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Parallax issues?
Posted: Sun May 24, 2009 4:32 pm
by greystone
I went out to the range this morning and the weather was perfect. Absolutely no wind which is very unusual for around here. The scope I'm using has been on 2 rifles-my Rem VTR and now my CZ. The picture below is a 5 shot group that I shot this morning and its something that I experience all the time. Its almost like I'm shooting 2 separate groups. On this group there is 2 shots high and to the left and 3 in the middle. This is a common issue with both rifles. I haven't been able to get this scope totally parallax free. I'm thinking that maybe I'm answering my own question here as I type this but could this be considered a parallax problem? And yup-everything is tight and the rifle is bedded and barrel is free floated.
Thanks
Dave
Re: Parallax issues?
Posted: Sun May 24, 2009 8:02 pm
by Ruger No. 1
what type of scope is it?
Re: Parallax issues?
Posted: Sun May 24, 2009 8:32 pm
by Jim White
Before you get to checking/looking at the scope make sure the load is a good accurate load in both rifles.
I can say from my initial load testing days with a scope that parallax can effect groups (back then I didn't know what parallax it was) and if you can't adjust it out I would say its time to look at a different scope, especially if it exhibits the same thing on two different rifles.
Other things that may be contributing is a inconsistent stock weld and/or, inconsistent look through the scope when sighting.
HTH,
Re: Parallax issues?
Posted: Mon May 25, 2009 5:43 am
by Glen
The 1st two shots from a clean oiled barrel can & often times do have a different POI. This may be the case here unless groups 2 thru however many exhibit the same characteristics. Now if shots,, example here,, 2 & 4 went left & 1,3,5 made the other group I would say it could be too much magnification for the distance you are shooting. I can't shoot good groups at 100yds on 18x with my Leupold but I can do real good on 14x at 100yds. Another thing that woill change POI is if your front rest isn't slick & the forearm binds just a touch when you go to settle the crosshairs on the target. HTH
Re: Parallax issues?
Posted: Mon May 25, 2009 8:45 am
by Bayou City Boy
Glen wrote:.......I can't shoot good groups at 100yds on 18x with my Leupold but I can do real good on 14x at 100yds.....
That is most likely a parallax issue between the two magnification settings and has nothing to do with magnification itself being the problem.
BR shooters use 24x and above, generally fixed power scopes, but the parallax issue is solved for them at the magnification they use. Too much magnification in a good scope won't cause accuracy issues by itself. Other issues are in play.
-BCB
Re: Parallax issues?
Posted: Sun May 31, 2009 9:05 pm
by jo191145
The lowest power scope I own is an 8.5X25 Loopy. I don't think I've ever dialed it down from 25X. Sure wish I could crank it up tho. I use it for testing on slave rifles. No such thing as to much magnification for targets in my book. That is of course as long as its quality magnification. BSA's need not apply
Greystone
Unless your using a BSA with the ocular lense loose thats still too much variation to be totally a parralax issue. Its possible your scope has bit the dust but theres still another 1000 possibilities.
Starting with, as Glen said, Foulers/fouling. Careful attention should be paid to the shots as they fall. Much can be learned from that.
Re: Parallax issues?
Posted: Mon Jun 01, 2009 2:26 pm
by greystone
Thanks to everyone that replied. I always shoot 2 fouling shots and this was the second group that I shot that day with IMR 4895. After I shot the first group I did make a scope adjustment. The first 2 shots were high and left and the next 3 were in the center of the diamond. The adjustment that I made should have put all shots on the top or slightly above the diamond. BTW the bullets are Midway Dogtowns and the scope defiantly isn't a high dollar item. Those were the last rounds that I shot and because of a construction project on the house I haven't even been able to get back to my reloading bench. No time. I have my eyes on another scope but its going to have to wait until the house project is over. I know the accuracy is there-just have to get it all together. Dave
Re: Parallax issues?
Posted: Mon Jun 01, 2009 6:39 pm
by BabaOriley
jo191145 wrote:
Unless your using a BSA with the ocular lense loose
HAH!
The ocular lens eh?
Until a couple weeks ago I never realized why there was any adjustment to the ocular lens focus on this scope (chinese made Millett TRS-1 4-16x50), because I could turn the side focus dial, and always get my target in focus. It did always bother me that at 100 yards, turning the side focus to 100 yards did not leave me with a focused target. I'd read how the printing on most side focus dials rarely lined up with where they actually had to be to give you sharp focus at indicated range, so I just wrote it off as a typical flaw in this design.
So I'd always kept my ocular lens in the middle of it's adjustment range (halfway screwed out). I've said for years I should get glasses, so a couple weeks ago, I decided to check something. I first looked at my target using typical settings. It was in focus. The side focus setting indicated something close to 150 yards I think (at 100). I then moved my head just a little side to side, and the crosshairs moved all over the place. Hmm... So I wasn't really parallax free. How could I have gone so long without checking this?
So how did I get the parallax to go away? I began by turning the side focus to indicate 100 yards, which did not put my target at 100 yards in focus. I then started playing with the ocular lens adjustment. I found that with the lens all the way screwed in tight (no not overtight), the target came into focus! Moved my head side to side and? MUCH BETTER. Very little parallax. Now did this improve my groups? I've been doing a ton of load development trying to find a load for the 34gr Dogtown using Ramshot TAC powder. I figure if I could get an accurate load, it would be much more affordable. Well I've seen hints of great accuracy, but it's been very inconsistent. If you read the threads concerning my testing, you'll see I've narrowed it down to a possibility of Kroil or CLP getting in the barrel, OR, something's loose on the scope.
And what do ya know I found tonight. I go to check for wiggle in the ocular lens of my scope, and sure enough. The tube wobbles.
What's worse is I'm pretty sure I could send it back (I think I'd be sending it to Bushnell now), and it would most likely come back unfixed. It's probably within tolerances for a scope in this price range. I can shoot MOA groups with it, just MOA 2" high left one time, and 2" left the next. I've been reading stories about people sending scopes back to Millett and never getting it back too now, so nice... I know some will say it serves me right for believing the hype. The box did have a big bald eagle head on it! Add it to my list of signs of our times, and how we're just selling our souls to the Chinese. Here was my contribution...
Anyone know how I might fix it? I guess if the ocular focus works with my vision while screwed in tight I can loc tite it there... ?
Thanks for the reference to the ocular lens jo. I'm glad I checked it now anyway...
Re: Parallax issues?
Posted: Mon Jun 01, 2009 8:59 pm
by Bayou City Boy
Scopes with ocular lenses and side focus....
The "side focus" is actually the parallax adjustment on a scope. You adjust the ocular eyepiece to eliminate blurring or to "focus" the scope. On good quality scopes one adjustment of the ocular generally works for all powers. On cheaper scopes, the ocular may have to be adjusted for different magnifications due to poorer quality lenses and refractors in the scopes..
When you have an ocular lens adjusted properly, dialing in the proper parallax distance for the scope generally aids in clarity, but the side focus is parallax adjustment only. If the ocular lens is not adjusted for clarity, no "side focus" parallax setting will completely solve the "Fuzzies" since that is not its real purpose.
-BCB
Re: Parallax issues?
Posted: Tue Jun 02, 2009 7:03 pm
by jo191145
The ocular adjustment is used to sharpen the crosshairs for a particular shooters eyesight. While it can be used to fine tune target clarity its main purpose is to focus the crosshairs. It should be a one time set it and forget it adjustment in a perfect world.
Use it for fine tuning clarity and you'll often find your crosshairs getting blurry. Just like rifles every scope can behave differently. YMMV
BabaOriley
Short story: Won a BSA Platinum 8X32 raffle prize. took it home figuring I'd give it a chance. Anything past 24X looked like the bottom of a coke bottle. (unwashed nonetheless) While adjusting the ocular on a 200yd target (not the correct method but I was doing it anyway) I noticed the crosshairs moving 2-3 moa while loose. The BSA has a locking ring for the ocular which should stop that wobble. Still that was enough for me. I boxed it back up and brought it back to the next shoot where some other lucky shooter brought it home as a raffle prize
Lifes to short, components and barrels cost to much to use cheap faulty optics
You might want to wiggle that loose ocular while looking at a distant target and see if the crosshairs move. If they do you know one problem that needs correcting.
Easiest fix? First remove the scope from the rifle. Dig a very deep hole. Throw in scope with large rocks on top, then soil and do not mark the grave in any way.
I was playing with Tac but discontinued because I simply do not have enough magnum primers to use. I tried Fed 205M and Wolf magnum (not really magnum just thick cups) and I felt they could not ignite large doses of Tac efficiently/consistently.
Thats just a gut feeling not any scientific fact
I only have a couple thousand 450's left and will save them and the ball powders until the decade comes that I can get more.
I'm running in a new barrel so I can't be sure of any accuracy standards.
I will probably try X terminator tho. Smaller charges of a faster burning ball powder might work with the mild primers I have.
I don't mind burning a little $$ to find out. Its what we do for fun right.
On the other end of the spectrum a bad scope means nothing will work.