Boresighting a shotgun w/scope

Bowtech9 · 07-20-2004, 10:05 AM

When boresighting a shotgun with a scope should you leave the choke in or screw it out? I have a extended turkey choke in the gun and boresighted it with it in.I then checked it after I screwed the choke out and the boresighing alignment was not in the same place as with the choke in. Anyone know which way it should be done?

UncleNorby · 07-20-2004, 10:58 AM

I suspect something besides the choke tube changed also. What sort of bore sighter was it? I'd say the alignment was not just right.

Bowtech9 · 07-20-2004, 12:07 PM

It is a BSA 30mm collimator with adjustable shotgun arbor. When I say the alignment changed it was 3 grid line lower horizontally but still dead on vertically. My guess the reason being that when the choke is removed the arbor goes in farther (deeper) because the barrel opening is larger than the tighter choke which make the collimantor a little higher. wow thats a mouth full! Does tha make sense?

UncleNorby · 07-20-2004, 02:51 PM

Not to me it doesn't. I would think the choke would be concentric. In other words, it shouldn't matter if the choke tube is in or not. If the arbor is adjustable it should center itself on any size bore, choke or no.

Bore sighters are just a tool to save some ammo (though you can use them to record scope settings for various loads). They get you close. I guess I wouldn't worry too much about it.

I think you were asking whether to bore sight with or without the tube. I'd go with the exact setup you would hunt with.

Bowtech9 · 07-20-2004, 05:23 PM

I left it where it was boresighted with the choke in and the way I will be hunting with it. I just thought I would get some feedback on how to do it before heading to the range to shoot it in. Trying to save the shoulder not ammo if you know what I mean. Thanks again

westbronco · 07-20-2004, 10:53 PM

I use the slug choke in my 870 scoped slug barrel, and shoot it at a close enough range to be sure to get on target. Then I back off to turkey shooting distance and finish zeroing the scope. Switching to the turkey choke and firing a few shot loads at distance confirms the setting. I think the X-full turkey choke would be too tight to handle slugs safely, so I make the switch to be safe. Good luck.

eldeguello · 07-21-2004, 12:47 PM

Quote:

ORIGINAL: Bowtech9 When boresighting a shotgun with a scope should you leave the choke in or screw it out? I have a extended turkey choke in the gun and boresighted it with it in.I then checked it after I screwed the choke out and the boresighing alignment was not in the same place as with the choke in. Anyone know which way it should be done?

What are you going to shoot? Shot or slugs? If slugs, then you'll want to shoot it without the choke in place anyway, so bore sight it without the choke. If you're gonna shoot it with the choke in place, and the boresighter spud only touches the inside surface of the choke tube when it is in place, that's the direction in which the shot will be squirted out, so boresight with the tube in place.

Bowtech9 · 07-21-2004, 05:43 PM

It is strictly a turkey gun it is the Ithaca Mod 37 Turkeystrom with extended turkey choke. So I will be shooting turkey loads thru a turkey choke. I boresighted it with the choke in and will be shooting it soon at the range to fine tune it.