bitter sweet day

nelly250

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Thunder Bay, ON
today was my first opportunity to shoot my tikka varmint past 300 yards (my range is only 300 yards, but I found a nice gravel pit) and it went well....sort of.

Range was 510 and I was just trying to figure out how much elevation to dial in so I was using my "junk" ammo. When I first started loading for this rifle I was using 64 grains of H414 then I did a haphazard ladder test at 300 yards and settled on 65.5 grains of H414 (300WSM). So I started toay with the 64 grain stuff that I had left over just to get the elevation on, as I was getting close I started to try for some tight groups, I fired 4, 3 shot groups all were surprisingly good and one was unbelievable right around an inch, under 1 1/4 for sure.

At this point I was super happy, as i was getting better groups at 500 than i usually do at 300. Then i switched to my "good" ammo (65.5 grains) and things went south. First group measured about 7 inches, two were within 2 inches, but the third was high and left. Second group same thing, 2 nice and tight and one way off. Third, complete miss, the wind was picking up. Fourth, dialled in the windage and again shots were decent, with one flier. All three fliers were high and left (more high than left) and I am pretty sure that I didn't pull any shots. Wind was right to left as well, and picked up as the day went on.

Unfortunately I had to cut the day short due to thunder storms, but basically, I am thinking my ladder test wasn't accurate and I should reduce the powder charge from 65.5 back to 64.0. One other variable with the ammo was OAL, my "good" stuff is a tad longer 2.868-2.869 vs 2.862-2.863 - I have no idea if that is enough to make a difference or not.

The crappy part is I just finished loading up over 200 rounds yesterday (which took forever) - all with 65.5 grains.

Does anybody think the difference in OAL could be a factor, or should I just lower the powder charge?
Also, I crimp with the lee factory crimp, which I am guessing means that I can't just seat the bullet a bit deeper on the rounds that I already have loaded.

cheers.
 
... I fired 4, 3 shot groups all were surprisingly good and one was unbelievable right around an inch, under 1 1/4 for sure.

At this point I was super happy, as i was getting better groups at 500 than i usually do at 300.

3 shot groups mean very little. Best spend a bit more and send them 10 per target.
w ww.ar15.com/forums/topic.html?b=3&f=118&t=279218
 
You might want to give this a read too...

ht tp://optimalchargeweight.embarqspace.com/#/ocw-test-example/4529811475

I found it alot easier decifer than the standard ladder test.
 
One enormous variable is temp and humidity.

With H414, you are using a powder that is temp sensitive. If you did your prelim testing in cooler weather and now shooting in hot muggy temps, the powder will act differently and yield a much different pressure curve.

Big reason, competitive shooters have moved to temp stable powders which are mostly extruded.

I assume this is a 7RM? {Never mind, saw that it was a 300WSM}

If it is, I can recommend Re25, H1000 and Retumbo as great options with the 162/168gr bullets. Retumbo has shot really well for me with the 180's. {H4831SC, H1000, Re25 would be great here}

I have an article on my website for LR load tuning that will certainly help.

I don't bother with 10rds groups as I find there is just as much error in the process as anything else. Arguably MORE.

Besides why continue shooting when the first 3rds are 2 MOA apart?

I prefer to do multiple groups equal to how the rifle will be shot and the accuracy sort.

If hunting, 3rds is plenty. If F class, 15rds is not out of the question but that is preceded by several 3 and 4 rds groups to confirm the load. The 15rds tests are simple the final torture test to make sure nothing is going to go south under match conditions.

If you are shooting well, under decent conditions with good loads, the first 3 WILL represent the next 7 BUT your ability (and barrels tolerance to heat) may not.

Do multiple groups to confirm.

I feel 3 4rds groups at 200yds is more informative then 1 10rds. Especially, if these groups are shot on different days.

Jerry
 
never thought of temp, ladder test was done in cooler weather - that could explain why the lower charge is shooting better in the heat. I should have put it together as I did read that H414 was temp sensitive (after I bought it).

Lots of good tips here - thanks guys.
 
Hi Nelly250, just been trying to PM you, however it appears your mail storage is full. Could you please let me know when I can email you about the scopes? Thanks

Russ
 
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