Max case web expansion for 33vx?

[harry_x1]

I am firing 300 gran Lazers, 115 grain N570 at 3120 fps in my 33xc. I get around 0.0035" expansion at pressure band after one firing. Is that too much pressure? No heavy bolt, but do see ever so slight ejector marks. Primers are flat but not that bad.

 

[918v]

You can’t measure pressure that way.

 

[harry_x1]

You can’t measure pressure that way.

ok...I am not interested in measuring exact pressure, just checking if I am having over pressure and at risk of blowing up the gun or excessively shortening brass life. I read on forums that heavy bolt lifts combined with excessive expansion at pressure band are a good hack to check on these things....is my understanding incorrect? is there a better and practical alternative?

 

[918v]

Barrel temperature will control how much the case expands at the web. Then there’s measurement error caused by your instrument or technique or both.

I like bolt lift, ejector marks, primer pocket tightness for gauging pressure.

 

[harry_x1]

Barrel temperature will control how much the case expands at the web. Then there’s measurement error caused by your instrument or technique or both.

I like bolt lift, ejector marks, primer pocket tightness for gauging pressure.

this is a new learning for me today...thanks for sharing this insight. But I am curious, how this actually happens, like how the barrel temp impacts expansion, in case you can elaborate...thanks

 

[918v]

When the barrel gets hot the chamber gets hot and expands, now the case is able to expand more vs a cold barrel and cold chamber which restrict the case from expanding as much.

 

[harry_x1]

When the barrel gets hot the chamber gets hot and expands, now the case is able to expand more vs a cold barrel and cold chamber which restrict the case from expanding as much.

Wow...I think that makes sense...that is potentially why cases with same charge also expand slightly differently. I am guessing the cases fired later in the string, when barrel is hotter, tend to expand more? If yes, then it solves one of the things that puzzled my mind, as all cases did not expand to same degree in a match.