Whats going on with this load?

[Matt5266]

Hoping @Formidilosus and others have some thoughts....

Tikka 223 18" barrel 1:8 twist
Banish 30 can

I never clean my barrels. This one has about 700 rounds on it. Can was cleaned about 200 rounds ago.

Gun has always loved the 77TMK load with 23.5 grains of XBR coal 2.26 cci400 lake city brass. Shoots 2770fps thats like a 50 round average. Usually prints about .5 inch at 100 with 10 shots.

Went out today since I swapped rings to sight in..temp was only about 70F groups were opened up, no stuff bolt lift but chronograph read quite a bit higher and I was also having some primer signs the group was about 1.1 its bigger in the Pic because I made some adjustments and shot a few more.

I then swapped over to the 73 grain eldm with the exact same load. I was having the exact same issue and even had a case rupture.. yikes. Group was about .5 until I made adjustments and shot a few more.

The chronograph data at 955 is the 77 load. The data at 1045 is the 73 load.

What you guys think?

Of course I have another 100 of the 73 eldm loaded up at the moment.

 

[fuzzymarindave]

Easy button is to clean barrel and chamber and try again. I've always thought that those type of brass failures are caused by the manufacturing glitches.

 

[mtnbound]

Hoping @Formidilosus and others have some thoughts....

Tikka 223 18" barrel 1:8 twist
Banish 30 can

I never clean my barrels. This one has about 700 rounds on it. Can was cleaned about 200 rounds ago.

Gun has always loved the 77TMK load with 23.5 grains of XBR coal 2.26 cci400 lake city brass. Shoots 2770fps thats like a 50 round average. Usually prints about .5 inch at 100 with 10 shots.

Went out today since I swapped rings to sight in..temp was only about 70F groups were opened up, no stuff bolt lift but chronograph read quite a bit higher and I was also having some primer signs the group was about 1.1 its bigger in the Pic because I made some adjustments and shot a few more.

I then swapped over to the 73 grain eldm with the exact same load. I was having the exact same issue and even had a case rupture.. yikes. Group was about .5 until I made adjustments and shot a few more.

The chronograph data at 955 is the 77 load. The data at 1045 is the 73 load.

What you guys think?

Of course I have another 100 of the 73 eldm loaded up at the moment.

How many loads do you have on the brass?
Were the fired rounds today from an existing batch, or were they newly reloaded?

 

[Matt5266]

How many loads do you have on the brass?
Were the fired rounds today from an existing batch, or were they newly reloaded?

This was the third firing. Newly reloaded. ( last month or so) same lot of primers, powder and bullets