Tightening It Up

Thursday morning provided a brief interlude to a lamentably large block of unflyable weather. By Thursday afternoon conditions had already returned to an uncooperative state and so I set about working on the next iteration of tuning my new rifle. To that end I replaced the OuterImpact rail with the recently arrived LaRue rail and undertook the task of properly leveling the scope.

To accomplish this you start with a reference level laid on a flat part of the gun such as the scope rail and then align a barrel clamp level with it such that the bubble centers within both…

With the barrel clamp level indexed to the gun you can remove the reference level, mount the scope, and place the reference level on the elevation turret…

Now with the screws slightly loose on the scope rings you can twist the scope until the level sitting atop it centers the bubble while being careful that the barrel clamp level continues to do the same…

After correctly aligning the roll of the scope with this leveling equipment a laser boresight can offer some insight into its pitch and yaw…

As expected, Friday morning’s wind took paragliding off the table, and notably that also does not make for the best wind for shooting, but you work with what you get…

This time I opted to shoot the Lake City 7.62×51 FMJ 149gr ammo I bought in bulk recently, having validated that its spec (M80 Ball Ammunication) indicates a lead core and gilded metal jacket (i.e. not steel core which chews up backstops and poses ricochet and fire risks). Overall it seemed to shoot fairly similarly to the Hornady 308 SST 150gr I shot last week, though I did have to make some elevation turret corrections to get on paper at 100 yards. Note that you can shoot 7.62×51 in a gun chambered for 308 but NOT the inverse.

This week initially the scope was dialed into the exact settings where I had left it at the end of the previous week’s outing…

… which last week after a bunch of iteration had gone from shooting into the dirt to a final target that looked like this when I was aiming for dead center…

Steve had joined me again and I asked him to look downrange with a naked eye instead of through the scope at the outset, assuming I would likely be hitting dirt again. In fact I was, this time above the target. After two shots into the dirt I swung the elevation turret clockwise from eleven o’clock to 1 o’clock and tried again. This time I got on paper and I took a couple more shots without adjustment to account for noisy data. This yielded a three shot group that spilled across what we were calling boxes 12 and 13 (counting the 3×3 box-of-boxes from upper left and reading like a book).

I took out half of the turret adjustment I had applied and then got the grouping comprised almost entirely of boxes 2, 3, 7, and 8.

The horizontal alignment of my shots proved tighter than last week and I suspect that this came at least in substantial part from the scope work I did, not just the alignment work but also installing the new rail with screws with Loctite on them such that the rail never became at all loose.

I took a break after putting twenty rounds downrange, spotted for Steve while he took a turn, and then set up on a clean sheet to fire off another fifteen rounds at 100 yards without any turret adjustments.

This felt like progress but with a lot of work remaining to be done. In hindsight my pattern makes it look like I took out too much of the earlier elevation correction I applied and I probably ought have re-applied some of it. The pattern also evinces a strong leftward tendency, part of which doubtless stemmed from the wind, but also I wonder about the trigger pull and shoulder mounting I am doing. On a couple of my wilder I shots I knew by feel before even looking at the target that I had screwed up just by how the butt of the gun kicked on my shoulder, yielding a slight sideward shift instead of squarely impressing.

I gather that I have arrived at the stage where shooter skill, both technical and physical/sensory, is at least creeping up on, if not overtaking, gun readiness as the dominating factor. I gather the biggest remaining issues on the latter include tuning cheek weld and eye relief such that I can quickly and stably acquire a sight picture. Swapping out the stock thus may prove the next highest ROI task. I also need to memorialize the elevation work I have done by re-indexing the turret cap.

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