Q: for those with pressure test gear or Quickload

Q: for those with pressure test gear or Quickload - at what point of bullet travel is peak pressure generally indicated and at what point is say 50% and 25% on the decaying curve?

Dont need exacts just rough number eg peak at 0.5", 50% at 6" and 25% at 10" - or more to the point, just how far down the barrel is say 25 or 30% of PMAX

I spose quickload could give the same info? (mines on dead computer)

Eg for say 308 and 338LM

For a 165gn SST .308 in a 26"barrel with 42gn varget as example. Pmax @ 1.2" and 50% pressure drop at 6.5" using quickload.

Great - just what the doctor ordered - thanks
Got a 25 or 30% distance ?

30% Pmax about 10.5"
25% Pmax about 14"

Thanks very much

Im a rookie when it comes to this sort of carry on but wouldnt that mean if pMAX is 1.2", to create the most effecient chambering and get the most speed, 308 in this case should jump 1.2" before it engages the rifling, creating the most velocity. I think i see where this post is going, if my thinking is correct...
Disclaimer, i have never used quickload and am only assuming this is what pMAX means.. dont eat me.

PMAX is Max pressure
You're over thinking things :D
I'm interested purely for building test barrels - no point in having a 30" tube, or a 5" if 15" will do the job

yip, i probably am, just finished my exams today so i have 4 months holidays before i start up at uni again next year, so i have ALOT of over thinking to do haha. But surely jumping the bullet a greater distance would increase velocity a bit. How much would the barrel friction be slowing the bullet up anyway? I wonder what muzzle speed would be reached if the bullet was fired without a barrel... Would be relatively pointless, but all interesting stuff

All sorts of interesting stuff with guns, and 'what ifs' and 'whys'

Quote:

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Originally Posted by PerazziSC3

yip, i probably am, just finished my exams today so i have 4 months holidays before i start up at uni again next year, so i have ALOT of over thinking to do haha. But surely jumping the bullet a greater distance would increase velocity a bit. How much would the barrel friction be slowing the bullet up anyway? I wonder what muzzle speed would be reached if the bullet was fired without a barrel... Would be relatively pointless, but all interesting stuff

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It may not increase velocity but a big jump does reduce pressure due to it having more momentum when it engages the rifling so you could load hotter (why a weatherby mark V has a massive jump), suppose in a round about way it does increase velocity due being able to take a hotter load.

hope this helps
Attachment 4085

Thankyou :)