300 Win Mag??? Weird Shooting Chrony Master F1 8.8:8.8 reading

bluedog69

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So just took a few shots with buddies 300 Win Mag. Factory Winchester 180's
gave about a 3010 average. (2 shots 3001 and 3022)

My handloads with Sierra 180 SBT gamekings, 72 gr of H4831, CCI LRM primer, COL 3.360 to fit in Mag(NEVER found lands even with bullet barely in case) gave a
readings of 2752, 2732, 2756 and 2798.

Shots were in this order 2752, 2732, 2756 handloads
then 2 factories 3001, 3022,
then handload 2798.

It is 90 degrees out and we were in the sun. Took gun and shells out of AC house and shot off deck.

QUESTION 1) Will this extreme heat(sun) raise FPS as the gun and shells get warmed up in the sun?

QUESTION 2) The last two shots 3022 factory and 2798 hand load the chrony screen displayed 8.8:8.8.
I shut it off and just for a split second it said 3022 then shut off? Then I took the handload
shot and 8.8:8.8 again. Shut it off and it read 2798 for about 1 second then shut off?
Anyone ever seen this displayed? 8.8:8.8? Chrony in sun getting too hot? All I have ever seen
in low light is err1 and err2 readings.


So far I am not very happy. 2" four shot factory ammo group and the same with my handloads. This is a new
TC Venture with a 4-16x44 Diamond back tacticial FFP Vortex. Gonna try cleaning it good.

QUESTION 3) Should I jump to 73 gr of H4831? No pressure signs, no sticky bolt lift etc. Was kind shocked to see
2750 ish on handloads and 3010 ish on factory El Cheepo Win ammo. 270 FPS difference on first 3 handloads and factory shots.

Any suggestions?
 

bsnyder

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colorado
I would check actions screws as the tc I’ve been around seem to always work loose. As far as the chronograph goes I’m no help as I know nothing about that one.
 

bluedog69

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I would check actions screws as the tc I’ve been around seem to always work loose. As far as the chronograph goes I’m no help as I know nothing about that one.
You mean screws attaching stock to action? Just make sure tight? Or certain ft lbs?
 

bluedog69

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Anybody have any data on Sierra 180 SBT in 300 Win Mag? I think H4831 and maybe H 4350 and IMR 4350 are all I have. Maybe some RL. H1000 is all gone I think.
 

baldhunter

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This was a kinda mild load around 3000fps with a 180gr Sierra Boat Tail but it shot really well.
200YD GROUP 001.JPG
 

Dmagna

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Your handloads with a 180 should be going 3000-3100 easy. I shoot 215s at 3000 in my win.

Keep adding powder till you reach pressure. Also that’s not good if you haven’t found the lands, try a longer bullet just to see where they are
 

Mike Matteson

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Jun 26, 2017
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Be careful some IMR powders reaction to temperature change. You can go to Hodgdon and get a down load on powder temperature extremes. It doesn't show all powder, but it helps a lot.
 

Alberta Wexit

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Mayerthorpe Alberta
Being from Canada and have some real temperature swings I try to always build reloads in warmer weather if possible. I will always try the loads at 75-85 F and look for pressure signs if they pass this test they will be fine for my normal hunting temperatures. Never had any real issue with IMR powders. I know there are probably better powders than what I used 30 or 40 years ago when a lots of my loads were developed.
 

Mike Matteson

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Being from Canada and have some real temperature swings I try to always build reloads in warmer weather if possible. I will always try the loads at 75-85 F and look for pressure signs if they pass this test they will be fine for my normal hunting temperatures. Never had any real issue with IMR powders. I know there are probably better powders than what I used 30 or 40 years ago when a lots of my loads were developed.
When I was using IMR powders(4831 & 4350). I develop load in the late winter in Mex lifornia. I had great accuracies and velocities with them. I below a primer out of the case in my rifle, had to work on getting the bolt to open. The 2 powder are double based powders, and that not a good mix for hot and cold weather. I hunt in the temperature range from 100+ to -20 below. Being you are in Canada, I don't know what your highest temp is, but I bet it gets plenty cold. Attached it Hodgdon Extreme Powder chart.
You might want to chronographs your loads in the hot weather and coldest weather to compare the difference in velocity if any. You might be surprised.
 

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