Ever had rounds from the same lot speed up?

[TheGerman]

Switched to a new lot of Lapua and beforehand I ran 2 patches through the barrel just to give it a quick wipe down and get rid of any material. No solvent or anything.

Re-zero'd the gun via shooting groups at 100 and everything was good. Within the next 15-20 rounds I'm all of a sudden shooting consistantly high.

Go back to the 100y zero target and I'm high through the entire group.

Only thing I can think of is that after 15-20 rounds the barrel was re-fouled to the point the rounds sped up whereas they were slower from me having put 2x patches through it?

Never seen this without having a full cleaning with solvent, etc.

 

[hafejd30]

Tuning in to see the suggested outcome...

If you ran oil etc on the patches or heated the barrel up I could see the change in such a short period of time. Only other time I’ve see this personally is when something came loose (scope base, brake/suppressor, scope fail) all just a guess tho. It’s frustrating when shit like this happens without a obvious cause....

 

[TheGerman]

I 'tested' it as I shota group after I saw it start going high and the group was high from my zero'd POI yet grouped together.

It basically started shooting higher, but consistantly.

That brought me to it speeding up.

 

[hafejd30]

I 'tested' it as I shota group after I saw it start going high and the group was high from my zero'd POI yet grouped together.

It basically started shooting higher, but consistantly.

That brought me to it speeding up.

Only time I personally noted a consistent shift like that is when a buddy scope (Ruger with a vortex) slid in the rings. Also have seen a shift due to scope base screw coming loose. That was more of 2 groups on paper etc.

The only barrels I’ve had that were affected to the point of needing to re-zero after 20 rounds were savage factory barrels

Very interested to see what your determined outcome is.

Assuming the ammo before and after the change was exactly the same, which from your post it sounds like it is

 

[straightshooter1]

I 'tested' it as I shota group after I saw it start going high and the group was high from my zero'd POI yet grouped together.

It basically started shooting higher, but consistantly.

That brought me to it speeding up.

I know it sounds counter intuitive, but if MV was speeding up you're POI would be lower, not higher . . . especially at that range. (consider line of sight through your scope in relation to the arc the bullet travels and where they intersect)

 

[TheGerman]

I know it sounds counter intuitive, but if MV was speeding up you're POI would be lower, not higher . . . especially at that range. (consider line of sight through your scope in relation to the arc the bullet travels and where they intersect)

I had thought of that as well.

But I'm also shooting high at distance.

I zero'd at 100, started shooting at 150-220 and then at some point I just kept being in the same spot over the target at 201.

Brought it back to zero, shot at the 100y target on paper and was above the spot I was zero'd on previously, but it was consistant, not like something was loose and shotgunning it.

Temp was within 5 degrees.

Not sure WTF was going on.

 

[acudaowner]

I just assumed it was the fact it's factory ammo and that was the reason so many load their own .But we have in the last 8 months seen increases of up to 100 fps faster and down 96 fps slower rounds in the same box our sd's ranged from 16's to 28's and its not like its just one or two per box but all through out . the only options i have seen are pay double for the ammo and shoot less , put up with it and keep shooting or start loading my own . I am leaning to start loading my own but will need a new place to live If I do so lol .

 

[littlepod]

Did you make sure to test for wind? A tail wind will raise your POI at 100 yards. You should zero at 25/50 to avoid environmental factors. I've never seen a lot of my ammo speed up / behave differently due to cleaning.

 

[camocorvette]

Only time I personally noted a consistent shift like that is when a buddy scope (Ruger with a vortex) slid in the rings. Also have seen a shift due to scope base screw coming loose. That was more of 2 groups on paper etc.

The only barrels I’ve had that were affected to the point of needing to re-zero after 20 rounds were savage factory barrels

Very interested to see what your determined outcome is.

Assuming the ammo before and after the change was exactly the same, which from your post it sounds like it is

This is rimfire ammunition he is shooting.
If the German is loading his own 22.... he has way to many matches and time on his hands.

 

[hafejd30]

I just assumed it was the fact it's factory ammo and that was the reason so many load their own .But we have in the last 8 months seen increases of up to 100 fps faster and down 96 fps slower rounds in the same box our sd's ranged from 16's to 28's and its not like its just one or two per box but all through out . the only options i have seen are pay double for the ammo and shoot less , put up with it and keep shooting or start loading my own . I am leaning to start loading my own but will need a new place to live If I do so lol .

Loading my own rim fire sounds like a hell of a good time on the old rock chucker

 

[RTH1800]

What! No chrono? Hate to ask but are you a ... um ..

 

[Powder_Burns]

Turret tracking test.

Perhaps carbon fouling in the chamber/throat area accumulated and is causing a pressure spike.

I’d chrono to confirm its actually speeding up and not a mechanical issue somewhere else.

 

[orkan]

Hence why I never touch my bore with anything unless some issue arises to cause a cleaning. It adds a variable to a situation with many subtle variables anyway. 9,000+ rounds on my main barrel presently without being cleaned, and it's still averaging in the .1's and .2's at 50yds.

Maintaining a 35yd-40yd zero (50yd max) is a good way of keeping excess environmental variables from affecting your decision making capability. At 100yd, environmental conditions affect POI too significantly to be certain of the cause of zero shift, from day to day. Conversely, close zero's and the environmental related bullet shift can be assigned to conditions much more easily. Where as at 100yds, one would need a dozen high quality wind flag setups between you and the target to even start to gain insight into the shift.