Group measuring

[lenweber2]

I'm seeing groups quoting size and although good groups I question size. 

Group size equal total size of group minus bullet/pellet size. Now thats ruff but close.

Agree or disagree?

 

[Aimright]

I just measure center to center, or outside edge to inside edge. I think your described method may be a little more accurate for “one ragged hole” groups where determining pellet centers or edges is difficult.

 

[Kgphotos]

When I measure my groups I just measure the outside edges of the two farthest holes and then subtract the diameter of the pellet. I find it easier than trying to determine the middle of the holes.

 

[nervoustrig]

Just FYI, taking the outside measurement and deducting the caliber does not give an accurate center-to-center measurement because the hole produced by a pellet is smaller than the caliber. The difference is most significant for domed pellets, and less significant for wadcutters because they punch a larger hole. Granted, for casual purposes the distinction doesn’t matter but when a guy posts a gloat-worthy group, it better be accurate or expect some pushback

 

[nomojo65]

https://www.airgunnation.com/members/nervoustrig/ I think it can also go the other way? If pellets are slightly unstable or going in at slight angle the hole can be larger!, and if you use card stock or heavy target paper “as you should shooting for groups” it’s not much of a concern, one more thing if you turn the target over and compress the back you can better determine by the lead ring produced by the pellet 

 

[nervoustrig]

Well that’s true but if the pellets are starting to tumble, it’s not generally a group that one would be interested in measuring

 

[nomojo65]

Why take my post out of context?, I didn’t say tumble! I said slightly unstable, which is definitely not tumbling, also as an example you can’t tell me that a .30 cal. Pellet @ say 890fps @ 100yd isn’t hitting the paper at an angle? and why is it ok to say a slug doesn’t fully stabilize until say 50yds but a pellet can’t start to destabilize at 100yds if you measure a slug @50 and a pellet @ 100 the size of the hole in the target may be “slightly larger” instead of “slightly smaller”, therefore giving a slightly larger hole vs. slightly smaller hole to get a accurate measurement from.., I guess in the end it doesn’t really matter for me, my groups never come down to a measurement so close as to worry about any of this anyway!

 

[nervoustrig]

Sorry, I'm not trying to misrepresent your point. However if the pellet is only slightly unstable, to me that describes a shallow yaw angle which means the pellet will not enter the paper at a sufficiently obtuse angle to cause a meaningfully discernable oblong hole in the paper. That was why I used the phrase "beginning to tumble". In retrospect, I should have said on its way to tumbling, meaning it has begun to yaw so severely as to punch an oval hole into the paper. In practice, I don't observe that until it has gotten so severe as to produce what I would call keyholing. Up until that point, what happens is the head punches a hole through the paper before the skirt gets there, and there is little to no evidence it entered at a shallow angle. The skirt may leave a little tear around the perimeter of the hole but that same thing occurs when a pellet enters perfectly straight due to the random orientaton of paper fibers, so the cause isn't readily apparent until the pellet is very nearly sideways.

 

[nomojo65]

Now I understand why my groups always seemed so small! Not being sarcastic, and you are correct in your above statements and reply’s

 

[nervoustrig]

Thank you sir, that was very thoughtful