Rifle Scopes US Optic ST-17 Ergo Focus Issue - A little help?

[GN4HIR]

Hey boys and girls. Did I miss something fundamental?

I mounted a USO ST-17 with Ergo on a GAP 308. I adjusted the occular bringing the reticle into focus against a plain background, set the parallax for 100yd, bore sighted, did the errector tube/Erek adjustment, shot a few rounds for zero, set and zeroed the elev/wind knobs. Sweet! Life is good. Rifle has a 100yd zero.

Off to 200yd line and trouble.. set parallax for 200 but the target image was not well focused. Rotated the Ergo through a range of adjustment from 100 to 500yd but never did achieve a sharp focus between the target image and the reticle.

Any thoughts? Not my first rodeo and I've setup and zeroed many scopes but this is the first USO.

Also, the round head phillips screw in the Ergo. I assume this is a 'stop' to keep you from excessive screwing (or unscrewing) the objective. I ask because it contacts my barrel keeping me from setting parallax for long range.. and I plan to shoot 1000yd in the morning.

 

[sobrbiker883]

Re: US Optic ST-17 Ergo Focus Issue - A little help?

If you had a clear reticle/target picture at 100yds you should be Ok on out.
Double check your diopter adjusment, it can be off enough to cause fits with the clarity, but close enough that shooting static at 100 your eye can focus everything on its own.
The numbering for the objective is a guide to get you in the ballpark, 200 is not a guarantee of parallax free at 200, just that it should be somewhere around there (again, any odjustment of diopter will affect the objective as well.

The little screw head is the only complaint I have with USO's ERGO.

If you can't get the adjustable objective squared away, talk to USO.

 

[GN4HIR]

Re: US Optic ST-17 Ergo Focus Issue - A little help?

Good suggestion, I will give that a try in the morning. I appreciate the help. Just haven't had this with my NF or IOR but it is likely me rather than the scope.

Do you think it is safe to remove the screw to rotate the objective an inch or so past the barrel and put it back in? I'm in the middle of the adjustment range, not on either end of the travel.

 

[sobrbiker883]

Re: US Optic ST-17 Ergo Focus Issue - A little help?

I'd see where you are at when you get in the field in the morning. Keep in mind that the 10X USMC scopes were set to be parallax free and fixed at 300. Parallax is more of an issue when you are shooting inside what the objective is adjusted for than when you are shooting beyond what it is adjusted for.

I did play with the screw on the last SN3200 I had, but I can't rmember if the entire assembly rotated when I had it out, or if things looked/felt like they were going to misalign. I do know that I put it back in because didn't want things to misalign and not be able to get it back. Take a small enough screwdriver with you should you wish to try it.

Remember when you check the diopter focus that its important you only <span style="font-weight: bold">briefly</span> glance at the reticle. The USO is directly the opposite of NF-turning the diopter a little makes a difference (unlike NF where a lot of turn needs tobe made for a discernable difference).

wishin' I were shooting 1K tomorrow.......

 

[GN4HIR]

Re: US Optic ST-17 Ergo Focus Issue - A little help?

Well.. in retrospect I think the thing out of focus was the user.

No scope problem at 1000yd once I got on target (KAC BulletFlight and mother nature initally disagreed by .6 mil, it too could be user error). I did have to remove the objective screw, rotate past the barrel and put it back in. I'm will call USO on Tuesday about other solutions.

Went back the next day to 200 to chrono (checking my fps input for BulletFlight) and was able to focus. Perhaps the USO doesn't seem to have as sharp a focus as I'm used to.. as it wasn't an obvious "in or out" of focus like my IOR which clearly goes from blur to crisp. The USO was pretty much in focus but never seemed to suddenly become very sharp indicating that magic point of focus.

Thanks for your help sobrbiker883.