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jtallen83

SDN-6's and POI Shifts

6 posts in this topic

I have two SDN-6's, a black and an FDE. While swapping them around to avoid a mirage I made a few observations. I didn't see much of a shift while running a Bushnell 1-6.5 but the new Bushnell 4.5-30 XRS showed me a bigger difference, I believe this relates to being more precise with the XRS and slowing down my pace while shooting these groups. First two pictures, 100 yards, FGMM 175gr. 7.62x51 version. Zeroed the scope for this load running the black SDN-6, first group suppressed ( high flyer was all me), second no suppressor;

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Next three pictures are 100 yards, FGMM 168 gr. and yes I did shoot some three round groups, the schit is expensive! First is with the black supressor, second is the FDE version, and third is no suppressor;

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I shot this pattern for two rounds cooling the rifle and suppressors in between and got consistent results. Surprised me to see there is even a POI shift between the two SDN-6's. This negates my plan for these suppressors to be interchangable, no way will I be keeping two separate sets of dope to accommodate this difference! All targets have a 1 inch grid pattern.

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Interesting. Does the POI go back to the same place when you return it to the original setup? If you were to shoot alternating groups first with the black and then with the tan...back to black...back to tan etc. ...would all the black strings consistently group together and all the tan strings group together.

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8 minutes ago, blue109 said:

Interesting. Does the POI go back to the same place when you return it to the original setup? If you were to shoot alternating groups first with the black and then with the tan...back to black...back to tan etc. ...would all the black strings consistently group together and all the tan strings group together.

Yes, they consistently return to the same POI each time they are put back on. Ran them on a 300 BO some in between their turn on the Matrix so they went on both warm and cold, showed no difference. When checking them with the suppressor alignment gauge they line up just a little different from each other, within the limits but off center a little in different directions. I'm thinking this must have something to do with the POI difference. The 51T adapters seem to place the suppressor in the same orientation no matter how you orient the suppressor when starting it. I'm hoping I will end up with groups as tight with the suppressors as without but this may not work out, I guess I will have to settle for good consistency.

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i get poi shift with my sig can its pretty enoying !! 300 blk was les than the 308 for obvious reason. 

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I get a 3 inch POI change with my 6.5 creedmoor with the SDN it is spot on without it is 3 inches high but with it ,it shoots 1 hole groups and without just a little wider....

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I read/ youtubed this and its the harmonicks of the barrel shifting with the weight of a can out front.. my question is if I zero with the can will it magnify the shift at greater distances? Ive olny shot at 100 yds.

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