Rain affect on load development

[Rol_P]

Thursday was a sunny pleasant day so I took my Montana rifle in 30-06 to the range for a little load development. My handload, which I used successfully in my Remington 700 CDL in 2013 to take a nice elk and mule deer is New Nosler cases, WLR primer, 61.0 gr Reloder 22 and a Nosler 180gr AccuBond set at 2.702" cartridge base to bullet ogive. I was confident when the average for 2 three shot groups @ 200yds was just under MOA.

Then I loaded the same load, the only difference being sized once fired Nosler cases in place of the New cases. I measured some new Nosler cases for base to shoulder dimension then sized my once fired cases to match the new as close as possible. I also vigorously cleaned the barrel before heading to NYDan's this morning in the rain and 60 degree temperature. No wind to speak of. My MOA group expanded to 4.38" @ 200yds. The first shot was 3" high @ 1:00, shots 2 & 3 were inside a 2" square bullseye, shots 4, 5 and 6 were scattered high right and left.

Four factors that I can think of may be causing the disparity from last Thursday's good results:
1... Me
2... Rain
3... Clean barrel
4... Once fired cases vs new.

We did try some Federal Factory 180 Accubonds in the rifle @ 200 yds, first group was 5 shots = 3.117", after a scope adjustment 3 shots = 2.07", so that indicates my ability was on par with Thursday's shooting.

We also moved the target back to 400 yds for giggles and my first three shot group was 5.21" from a bench. Second target was not so good as I forgot to use the 400 yd hash mark on my lower reticle at least once.

The plan is to hunt elk with this rifle in Montana starting Oct. 24th so I need to get load development behind me and practice shooting from field positions.

Any thoughts and/or observations that may help me improve my performance? All suggestions will be most appreciated. Thanks in advance. Rol

 

[NYDAN]

As a point of observation, it seemed to me that it was raining harder when Rol_P shot the larger size groups and it was raining less hard when he shot the better groups.

Does anyone know for sure whether or not rain drops deflect bullets when shooting at 200 and 400 yards? It seems to me that shooting in the rain is different that shooting in the snow and that rain could cause a bullet to deflect.

Dan

 

[cloverleaf]

Unless you've ruled out a clean barrel as a cause, I'd shoot again. Rain is pretty much a non issue in terms of accuracy unless it affects vision of the target, or so Im told..... My rifle has a small window for "accurate" shots fired. Definitely not the first three, for me. Couple that with operator error and you know why I call my rifle "Aggie" (short for aggravation) .CL

 

[DrMike]

The mass and velocity of raindrops relative to the mass and velocity of the projectile is negligible. Barometric pressure, wind speed can affect accuracy, however.

 

[SJB358]

I'd reshoot on the dirty barrel keeping brass the same. Never seen rain affect shots for the rifle but it is miserable for me! :lol:

 

[Rol_P]

Thanks for the insights fellas. I neglected to mention in the original post that I was shooting from the dry comfort of NYDan's garage.. So we only got a little wet when changing targets or moving the backstop.

Dan has a neat "sand box" to play in.. It is about 3'wide, 2'high and nearly 4'deep made of plywood supported on 2x10 boards on the sides so that he can get the fork lift on his tractor under it to move to different ranges in his field and bring it back to the barn to keep it covered when finished. He recovered a few 180 Accubonds from the sand yesterday.

 

[Wyo7200]

This is along shot, but what was the temperature of when you shot the first group in 2013? I'm working on a thing with reloder powders that is interesting. I was going to type it up tonite and share it in the quickload questions thread. I've nailed down the R25 and R17 sensitivity- my r22 will always be shot in cold weather so it's development was done at 30*. About to do r15. If it's anything like I'm seeing here, it's difference of temperatures of when the load was developed.

 

[NYDAN]

Dan has a neat "sand box" to play in.. It is about 3'wide, 2'high and nearly 4'deep made of plywood supported on 2x10 boards on the sides so that he can get the fork lift on his tractor under it to move to different ranges in his field and bring it back to the barn to keep it covered when finished. He recovered a few 180 Accubonds from the sand yesterday.

The "neat sand box" actually came for Rol_P. He provided the wooden box and boards, helped cut the box down to size, and helped assemble the finished product. We filled it with very sandy and wet top soil and stapled the targets on it.

I was surprised at how effective it was at stopping those 180 gr. AB's. The mushrooms were picture perfect. Most were over twice the original diameter.

 

[Whitesheep]

When I experience a different outcome from the same load at a later date I generally assign it to "a bad day at the range" which means I am troubled by my personal inconsistency. (When I can I blame it on the wind, but my friend and coach rarely lets me get away with it :x )

I believe Wyo7200 as a very valid point about temperature sensitivity of powder. That being said I would expect the POI to change with temperature and humidity, but not the group size. What am I missing here?

The best answer is to only keep records of good range days and discard targets you don't like. Just kidding as I am still searching for the better consistency if not better excuses. :mrgreen:

 

[SJB358]

When I experience a different outcome from the same load at a later date I generally assign it to "a bad day at the range" which means I am troubled by my personal inconsistency. (When I can I blame it on the wind, but my friend and coach rarely lets me get away with it :x )

I believe Wyo7200 as a very valid point about temperature sensitivity of powder. That being said I would expect the POI to change with temperature and humidity, but not the group size. What am I missing here?

The best answer is to only keep records of good range days and discard targets you don't like. Just kidding as I am still searching for the better consistency if not better excuses. :mrgreen:

I like the way you do business... We may have to write this out, make it a sticky and make it Nosler SOP! :lol:

 

[lhsako]

Unless you've ruled out a clean barrel as a cause, I'd shoot again. Rain is pretty much a non issue in terms of accuracy unless it affects vision of the target, or so Im told..... My rifle has a small window for "accurate" shots fired. Definitely not the first three, for me. Couple that with operator error and you know why I call my rifle "Aggie" (short for aggravation) .CL

>> small window for me as well w/ some rifles. usually the 2nd thru 6-7th shots out of a clean, cold barrel, after 2 fouling shots. btw, I use brass that I'm ready to pitch and bullets that have proven less than accurate at staring load levels to foul the bore. save $$$$.
I'd shoot again before I gave up on the load.

 

[Rol_P]

I am doing a seating depth check. Started this morning with loads that were set deeper than those used in the rain.. Seems deeper gives a tighter group. Suspended testing when company arrived at the range. Will resume I the morning weather permitting.

 

[Horsethief]

Unless you've ruled out a clean barrel as a cause, I'd shoot again. Rain is pretty much a non issue in terms of accuracy unless it affects vision of the target, or so Im told..... My rifle has a small window for "accurate" shots fired. Definitely not the first three, for me. Couple that with operator error and you know why I call my rifle "Aggie" (short for aggravation) .CL

An overly clean barrel and low visibility at long range (and I know that is a relative term) means shot groups can grow easily. Shoot again on a clear day with less cleaning of the barrel.

 

[DON]

I can tell you from my experience, shooting my 300 RUM, that I did have my groups open up shooting in the rain at 100 yards. I do believe the rain did affect the outcome as it was raining pretty hard. Shot just to see what would happen. Shot again later on another day, no rain, same load similar temperature, the groups were tight again!

My 300 RUM seems to group tighter with once fired brass verses new for some reason, even though I full length re-size the new brass.

As earlier suggested, I wouldn't freak out, just re-shoot on another day under normal conditions similar to when you shot those good groups. Also we all have had just a bad day at the range :shock: It will drive you crazy, puts you on a mission thinking something is drastically wrong when nothing is, only to find I had to much coffee prior to time behind the gun :wink:

Don