POI shift with barrel chop

[vaeevictiss]

I recently had the barrel on my 700 sps .308 chopped and threaded from 26" to 22" and topped with a break. Now I understood I would have to resight the scope with this kind of work, but is 9" to the right (@100yds) normal? It seems a bit extreme. My scope was able to do it, but I'm concerned about longer ranges.

Could the crown have gotten knicked or the barrel not be mounted straight?

[Palladin]

Sound like crown issues... Is the barrel tapered? And if it is, how would one clamp it to ensure the chop was 90° to the bore axis? I'm not familiar with the technique to do this properly.

[davsco]

was the scope re-mounted? that could have something to do with it.

have you shot 3 - 5 shot groups at 100 yds? is the accuracy pretty much the same as before? if you're getting good accuracy, i wouldn't worry about the 'shift' too much.

[M1A4ME]

Barrels "whip" when fired. If they "whip" consistently you get a better group.

When you shorten the barrel it "whips" differently.

You should see some of the slow motion videos of rifle barrels as they are fired. Unbelievable.

[grumpyMSG]

Your crown didn't get nicked, it was chopped off when you shortened the barrel. You could have several things adding up to your being 9 inches off. Your new crown may not be perpendicular to the bore. The barrel may have been removed from the receiver and is not re installed at the same torque. You said that it was threaded and a brake installed, was the break installed square to the bore? Was the brake torqued correctly when it was installed? I can tell you from experience, that if a soldier removed the flash suppressor from an M16A1 (no need to worry about the timing of the 6 slots) with a flat screwdriver, so he could "clean" his rifle better, and then he reinstalled it himself with the same screwdriver, that rifle's POI would shift an in inch or more in 25 yards (Army zero range). That would work out to a 4 inch or more shift. Did you pull the bolt out, align it on a target (looking through the bore) and then check where the scope was pointed?

[gunderwood]

have you shot 3 - 5 shot groups at 100 yds? is the accuracy pretty much the same as before? if you're getting good accuracy, i wouldn't worry about the 'shift' too much.

+1

Check everything to make sure nothing is loose or obviously wrong, then shoot some groups. If it groups fine, your probably ok. POI changes are expected.

[vaeevictiss]

Yea I'll try to shoot some groups this weekend. Didn't have much time with the shitty weather this weekend.

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