not been sorted by weight. Primers are BR-4s and I have been told that other primers should lower the SD even more. I did not notice any measurable difference in point of impact at 100 yds. Each group tested was 50 rnds, or 1 of my range boxes. Thought some might be interested in those variables.

New Starline .223 50 cases sized and loaded with 23.5 gn of Varget. SD 20+
" " " 50 cases sized, and weight sorted to 1 gn with 23.5 gn Varget. SD 12+
" " " 50 cases sized, weight sorted to 1 gn with flash hole de-burred loaded with 23.5 gn of Varget SD 6.5+


Whatta Hobby!

[JohnMOhio]

Every little bit helps in getting the best results and close to the same results.

[Major Tom]

Years ago I gave up reloading for the best/smallest group @ 100 yards. Now, I am happy to get 'head' shots @ 100 yards with rifle and handgun.

[JohnMOhio]

As I understand all of that to some degree, what you have done proved to be more efficient rounds. Different weights of cases, different volume, same charge, different velocity, different impact on target. De Buring flash hole, allows for better ignition of the powder. All work done allows you to make the most accurate ammo with the method and equipment you have. Others may just order some new brass, load it up, shoot it and then sell the brass as once fired. As to the accuracy doing that, it may come out as acceptable to them, not necessarily to someone that wants the ultimate accuracy. The former would be considered a reloader, the later would be considered custom hand loader. That is the way I see it.

[nf1e]

What I intended to say about the group not actually measured for changes at 100 yds is that one hole is good enough for me. Target shown is a 10 shot group at 100 yds on a MR-31C. Intentionally shot hi and left so as not to obliterate the X aim point. With the shooters wobble factor considered, that ain't too shabby. Whatta Hobby!





1215 73 1.jpg

[JohnMOhio]

Doing alright for an old man. You still have it, haven't lost a step. What about using that rifle and ammo combination for the 10 dot challenge you often speak about.

[nf1e]

10 dot challenge I shoot is for M14 type rifles only. We did run a 10 dot at one time with 1/4" dots for bolt rifles instead of the 1" but interest waned when hits were minimum. A challenge isn't supposed to be easy. Whatta Hobby!