Odd findings today

[danatkins]

So shooting hornady brass 3 different ways of prep just for my a little testing
1st 10 was just once fired and bumped .2 with hornady die
2nd was done the same then I ran a the cases through a mandrel die .262
3rd was universal deprimed then ran through the resizing die with the the decapping rod and sizer button removed followed by the mandrel
My groups improved but my sd went up anyone else find that odd

Loaded on rock chucker powder thrown from one of the lee perfect powder measure and weighted lyman accu touch 2000

 

[Doom]

It’s not surprising in the least. Group size at 100yds or 200yds and standard deviation seldom correlate. Other factors are at play.

Also, what your statistics actually show is there is 95% confidence that the true SD of the first group would be between 6 and 16, and the last group between 10.8 and 28.7. This is what you would expect if you loaded and sampled more rounds.

It’s extremely hard to perform a test like this because its nearly impossible to control all the variables. In this case, one major source of variation is your scale. It will only display to the nearest 0.1 gr so a 39.95 gr load to 40.04gr load will both show 40.0 gr. That is probably 6 fps just due to powder charge.

What I would conclude from your test is that using a mandrel in either case gave me better accuracy than using just a FLS die and setting the shoulder back.

 

[nn8734]

I wouldn’t concern myself with SD/ES on only 10 shots. In my experience the “SD” curve is somewhat of an arc. Small number of shots (3-7), low SD. Shot count increases to 15-20, SD/ES peaks in that range. Increase shot count to 30, it comes back down to somewhere in the low double digits which is perfectly fine for practical shooting purposes.

In fact, I’d argue that single digit SD numbers only get critical to have if you are shooting for groups at or near the system’s max effective range towards transonic (F class/bench rest).

Otherwise if you are consistently shooting at the limits of the cartridge and not getting desired results, I’d up-gun to a more powerful one.

Lastly, if you’re looking for better consistency try out some better brass.

 

[spife7980]

It will only display to the nearest 0.1 gr so a 39.5 gr load to 40.49 gr load will both show 40.0 gr.

huh?

39.5 +/- .1 =39.4-39.6

 

[danatkins]

So pretty much this is normal? This is just my practice plinking load haven't got my regular match load worked up yet but my long range load gets me out to one mile. I'd like to have some lapua, starline, Peterson or alpha but being a dad of 3 girls under 10 kinda makes me pinch pennies. I'm gonna upgrade my scale at some point but haven't decided with what yet. Thinking very seriously an rcbs matchmaster

 

[acudaowner]

I thought about that match master scale but decided for around the same money I could find one of those A.&.D FX120ior maybe something newer if I can find it for around the same price .

+ it's compatible with a AutoTrickler V3 Powder Dispensing System lol then I can automate my process and get closer to a 24 hr production of ammo .

 

[Doom]

huh?

39.5 +/- .1 =39.4-39.6

Thanks. Brain/finger coordination FUBAR.

 

[nn8734]

So pretty much this is normal?

Normal.

Why not use your “long range load” for matches?

If it works to a mile reasonably well it should work for any match you might be shooting.

Also your “practice” load and “match” load should be one and the same. Doesnt make any sense to practice with different ammo than the ammo you would use when it counts. So in essence your “long range load” could/should, in theory, fulfill all roles intended for that rifle.

 

[danatkins]

Because I'm not gonna sling atips if I don't have to. Only reason I bought them originally is cause I could find any eldm. My plinking load is just 140 bthp I've got some 140 eldm to load up but don't wanna throw the expensive stuff down range just to work on my form