Thread: Test load temps

Hi all, I'm out to do some more load development tomorow.

I have read allot about preassure spikes with warm loads and being winter I was thinking of warming up my loads in a chilly bin with a hot water bottle to try to simulate summer which is when I do most of my shooting (I enjoy thos long summer days spotting and destroying hares).

What sort of temp would you guys be aiming for? I did a bit of googling and found measured temps in sumer are all over the place some as high as 42 down south, we don't get that high up here but we probably see mid to low 30s occasionally, this would be in direct sunlight mid day. Would you recomend warming the loads that much or just work on more of an average temp of like 25 ?

What sort of temps do you do most of your load development at?

Cheers all.

I would guess a average would be ok. It also depends on how close your going to keep your load to any pressure signs.
If you keep a bit below pressure signs, when summer rolls around I doubt your going to blow yourself up. But if it's your load for your rifle and your the one shooting it, just remember to monitor cases for pressure as the temps heat up. Think of it as a unfinished load until summer has passed.
I wouldn't give the load to a friend or learner who won't keep pressure in mind, at least until proven.
What caliber are you shooting?

6.5x55 with 140gr sst for know, cheers man.

I want to be below pressure signs I was just worried if I loaded up with the current temps when summer rolled around I don't want to have to rework the load to get back under pressure signs, what you have suggested sounds about right to me just thought I would see what others are doing. I'm the only one shooting this rifle but you can't tell what the pressure is doing till after the shot.

I hear ya, I try to mostly do loads in summer, the heat and less busy.
I have done one or two in the winter, the load has been up there but not maxing out and it was fine. It wasn't a super duper long range gun so I wasn't too worried.
6.5 should be a pretty mean hare rifle, good times.

Every powder is different, some powders get "hotter" as temps cool which is the opposite of conventional thinking.
Do some googling of the temp sensitivity of the powder you are using and then test for yourself.
Unless you are right on maximum or using some very temp sensitive powder you really shouldn't see big differences in NZ climate.
Even if you said average 5 degc winter and 25deg summer that is still only a 20 deg spread.

Originally Posted by veitnamcam

Every powder is different, some powders get "hotter" as temps cool which is the opposite of conventional thinking.
Do some googling of the temp sensitivity of the powder you are using and then test for yourself.
Unless you are right on maximum or using some very temp sensitive powder you really shouldn't see big differences in NZ climate.
Even if you said average 5 degc winter and 25deg summer that is still only a 20 deg spread.

I didn't think about that, too spoilt using adi powders which I believe are mostly pretty good with temp changes.

I think VNcam is on the right track. Most of the internet drama's about temp sensitive powder seems to come out of America. Where temps can go from -10C' up through 40C' .
If it was a real serious problem I think tins of powder would have to come with warnings about leaving the 5th fired round in the breech for too long, if you get my drift.

if you are not pushing the envelope eg 2-3grns above book max or trying for that last fps you should be fine...... a nice accurate load that is a bit below max will be better to shoot and easier on components and shooter anyway..... firing off a load and seeing primers looking like pancakes is NOT a pleasant experience,far better to find happy medium and live longer.

I ended up throwing the ammo box in a chilly bin with a hot weat sack and a thermometer, it bought the ammo up a few degrees to about 24-25 not to scientific though, it was a pretty sunny day so probably didnt need to bother.

Book max is a bit vague as its 6.5x55 and all the load data I can find is for older actions, after a lot of looking around I have found for 140gr most people are working up to a max of 47-47.5gr 2209, that was one of the things I wanted to confirm today, got very light extracted wipe at 47 and a clear wipe at 47.2 so stopped there.

I am trialing this 10 shot style of load development that's all the rage on youtube mostly just for somthing to do, results we're interesting.

My chrono may be reading a bit high not sure it's new first time out.

45.5 2716fps this was mostly just a check/test load to make sure I'm not way out or somthing
46 2784fps
46.25 2804
46.5 ERR realy wish I had this read
46.75 2826
47 2850
47.25 2848

So from that there is a flat spot in 46.25-46.75 as that's only a 22 fps jump for .5gr every other .25gr was atleast a 20 fps jump excluding the 47 and 47.25 which read the same but did have slight pressure, I may explore this if a load at 46.5 doesn't group well but I'm happy with 46.5 and if that velocity is correct I feel I'm pushing it hard enough.

So next is to load up a few rounds at 46.3, 46.5, 46.7 and see how they go for group size, as I say this is mostly an experiment, if this actually works and gets me onto a go grouping load without having to shoot lots of groups is a fair advantage, it's tricky for me to get to a decent shooting bench setup for load development and this cuts it down to one trip to confirm the final groups.

Sorry need a few more space bars in there next time to make it easier to read

Between zero degrees and 30 degrees, I get 110fps faster at the warmer temp. Also, much higher pressure. Doing load development in winter (in the snow like I did), ensure that you are very aware of the increased pressure when warmer and make suitable allowance for it.

Not sure if any body is interested in this but I went out and did some more testing today, I got an average of 2730 fps today with the rounds at 12 degrees, that gives me a velocity change of about 85 fps just with around a 12 degree temp difference.

Good to know rusl, but did that fps change induce any other pressure sign changes?
I'm sold on the OCW method now for that last grouping session.

This load was not showing pressure signs at the higher temps and none today with the lower temps, lower velocity with lower temps so I'm assuming lower preassure, cant tell though.

What are you using for a Crony ?