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Andrew Murray

G'day all.

This post will serve as bit of a journey. Part one begins here:

If you search this forum you'll see my posts about the purchase, accurising, load development of my Howa 1500 in 308.

Critical Details and Rifle Info
The rifle is a Howa 1500 24" Heavy barrel in a Hogue stock, it is fitted with Howa's 2 stage HACT trigger.
The rifle was bedded, trigger adjusted so that is snaps like glass.
A load was developed using Hornady's 168gr Z-Max projectiles (Just the 168gr A-Max with a green tip). 48grs of AR2208 seated to 71mm COAL. Producing avg velocity of 2810fps, ES of 15fps

This combination provided 0.3MOA groups on good days, well under 0.5 on most others.

Of significant note is that this rifle does NOT pass the 1 o'clock test, however the groupings did not seem to be aware of this. Occasional bad shots would blow the group out, however I have always been convinced this is operator error, simply due to my awareness of the rifle, and my self.
Note: Actions screws tensioned to 55 in/lb.

Nathan: I read on here somewhere that backing off rear actions screw can overcome failure of 1 o'clock test. Can you confirm this or speak to the effects of "work around"?

Substance of present issue:
12 months ago I drilled a fallow deer square in the face from about 200m. A friend followed a shot (on a rock), dead on target, immediately after. Rifle shooting very well. I was low on ammo and decided to reload again.

I did up approx 60 rounds. I have taken taken some game at close range (within 150m) with this ammo and all have dropped instantly. No cause for suspicion.

I shot at some paper (range was 140m) and was horrified to find that my groups were about 3.5-4MOA, all over the place. I shot the last 5 rounds of my previous batch of ammo; this group was strung out horizontally however it was gusty winds and the ammo was now 4 years old. Over all the spread was right on 1MOA.

Fortunately I had my chronograph handy and measured the velocities over 10 rounds from the newer batch. Velocities in fps below:
1 - 2797
2 - 2820
3 - 2792
4 - 2809
5 - 2785
6 - 2781
7 - 2860
8 - 2871
9 - 2854
10 - 2869
ES is 90fps

Note: The newer batch of ammo was made up using digital scales, the previous was measured using Lee balance scales. No significant pressure signs on any cases. Some flattening of primers but edges still rounded, no cratering.

This leaves us some courses of action to return the rifle to its proper form.

1. Pull ammo and redo at calibrated/correct powder charge. - Most likely fix and easiest.
2. Redo load development - start at 45grs and work up at 0.5gr intervals, fine tune once sweet spot is located. Possibly a solution due to age between batches of powder. May find a "different sweet spot" at another charge level
3. Redo bedding - Will fix 1 O'clock test failure, if I do it right, significant effort however

Stay tuned as I work through the details. And please feel free to comment! Add your thoughts!