Issue with Fastfire III and sighting in

[ehavs]

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Hey all,

I shoot a 12 gauge remington 870 and installed a Fastfire III on it using a speedbead mount.  Shoot the 3.5 inch magnum loads and I cannot get this thing to sight in.  It feels like I have it then when I shoot again the sight gets off kilter.

Have any of you had this issue with magnum loads out of a 12 gauge?  Do you think it may be a defective sight?  Any suggestions?

Thanks

[Snoodsniper]

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You're probably flinching.

[Sasha and Abby]

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shoot lite loads and see if that does not correct the "problem" 

[Snoodsniper]

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Make sure your barrel nut is bubba tight. Once it's dialed in do not remove the barrel for cleaning until the season is over. Removing can/will affect the POI.

[paboxcall]

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Make sure your barrel nut is bubba tight. Once it's dialed in do not remove the barrel for cleaning until the season is over. Removing can/will affect the POI.

Good advice. One work around is to put a small black Sharpie mark on the barrel nut and tube to make sure its tighten back to exactly the same position.

[rakkin6]

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Yeah I would check poa/poi using a low brass shell and make sure you are good. If it is on after that I would say drop down to a 3" she'll lol. I have shot 3" longbeards and 3" 2 1/4 oz TSS out of my 535 and 835 both with FF3 and have had no issues.

  If it is off with the low brass I would contact Burris they have good customer service. I had an issue with their battery cap on one of mine. Had a brand new one in 4 days.

Sent from my moto z4 using Tapatalk

[Pluffmud]

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Also make sure you stock is firm as well. That speed bead could shift a little if you have the stock nut loose.

[WV Ridge Reaper]

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Make sure your barrel nut is bubba tight. Once it's dialed in do not remove the barrel for cleaning until the season is over. Removing can/will affect the POI.

Good advice. One work around is to put a small black Sharpie mark on the barrel nut and tube to make sure its tighten back to exactly the same position.

I am a firm believer in this on every gun ff or not...After that tho I rack the bolt let it slam shut and snug one more time just to be sure.

[BandedSpur]

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The speedbead mount could be the problem. I put one on an 1187. The POI kept shifting so I eventually checked and found that the speedbead mount itself had cracked and was no longer rigid, allowing POI to drift. Contacted Burris. They agreed to ship me out another mount asap, my choice of speedbead or 336 mount. Since I had issues with the first speedbead mount, I chose to get the 336 mount and do a drill and tap. Great customer service from Burris.

[SumToy]

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drill and tap the gun..   Put our base or burris 336 

[CALLM2U]

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While I have limited experience with the Speedball mount, there are many reports out there on the internet (which means it has to be true  ) of issues with them shifting POI. 

I would drill and tap if I was you. 

[strum]

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drill and tap the gun..   Put our base or burris 336