What can cause an outlier group with the same load?

[JohnMill]

Work up a load that will continue to shoot .1" groups at 100 yds. When this is completed write it down ..... everything, temp, humidity, velocity and other things. Because tomorrow is a new day and it will change. I always try to predict the conditions and load accordingly. I know that sounds strange but to me a temperature swing also changes the humidity which will affect your groups, you may need to adjust a little up or down.

Darrin

Thanks Darrin, I used to keep and use a whatchamometer (temp and humidity) when I was shooting short range. Sorta forgot about it when I went to 600. I'll get another

 

[JohnMill]

Started at 100 and narrowed it down to powder and rough seating depth. Then went to 400. The groups shot today were trying to verify the 400 tests. The only reason the vts were on there is because I have a known load already with them that I’ve shot in a few competitions and wanted to see how these would compare.

What is your goal for 100 yard groups? My 100 yard groups seem to be deceiving when I take them to distance. And are you shooting 5 shots for group?

I try to tune for mid tenth groups at 100 (5 shots),with good ES and SD. Round groups, no more than half a bullet vert.Also, when you determine "touch the Lands" Alex Wheeler's method (on his website) is best. Otherwise it's arbitrary.Full lngth size for the test or you might be dragging the brass loose 'stead of the bullet.
Thanks Falfan for starting this thread.
John

 

[Tim Singleton]

I know this may not be much of a substantive contribution to the topic
But here goes anyhow

One if the major hurtles we need to cross is the load development concept of finding one combination that the gun shoots.
The big problem is they rarely repeat from day to day
What the guys that have been actively competing for 10 and 20 years know is what the gun is capable of doing.
That is their load development

Then on match day if it's not at it's best you gotta change something or be happy with bottom or middle of the pack
So find out what it has in it. Learn what it will do at a different seating depth be prepared to change something if you have to

 

[Tim Singleton]

I may be talking out of my element with the being prepared to make some changes on match day. Maybe @Bart will answer if I’m way off base between short range and mid range at least out to 600 yds. I know the br and bra hold tune a little better than most and a lot of folks go pre loaded

I still think you’ve gotta be prepared to make those changes to seating depth and powder based on what you see on the target and what you know your gun is capable of
A couple weeks ago I started a match with what i thought was the right load and seating depth. Finished the morning 22nd
I could have just swallowed that pill the rest of the weekend and have before but I made some changes to seating depth and powder finished 2nd that afternoon and dang near won the yardage.

Then we had to shoot on Sunday and nothing I tried would work!
All that to say, if Bart doesn’t see what he likes on his first target.
I don’t think he will keep on shooting that load hoping it’ll work on the next one

 

[JFrank]

Tim
You mentioned seating adjustment as well as powder, can you expand on the powder change?
Also do you have a mental diagnostic tree or flow chart as a guide or keep notes in a log book?
What does that look like when your at a match?
Jim

 

[Tim Singleton]

Tim
You mentioned seating adjustment as well as powder, can you expand on the powder change?
Jim

I swapped from LT32 to N133 after the second target there was some improvement bit not enough the 5th target I made a seating depth change
The last target of the morning was what the gun was capable of
Shot the afternoon agg pretty well

 

[JFrank]

In a short range match is it common to have several loads ready to go?
How much time do you have in between relay to make these decisions?
I'm assuming your at a short range match "
Correct me of course

 

[Tim Singleton]

In a short range match is it common to have several loads ready to go?
How much time do you have in between relay to make these decisions?
I'm assuming your at a short range match "
Correct me of course

Yes short range is what I was talking about
It is common to have several loads ready especially the first target and if things aren’t going well. You will be trying other things on the sighted during your match
You have 30 minutes between relays
I keep notes and make notes on practice targets. I think once you’ve done it enough you begin to be able to read the targets better and know what you need to do to some extent anyway

 

[JohnMill]

Yes short range is what I was talking about
It is common to have several loads ready especially the first target and if things aren’t going well. You will be trying other things on the sighted during your match
You have 30 minutes between relays
I keep notes and make notes on practice targets. I think once you’ve done it enough you begin to be able to read the targets better and know what you need to do to some extent anyway

Sounds like good planning. I generally test to a fare thee well and take my best load to a match. I have changed loads many times during a match. I have never (read NEVER) had an improvement while changing loads during a match except when I changed back to my original. The heat of battle may lead one to make great decisions but with25 years of experience I now know I am not that one. YMMV.

 

[Ghansen]

I had a bad run with a batch of projectiles I was using. Having had good success previously with both 66g- 67g FB and BT from this maker in my 6PPC I resumed my search for "1 holiness" with a newly sourced lot of 1000 and for the life of me I couldn't figure out how my 3 shot tuning groups could test both bad or great and when I had a few good tests then BAMM I had a shotgun group or flyers that left me disheartened for my efforts and looking for ghosts. In this rare case it was something to do with a new finishing die that was non concentric.

My recommendation to begin flyer elimination is to retest with a batch of some known performing projectiles. Then follow a focused elimination sequence which includes questioning "is the shot random or your first or last shot". Introduce Voodoo and use brass that has previously been a flyer only for barrel warmer and rough sighter.

I switched to a new lot of projectiles and began consistent fine tuning, had a win and top ten placings in a quality field when all things aligned. Also, I do use a barrel tuner to broaden the tune range.