Pressure Signs with starting loads

[Steve Davis]

It will likely be a week or 2 before I get a chance to make up some more ladder loads and get to the range but will try to provide an update when I can.

There is still one question that I have. When you have pressure signs with low vel then the issue isn't high pressure. It is something else. What do you think could be causing your issue? @OutdoorEdventure has changed our listed start load down to 39gr now because you made him nervous. Lol! A couple grains higher than what Hodgdon shows is not unusual but pretty typical. I have loaded the Creed with the 124gr HH quite a few times using Varget. We typically start at 38gr and work up. Most rifles top out 40ish gr with a vel of 3000 fps give or take. Hodgdon shows a start load of 36gr with a 123gr Sierra and a max load of 39.8gr and a vel of 2887fps. Ed has our listed start load at 35gr (I don't know if he changed that too). Anyway, my point is the 42gr start load that you used would have generated much higher vel if it was indeed too hot.

My thinking is you either have a large chamber or small brass giving the brass too much room to move and then looking like there is high pressure or you have some lube still on the brass or in the chamber allowing the brass to move too freely in the chamber. Too smooth of a chamber can show too. If the brass can't grip the chamber then it shows too much bolt thrust. I think there is a term for this.

 

[Bleeb]

There is still one question that I have. When you have pressure signs with low vel then the issue isn't high pressure. It is something else. What do you think could be causing your issue? @OutdoorEdventure has changed our listed start load down to 39gr now because you made him nervous. Lol! A couple grains higher than what Hodgdon shows is not unusual but pretty typical. I have loaded the Creed with the 124gr HH quite a few times using Varget. We typically start at 38gr and work up. Most rifles top out 40ish gr with a vel of 3000 fps give or take. Hodgdon shows a start load of 36gr with a 123gr Sierra and a max load of 39.8gr and a vel of 2887fps. Ed has our listed start load at 35gr (I don't know if he changed that too). Anyway, my point is the 42gr start load that you used would have generated much higher vel if it was indeed too hot.

My thinking is you either have a large chamber or small brass giving the brass too much room to move and then looking like there is high pressure or you have some lube still on the brass or in the chamber allowing the brass to move too freely in the chamber. Too smooth of a chamber can show too. If the brass can't grip the chamber then it shows too much bolt thrust. I think there is a term for this.

That's an introspective observation Steve. Bolt thrust is a type of "breech pressure". It can be caused by undersized or lubed (not delubed after sizing) brass. It can also be caused by oils and solvents on the bolt, raceway, chamber and feeding ramp or lip being transferred onto the case upon chambering. Brass is essentially a ballon seal in the chamber.

 

[Muddyboots]

The one thing I will add is the Hornady tool is called a Comparator since it is not considered a precision tool but simply a means to get a "relative" number for the bullet jump. When the jump is actually really close to the lands, the potential for pressure spikes can become a concern due to multiple variables in the measuring process.

 

[gltaylor]

Very true, and agree. Hornady's comparator is not a precise measuring tool. Since you have to "feel" bullet contact with the lands, if "I" measure cartridge OTB for a cartridge several times it is not uncommon that "I" get 2-3 numbers.
My recourse is usually choose the shortest number, then go at least .020 shorter.
Hammers do not do well close to the lands ( in my experience).
I agree with Steve. This is still not adding up?
When you re'do your load work-ups, please share results. This has become very interesting.

 

[Bleeb]

Very true, and agree. Hornady's comparator is not a precise measuring tool. Since you have to "feel" bullet contact with the lands, if "I" measure cartridge OTB for a cartridge several times it is not uncommon that "I" get 2-3 numbers.
My recourse is usually choose the shortest number, then go at least .020 shorter.
Hammers do not do well close to the lands ( in my experience).
I agree with Steve. This is still not adding up?

Yup. When I ran the 162HHTs at 65 thou from the lands I got much better pressure, ES and accuracy than when I ran them closer.