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I've been trying to sight in a red dot scope on my MKIII678 @ 50 yds. from a rest. I found that when I loaded 5 rounds into a magazine and then shot 5 round strings 1 shot is 3-4" typically from center [high] while the remaining 4 shots are all within 1" of dead center. Thinking that the last shot might be the culprit I loaded 4 different magazines with 1 round each and sure enough each shot was 3-4" high. I'm curious why I’m having this problem and what I can do to eliminate it. Any suggestions ?

Actually it sounds like the first round is your traveller. It might be barrel temp, or, and feel free to discredit this everyone, could the bolt locking open happen fast enough to rock the pistol before the projectile leaves the barrel?

jjfunk wrote:Actually it sounds like the first round is your traveller. It might be barrel temp, or, and feel free to discredit this everyone, could the bolt locking open happen fast enough to rock the pistol before the projectile leaves the barrel?

I think it is more likely the first round. 1911's are known for this. Some of the custom shops like to discard the first round when talking about group size. It might have something to do with the fact that there is less energy chambering the first round.

I don't think there will be an easy fix.

wlambert

If I had to pick a round, I'd say the first also. That would be the one that's most different from all the others.

But I can't say why.

What are you doing when you shoot the last round and immediately after pulling the trigger? Won't discount the first round theory, but if you are not following through with the last round, that could account for a flyer. I've caught myself starting to put the gun down on the last round, dropping my head, while I'm firing the last round.

Sometimes this happens as the pistol is not closing the slide/bolt after the last shot is fired. Sometimes it is mental. All I can say is try loading five rounds in a magazine and shooting only four. Manually unload the last round. Check your target and see if your four shot group is together or if one is high. You can also check this with more than five, just don't shoot the last round or the last couple of rounds and check your target for groupings. This type of testing will reveal if the first or last shot is the flyer.

R,
Bullseye

Thanks for the advice; I'll revisit the range and give an update later in the week....