When I'm shooting my POI keeps changing. There will be 3-5 groups in one location, then the POI will change and the groups will be just as tight, but at the new location. Is this the scope MCT (5 - 20) or the rifle (FX Boss)? Any thoughts would be appreciated.
POI Change
- Thread starter chasdicapua
- Start date
What distance are you shooting at ? Is the POI shift happening when you shoot at different distances or the same distance ?
Could be the wind that's taking your pellets away. But there could also be other factors to consider here. The ones you can omit are pellet clipping since its holding groups tightly. If the shroud was clipping, getting tight groups is difficullt. Assuming that's not the cause, Possible reasons for POI Shift below. Try eliminating these causes in sequence.
1. Trigger pull. Check the graphic on this link. If your groups are moving right or left it could be your finger on the trigger. http://airgunnation.dev/topic/2-essentials-for-accurate-shooting/#post-31461
2. The rings on the scope have gotten loose
3. Barrel requires cleaning
4. While unlikely, it could be a bad tin of pellets.
These are are the most common causes. Less likely causes below
1. Could be the scope - if the scope rings are tightly fixed then I would try remounting the scope. If that doesn't work, try another scope
2. If the above step also doesn't work and your POI is still changing then I would question the gun. But usually fx guns don't have issues on POI change. Usually it's one of the above mentioned causes.
Upvote 0
Are the different groups shot at the same time off the same rest and with you in the same position, using the same hold?
Because if you have not got the parallax and reticle focus set up right, you will get results like that from minor changes in eye position relative to scope.
Presume you mean an MTC Genesis 5-20 (nice) and nice rifle too.
Because if you have not got the parallax and reticle focus set up right, you will get results like that from minor changes in eye position relative to scope.
Presume you mean an MTC Genesis 5-20 (nice) and nice rifle too.
Upvote 0
FearnLoding, the distances are 50 - 60 yards and the POI shifts happens at the same distance. Yes, the trigger finger. So much resting on such subtle movement!! I'll check the scope rings and pull some patches through as well.
Upvote 0
MarkUK, Yes to all aspects of your question. Same position and hold on the same rest. Yes, I put a bit of attention being sure my eye is centered on the scope. Or is the scope centered on the eye?!!
Upvote 0
"3-5 groups in one location, then the POI will change and the groups will be just as tight"
This seems not too complicated to resolve if the groups remain tight...
Most likely it is a Parallax problem but could be a defective scope (Reticle shift) or a bad mounted scope...A bad mounted scope can be "Torqued" by not seating straight on the bottom half of the rings or over torqued screws (less likely).
The other thing could be a "Touching or Loose Barrel" ...Check that the barrel is tightly attached to the action with those set screws or whatever fixing method the manufacturer used and then check for secondary fixing points around the fore end of the stock...If barrel is floated check it doesn't touch anything when fired, it the barrel has a frontal fixing point (s), check that it is tight at both points: Bracket/stock and around barrel...
For checking parallax use a rest and put that reticle over a horizontal line at the 60 Y you are shooting, then move your eye up and down without touching the gun...If the horizontal of the reticle moves as you move your eye, adjust the side wheel or front objective for Parallax...If your scope does not have Parallax adjustment, since you are shooting at 60 Yards, the scope most likely came set Parallax free at 100 Yards and needs to be re-adjusted...Many scopes allow re-parallaxing by moving the frontal objective outwards just a tad, easy to do if you know what you are doing and if you have the tools...Otherwise, manufacturers can do it but there are many people who do it for very little money...I have done 3-4 for myself and a few for some friends (I use centerfire re-parallaxed scopes on my guns).
You can shoot without re-parallaxing accurately if you look through the scope the VERY SAME WAY every time, it is not too difficult and there are many shooters doing it, In my case I rather re-parallax.
Regards,
AZ
This seems not too complicated to resolve if the groups remain tight...
Most likely it is a Parallax problem but could be a defective scope (Reticle shift) or a bad mounted scope...A bad mounted scope can be "Torqued" by not seating straight on the bottom half of the rings or over torqued screws (less likely).
The other thing could be a "Touching or Loose Barrel" ...Check that the barrel is tightly attached to the action with those set screws or whatever fixing method the manufacturer used and then check for secondary fixing points around the fore end of the stock...If barrel is floated check it doesn't touch anything when fired, it the barrel has a frontal fixing point (s), check that it is tight at both points: Bracket/stock and around barrel...
For checking parallax use a rest and put that reticle over a horizontal line at the 60 Y you are shooting, then move your eye up and down without touching the gun...If the horizontal of the reticle moves as you move your eye, adjust the side wheel or front objective for Parallax...If your scope does not have Parallax adjustment, since you are shooting at 60 Yards, the scope most likely came set Parallax free at 100 Yards and needs to be re-adjusted...Many scopes allow re-parallaxing by moving the frontal objective outwards just a tad, easy to do if you know what you are doing and if you have the tools...Otherwise, manufacturers can do it but there are many people who do it for very little money...I have done 3-4 for myself and a few for some friends (I use centerfire re-parallaxed scopes on my guns).
You can shoot without re-parallaxing accurately if you look through the scope the VERY SAME WAY every time, it is not too difficult and there are many shooters doing it, In my case I rather re-parallax.
Regards,
AZ
Upvote 0
Make sure your not canting the rifle. That causes poi shift without a change in group size.
Upvote 0
Absolutely!....Good advice Fbom8...
I took it for granted (shooting from a rest with a level) and missed that one, that will be the first thing to check !!...
Regards,
AZ
I took it for granted (shooting from a rest with a level) and missed that one, that will be the first thing to check !!...
Regards,
AZ
Upvote 0
I put on a different scope and the POI still changed (about .5 inches). But again, it then grouped well (.645 at 50 yards) at the new POI. I cleaned the barrel and the patches were almost clean when I pulled them through,so that's not the problem. Barrel is tight. I'm using a level, so the rifle isn't canted. I'll have to have my wife watch the barrel when I fire it to see if it touches the air tank. I'm kind of new to scopes, so is there something more to correct parallax set up other than making sure the target is in focus as well as the reticle? Also, how does one know for sure if the scope is mounted correctly, ie. not torqued? Your input is appreciated.
Upvote 0
Chas...... I have a MTC Genesis 5-20x50 I was using for FT on a Daystate MK4. It performed flawlessly. They are a great quality, clear scope.
Now my friend has a wood stocked FX Royal 400 .22 He had the same problem and asked me to take his gun and see if I could fix it. I am a gunsmith for powder guns and now PCPs. His problem was the whole action and barrel was moving slightly even though it was tightened down by the center bolt. It was moving left to rt very slightly. Barely noticeable.
The fix was easy but shims were too thick to stop it so it took two pieces of masking tape on either side of the receiver block to work. It basically worked like a cheap glass bedding. Holding the block tight with the barrel free floating is the first step in consistent accuracy.
I have the same FX Royal400 in .22 with the synthetic stock with no problems. I did add a Hawke level to the gun to hold it level for benchrest shooting. Canting the gun will also reflect POI shift as someone above stated. Your barrel is not loose as it would throw the pellets all over. Try seeing if the action is rocking slightly left and rt in the stock like my friends gun was doing...
Now my friend has a wood stocked FX Royal 400 .22 He had the same problem and asked me to take his gun and see if I could fix it. I am a gunsmith for powder guns and now PCPs. His problem was the whole action and barrel was moving slightly even though it was tightened down by the center bolt. It was moving left to rt very slightly. Barely noticeable.
The fix was easy but shims were too thick to stop it so it took two pieces of masking tape on either side of the receiver block to work. It basically worked like a cheap glass bedding. Holding the block tight with the barrel free floating is the first step in consistent accuracy.
I have the same FX Royal400 in .22 with the synthetic stock with no problems. I did add a Hawke level to the gun to hold it level for benchrest shooting. Canting the gun will also reflect POI shift as someone above stated. Your barrel is not loose as it would throw the pellets all over. Try seeing if the action is rocking slightly left and rt in the stock like my friends gun was doing...
Upvote 0
Thanks Strikefast, I'll check it out. I did check the screw that holds the stock on to the action and it was slightly loose. I'll take it off and put tape on either side of the receiver to be sure it snug. Yes, great scope, I hated to think that was the problem. Now I know it's not.
Upvote 0
If you do figure it out post your result. It may help me or other members. You can never learn enough in my humble opinion. Hell I learn something new every day even when I think I know it all...lol
Upvote 0
That's for sure. I would say that 90% of what I know about airguns I learned from others on this and other forums. I will definitely post the results.
Upvote 0
"I’m kind of new to scopes, so is there something more to correct parallax set up other than making sure the target is in focus as well as the reticle? Also, how does one know for sure if the scope is mounted correctly, ie. not torqued? Your input is appreciated."
The most important part will be to check that lower part of bases are torqued tight on your rifle, then level the rifle and put the scope and align the vertical line of reticle to a cord with a weight so it is a straight line, use the corner of an open wall, etc. If it were me doing the mounting, I would use an aligning bar I machined for making sure the bottom bases are perfectly straight and not torqueing the tube of the scope, and it they were, I would lap them...But let's assume that those bottom rings are aligned...
You have your scope over the bottoms part of the rings aligned...Then put the upper part of the rings...Make sure you use those uppers as they came from the store you bought them, depending on the quality and brand, some of those are machined and while you can mix them don't do it because they are matched... Put some masking tape and mark them.
Put the upper parts of those rings and torque those screws making sure the gap in between the bottom and upper parts are about the same...Torque those screws to 40 in./lb and if you don't have a torquimeter, then do it to where you feel good resistance and then 1/2 turn more...Use blue lock tite (never use red) so no screws come loose.
For checking your parallax, align the HORIZONTAL of your scope to a horizontal line at the distance you are shooting and then adjust your parallax knob on your scope, the horizontal of your scope and the line on the target should loos as 1 line...Then move your head up and down and see if that line moves, if it does you need to adjust that parallax knob until it doesn't.
Clean your gun, fill it to the max pressure and shoot...With a clean and full of air gun expect a few 3-6 shots maybe going to different places...This is normal while the regulator (if regulated) or the valve (if not regulated) set and also while the barrel gets a little lubricant from the pellets...After 6-8 shots shoot several 5 shot groups...
If your gun keeps on moving the POI, then you have a crown that may have a burr or is damaged, or your barrel is touching something (if fully floated) and if not floated, the touching point may be too tight or too loose...Check this as I have encountered innumerable problems caused by this issue (over and under pressure in the touching point)...The last thing to check will be your stock and action...They should be tight..Adjust them to the same torque as the scope.
If your problem persists then check your velocities with a chronograph, if variations are within 1-2% of the max velocity you are shooting, then you are fine...The last step are your pellets: Try heavier and lighter and try different brands...Try: JSB's and H&N Barracudas in different weights...You can also try Crossman Premier (The ones that come is the carton color box, I believe 1250 pellets/box).
If still have a problem, then you really have a problem and that could be your barrel is not good, damaged crown, or ????...Someone needs to shoot it and eliminate all possible variables.
Note: I am assuming that you have a very steady table and rest and that you have enough shooting skills to be consistent.
Please let us know your findings and how you are doing....
Regards,
AZ
The most important part will be to check that lower part of bases are torqued tight on your rifle, then level the rifle and put the scope and align the vertical line of reticle to a cord with a weight so it is a straight line, use the corner of an open wall, etc. If it were me doing the mounting, I would use an aligning bar I machined for making sure the bottom bases are perfectly straight and not torqueing the tube of the scope, and it they were, I would lap them...But let's assume that those bottom rings are aligned...
You have your scope over the bottoms part of the rings aligned...Then put the upper part of the rings...Make sure you use those uppers as they came from the store you bought them, depending on the quality and brand, some of those are machined and while you can mix them don't do it because they are matched... Put some masking tape and mark them.
Put the upper parts of those rings and torque those screws making sure the gap in between the bottom and upper parts are about the same...Torque those screws to 40 in./lb and if you don't have a torquimeter, then do it to where you feel good resistance and then 1/2 turn more...Use blue lock tite (never use red) so no screws come loose.
For checking your parallax, align the HORIZONTAL of your scope to a horizontal line at the distance you are shooting and then adjust your parallax knob on your scope, the horizontal of your scope and the line on the target should loos as 1 line...Then move your head up and down and see if that line moves, if it does you need to adjust that parallax knob until it doesn't.
Clean your gun, fill it to the max pressure and shoot...With a clean and full of air gun expect a few 3-6 shots maybe going to different places...This is normal while the regulator (if regulated) or the valve (if not regulated) set and also while the barrel gets a little lubricant from the pellets...After 6-8 shots shoot several 5 shot groups...
If your gun keeps on moving the POI, then you have a crown that may have a burr or is damaged, or your barrel is touching something (if fully floated) and if not floated, the touching point may be too tight or too loose...Check this as I have encountered innumerable problems caused by this issue (over and under pressure in the touching point)...The last thing to check will be your stock and action...They should be tight..Adjust them to the same torque as the scope.
If your problem persists then check your velocities with a chronograph, if variations are within 1-2% of the max velocity you are shooting, then you are fine...The last step are your pellets: Try heavier and lighter and try different brands...Try: JSB's and H&N Barracudas in different weights...You can also try Crossman Premier (The ones that come is the carton color box, I believe 1250 pellets/box).
If still have a problem, then you really have a problem and that could be your barrel is not good, damaged crown, or ????...Someone needs to shoot it and eliminate all possible variables.
Note: I am assuming that you have a very steady table and rest and that you have enough shooting skills to be consistent.
Please let us know your findings and how you are doing....
Regards,
AZ
Upvote 0
Thanks Azuaro. The barrel is full floating and not touching anything upon firing. I had my wife watch. The grubs screws holding the barrel on are definitely not loose. But how to know if they are too tight? Take the barrel off and reattach it? I remounted the scope, but it was shooting quite a bit left. Perhaps the rings are a bit off. This is really an odd situation as I got two sub MOA groups in a row yesterday at 50 yards, and then a fairly big POI shift and then some fairly good groups again at the new POI. I'll check the parallax as you suggested.
Upvote 0
"But how to know if they are too tight? Take the barrel off and reattach it?"
No, leave those screws alone...The issue about the right torque in screws is for not inducing tension/compression forces (stress) that only aggravate our problems, and also for preventing marring threads, but most importantly the internal threads...A screw on your rings or attaching your barrel you can replace cheap and easily, but the threads on the receiver or scope rings would need to be enlarged and re-threaded)
Try something very simple...Use some masking tape (1-2 turns) around the tube of your scope as shimming and then tighten the scope rings as we have been discussing...Trim the tape narrower than the width of the rings so you don't see it (Esthetics).
Then just make sure those scope screws and the ones attached to the receiver are tight and shoot some other groups.
If shooting too much to one side, you can reverse the rings (complete bottom and upper parts) and see if this corrects the issue...
It is difficult to see when a barrel touches something upon firing, if your barrel is fully floated and well attached to the receiver, go by clearance...Use the old "Dollar Bill" method of passing a dollar bill around the barrel from the receiver all the way to the crown, if it touches there is a problem, if it doesn't you can be assured that it is OK.
I didn't ask: Do you have some kind of air stripper or moderator as the new guns come with?...If you do, let's try the gun without it to eliminate another variable.
Let me know how you are doing, send me a PM so I can see your reply sooner or post it here, whatever works best for you...I usually read what is going on all over the Forum and sometimes it takes long for reading a reply.
Regards,
AZ
No, leave those screws alone...The issue about the right torque in screws is for not inducing tension/compression forces (stress) that only aggravate our problems, and also for preventing marring threads, but most importantly the internal threads...A screw on your rings or attaching your barrel you can replace cheap and easily, but the threads on the receiver or scope rings would need to be enlarged and re-threaded)
Try something very simple...Use some masking tape (1-2 turns) around the tube of your scope as shimming and then tighten the scope rings as we have been discussing...Trim the tape narrower than the width of the rings so you don't see it (Esthetics).
Then just make sure those scope screws and the ones attached to the receiver are tight and shoot some other groups.
If shooting too much to one side, you can reverse the rings (complete bottom and upper parts) and see if this corrects the issue...
It is difficult to see when a barrel touches something upon firing, if your barrel is fully floated and well attached to the receiver, go by clearance...Use the old "Dollar Bill" method of passing a dollar bill around the barrel from the receiver all the way to the crown, if it touches there is a problem, if it doesn't you can be assured that it is OK.
I didn't ask: Do you have some kind of air stripper or moderator as the new guns come with?...If you do, let's try the gun without it to eliminate another variable.
Let me know how you are doing, send me a PM so I can see your reply sooner or post it here, whatever works best for you...I usually read what is going on all over the Forum and sometimes it takes long for reading a reply.
Regards,
AZ
Upvote 0
Hi I just thought I would share my experience. I recently put a 500 mm slug liner on my rifle that I am using, 21grain H &N HP slugs. I've spent the last two weeks trying to get it to group properly ,the groups are okish, but change from left to right for no apparent reason. I tried all of the usual stuff to get it right but nothing worked. I had almost given up until yesterday I had a thought. I turned down the regulator by 5bar, made sure my velocity was still at 930fps, and bingo I'm now getting one penny sized groups at 70 yards with no left and right movement whatsoever.
Upvote 0
To take the parallax issue out of the equation, try this.
Back your eye away from the ocular lens until you see a black ring around the outside of the scope image. It doesn't take much but you have to see the black ring. Now, move your head around until that black ring is the same width all the way around. That ring is kind of like your rear sight. If the ring is the same width all the way around, you're looking right down the center of the scope with no parallax issues. the black ring is like a rear sight....same width all around (rear sight) crosshair (front sight) hold it and squeeze it! Done deal!
Back your eye away from the ocular lens until you see a black ring around the outside of the scope image. It doesn't take much but you have to see the black ring. Now, move your head around until that black ring is the same width all the way around. That ring is kind of like your rear sight. If the ring is the same width all the way around, you're looking right down the center of the scope with no parallax issues. the black ring is like a rear sight....same width all around (rear sight) crosshair (front sight) hold it and squeeze it! Done deal!
Upvote 0
Wow, this post was a blast from the past.
Yeah, I use the black ring method as well. I'm not completely sure how helpful it is, but it makes sense to me.
Chas
Yeah, I use the black ring method as well. I'm not completely sure how helpful it is, but it makes sense to me.
Chas
Upvote 0