Home Forums Hunting & Shooting Ask The Gunwriters R17 and H4831sc Temp 'Test'

This morning it was cold outside so I did a quick test.

Rifle #1

300 WSM
63.5 grains R17
175 SMK
CCI 250

I've been shooting this load for the past 3-4 years and it's always averaged around 2960-2980 fps at temps 20-70F. Give or take.

This morning I started out with a cold rifle and both cold and warm ammo.

I shot the cold ammo first(-20F).


Then I shot the warm ammo(+80F?).



Cold ammo averaged 2900fps.

Warm ammo averaged 2980fps.

I then shot cold ammo in a warmed up gun and it averaged 2950fps.

Only 3 shots per 'test'.
I didn't test for accuracy, it was breezy and I snuck the test in while i was susposed to be feeding cows....grin

Okay, so R17(my lot# anyway) loses about 80fps from a 100 degree temperature drop.


I also had my old truck gun in the back seat so of course I had to shoot it over the Chrony.

270 WCF
58.5 grains H4831sc
135 SMK
CCI 200

That load averages about 2920-2940fps during normal temps.

It clocked 2850fps.

According to my crude test it actually appeared to lose a little more velocity than the R17 load. That really surprised me.

That is very interesting to me too. I'm wondering if all the RL powder temp sensitive talk is from the RL powders of several years ago? That's what some folks say anyway.

-20F????? Are you kidding me?

RL 17 has been good for me, I don't get down in the negatives here so my tests are limited 70-80's in the summer and the 10-20's in the winter.

Like most powders that are temp stable it did lose much until the temps got down in the high 20's and it went down from there until I was at about 60fps for the biggest spread.

Velocity loss in not linear from my testing, it will be stable over a fairly large range then give sudden drops and then stable again. Kinda weird but makes sense.

22 and 19 still show some big swings depending on the cartridge.

JG, I wonder if it isn't also lot to lot variations?

HW, pretty much what Dober and I found out a couple Winters ago as well. I think R17 lost about 40-50fps going from say 0-10F compared to 60-70F. We did do 400 yard accuracy tests and for big game hunting it wasn't anything to worry about.

Good info Sam. I've been using RL17 in a 243 and have been a little curious. I've not been all that worried, because our temps don't swing as much as yours--especially on the low side!

Good info.

I did a test a few winters back with RL22 in my 30-06 load.

moly'd 208 AMax
60gr RL22
22.5" bbl

Summer velocity (70s-80s) - 2720 fps

Spring/fall (30s-40s) - 2680 fps.

Winter (-20F ammo/rifle left out overnight) - 2620 fps.


Turned out to be about 100 fps for 100 degrees. Velocity and temp seem to correlate in fairly linear fashion.

Yep nothing to worry about, at least in the temps I hunt it.

Also lot to lot variations have a whole lot to do with reported velocity loss than some folks care to admit.

I have ran different lots and lost velocity and accuracy, but then went back in the reloading room and bumped the charge up until I got close to the same velocity and the accuracy came back as well. There was no more variation in velocity for that load in temp swings as from load from the previous lot.

The pic of the battery on the heater vent looks familiar...grin.

When I chrono in the colder temps I have to keep the the battery in my pocket and shoot quickly when I get the chrono up and ready.

Was lookin' at the weather map earlier today, it was 40 here, and -7 at Wolf Point....

Thanks Sammo.
I love 17.
Good info.
Hope I never have to test it out in -20.

SAS, the breeze did make it a little brisk...grin


Shane, oh yeah, the Chrony was already starting to lose steam after about 15 minutes.

Short cold snap, tomorrow back up into the +30's!


I'm always looking the forecast and checking out the entire state. 'Flave knows I'm a weather geek and gives me chit....grin

Dude, trust me I don't go shooting hardly ever if it's below even zero. This was just a quick test and then I warmed back up in the pickup!


Scenar had trouble with R17 and his LR cold weather yote hunting. Can't remember the details, maybe Pat will let us know.


Shane, what did you find out regarding accuracy, R22?

Sam, Accuracy has been great at temps down into the teens.

Down below zero, I couldn't tell ya......grin.

Thanks for the info, Sam...good test.

Two things...

One, anything below zero is too damn cold to be shooting in (at least for any 'precision' work (Scenarshooter to the contrary!)

Two, you should NOT have admitted to owning (and shooting) a .270...

I can see where cold weather accuracy could suffer in a string of fire if a guy shoots cold ammo in a cold gun, then as the barrel warms a bit, a round could warm in the chamber, and gain significant speed.

I remember reading that and thinking anyone crazy enough to be shooting 'yotes at -40 degrees is probably admittable under the DSM-V and can not be trusted...

Simple unifocal anecdote: i hunted the NE Sandhills this past middle of November. A short-lived blizzard followed freezing rain on Friday night and -20 degree temps followed on Saturday.

I killed a whitetail late Saturday morning at ~ 475 yards with a 284 loaded with 150-gr TTS
Xs at 2900 fps with R17, as deveoped last summer. I had a Zeiss 3-9x with the Z-Plex 600 and held just a bit high with the correct reticle at the optimum power as determined on the Zeiss website calculator (includes bullet BC, elevation, MV, etc) beforehand.

The bullet struck the buck in the chest where I held and I determined that in the future should I desire to hunt in such conditions again, I would go lie down on the couch until the feeling passed.

As to R17, it passed the test IMO.

Sam,

Thanks for the write-up of the test.

I've gotten better results from all the Alliant Reloder powders in recent years than when I first started cold-weather testing 20-some years ago. I suspect they learned something when they had to change the formulation of RL-15 for military use in the late 90's. 15 used to be really bad in cold weather, but became pretty good after the military testing.

Kinda surprised about the H4831 result, as I haven't seen that much change with any of the Extreme powders when used in typical loads--and 150's in the .270 have to be considered a typical load. One thing I'm wondering: Was the test in the same sort of light conditions as the last warm-temp chronographing you did of that load? I've seen Chronys give different results in cloudy and bright conditions.

The photo of the dashboard also looks familiar! Lately I've deen taking two new batteries when doing cold-weather testing, and switching them out for each string of shots. In between I put the cold one in my shirt pocket, inside my coat, to warm up.