Interesting Observation: Speed increased when wet cases used

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Haagen_Dazs

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Some food for though. I was loading up some rounds to do some load development for hunting and after waiting 24 hours after ultrasonic cleaning, the cases were still a little bit wet on the inside.

I didn't notice until after I loaded the cases and tried to re-weigh one of the charges and saw alot of the powder was stuck inside the case.

When I put the data into my spreadsheet, I found the the fp/s per grain (in bold) went way up on the wet cases.

Very weird. Any chemists here? I fired the rounds about 1 hour after loading.


Charge Projectile COAL Lands Range Group Size (") Results (MoA) Velocity (ft/s)


24.6 Sierra 65gn GameKing 2.340 0.030 290 1.216 0.711 0.4 0.2 0.09 2906 13 1 118
24.9 Sierra 65gn GameKing 2.340 0.030 290 2.955 1.811 1.0 0.6 0.58 2930 102 55 118
25.2 Sierra 65gn GameKing 2.340 0.030 290 0.248 2.035 0.1 0.7 0.05 3004 41 20 119
25.5 Sierra 65gn GameKing 2.340 0.030 290 0.750 1.256 0.2 0.4 0.10 3030 83 43 119
25.8 Sierra 65gn GameKing 2.340 0.030 290 1.152 2.563 0.4 0.8 0.32 3072 14 1 119
26.1 Sierra 65gn GameKing 2.340 0.030 290 2.316 2.416 0.8 0.8 0.61 3072 126 67 118
26.4 Sierra 65gn GameKing 2.340 0.030 290 1.976 1.575 0.7 0.5 0.34 3075 141 70 116
25.1 Sierra 65gn GameKing 2.335 0.250 290 1.880 2.147 0.6 0.7 0.44 2975 20 11 119
25.3 Sierra 65gn GameKing 2.335 0.025 290 2.402 1.413 0.8 0.5 0.37 3001 27 11 119
25.6 Sierra 65gn GameKing 2.335 0.025 290 1.286 3.112 0.4 1.0 0.43 3038 21 10 119
26.6 Sierra 65gn GameKing 2.335 0.025 290 2.067 2.400 0.7 0.8 0.54 3161 30 15 119
25.4 Sierra 65gn GameKing 2.310 0 TTL 450 ? ? ? ? ? 3010 88 40 119
25.7 Sierra 65gn GameKing 2.310 0 TTL 450 ? ? ? ? ? 2984 221 95 116
26.0 Sierra 65gn GameKing 2.310 0 TTL 100 0.760 0.755 0.7 0.7 0.52 3087 21 8 119
25.7 Sierra 65gn GameKing 2.310 0 TTL 100 0.620 0.904 0.6 0.9 0.51 3119 87 43 121 Wet Case
26.2 Sierra 65gn GameKing 2.310 0 TTL 100 0.379 0.528 0.4 0.5 0.18 3189 107 44 122 Wet Case
26.5 Sierra 65gn GameKing 2.310 0 TTL 100 1.162 0.478 1.1 0.5 0.51 3208 139 73 121 Wet Case
 
Its really interesting to see the effect different conditions of ammo will produced when fired. A friend did some testing with ammo that was submerged in water and then chambered and fired. The point of impact changed as did the speed. I can only imagine what clumpy stuck together powder would have. Different types of powder subjected to different environments and conditions would also play a big role. My dad told me a story about leaving a box of ammo in the pickup truck on a farm for a year so, took it out and decided to shoot it and it almost blew the gun up, kicked the crap out of him too. Turns out they were loaded with a good amount of slower burning powder but from getting bounced around in the truck and the vibrations it broke the powder down into a fine dust, and when she ignited, she blew her whole load real fast.
 
Case expands / seals to chamber. If do not wipe lube off case or case is wet then more difficult for case to seal to chamber, can cause case head pressure on bolt face / bolt thrust, and pressure spike - more FPS. If notice dent in shoulder / case this can also be cause by lube or water as impedes expansion of case.

Thus for your safety and longevity of your firearm, no oil in chamber, no lube on case, no water on case.
 
Possibly an effect of the residual water turning to steam? Water injected engine designs make use of the same effect.
 
raks said:
Possibly an effect of the residual water turning to steam? Water injected engine designs make use of the same effect.
Click to expand...


That's what I was thinking, too. An interesting idea - make use of some of the waste heat to vaporize water, and add to the volume (and therefore pressure) of the gas, while also reducing the heat
 
I have seen higher pressures due to the outside of the case having gotten wet while shooting in the rain but never shot any where the cases were wet on the inside.

I would think it would have affected ignition not made for higher velocities. Strange.
 
Im with the comparison with the new water injected engines. Makes sense physically. Screw powders like VV N-540, Ill just add a bit of H20 in my cases!

This could make for an interesting experiment once Im done all my load development.
 
26.5 Sierra 65gn GameKing 2.310 0 TTL 100 1.162 0.478 1.1 0.5 0.51 3208 139 73 121 Wet Case

26.6 Sierra 65gn GameKing 2.335 0.025 290 2.067 2.400 0.7 0.8 0.54 3161 30 15 119

I don't see anything here that I would attribute to a wet case. That 40-50fps variance could be cause by any number of things. A small variance is case capacity springs to mind. The sceptic in me wants you to take 20 empty cases, moisten the inside of 10 of them, load and shoot. See if you get any meaningful results.;)
 
John Y Cannuck said:
I'll buy that.

Reduction in case volume. Doesn't take much to make a difference, and increase pressure as well.
Click to expand...

Again the sceptic in me says if there was enough water in the case to affect volume, the powder would be wet and would burn erratically and of course velocity would be effected. But not necessarily faster or slower consistently. The sceptic says " Go test or go home!" ;)
 
The jet aircraft I worked on in the military used water/alcohol injection, this made a denser mass of air going into the jet engine on takeoff. The engine EGT or exhaust gas temperature went down during the burn but the engine had more thrust.

You might have discovered reloading rocket science. :D

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Try some bean juice next time inside the case and see if it stinks or smells bad after you pull my finger, I mean pull the trigger. :rolleyes:
 
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