[aguditis]

So, last year after deer season I bought my girlfriend a 20ga 870 with bird and rifled slug barrels. I tried sighting in the rifled barrel soon after we got it with no luck. Four different types of ammo and it would not group. Every time I changed the sights it would get all screwy not tracking the right way, sometimes changing so much it was off the paper, IN THE WRONG DIRECTION.

I changed to tru-glo sights thinking that this may help. Although the groups had improved a great deal, it wasn't happening...

Let me try to explain whats going on. When I start shooting the elevation is dead nuts 1.5" high at 50yrds but 4" to the right. I move the rear sight to the left to correct the problem and it shots 6" to the right and 8" high. If I move it a little farther to the left its back to 1.5" high but 4"to the left.

I've tried just about every combination, moving the sights around and nothing will be consistent and the groups are getting worse. Now that I've put $100 worth of slugs, new sights and countless hours into this barrel, I may need to go to anger management.

My 12ga 870 with the same setup is dead nuts every shot, every time so I know its not me.

Please, any suggestions? I don't really want to ditch the barrel and start over but at this point that's all I've got...

 

[Phlyan Pan]

The 870 is a pretty common gun, maybe find someone with a 20 gauge barrel you could try on that gun and swap them to try it out. See if the other barrel shoots different or not. If not, I think if you put a cylinder choke in the long barrel you can shoot a rifled slug out of it...verify that before you do it I'm not 100% sure.

I'm assuming you've inspected the bore as well as you can? How old is the barrel/gun? I'm not an expert but if the throat is shot out would it cause erratic accuracy? There's no choke in a rifled barrel right?

 

[one-shot]

Did you buy the gun used? The previous owner could have leaded up the barrell causing you alot of headaches.

 

[aguditis]

Nope the gun was bought brand new, and to my untrained eye the rifling seems fine... I thought about a different barrel but this is the only 20ga 870 between me and all my buddies. I'll try the rifled slugs through the smooth bore but first I need to go but more slugs

 

[Noodles]

Make sure the magazine tube cap is tight! And when it's tightened all the way down, the barrel won't move relative to the receiver by putting pressure on it.

 

[aguditis]

I just checked and the mag cap is tight and it hasn't been touched sense shooting it yesterday. I could not tell if putting pressure on the front stock changed the barrel at all but I would say no, it didn't... Would this really effect anything as the sights are affixed to the barrel? It's not like they are misaligned with the reciever...

It has been shot both off the bags and out of the lead sled...

 

[Noodles]

If the barrel moves under recoil, it's going to significantly effect your point of impact. If the sights are mounted to the barrel, they'll just move with it.

 

[aguditis]

So how would I go about troubleshooting something like that?

 

[Noodles]

Well, if you shake it down good and there's no movement, it's probably good.

 

[Darthgamer138]

You aren't shooting rifled slugs in the rifled barrel are you? That will cause inaccuracy. You are not supposed to do that.

 

[Phlyan Pan]

Yeah should be sabots out of a rifled barrel.

 

[45 nut]

Try hornady sst sabots they have worked very well out of my 870

 

[aguditis]

I've tried Hornady SST, Winchester Supreme Elite, Fusion Sabots and lastly Federal rifled slugs just to see what would happen.

 

[stevec]

my 870 12 ga is giving me same problem. I am shelfing that project until next year. I threw big $$$ down the barrel and couldn't even kill paper. I was using 3" shells which was mistake #1. The recoil was jaw rattling i was shooting off a my knees instead of a solid rest mistake #2.

i am hoping a bench rest with sandbags and some Hornady SST slugs will solve the problem after deer season

 

[Camper4lyfe]

Check your front sight to make sure it's tight and not moving. I super glued mine because it had gotten knocked and my sights were WAY off to one side and I still couldn't get it set right. I moved the front sight back to center, got it sighted in, and glued the crap out of it.