me or the gun?

[Renton83]

So I've been target shooting for over 20 years and I get sub 1moa accuracy at 100 yards but whenever I go longer my groups open way up. I am shooting a tikka t3 with 243win and a heavy barrel and 4-12 scope. I am wondering how you can tell if accuracy is due to the rifle or shooter? I am shooting at 220yards on a bench with a sandbag under the rear stock to control elevation and to keep it steady. The best group I can manage is over 2inches while most are over 3. Here is my latest target I shot using handloads that gave my great accuracy at 100yards, I was pretty frustrated when I saw how big it opened http://imgur.com/Pg6ZN0M
and here is my target at 100 yards with 5 rounds http://imgur.com/LIRQOIy

 

[sage5907]

Just looking at the group I would say three things. You may be loosing your concentration when shooting at the longer distance and not have the reticle on target when you finish the trigger pull. You may be aiming at an area and not using a small enough aiming point. Since the group is stringing horizontal I would say you're holding the rifle flat but letting it move from side to side when you finish the trigger pull. Pull the rifle firmly into your shoulder so it doesn't move around.

 

[Everready73]

Did you try shooting from a lead slead or something similar to eliminate as much human error as possible. The only other things i can think of is maybe try different ammo. Also if you shoot the 100yd groups first are you giving your barrel time to cool, or just going straight to 200yds. Letting the barrel cool could help keep the groups tighter

 

[Bart B.]

It's normal to have a 5X spread in group size shooting several 5-shot or 10-shot groups.

Happens all the time in benchrest competition.

Therefore its just normal that all of your variables and those of the rifle and ammo ended up with the groups you shot. Shoot two 10-shots atop each other; that's a much better way.

 

[Renton83]

Ok thanks for the advice. I wonder if wind could be making it string horizontal ? i may try a lead sled to see if it's me or not.

 

[Fla_dogman]

Yes the wind will greatly effect the group at 200 yds

Sent from my Nexus 10 using Tapatalk

 

[outlawjw]

So will not adjusting your paralax

 

[Captcurt]

Ok thanks for the advice. I wonder if wind could be making it string horizontal ? i may try a lead sled to see if it's me or not.

As Outlaw stated. Horizontal stringing could be parallax. I shoot a 4X14 power scope and at 14 I will string shots at 100 yards if my AO isn't adjusted right. Still get sub-MOA group but it will be in a horizontal line. It is more critical at longer ranges.

 

[splattergun]

have someone else whom you know shoots about as well as you shoot your rifle at 100 and 200 yards. If he gets the same results as you, it could be the rifle. If his 200 yards groups at better than yours, check your technique.

 

[sirgilligan]

Just guessing, but wind would come to mind first. Also, bullets behave differently at different velocities. From the muzzle to 200 yards the bullet (depending on its shape and B.C.) could slow between 500 and 900 feet per second.

 

[Renton83]

For some strange reason my scope doesn't have parallax adjustment even though it's high quality. It's a meopta meopro which I've read good reviews about. I'm going to try my friends target rifle next week and see how I do with that.

 

[BWB]

Parallax effect needs to be considered, but is easily exaggerated.
Check it for yourself by moving your eye behind the scope with the reticle on your target at 200 yds.
Being careful to keep your eye carefully centered behind the scope each shot will minimize or eliminate the problem (should be doing this anyway).
Horizontal dispersion is most likely wind.
Also there is plenty of technique involved in shooting small groups from the bench - making sure to do everything the same each time without "bending"the rifle. Small errors are magnified as range increases, and doping the wind becomes far more important.
Don't forget that a 1 moa group is twice as large at 200 yds as it is at 100.

 

[Sniper66]

When I shoot long distance prairie dogs...say 300 yards. I pick a spot on the dog just like I do at 100. Since it looks so small the temptation for me is to visualize the whole dog in the center of the scope. But, picking a small spot on the target (dog) helps with concentration and focus. Your brain naturally cooperates to focus on the spot you are thinking about. Breathe properly and have fun. Tom

 

[jmr40]

Parallax error at 200 yards will at most be about 1 bullet diameter larger group size. Your scope is very high quality, but is a hunting scope where the tiny difference in parallax isn't a concern. On target rifles .2" larger groups at 100 yards can matter. Not so much for hunters.

It is the rare shooter and rifle that can maintain the same relative group size as range increases. If 1 MOA is what you are shooting at 100 yards then 1 MOA( or 2" ) is the best you can hope for at 200 yards. Most shooters will see a 1 MOA ability at 100 yards turn into 1.2-1.5 MOA at longer ranges. If you are shooting 1" groups at 100 yards then I would expect 2.5"-3" groups at 200 yards. That is still at or under 1.5 MOA.

 

[Walkalong]

When I was actively shooting Benchrest I preferred shooting at 200 yards, while most preferred 100 yards. It should all be the same. I don't know why you are not able to keep under 2" (1 MOA) at 200ish yards, unless it's in your head, or it's the wind. The reason I liked shooting at 200 yards was the wind seemed to be a bigger factor. Maybe it was just in their heads though.

And no, we don't always shoot the smallest group the rifle is capable of, and sometimes shots blow into the group, instead of out, and there is always the fact that we tend to highlight (remember) the small groups and forget about the big ones. Human nature.

 

[Renton83]

That's what I love about target shooting, always room for improvement. When I was growing up my dad would only let me shoot iron sights as he said to master that before using a scope and I feel like it has helped me in the long run. My next rifle I would like to try a good aperture sight as I still have a fondness for iron sights, also I don't like the idea of paying a small fortune for a good target scope. As much as I love 243win I think I prefer 308 as wind isn't such a issue.

 

[Bart B.]

It’s physically impossible for a given group size in some subtended angle at one range be the same size an another range. Unless all bullets:

* are perfectly balanced and have the exact same shape, weight and ballistic coefficient as they exit the muzzle.

* leave at the same muzzle velocity, angle and direction from the LOS.

* go through identical atmospheric conditions all the way to the target.

So, in the best and most stable conditions, groups tend to open up a small percent in subtended angle in each hundred yards down range.

One exception; if they exit on the muzzle axis upswing at the right place, faster ones leave sooner than slower ones and their flatter trajectory compensates for their bullet drop at target range and the slower ones leave at a higher angle and their greater drop at target range is compensated for. This is called “positive compensation.” It was first observed a hundred years ago when the British Lee Enfields shooting .303 ammo shot smaller subtended angle groups at 800 to 1000 yards than they did at 300 to 600 yards. People now often put heavy tuning weights on their rifle barrel muzzles in both rim and centerfire rifles to positively compensate for muzzle velocity spreads.

Use ballistic software with a 1% change in velocity and a ½% change in BC for your favorite load to see the changes. Calculate wind drift for a given bullet going to a 300 yard target then calculate drift at the target with the wind only in each of the 100 yard range bands; which range band has the most effect on drift on target?

Once you’ve got perfect ammo that has no variables in the bullet as it exits the muzzle, us humans’ variables start taking over. None of has mastered their hold on shouldered rifles so repeatable that the bore axis at the muzzle upon bullet exit is always the same direction and amount from the line of sight. Rifles start moving in recoil while the bullet’s in the bore. How much depends on the barrel time recoil force and our body’s center of mass and its direction is from the rifle’s recoil axis. None of us hold it exactly the same from shot to shot. Which is why benchrest rifles shoot bullets most accurate when they’re fire in free recoil untouched by humans (except for a finger barely touching their 2-ounce trigger to shoot them). People having top level ranking in competition with a rifle and ammo that tests ½ MOA from an accuracy cradle shoot it slung up in prone into groups 3 to 4 times larger.

The first few-shot group of several is seldom the smallest one shot. A look at benchrest groups shot in a match by one person shows a many time spread in size of their first group of several for each day. And their 200-yard groups are about 1/10th MOA bigger than those at 100. Same for 300-yard ones relative to 200 yard ones. No human variables in these groups except that some folks are better at correcting for wind than others.

Using the smallest few-shot groups shot as ammo’s accuracy is a bad idea. They happen when the less than perfect ones’ variables plus those of our own cancel each other out, or, when everything is perfect. How do you tell which it is? If you shoot 20-shot groups each time, they’re much closer to the same size as 3- or 5-shot ones.

 

[243winxb]

243 Winchester

A scope with more power and parallax adjustment may help. A variable is a good choice. My Leupold 36X is about useless for me in the heat waves/mirage. The heat coming off the barrel can be reduced, elimiated by using a barrel heat shield of heavy paper or lite cardboard affixed to the barrel. A small aiming point and wind flags help. I like Berger bulllets in 243 and Redding type S bushing FL die.

[/URL][/IMG] The average MOA should be better at 200 and 300, then at 100 yds, as the bullets go to sleep down range, shooting with no wind or sun out for me.

 

[Bart B.]

Use the calculator in this link to figure out what your maximum parallax error will be:

https://www.lelandwest.com/parallax...essionid=8430df1e193d3d4eecbc241a2b6a31f62675

Note that reflex cameras correct for parallax just like scopes do, but you cannot correct it by keeping your eye at the eyepiece center.

Regarding:

The average MOA should be better at 200 and 300, then at 100 yds, as the bullets go to sleep down range,

Are you saying bullets at the outside edges of some down range group head back towards the middle as they go to sleep? How do they know what direction to go?

 

[BWB]

Can't agree with the "should" part, but there is some basis for this at extended ranges.
The explanation is complicated and technical, but very clear. I would refer anyone seriously interested in this broader subject to Brian Litz's book Applied Ballistics For Long Range Shooting. This is an amazing resource.

 

[Bart B.]

I don't think the explanation's complicated and technical at all for longer range groups to be smaller in MOA than at shorter ranges.

It's been known for over a century that when bullets leave on the muzzle axis up swing at the right place, slower ones leaving later have a higher departure angle that compensates for bullet drop. Faster ones are just the opposite.

It's called positive compensation.

Tuning the rifle barrel's resonant and harmonic frequencies by changing its shape is done for a given load. Or adjust a load so its bullets leave at the right place on the muzzle axis up swing.

 

[243winxb]

Are you saying bullets at the outside edges of some down range group head back towards the middle as they go to sleep? How do they know what direction to go?
__________________

No. They stabilize. When bullets stabilize there's less deflection from outside sources. Wind, air density, magnetic anomalies in the ground and vortex energy. And then you have Voodoo.

 

[Bart B.]

I'll explain the "voodoo" part.

Sierra tested their bullets at 100 yards in their California plant before moving to Missouri in 1990. Their best match bullets put 10-shot test groups under 2/10ths inch once every 15 to 20 minutes during the production run as 10 bullets dropping out of the pointing dies were seated in primed and charged full length sized cases. Sierra's 30 caliber 168-gr HPMK's specs were 1/4" average and none over 3/8" else the lot was sold as seconds. Nowadays, all their match bullets (33 caliber and smaller) have to shoot under 1" in their 200-yard range.

Benchrest competitors often add a click or two to their powder measures to dump another 1/10th or 2/10ths grain of powder in cold weather. The thicker air requires the bullets used to be spun a little faster to spin stabilize. Their muzzle velocities and twist rates spin bullets just fast enough so the tiny unbalance some have won't cause too much jump off the bore axis due to centrifugal forces

Therefore, it's my opinion, as well as Sierra's and the stool shooters, that if bullets are spun in the right range of rpm's for a given velocity range, they are well stabilized by the time they go through the 100-yard point. If spun too fast, then they won't stabilize (or go to sleep, if you prefer) until later in their flight. Which is why bullets shoot most accurate when spun just fast enough to stabilize as soon as possible.

 

[WVRJ]

I experienced something similar this past Sunday.I was shooting one of my 223's,it's a M700 with a Shilen barrel,and that rifle will always shoot under .5 MOA.But on Sunday,it wouldn't come close to that,all the groups I shot were around 1 MOA,or just a bit more.I stopped and gave the rifle a quick check over-scope mounts,bedding bolts,etc. but found no problem.I put it in a Caldwell Rock BR's lobe bag and shot 5 shots free recoil.The first group shot that way was .290 for 5 shots.Yep,it was me.I've been doing this foolishness for some 35 years,but be it a loss of concentration,a slight flinch or what,I don't know.The trigger on that rifle is a Rifle Basix,and while it is light,there's some creep,and it varies from shot to shot.Maybe I was tightening up right when the shot broke,not sure.So many things can affect accuracy,and as a rifle shoots better and better,those tiny variables can really come into play.As for my situation,it wasn't the rifle so much as the man behind it.

 

[Bart B.]

Most people don't realize how much a small change in the way a rifle's held will effect a change in bullet impact relative to the aiming point.

Having shot the same rifle and ammo in a team match with three others, we all had different zeros for the target range. Sometimes, one would say it's the way we look through the sights. To which I replied that it's an age old myth. Some would ask how I could prove it's a myth.

So after the match, I would put a collimator in the muzzle, adjust the sight close to bore sight then have each one adjust the sights to zero on the collimator reticle. All ended up with the same sight setting. Then all agreed that it was the way we held the rifle and it recoiled a little different for each of us as the bullet was still going down the barrel.

A good prone marksman knows that once a zero's set, if the fore arm's elbow is moved to some other resting point, that change in the way the rifle's held will move shot impact to some different point relative to where aimed. Changing ones hold on a benched rifle is no different.