Load development in rain

[RockyMtnMT]

We have an enclosed trailer set up for reloading that we take to the range for load development. This works great as we can work through load development and testing in one trip to the range.

So now to my question. Yesterday was a rainy day but we decided to go anyway. Things were going very well until it started raining hard. When the rain became hard I started to have pressure spikes. Could this be caused by the extreme humidity that was happening? Anybody else have this type of experience?

Steve

 

[SidecarFlip]

Why I quit going to the 'range' sometime ago (I belong to a Sportsmans club that has a range available)

I built my own range out back (with a roof over the bench) thats good for 350 yards. My reloading room is in the shop, about 100 feet from my 'range' and it's climate controlled so no issues with anything.

The RH may well have an impact on your burn rates depending on the propellant. Some propellants are more suseptcible to changes in RH (and temperature) than others are.

 

[RockyMtnMT]

Temp was not an issue but the rain became hard. Bench was covered. When rain became hard it was misty out. In all reality I am hoping that the spikes were due to throwing powder in the wet condition. Powder was RL-33.

Steve

PS

Flip, have you had spikes due to moisture?

 

[Pdvdh]

Steve,
Begin reading at around post #58 in the below Thread. Wetted brass casings can exhibit signs of increasing pressure because of the reduced friction between the exterior of the casing and the chamber of your rifle. But the pressure itself does not increase. If your cartridges had water on the exterior of the brass casings, then this is what you experienced.
Paul

http://www.longrangehunting.com/for...gression-thread-130521/index9.html#post993133

 

[RockyMtnMT]

Steve,
Begin reading at around post #58 in the below Thread. Wetted brass casings can exhibit signs of increasing pressure because of the reduced friction between the exterior of the casing and the chamber of your rifle. But the pressure itself does not increase. If your cartridges had water on the exterior of the brass casings, then this is what you experienced.
Paul

http://www.longrangehunting.com/for...gression-thread-130521/index9.html#post993133

Had 100 fps increase in vel also.

Steve

 

[Pdvdh]

Then you've got a bad chronograph or increased pressure. And if it's increased pressure, the source of increased pressure remains unknown.

 

[RockyMtnMT]

Using a magneto speed and increased case pressure signs and vel increase happened together. Just loaded a doz more in the loading room to shoot tomorrow. Hopefully don't see any strange increases. If it happen again tomorrow then the cause will be something different. For now the only thing I can come up with is moisture contamination inside the loaded round.

Was just hoping that there is another knuckle head like me that has been loading ammunition outside (covered but still outside) in a rain storm, that could confirm my suspicion of moisture causing a spike in pressure.

Steve

 

[MNbogboy]

I have had the same experience...rain/wet cartridges...all the signs; with heavy bolt lift and flattened primers....Same load before and after no signs...I have no means of pressure testing but it had me stumped...A theory was that steam pressure on the outside of the case (created by pressurizing the water) some how counter-acted the internal pressure?...I didn't know if it was imagined or not and had not heard of it before either.

The signs at that time were scary at least and I have never had the guts to try to recreate it.....My chrono is permanently housed in a semi dry "box" but dark conditions associated with rain normally may have "scewed" results so I don't recall if there was a correlation or if I even had looked for any association.

I could dig back through my records and maybe find the data/weather sheet but that was several years and maybe several thousand pages but that could take some time (probably four years ago cartridge was either .260 or .257 AI...but that is as much as I remember).

I too have a home range and its only a 200 feet to my dry shop...I too test during all conditions but always take care now to keep my ammo free from rain/snow and water drops....

Good to see that I am not totally crazy!..and maybe others will chime in and we all can learn from this...

Good shooting,
Randy

 

[Mateo]

I was just out last weekend and had something similar. I was shooting a short, fat case and my ammo was getting slightly wet from the rain and snow. (Yay, Canada) and a few would give me seemingly random pressure signs. I always get ejector marks before anything else. And I started getting those. Accuracy was still ok. I suspected the water was getting in the chamber and causing a hydrolic barrier between case and chamber wall.

 

[RockyMtnMT]

Shot yesterday and did not have the issue. So it must have had something to do with the wet conditions. I think that wet gun/ammo will show false pressure signs but not give higher vel. I think my higher pressure was due water contamination to primers or powder, causing some change in burn characteristics, creating the higher chamber pressure.

Not all was good at the range though. Figured out that my scope is not tracking correctly. Not sure how long I have been chasing that thing.

Steve

 

[Pdvdh]

Not all was good at the range though. Figured out that my scope is not tracking correctly. Not sure how long I have been chasing that thing.

Steve

I hate it when that happens. Nothing more frustrating than a scope that dies a slow death.

 

[Canadian Bushman]

I was just out last weekend and had something similar. I was shooting a short, fat case and my ammo was getting slightly wet from the rain and snow. (Yay, Canada) and a few would give me seemingly random pressure signs. I always get ejector marks before anything else. And I started getting those. Accuracy was still ok. I suspected the water was getting in the chamber and causing a hydrolic barrier between case and chamber wall.

This seems logical to me.

I read an article by eduardo abril de fontcuberta years ago where he spoke about winning the fcsa hunter class world championship.

He stated while shooting ftr in GB he learned the importance of keeping his ammo dry because a wet round would spike the pressure. He went on to state he has even seen guns blow due to wet ammo.