Steps for adjusting for target focus and parallax?

[Joe L]

My Savage Model 10-FCP-K is excellent. My Bushnell DMR 3.5-21x50 scope is excellent. The limitation I have when shooting this rifle/scope is in how accurately I can adjust the parallax.

When I have groups over 1 MOA, I know I did something wrong, usually poor parallax adjustment. Here is a target from this morning at 300 yards. The slashed holes were shot first, when I THOUGHT I had the parallax correct. I made one more tweak, and the unmarked group was the result.

http://joelynch.smugmug.com/Firearms/Savage-Model-10/i-GDKrQMz/0/M/300%20yd%201-20-13-M.jpg

My problem is that I can't hit the parallax consistently at any distance. I think I should adjust for clear target focus first, then check for parallax by moving my head snd seeing if the target/crosshair relationship shifts. The problem I have is moving the gun when moving my head to check for parallax. I use a bag at the rear and a bipod at the front. Maybe substitute a harder bag at the rear until I get the parallax adjustment right?

Joe

[david8989]

Sounds like you need to adjust your diopter. You may have done this already but this is the way I go about it. I will set up at a known 200yd range and set my parallex to the same. Then i'll fiddle with my diopter to get a clear focus of the target. After I do this I don't touch the diopter again unless my eyesight changes. Then adjust your parallex for focus & parallex free shooting. I've never had a problem doing it this way.

[J.Baker]

This is why I personally hate and flat-out will not buy another side-focus scope - you give up the more precise adjust-ability offered by the much larger diameter adjustable objective, and in my experience the AO holds it's setting much better from shot to shot to shot. In fact, I've yet to own a side-focus that solidly held it's parallax setting from shot to shot, and that includes several Leupold VX-3/III's, a Vortex Diamondback and Viper, and a Sightron SIII so it's definitely not that they were "cheap" scopes - far from it.

Unfortunately side-focus is the trend these days because it looks cool and one's options for a good'ol adjustable objective are getting fewer and fewer.

[Joe L]

Jim, David--I got a response over on the rifle section of SIGforum that may explain what I'm seeing. The suggestion there was to adjust the side focus Only from infinity to the target distance and, if one goes too far, start over. The reasoning was that slop in the side focus would allow the focus cell to move on recoil unless the adjustment was made far to near.

This is actually consistent with what I was seeing this morning on the two 5 shot groups before this one. After adjusting the parallax, from near to far, I'm pretty sure, the first two shots were 6" away from the last 3, which grouped together like above. I saw this twice. On the group above, the small tweak between the first 5 marked shots and the second 5 shot group was from far to near. I think. Looks like it takes two rounds to take the slop out of the internal linkage in this scope before it settles down. Maybe. Any thoughts?

The rifle/scope/ammo combination are absolutely amazing when I get the parallax correct, from the right direction perhaps, and I don't change anything for a few rounds.

Joe

[J.Baker]

Yep, that's been a "given" procedure for side-focus scopes for a number of years now and is part of my reasoning for not liking them. You don't have that issue with AO's, and after all these years of SF there's no reason this should still be an issue - especially in this day and age of precision CNC machining and the ability to have ultra-tight tolerances.

As far as I'm concerned "acceptable slop" in a "precision optic" is an oxymoron.

[Joe L]

MrFurious--Believe me, I understand why you feel that way now!

Now I know what I've been doing wrong, so I will see if I can refine the sequence of steps to get the scope set up and see if I can get it just right every time. I wasted 15 rounds today alone fighting the scope adjustment. I'm green enough so that when I see a spread like I get when the parallax is off, I start doubting everything I'm doing. Takes some of the fun out of shooting up $30 worth of scarce box ammo.

Today's investment in time and ammo has been a good one. I'm learning, with a little help from you guys and these forums. I appreciate it.

Joe

[david8989]

Hell, i've been using side focus scopes for a while now and didn't know that. Guess I'll give it a shot and see if anything changes. Thanks Joe, i'm always game to learn something new.

[Joe L]

I've shot the rifle a little more, today at 547 yards. Started the parallax adjustment with the knob at infinity, and then slowly rotated it towards the closer range. Did not reverse direction. I also rested the gun on a hard rear rest with the sight on the target or frame, then checked parallax with my cheek off the stock. I got it right. Then I went back to normal soft rear bag prone setup. All I had ammo-wise to shoot was some Fusion 180 gr and it shot OK, not great. Worst problem I had today was shooting up a hill from prone. Really put a strain on my neck. I don't think today's 8" 10 shot group was all due to the ammo. Some of the larger than expected group size resulted from me not being able to get comfortable behind the gun due to the shooting angle. I shot a 4" group at this distance with Rem Premier Match 168 a month ago, and I'm not sure why I was fairly comfortable then and not today, other than I'm older, LOL.

The key for me for the parallax adjustment is to get the gun steadied and my cheek off the stock to check for parallax correction while moving the knob in small increments from infinity to shooting distance. This seemed to work, but I need more practice, that's for sure.

Joe

[Joe L]

The key for me for the parallax adjustment is to get the gun steadied and my cheek off the stock to check for parallax correction while moving the knob in small increments from infinity to shooting distance. This seemed to work, but I need more practice, that's for sure.
Joe

Well, I've had considerably more practice and this works perfectly, every time. Here are results from a few weeks ago.

http://joelynch.smugmug.com/Firearms/Savage-Model-10/i-hBHwR3K/0/M/300%20yd%203-17-13-M.jpg

Similar results at 500m. Thanks, gentlemen.

Joe