Pressure issues, need some help

[DLT]

First off I want to start by saying this is a home build rifle. Origin action with a factory savage 6 creedmoor barrel. I owned another rifle this barrel was on which was all factory and it was a hammer. I sold the whole rifle, they rebarreled it and I bought the original barrel back (it always shot well). I installed in on this origin to play until I decided on what chambering to switch to. Now the fun part. I have been shooting 39.5 of H4350 with a 107smk around 3050fps with out much of a hiccup.
Today I decided to try Vv-n160. Looked up their load data and decided on a safe charge at 39.5gr. I loaded up 4 and hit the range.
First round was 3150, and blew the primer out. The case did not stick. I pulled the other 3 loaded rounds and came down 1 whole grain to 38.5gr.

The first round I was scared and pointed it into the pond and pulled the trigger, speed was 3,014 with no pressure signs so I fired the other 2 into a single hole. Excited, i went and loaded 3 more but the first one locked the bolt and stuck the case. I was able to get it out thank goodness.
I rechecked my scales they were zeroed and set to the correct charge weight. The rifle has .005 clearance of headspace from the go gauge. Could that be my problem ? I have measurements written down and my tools on hand if you want to ask any questions.

I want to add Vv load data was using small primers where my brass is large rifle. I am also bumping my fired rounds .001.
If it’s not the headspace causing it or the large primers for small primer load data I’m at a loss.

 

[DShortt]

You switched powders. Your brass/primer/bullet combo does not like the new powder.

 

[DLT]

You switched powders. Your brass/primer/bullet combo does not like the new powder.

Yes I did but that doesn’t explain much to me as to what happened. I was using vv load data not a max charge. unless it’s a big no no to use large rifle primers in place of small rifle data. I just switched powders like any of us has done hundreds of times. I did not have my scale set wrong or use an out of line powder.

I have made mistakes before but with a little work or asking the right questions I found out and learned why things did what they did. Not sure about this go round.

 

[DShortt]

I would guess, based on the information you provided, it's the large primers and that powder.
Again, based on the information you provided, ignition and burn rate isn't consistent with your combination.
I personally would cease using the new powder.
Did you happen to record the velocity when the primer blew the first time and the action locked-up the second time? I'd bet the velocity was off quite a bit.

 

[kevinbritvec]

Back it off, obviously.

A really good and thorough barrel cleaning always helps and never hurts.

I am so enamored with VihtaVuori N150 that I can't possibly criticize your plan to use that powder.

Your rifle is not VihtaVuori's rifle. Unless you have the same brass, same primer, same powder, all from the same lot numbers, any results you have are subject to the same variations everyone else suffers.

A lot of people run maximum loads with no ill effects. I don't even try.

I use a chronograph and take barrel length into consideration. I develop all of my ammo somewhere below maximum velocity, somewhere below maximum powder charges, seeking accuracy above all else. I'm weird like that.

 

[std7mag]

Wait...

You set the headspace up .005" beyond the go gauge.

Then you bumped the shoulder back another.001" on previously fired cases.
The cases that you fired from this setup?
Or that barrel before you screwed it on the new action?

Where are you seating the bullets?
Jam?
Or a set distance off of the lands?

 

[243winxb]

Vv-n160. Looked up their load data

Do they use different brass, different volume?