team tractor Posted March 21, 2016 Report Share Posted March 21, 2016 I'm seeing more and more measure the groupings from the centre of the bullet hole and not the overall of late. What's the correct way of measuring ? I've always measured from out to out Quote Link to comment Share on other sites More sharing options...
activeviii Posted March 21, 2016 Report Share Posted March 21, 2016 Outside to outside minus bullet diameter. Quote Link to comment Share on other sites More sharing options...
team tractor Posted March 21, 2016 Author Report Share Posted March 21, 2016 Seen this on FB this morning. Isn't this wrong Quote Link to comment Share on other sites More sharing options...
rjimmer Posted March 21, 2016 Report Share Posted March 21, 2016 Outside to outside minus bullet diameter. +1 Quote Link to comment Share on other sites More sharing options...
figgy Posted March 21, 2016 Report Share Posted March 21, 2016 (edited) Lots are measuring centre to centre of the bullet holes. Most measure the outside diameter of the group at its largest part. This seems to be the old way. To me the true way as it's the size of the hole group has made that counts. Team Tractor by the looks of it the verniers are measuring centre to centre same measurement as outside of group minus bullet one diameter. Edited March 21, 2016 by figgy Quote Link to comment Share on other sites More sharing options...
Grandalf Posted March 21, 2016 Report Share Posted March 21, 2016 Team Tractor by the looks of it the verniers are measuring centre to centre same measurement as outside of group minus bullet one diameter. +1 Exactly the same. Just easier to measure the outsides and subtract. Quote Link to comment Share on other sites More sharing options...
1066 Posted March 21, 2016 Report Share Posted March 21, 2016 (edited) +1 Exactly the same. Just easier to measure the outsides and subtract. +1 There's some excellent free software for measuring groups http://www.ontargetshooting.com/download.html This gives you exact measurement, also works out MOA. You just need to know what range you are shooting at. To be able to compare data and have meaningful results I think a "group" should be five shots and at a known distance, three shots at a bean can at about 70 paces doesn't give a lot of useful information. I also think that all shots should be counted, not "this one was from a cold barrel, this one I pulled a bit etc. etc." Edited March 21, 2016 by 1066 Quote Link to comment Share on other sites More sharing options...
figgy Posted March 21, 2016 Report Share Posted March 21, 2016 I think if your checking for best ammo or drop off at distance discounting a shot you know you pulled is ok as you don't want to count it in your calculations. For shooting groups I agree it's still one of your shots, good groups are made by not pulling shots. Quote Link to comment Share on other sites More sharing options...
Dekers Posted March 21, 2016 Report Share Posted March 21, 2016 Outside to outside minus bullet diameter. .....and that is the same as centre to centre! Quote Link to comment Share on other sites More sharing options...
team tractor Posted March 21, 2016 Author Report Share Posted March 21, 2016 .....and that is the same as centre to centre! Seems daft centre to centre as to me it's not the overall. I can manage 1/2" at 100 yards with my howa this means Quote Link to comment Share on other sites More sharing options...
the enigma Posted March 21, 2016 Report Share Posted March 21, 2016 Centre to centre seems to be the most common way to express group sizes. If you have a set of digital calipers, zero them at your bullets diameter, and then measure ouside edge to outside edge, and the reading you get will be centre to centre. Quote Link to comment Share on other sites More sharing options...
kent Posted March 21, 2016 Report Share Posted March 21, 2016 Centre to centre is the excepted way and used in competition Find the largest space and measure inside edge of one bullet print to the outside of the other ( saves the maths) Oh yes bad shots and fliers do count lol Quote Link to comment Share on other sites More sharing options...
Doggone Posted March 22, 2016 Report Share Posted March 22, 2016 To make sense of centre to centre, if you put 3 bullets through the same hole and the size of the hole was the same size as the bullet the group would be zero, not the bullet diameter. If you did the same with say a 50 cal bullet and a 22 bullet the two groups would be the same, zero, not half an inch, and a quarter of an inch. Andy Quote Link to comment Share on other sites More sharing options...
team tractor Posted March 22, 2016 Author Report Share Posted March 22, 2016 To make sense of centre to centre, if you put 3 bullets through the same hole and the size of the hole was the same size as the bullet the group would be zero, not the bullet diameter. If you did the same with say a 50 cal bullet and a 22 bullet the two groups would be the same, zero, not half an inch, and a quarter of an inch. Andy Finally someone's made it simple that makes sense Quote Link to comment Share on other sites More sharing options...
Savhmr Posted March 22, 2016 Report Share Posted March 22, 2016 Centre to centre which makes perfect sense (or largest group size minus diameter of bullet as above). All shots should be included unless you can be certain of any shot which was (not "may have been") pulled. If you think you pulled a shot but don't know which one, the group should be re-shot if testing for load dev. Anything else is a pointless exercise. Quote Link to comment Share on other sites More sharing options...
welshwarrior Posted March 22, 2016 Report Share Posted March 22, 2016 To put it simply if you measure centre to centre you get a truer representation of the group size with you 223 it is under a 1/4" difference with a 577 it takes a 1/2" group and makes it over an 1" if you do outside edges. Quote Link to comment Share on other sites More sharing options...
Vince Green Posted March 25, 2016 Report Share Posted March 25, 2016 (edited) What does it matter? People halve the size of the group before they post it on here anyway Edited March 25, 2016 by Vince Green Quote Link to comment Share on other sites More sharing options...
1066 Posted March 25, 2016 Report Share Posted March 25, 2016 What does it matter? People halve the size of the group before they post it on here anyway You have to discount the flyers first Vince. Quote Link to comment Share on other sites More sharing options...
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