Groups open up on a 50 round day

[6BRinNZ]

Hi,
this is .308 FTR
Barrel has 450 rounds on it
Load dev has gone well with vertical holding between .3 - .6 moa 300 - 1000
Generally speaking load dev has been in cooler temps by say 10 - 12 deg c and no more than 24 shots in a day.
First time using it in a comp in hot sunny days with 4 x 10 counting matches, I have found that the groups open up ~ 30 rounds.
Generally speaking I have to bring the POI 3 - 5 clicks (1/8 click) down to help center the group for the later relays.
It seems like it wants to shoot as I'm not chasing vertical like I would a barrel that is fouled out but the groups are larger and I have to click down during the shoot.
A month a go on a clean barrel it held .5 moa vert for the first 10 shots (first counting relay) - it hammers on the early relays.

What would you all do to fix this?
I suspect I am on the hot side and the extra round count and heat is taking me over the top as the day goes on.
I manage the carbon and copper in the barrel and use a borescope for cleaning. Could I be cleaning too much - but I don't need fouling shots to be confident of a clean in points for the first relay.
I don't think its a barrel issue as it seems like it wants to shoot - I have had barrels that have fouled out and those are just wild rides - its not like that.
I'm thinking of knocking it back a couple of 10ths in powder.

Any thoughts appreciated.

 

[fkimble@charter.net]

If you have a match before you get a chance to check things out, try dropping the powder charge a couple .x's for the last match.

Frank

 

[K22]

Ball or extruded powder?

 

[6.5 forever]

If you have a match before you get a chance to check things out, try dropping the powder charge a couple .x's for the last match.

Frank

I like Franks suggestion.

 

[dantiff2]

If you are seating bullets super close to the lands, I'd check the throat/ lead with a borescope to see if you are getting into carbon after x number of firings. It's one reason I always try to find a load 20-25 or more off the lands.

 

[Rat Rifle]

This month, I will be starting with a new barrel. In 2 target relays, I will be shooting 20 rounds, including sighters and score. I am going to clean after each relay and see if that’s what the barrel likes. I have had a barrel that wanted 20 rounds down it before it settled down, and then wanted to shoot dirty for the rest of the match, maybe 200 rounds. I always cleaned it after a match, because I felt if I pushed it too far, it would fall off in the middle of a match. Then the 20 round fouling would have to start over. I suspect a top competitor would pull a barrel like this and move on? I suspect every barrel will have its likes, and the shooter will have to decide if it suits his needs.

Of course, there are a multitude of other reasons I may not shoot well, and cleaning is just one that must be addressed ???

 

[dantiff2]

This month, I will be starting with a new barrel. In 2 target relays, I will be shooting 20 rounds, including sighters and score. I am going to clean after each relay and see if that’s what the barrel likes. I have had a barrel that wanted 20 rounds down it before it settled down, and then wanted to shoot dirty for the rest of the match, maybe 200 rounds. I always cleaned it after a match, because I felt if I pushed it too far, it would fall off in the middle of a match. Then the 20 round fouling would have to start over. I suspect a top competitor would pull a barrel like this and move on? I suspect every barrel will have its likes, and the shooter will have to decide if it suits his needs.

Of course, there are a multitude of other reasons I may not shoot well, and cleaning is just one that must be addressed ???

Really depends on whether or not this barrel is working for your needs. If you don't mind 20 rds to get to the node, then so be it. I've never had one like that. Usually one, two at the most but I always do load work up on a clean bore.

Edit: Try Lockease (graphite) after your cleaning regimen to see it that helps with fouling shots.

 

[wildcat3d]

Just a thought, but have you checked the bedding? had one that would shoot high as it heated up, turned out to be bedding plus receiver torque.