General grouping question

[gotime]

So my groups stay the same size, but as I move from left to right on paper, the groups move further left from my point of aim. Any explanation for this and how to fix it?

[kcheung2]

Could be a few factors. I'm assuming this phenomenon is consistent & repeatable, not just it happened the last 10 rounds & you called it a day. In which case, check to be sure all the screws are on tight. Off the top of my head, it could be either parallax error or barrel warp from heat.

For parallax, adjust your scope's focus knob so that the target & the reticle are both in focus. Ignore the actual distance number on the knob. Then try to hold your rifle the same way, with your cheek in the same position, when you switch targets.

For barrel warp, let it cool down. Also make sure that your ammo is the same temperature from first round to last. That means after firing, don't immediately chamber the next round, then spend about 30 seconds readjusting your shooting position or your scope, all the while that round is slowly warming up inside the hot chamber. Load the round just before you're ready to shoot.

You could also try bedding, shims, or free floating, but those are more involved topics.

There's probably other factors too, I'm sure someone will add to this.

[ChuckDizzle]

I think parallax error is the most likely culprit. Is it a free float barrel? Most free float rifles tend to open up with heat, but maintain point of impact.

Non floated rifles tend to string in a particular direction as they heat up.

[JackEllis]

How much are the groups moving and what’s the width of the target sheet?

My uneducated guess is, you’re sight line through the scope is shifting slightly as you move the rifle from one target to the next.

Try shooting from right to left and see if the groups move right.

[gotime]

Newish rifle I'm still trying to find accurate and dependable ammo for. Tikka T3x in 6.5 Creedmoor. I use my watch timer and go 3 minutes between rounds to let the barrel cool a little. Found two Hornady rounds that are consistently 1MOA (Match and Superformance). Imagine three 3x3 squares with a bullseye. Far left square I'm in the eye. Middle square I'm still grouping 1", but now it's about .75" left the eye. Far right square my group is maybe 1-1.25" left of bulls eye.

I'm using a Vortex HS 2.5x10 with no Focus, just elevation and windage adjustments. Parallax shouldn't be an issue at 100, right?

[ar15barrels]

I'm using a Vortex HS 2.5x10 with no Focus, just elevation and windage adjustments. Parallax shouldn't be an issue at 100, right?

Yes it will.
Fixed parallax scopes are usually set to be parallax free somewhere around 150-300yds.
You can ask the manufacturer for what distance your scope is parallax free.
Then put your target at that distance.

Trying to shoot groups with parallax error is NOT going show you the full potential of the ammo/shooter as the sighting system is a significant part of the accuracy equation.

[diver160651]

General grouping question

Yes it will.

Fixed parallax scopes are usually set to be parallax free somewhere around 150-300yds.

You can ask the manufacturer for what distance your scope is parallax free.

Then put your target at that distance.



Trying to shoot groups with parallax error is NOT going show you the full potential of the ammo/shooter as the sighting system is a significant part of the accuracy equation.

My vote is shooter offset.

If he was moving correctly he’d have the same level of parallax issues as he has shooting straight. So while he may have parallax issues, that’s a symptom of not repeating his positioning.

OP:
You might be surprised just how much it can make a difference if the shooter doesn’t move in the same exact relation to the new direction the barrel is pointing.

More often than not people swing the gun but forget to move the entire body in the same relative position, allowing the same cheek-weld.

Here is a clip where I approached the obstacle wrongly indexed on target to the left. I had to find the correct target slightly to the right. Once I found it, notice I took the extra time to realign my hips, etc.

https://youtu.be/YLy_1aAPdLk

It makes a big difference. I’ve rushed and skipped those steps and when I have, I paid in tons of misses.

It seems the more unstable the setup is, like if on a cattle gate simulator like in the clip or rope swing, you’ll easily see the negative results of misalignment. One the other end, BR guys use rests that eliminate the shooter offsets. These guys can shoot sideways with no ill effect.


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[sigstroker]

If you have an ARCA rail, MPA now has a "cow gate system" wedge lock thingie.

Do you diddle a parallax adjust in the middle of a stage?

[ozarkpugs@gmail.com]

Could be not positioning trigger finger the same with slight movement of rifle

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[LynnJr]

If your shooting from a bench and using bags you can bind a gun up to tightly by pushing it left or right rather than moving the bag and that will ruin your groups as well.

[diver160651]

General grouping question

If you have an ARCA rail, MPA now has a "cow gate system" wedge lock thingie.

Do you diddle a parallax adjust in the middle of a stage?

[ar15barrels]

Do you diddle a parallax adjust in the middle of a stage?

If the change in target distance is enough to throw the parallax off more than the rifle's typical group size, then yes.
If the parallax is off less than the group size, then no.

[sigstroker]

No, I generally guess the mid point before the stage starts or clear it up if it is obviously bad. That's only problematic on our sized targets, if you don't have the same cheek-weld shot to shot. That along with the trigger press and all that stuff that bad or poorly controlled mechanics brings when moving shot to shot is what makes us have the offsets.

Some people might wonder why their zero shifts just the tiniest bit left or right etc range trip to range trip; something is different in them - not the gun. Most will NOT see large offsets at the range as their targets are generally in the same general direction every time and the surface and shooting type/style is consistent.

It is also worth noting that these offsets come in a variety of forms. As an example guys new to positional, often sail over a lot of the targets. This happens if they are used to driving their bipods way to hard off the bench or prone. Then when shooting off something super slick that will not support the same drive, like a ruck, truck hood or barricade, most shots will go much higher, enough to start missing in some cases if they are running something like a 6.5 and bigger.

So it sounds like when you practice, you're better off leaving the bipod "fly free" to better simulate stage conditions?

Sig -Yes, I also have a MPA and full length RRS width dovetails on most positional rifles. I ran the stops and they work, but it is slow to adjust if you want them tight. So I just slide my bipods back on the rails until it is firmly in front of the obstacle and bag to help with the recoil.

Cool trick!

What's scope shading?

[diver160651]

So it sounds like when you practice, you're better off leaving the bipod "fly free" to better simulate stage conditions?



Cool trick!



What's scope shading?

I think you're asking about "free-recoiling". I think the answer is a bit more complicated than yes or no. I am not a fan of free-recoiling, but I'll make an effort to explain what most are doing.

You've seen my comunication via the keyboard and it often doesn't make sense or sound the way I intended. Apologies up front.

F-class guys often free or semi-free recoil their bi-pods. They're interested only in as little shooter in their groups as possible and don't need to worry about self-spotting. Wind flags, practice sessions, spotters for longer ranges all fill in for the lack of self-spotting.

With positional shooting or field shooting as you know, seeing the impact and misses is key.

As an example of this, the move to lighter recoiling rounds like the 6mm, continues even inside the 6mm cartridges as people are stating to reconsider even the XC, Dasher, LR and BRX, for the 6BR, because they seem to mag feed a bit better now with the kits from PVA without the need for a control round feed action like the TL3. So with of these heaver rifles with lower recoiling 6mms like the BR, you can almost semi-free recoil and still see your impacts. While a few do indeed free-recoil, most try to use the best mechanics they can. It might be worth noting that bipods are not used in positional shooting nearly as much as they are in the staging area to hold up the rifles..

Often when we see guys shooting off the bipods, on the bench or prone it is with either a much lighter system or larger caliber than you see in positional matches. These certainly take more shooter drive (bipod load) to see impacts than your 6mm positional gun. BUT, I think most people hear "load the bipod" they just WAY over do it. You'll often see guys using devices on a bench like a rug, or when shooting prone a matt that has a bi-pod damn or maybe just crazy spiked feet. This is usually a sign that these guys are over driving (over loading) the bi-pod to start with. These guys will see the crazy offsets when they change their load pressure.

So the short answer to your first question is, no. But you're onto the correct logic in my opinion, trying to make both as close as possible. I do not free-recoil my bipods, nor do I on obstacles, but I try to stay consistent with just enough load or shooter in the gun so I can self-spot.. I think most positional guys try for the same, but some are free-recoiling.

Scope Shading or shadowing, is slang for an old LR technique used especially when adj. parallax "side knobs" were not so prevalent. Prior to that, many were on the objective bell. If you were on the gun in final position, like in a hide, it was difficult to use. So you could pull your head back ever so slightly and reveal a shadow around the edge of the ocular. If you keep that shadow perfectly even around the edges it means you are looking straight thru the scope tube and that will aid in constancy and offset the parallax issues. I'm not suggesting run in a F-class or BR mach like that, but it is effective even today for some uses. You could probably run an entire mach positional mach using 400 parallax setting and still be fine. It is super fast but a bit crude.

[ChuckDizzle]

Wow, scope shading. I have used it many times, but never knew it was an actual technique with a name to it. Just seemed to make sense.