temerature change and effects on rifle ammo

LD375

Handloader
May 18, 2009
1,239
3
Hi fellas, I'm just getting ready for my spring bear hunt and took the 300 win mag to the range yesterday to fine tune, here's what happened with the 180gr Nosler Partitions

Last time out was in March temp was 41 deg F
at 50yds 1.2" high and 2.5" high at 100 yds

Yesterday temp was 70 deg F
at 50yds I was hitting 2.5" high at 50yds, that's almost double, so I resighted and all is good now, I usualy sight in my rifle in the fall, but with the bear hunt in 2 weeks, I had to make adjusments,

Warmer weather does effect some powders causing more velocity and a higher POI.

Anyone else ever experience this effect in the past?

Thanks,
Lou
 

Guy Miner

Master Loader
Apr 6, 2006
16,654
1,393
Well, with that much of a shift, at that short a range, I doubt it was just a temperature & ammo thing...

Guy
 

LD375

Handloader
May 18, 2009
1,239
3
Guy Miner":1188xl4y said:
Well, with that much of a shift, at that short a range, I doubt it was just a temperature & ammo thing...

Guy

Hi Guy, all groups were in one hole, all screws etc were tight as well, clean barrel as well, I'm still shaking my head :roll:
 

Bruce Mc

Handloader
Oct 26, 2005
1,033
78
I've never had a velocity difference caused by temperature move the point of impact at normal ranges. Re 22 has been the worst variations, as much as 120 fps, but the POI never changed at 100yds. Perhaps your scope took a bump during the off season. Is your barrel free floated, temperature can change barrel pressure.
 

LD375

Handloader
May 18, 2009
1,239
3
Bruce Mc":5sa96vh6 said:
I've never had a velocity difference caused by temperature move the point of impact at normal ranges. Re 22 has been the worst variations, as much as 120 fps, but the POI never changed at 100yds. Perhaps your scope took a bump during the off season. Is your barrel free floated, temperature can change barrel pressure.

Hi Bruce, yes the barrel is totally free floated,
Lou
 
A

Anonymous

Guest
I've never had a POI shift that much...and I hunt/shoot about as wide of a temperature delta as people tend to. That's really quite a lot of shift- something like 3MOA.
 

DrMike

Ballistician
Nov 8, 2006
35,235
1,811
That is a significant shift, Lou. I'd be inclined to check again, at 100 yards if possible. Sounds more like a problem with scope and/or pressure on the stock than any velocity variation.
 

Ridgerunner665

Handloader
Oct 28, 2008
2,441
46
Yep.... My money is on stock issues.... If its synthetic, loose fit in the action area and/or a pressure point in the barrel channel.

If its wood... Just the usual shift with temp/humidity swings.

Possibly parallax in the scope too I reckon... How consistent is your cheek weld?
 

LD375

Handloader
May 18, 2009
1,239
3
DrMike":19ayon8n said:
That is a significant shift, Lou. I'd be inclined to check again, at 100 yards if possible. Sounds more like a problem with scope and/or pressure on the stock than any velocity variation.

I'll have to re check again this weekend Mike, could of been me or something, aside from that, the rifle is shooting the same as before just 1-1/12" higher, mind you back in March temp was 5 degrees Celsius, yesterday was 22 degrees Celsius, maybe my ammo is temp sensitive, I'll go back to the range this weekend to confirm,

Thanks fellas,
Lou
 

LD375

Handloader
May 18, 2009
1,239
3
Ridgerunner665":4mcg9zsb said:
Yep.... My money is on stock issues.... If its synthetic, loose fit in the action area and/or a pressure point in the barrel channel.

If its wood... Just the usual shift with temp/humidity swings.

Possibly parallax in the scope too I reckon... How consistent is your cheek weld?

Going to try again this weekend, I never sight in my rifles in warm/hot weather, because I always hunt in cooler weather, the rifle is a tack driver, so to rule things out, it's gotta be either temperature sensitive ammo, and or my LOP with just a T-shirt on, I have a slip on recoil pad that I'm going to use this weekend to simulate me holding/ shooting the rifle just like I was wearing my hunting outfit, It's not the rifle for sure, my bet goes on the ammo and or cheek weld with the shorter LOP while wearing just a T-shirt, I'll keep you posted with some pics of my groups @100yds while using the slip on pad to increase my length of pull, I'm confident all well pan out for sure (y)

Lou :wink:
 

JD338

Range Officer
Staff member
Nov 4, 2004
21,900
1,339
Lou,

I agree with the others that it's more of an issue with the stock.

JD338
 

BretN

Handloader
Jan 22, 2015
569
0
If it's the Tikka in your signature line, I'd be very surprised if it was your stock causing the issue, unless you recently took it apart and maybe didn't get it put back together right. Those Tikkas, both wood and synthetic are free floated to the extreme side. Also, both wood and synthetic stocks are stiff, such that you won't get the stock to touch the barrel without a lot of force.

What type of scope and mounts are you using? I recently had a 15 year old Leupold repaired by their techs because it wasn't holding zero. Left to right was ok, but it would shift 6-8" at 100 yards. Only problem I've ever had with a Leupold, and they fixed it like new.
 

LD375

Handloader
May 18, 2009
1,239
3
BretN":1fadfr5s said:
If it's the Tikka in your signature line, I'd be very surprised if it was your stock causing the issue, unless you recently took it apart and maybe didn't get it put back together right. Those Tikkas, both wood and synthetic are free floated to the extreme side. Also, both wood and synthetic stocks are stiff, such that you won't get the stock to touch the barrel without a lot of force.

What type of scope and mounts are you using? I recently had a 15 year old Leupold repaired by their techs because it wasn't holding zero. Left to right was ok, but it would shift 6-8" at 100 yards. Only problem I've ever had with a Leupold, and they fixed it like new.

Hi Bret, here's my rifle, custom stock from my buddy in Montana, along with aluminum bolt shroud, and stainless steel recoil lug, groups under 3/4" @100yds, I'm with you, it's not the rifle and or scope.
Lou :)

 

LD375

Handloader
May 18, 2009
1,239
3
I also spoke with John from Federal Premium today, and he agreed with me, there ammunition is made for accuracy, and YES is temperature sensitive, I'm most likely doing close to 100fps or more now than back in March, I'm most likely pushing close to 3100 fps in this heat, either way, going back to the range just to do my final adjustments, thanks again fellas,

Picky Lou :wink:
 

BretN

Handloader
Jan 22, 2015
569
0
That's a nice looking rig Lou. Good luck with your hunt. Did you get the stock and shroud from the Tikka performance/mountain tactical guys? I like the stock. Is it free floated as much as a Tikka standard stock? Thanks
 

LD375

Handloader
May 18, 2009
1,239
3
BretN":lrgh9psk said:
That's a nice looking rig Lou. Good luck with your hunt. Did you get the stock and shroud from the Tikka performance/mountain tactical guys? I like the stock. Is it free floated as much as a Tikka standard stock? Thanks

Thanks Bret, yes I got the stock as a birthday gift from my wife :) from Jason and his wife Lynn from mountain tactical, very nice people for sure, I also added the aluminum bottom metal, but I got that from here via atlas works, yes the barrel channel is totally free floating for a great drop in fit, the same if not better than the original factory walnut stock, also mountain tactical stock come equipped with a 1" limbsaver recoil pad, and stainless steel recoil lug as well, hope this helps you :grin:

Lou (y)
 

SJB358

Ballistician
Dec 24, 2006
31,355
658
That's a great looking rifle for sure Lou. Those pictures never hurt the eyes.
 

LD375

Handloader
May 18, 2009
1,239
3
Thanks guys :grin: ..I'm going to re sight my rifle in for this hunt, maybe 100yd max based on this hunt, here's a pic of a nice bruin coming to my bait, he's not very big, but seems to be in good shape though,
Lou (y)
 

DrMike

Ballistician
Nov 8, 2006
35,235
1,811
He looks a lot like a massive helping of brats! Yeah, he would taste very good.
 
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