Any downfalls to load testing in the cold?

[DWFAN]

Im new to rifle loading, and have 125 test rounds to try. i dont see any temps above 38f any time soon. Is testing in the cold a waste of time or are there any other issuez i should be aware of?

im loading for my JPCTR02 with Reloader 15..

[HS101]

Just be aware of how the temp will affect velocity... A little searching looks like it will slow down in the cold. Try it, just be prepared to adjust the load in the summer heat.

[outerlimits]

Perhaps more important to the trajectory is the air density

[Corey]

go ahead and test them out now and get a good idea of where you want to be, then a quick range trip when the weather turns around will allow you to fine tune anything and you'll be ready to rock and roll.

[mscott]

Just keep in mind that a load which appears safe at 30 degrees may be too hot at 80 degrees. I've noted a 100fps swing using H335 and BL-C2 powders.

Edited December 14, 2010 by mscott

[DWFAN]

The wind has died down, so atleast ill be able to see if it groups or not. thanks, just didnt want to waste my time and body temp.. hahaa..

[DWFAN]

Just keep in mind that a load which appears safe at 30 degrees may be too hot at 80 degrees. I've noted a 100fps swing using H335 and BL-C2 powders.

If the load i go with is one close to max ill keep that in mind and chrono more as spring approachez.

[caz41]

Are you testing for FPS or grouping or both?

[DWFAN]

Are you testing for FPS or grouping or both?

Mainly group, but will be chronoing to verify whats going on.

[Ken Kwiat]

Really all depends how anal you want to be.

Not Anal response: Yes, you will generally measure lower velocities. But, keep good data (I always record my chrono data, temp, altitude, and DensityAltitude which is the magic composite of "air density" that most LR shooters use). If you don't have a way to measure DensityAltitude (as with a Kestrel), it's good to have at least the temp + a guestimate of humidity. I don't think you'll get horrible variations in velocity -- maybe 40-50 fps vs. a typical summer day but it'll also depend on what powder you're using. Note: OK, others are saying more variation; could be as I'm saying this w/o consulting my range log. Might your winter zero change slightly from your summer zero? Sure, but I assume you'll be re-checking zeros often. I check zeros every other range session or so -- stuff changes, it's a great diagnostic check.

Moderately Anal: If you want a bit more definitive data, run some numbers yourself to see if the velocity drops will affect your application. It would be about a two minute test using JBM's ballistic calculator or similar. Note: I tried to do it and post some results but it appears JBM's website has been hacked or something. Most ballistic calculators take into the account the DensAlt for zero/chrono vs. the particular target conditions that you are creating the dope table for. For example, you enter DensAlt (or altitude, temp...) for zero/chrono and then a separate DensAlt for conditions that you want the trajectory/wind dope sheet/card for. My gut tells me that maybe you'll see a .1-.2 mil (.36-.72") shift downward at 100 yds.

Very Anal: the above scratches the surface at best.

That's why you really have to ask for your intended application, e.g., standard 3-gun shooter requiring 1 MOAish accuracy across a wide range of temp or DensAlt ranges and shooting 300 yds and in? I do load development in the winter often. Sure, I'm re-checking velocities as the temps rise -- moreso for LR application though. As long as the velocity drops are consistent across your sample, i.e., your standard deviation doesn't rise dramatically, your groups should be unaffected.

[DWFAN]

Thanks for the replies guys. My Chrono numbers are pretty close to what the book says I should get. Found some really good loads in the 5 bullets I tested. I also pulled a few shots which hurts to see how tight the groups are.

These were the top two with 69 and 77 SMK.

Also had some really tight groups with 60gr VMAX.

The 75 and 68gr Hornady BTHP werent as good, but those were the first ones down range, and i think I settled in and just was shooting the other's better, so I'll test them again another day.

I did all my testing just from the bi-pod and no rear bag through an 18inch 1:8 bbl.

Here are some results.

Powder Primer grains bullet weight temp AVG Stdev group

RL15 CCI400 23 Sierra MK 77 30 2567 19.7041 0.715

RL15 CCI400 25.5 Sierra MK 69 30 2839 26.8924 0.735

RL15 CCI400 26.5 Hdy Vmax 60 30 2946 41.5151 0.96

RL15 CCI400 24.5 Sierra MK 77 30 2664 26.5000 0.96

RL15 CCI400 24 Sierra MK 69 30 2640 22.1133 0.965

[outerlimits]

Suggest you check groups at 200 yds or more-that's when things matter.100 yds means nothing.

[DWFAN]

I agree. My range has a 200 yard line and thats the next stop to test quite a few more rounds and dial in my scope.

[RBros]

RL15 is pretty temp sensitive. Just be careful as Summer approaches or the chamber gets to hot. It will spike very quickly

[R-Bros_JLR]

Another thought is to give TAC a try with those 77s. I've had pretty good luck running around 23.5gr and get 2750+ out of my 20" WOA 1:7. It doesn't seem to be as temperature sensitive as RL15 is.

Edited December 22, 2010 by R-Bros_JLR

[Joe4d]

The biggest downfall I have found testing in the cold,,, is......ITS FRIKKING COLD ! COLD SUCKS! COLD WIND SUCKS EVEN MORE !

[DWFAN]

The biggest downfall I have found testing in the cold,,, is......ITS FRIKKING COLD ! COLD SUCKS! COLD WIND SUCKS EVEN MORE !

HA! Yep, it was, but luckily for once, the wind wasnt blowing.

Ive read mixed reports about the R15 in the last year or two about being Temp sensitive. I guess I'll find out. I picked up a 5lb jug today at Grafs and Santa may be bringing me some saturday also.

I cant find any TAC anywhere locally, but DARN.. I was at GRAF's today and didnt ask. Online they show 1 lb bottles in stock.