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11/9/2018 9:21:38 PM
Posted: 6/10/2018 10:31:20 PM EST
So i'm not a super sniper shot like some people here. Apologies in advance for >1moa group, and for only posting one group. Got to take my grendel to 200 yards. It was the first time I had ever shot beyond 100 yards. I had it on a front rest and rear rabbit ears bag, hornady factory SST ammunition. I only had one chance at a 5-shot group at this range.I observed significantly more spread in the vertical than the horizontal. It doesn't look like random chance to me, and while the shots appear spread in the vertical, I don't think they were moving monotonically in a vertical direction. Target is below (note that the bottommost hole is from a 7mm wby), squares are 1", distance is 200 yds.



I haven't seen this at 100 yards, but i also don't usually use nice rests with rear bags. Yes, it would be nice to shoot five 5-shot groups and then compare, but time was limited and I don't have a nice range in my backyard. I know that I need to get more data. . I'm mostly asking because if it is likely a trigger/breath control problem - then that's something to work on even at shorter ranges. There is also slop between the upper and lower (i bought a matched set from a manufacturer to avoid that problem....). That shouldn't be causing the issue, right?
Link Posted: 6/11/2018 6:39:50 AM EST
Link Posted: 6/14/2018 10:14:37 PM EST
[Last Edit: 6/15/2018 11:23:02 AM EST by newBMowner]
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Originally Posted By Rob01:
1 MOA from factory hunting ammo in a semi auto isn't bad though.
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Agree, getting just over MOA at 200yds with factory ammo is actually pretty respectable. Nothing to sneeze at for sure if the gun is consistent.
I wouldn't make too many assumptions or attempt too many corrective actions until you've explored things a bit more. One 5 shot group is not really significant. Had you been able to shoot several 5 shot groups or even a single 10 shot group you might have observed that the dispersion of the impact points was circular (more like what you were seeing at 100yds). One group with only 5 shots is just too small a sample size to draw conclusions (and on top of that it's only 1 type of ammo in the mix as well).

Put a few more rounds on paper under the same conditions, then see where you and the gun are at would be my advice. What you've got so far certainly doesn't look bad if the gun can do it consistently.
Link Posted: 6/16/2018 8:20:24 AM EST
The group isn't bad but let's throw all the human factors out and think cold vs. warm barrel. I typically shoot 5 rounds to warm the barrel and find the groups to be more consistent after that. You might not see much difference at 100 yards but you will at 200 and beyond.
Link Posted: 7/14/2018 12:28:04 AM EST
I agree that it could just be the gun/ammo. There's more vertical spread, but it doesn't look very significant to me. Try some match ammo. Try a solid rest, see what it does with most possible error removed.

When I was trying to find a good accuracy load for my Rainier Ultramatch wylde barrel, 53gr SMKs strung perfectly vertical for me. Less than .1 moa horizontal spread, minimum 1.5 moa vertical spread. With all powder charges of the 2 or 3 powders I tried. Group size varied, but almost all strung straight vertical.

I haven't seen anything like it before or since Never got around to playing with it to see if I could dial it in. Couldn't get it to shoot to my expectations, now it's sitting in the back of my safe.
Link Posted: 8/17/2018 5:28:59 PM EST
If the gas block isn’t forward of the barrel shoulder by about 1/32”, the gas tube can contact the gas key and pre-tension the barrel causing some vertical stringing. The gap is the design dimension which takes the hand guard cap into account.
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