Home Forums Hunting & Shooting Ask The Gunwriters Why would a rifle shoot 1/2 MOA at 100 and 2 MOA at 200 yd???

Swifty,

HA!

country boy,

How did you check parallax?

I had another thought, but need to ask another question: Have you shot other rifles on the same range at 100 and 200 yards?

I think I can rig that up. Should be interesting.
[/quote]

I could be wrong but it seems that bullets hitting even a piece of paper at high speed could cause them to deflect a little, opening up the group at 200. Just guessing.

As to the initial question, it's because they are fickle damned things.

JayJunem,

I believe Bryan Litz uses electronic targets when testing relative group size at different ranges, for that very reason.

Horizontal spread could indicate an issue with the rear bag.

I placed the rifle securely on the bags, aligned the scope to my target, and slowly moved my head in various directions to look for apparent reticle shift. I did this with my 100 yd target and my 200 yd and could not see any.

yes. Many times. With several different rifles. Usually after I get a load that I like at 100, I go to 200 to confirm and zero and then practice out to 400.

Definitely going to check into that. MD said something earlier about the sling studs and I'm pretty sure my rear sling stud was on my rear bag, so I'm going to change my setup next time out.

That right there explains it. I always remove them for load development.

That's interesting.

I know nothing about electronic targets. I'll have to Google that.

I hope you're right. Easy fix.

There is truth in this statement. As we put more rounds on a barrel, we usually see a drop in X counts at 600 yards as the first sign it is nearing it's end. Scores will drop next and flyers will appear at the short lines (200 and 300 yards) more frequently. It's not uncommon that while this is going on, the barrel will continue to pump X's on a 100 yard reduced target. The more frugal amongst us will turn that barrel/upper into a "reduced course only" upper. The no-nonsense folk pull the barrel at the first hint of a drop in performance and add a tomato stake to the garden.

My learning is to always check your accuracy at the maximum distance your shots matter at.

A whole lot of energy has been spent here, mostly constructively. Several have pointed out some very good points.

PaulBarnard's post to the efect of "change the shooter" is probably the best.

Next week I get new lenses in both eyes and going blind has shown me more than a few things... double entendre intended.

Carefully focusing the reticle is critical and sizing the target for the scope and power at the specific range is critical. Making a very hard black square on a very white background such that the reticle is placed against said high-contrast corner will allow the blind to see again! Just a few days ago I had to go to the local range, which I absolutely dread. Friend could not manage minute-of-moose. Simply making him use the center of his finger pad made his shooting go from ridiculous to repeatable.

Power changes should not cause a problem for accuracy, but may cause a change in hold because the increase in power shortens eye relief which forces a change in hold. Without the change, the P word...

Another variable I have seen many times involves rapidly changing weather both at ground level and at elevation. Rapidly moving clouds toss shadows and hot spots all over the place and force the eye into contortions trying to keep up.

If the op failed to see any parallax maybe he should look again...

Sizing the target to the scope is often a lot bigger issue than many realize.

Forgot to add the old eye sight test of the ancients. Redundancy not intended...

Mizar and Alcor are a couple stars in the Big Dipper and if you can see them as two stars your eyesight is at least 20-20, or so they say. Point being it is hard to meter everyone's eyes in a crowd, Best to look at what one's own eyes can do and maximize the potential.

I could be wrong but it seems that bullets hitting even a piece of paper at high speed could cause them to deflect a little, opening up the group at 200. Just guessing.
[/quote]

Maybe set up a first target at 100yds with two aiming points, one right on the center of the paper and another right on the upper edge of paper and the rifle sighted in 2" high. With a paper at 200 hundred right behind the first one, but taller in order to cath the bullets aimed at the higher bullseye. Like that those bullets would fly high over the first target and not having to go through the paper it will not deflect at 200. And see how the groups compare to those that go through the first paper.

I think it is going to be a very interesting experiment I`d love to do it myself nut unfortunately I don`t have an appropiate place to do it. Please keep us updated with your findings.

Thank you

chamois

When I had discussed the opposite situation (smaller observed MOA groups at longer distance than at shorter) with Bill Davis Jr in the pre-acoustic target days, he suggested shooting through onion paper at shorter range to avoid altering the downrange path.

Franklin Mann in his 1909 book "The Bullets Flight from Powder to Target, used this method to document bullet's paths as they travelled down range.

Today you can use acoustic targets that triangulate the bullets position as it passes through the target plane without having to touch paper. Here's one example.
https://oehler-research.com/system-86-acoustic-target/

My scopes aren't adjustable for parallax, and the Leupold ones are nominally set to be parallax free at 150 yds. Is there a theoretical or practical maximum parallax error at 100 & 200 yds.?

Maybe set up a first target at 100yds with two aiming points, one right on the center of the paper and another right on the upper edge of paper and the rifle sighted in 2" high. With a paper at 200 hundred right behind the first one, but taller in order to cath the bullets aimed at the higher bullseye. Like that those bullets would fly high over the first target and not having to go through the paper it will not deflect at 200. And see how the groups compare to those that go through the first paper.

I think it is going to be a very interesting experiment I`d love to do it myself nut unfortunately I don`t have an appropiate place to do it. Please keep us updated with your findings.

Thank you

chamois
[/quote]


This has already been done decades ago with onion paper.

[quote=jwp475

This has already been done decades ago with onion paper.

[quote=jwp475]


Depending on how many decades, maybe none of us was born by then...

If you don't mind ilustrating us with the results...

Did the (angular) grouping change with the distance?

Fortunately Dr. Mann’s book is still available. Should really be required reading.