MOA guns

[3Crows]

There are MOA rifles and there are MOA shooters. MOA rifles are probably more common than MOA shooters. Unfortunatley, I can consistenly claim I am non-MOA. My rifle, several actually, PBs and a couple of Marauders, at a 100 yards indoor range, clamped in a rest or off bags, shoot MOA. Well, I take that back, I shoot the MRods (.25 caliber at 50 yards for hunting purpose, under .5 inch groups). My Kimber Mountain rifle in 6.5CM will go three shots from cold in one hole at the indoor range. That is under MOA. And it will do it from cold every time with quality ammo. Now, across a ravine, at 300 yards, with a quartering wind and throw in 20 degree temperatures and maybe some sleet, it may can, but pretty sure I cannot.

 

[rsfrid]

In light of the above discussion, I have been preaching that it’s the average group size over a large number that declares whether a gun/shooter is a MOA shooter or not. Here is a two day batch of groups shot at 7 yards with a HW44 177 cal pistol. MOA at 7 yards is only 0.07” for any group size. Remember when calculating center to center by overall group size minus pellet size, you should be subtracting the size of hole pellet makes, NOT the diameter of the pellet. In the case shown here, I measured a single free pellet hole at .157” not .177”.

 

[steve123]

100Y 1 moa capable pcp's/ammo exist nowadays and might not have been the case even 5 years ago. Many of us have shot sub moa at 100Y with pellets and slugs but doing it consistently is very hard.

More about this subject go look at the N50@100Y thread in the Benchrest forum.

 

[RIshooter]

In light of the above discussion, I have been preaching that it’s the average group size over a large number that declares whether a gun/shooter is a MOA shooter or not. Here is a two day batch of groups shot at 7 yards with a HW44 177 cal pistol. MOA at 7 yards is only 0.07” for any group size. Remember when calculating center to center by overall group size minus pellet size, you should be subtracting the size of hole pellet makes, NOT the diameter of the pellet. In the case shown here, I measured a single free pellet hole at .157” not .177”.

View attachment 427449

I don't understand the "minus pellet size" part. Center to center is center to center regardless of pellet diameter, no?

 

[rsfrid]

I don't understand the "minus pellet size" part. Center to center is center to center regardless of pellet diameter, no?

Some do actual caliper measurement of overall group size then subtract one pellet width. If you have no way to accurately measure exact center to center, then this method works just as well. The problem with this method is the total group size width would be wrong if one used paper overall width minus the stated diameter of pellet because hole created by pellet is rarely the reference size (for example a .177” diameter pellet will normally create a hole other than .177”). Hope this helps.

 

[RIshooter]

Some do actual caliper measurement of overall group size then subtract one pellet width. If you have no way to accurately measure exact center to center, then this method works just as well. The problem with this method is the total group size width would be wrong if one used paper overall width minus the stated diameter of pellet because hole created by pellet is rarely the reference size (for example a .177” diameter pellet will normally create a hole other than .177”). Hope this helps.

Ok... are you saying that each pellet creates a different sized hole? Or can it be assumed that they are roughly the same size?
If you assume they're roughly the same size, then side to side is the same as center to center... it's all relative.
If they're different sizes within any given shot string, then I can see how it could get complicated. (Maybe I should invent some translucent crosshair stickers that can be stuck over the holes for true center to center measurements, or maybe I just smoked too much )
I'm a carpenter so I have a good understanding of physics and spacial reasoning, but I'm fairly new to airguns, so I may be missing something?

 

[Peashooter]

I deal in SOS when shooting, that is Size Of Smile on my face, usually generated when i hit right where or very close to where i aim.

Most often it is individual shots that do it, but groups can also be high SOS score for me.

If anything in relation to groups, for me its more a matter of geometry, i like a round hole, maybe a little bit ragged, but mind you i seem to be a expert in shooting connected holes but in a horizontal line across the paper, and it just freak me out some times.

The nice round hole group is extremely rare at the ranges i operate at, so i am generally happy if actual holes or splatter on target touch each other.

 

[RIshooter]

I deal in SOS when shooting, that is Size Of Smile on my face, usually generated when i hit right where or very close to where i aim.

Most often it is individual shots that do it, but groups can also be high SOS score for me.

Awesome answer

 

[Sawney Bean]

Ok... are you saying that each pellet creates a different sized hole? Or can it be assumed that they are roughly the same size?
If you assume they're roughly the same size, then side to side is the same as center to center... it's all relative.
If they're different sizes within any given shot string, then I can see how it could get complicated. (Maybe I should invent some translucent crosshair stickers that can be stuck over the holes for true center to center measurements, or maybe I just smoked too much )
I'm a carpenter so I have a good understanding of physics and spacial reasoning, but I'm fairly new to airguns, so I may be missing something?

My understanding is that the reason wadcutters are flat is so that they will cut nice, clean uniform holes in paper when target shooting. Domes and pointed pellets are more likely to tear nonuniform holes as they pass through. It only really matters if you're in competition or have an obsession with group size anyway.

 

[RIshooter]

My understanding is that the reason wadcutters are flat is so that they will cut nice, clean uniform holes in paper when target shooting. Domes and pointed pellets are more likely to tear nonuniform holes as they pass through. It only really matters if you're in competition or have an obsession with group size anyway.

That makes sense, thanks.

 

[JungleShooter]

𖣠 MOA guns?
I doubt I have one.
However, I have several MIL guns.


𖣠 MOA shooters?
I doubt I am one.
However, I am at least a MIL shooter.


Matthias

 

[boscoebrea]

And here folks is a lesson in pretzel logic, Humans seem to find a way to make something simple into a complex fadella of unsroepus meand.....
My class in statistics has forever changed my view of the world; believe me when I tell you that the medical professional uses it to keep you alive or let you be.

 

[Mycapt65]

The wind up close has a longer time to blow your pellet off course, because it’s acting on it in the beginning of its flight path. Think of it as a force accelerating the pellet off course and the pellet will continue going off course for the remainder of its journey. If the wind can accelerate the pellet to say 1 fps in its direction of travel then that would be well over 1 foot off target 300 yards later if the pellet were initially traveling at 900 fps, (remember the pellet will decelerate the entire time).

Also projectiles will be more affected by wind drift the faster they go. I can't explain why but some time on a Ballistics calculator with show the same pellet (or bullet) will have more drift at 900fps than 600fps. I couldn't believe it until someone much smarter pointed it out. I think velocity increases yaw angle or something like that.

 

[RIshooter]

𖣠 MOA guns?
I doubt I have one.
However, I have several MIL guns.


𖣠 MOA shooters?
I doubt I am one.
However, I am at least a MIL shooter.


Matthias

Also projectiles will be more affected by wind drift the faster they go. I can't explain why but some time on a Ballistics calculator with show the same pellet (or bullet) will have more drift at 900fps than 600fps. I couldn't believe it until someone much smarter pointed it out. I think velocity increases yaw angle or something like that.

I believe this has to do with the rifling of the barrel. The faster the projectile is propelled, the faster it spins, which causes more drag on one side causing it to drift.

 

[Tumblinginflight]

Also projectiles will be more affected by wind drift the faster they go. I can't explain why but some time on a Ballistics calculator with show the same pellet (or bullet) will have more drift at 900fps than 600fps. I couldn't believe it until someone much smarter pointed it out. I think velocity increases yaw angle or something like that.

Can you link to your calculator? Have you verified the wind drift phenomenon yourself?

 

[OldSpook]

I believe this has to do with the rifling of the barrel. The faster the projectile is propelled, the faster it spins, which causes more drag on one side causing it to drift.

That is called spin drift.

 

[OldSpook]

It seems to me somewhere along the line I was told by my command that acceptance of M16s for issue required the rifle shoot a MIL CEP with 95% probability. I have no idea if that is correct. The first one I was issued would shoot 3 under a dime at 25 meters (prone supported) when the LT was looking over my shoulder.