Testing reloads in hot weather

J

jerrya

CGN Regular
Rating - 100%
29   0   0
Location
Calgary
New to reloading this year so I need some advice on this issue. Early this spring I developed a load for my 300 winmag using 79.5 grains of H1000 with nosler partitions. The weather was always quite cool in the single digits to maybe 12 degrees. I never had any pressure signs. I had just picked up some rl26 to try in my sons 270wsm and thought I would try using it with my 300 also.
I went to the range yesterday to try the new loads and a few of my previous loads, the temperature was about 25 c , pretty dam warm. Using the H1000 with the partitions I experienced stiffer bolt lift and slight impression from the ejector, I am assuming it might be because of the hot temps. Assumption correct?
On another note the accubonds I loaded with 80 grains of RL26 worked out real nice with no pressure signs. A fella there with a chrono let me try a round and was getting 3191'/sec. with good accuracy.
 
on a hot day I noticed my group would open up a little. I also let some 308 ammo under the sun for maybe 30 min at 30 C and I had flattened primers when I was shooting. I let my ammo in the shadow because of this.
 
H1000 is very stable (approximately .21 fps per degree F). I'm pretty surprised with your results if you believe temperature is the only factor involved.
 
Ejector mark and stiff lift - you are over max for your rifle. If a case lets go, it is not pretty.

When I develop a hunting load, I assume it will be shot in cool weather, so don't worry about hot weather. Target ammo is different, so I find a load, then test it with an extra half grain, to make sure I am not on the edge of having problems.

If you are ever in a position where you have to shoot "hot" ammo (say in a match; or a hunting trip that turned hot) there is a way to drop the pressure. Smear a film of grease on the bullet ogive area. This will drop pressure about 5,000 psi.
 
Ganderite said:
Ejector mark and stiff lift - you are over max for your rifle. If a case lets go, it is not pretty.

When I develop a hunting load, I assume it will be shot in cool weather, so don't worry about hot weather. Target ammo is different, so I find a load, then test it with an extra half grain, to make sure I am not on the edge of having problems.

If you are ever in a position where you have to shoot "hot" ammo (say in a match; or a hunting trip that turned hot) there is a way to drop the pressure. Smear a film of grease on the bullet ogive area. This will drop pressure about 5,000 psi.
Click to expand...

Leave it to Ganderite to have a solution. Glad to have your experience on here.
 
I assume this is with 180 grain bullets? 79.5 isn't too bad normally. I do 80 and don't see pressure on hot days. Did you clean the gun recently and have some oil in the chamber maybe?
 
Can you try seating the bullet out further or are you already into the lands? Adjusting the seating depth may or may not affect how well your load groups. It could get better or it could get worse but it will lower pressures.
 
hend238 said:
Can you try seating the bullet out further or are you already into the lands? Adjusting the seating depth may or may not affect how well your load groups. It could get better or it could get worse but it will lower pressures.
Click to expand...

It could actually increase pressure if you are seating close to the lands.
 
stubblejumper said:
It could actually increase pressure if you are seating close to the lands.
Click to expand...

That's why I asked if he was already into the lands in my first sentence. Pressure won't go up just because you are closer to the lands by seating further out.

Edit; If he has room to seat the bullet out further and not jam the bullet into the lands the pressure will decrease. Will it make a difference with his loads in the conditions he's speaking about? No idea.
 
Last edited:
Dake21 said:
on a hot day I noticed my group would open up a little. I also let some 308 ammo under the sun for maybe 30 min at 30 C and I had flattened primers when I was shooting. I let my ammo in the shadow because of this.
Click to expand...

I have seen many a F class competition shooter keep their ammo in a cooler on hot days in the sun. No shade on the firing line.
 
Purple shoulder said:
I assume this is with 180 grain bullets? 79.5 isn't too bad normally. I do 80 and don't see pressure on hot days. Did you clean the gun recently and have some oil in the chamber maybe?
Click to expand...

Yep, 180 grain accubonds, this is hunting rifle. I think I will leave it until cooler weather again to try that load again. Like I said it was fine earlier this spring. Rifle is cleaned after everytime out. I suppose its possible there may have been a bit of oil in then chamber, but I had fired a few rounds with the RL26 previously with no indications of a problem.
I could also seat the bullet out further as I have room I just hadn't got to that point in development.

Thanks for the suggestions
 
Last edited:
I sight my rifles in couple of days before hunting season.
A gun sighted in during 30 degree weather in July is going to give different results on a frosty morning in November when you are locking the cross-hairs on that buck.
Not that it makes a difference in most cases when your shooting at an animal the size of a barn door at 50 yards or less.
 
jerrya said:
Yep, 180 grain accubonds, this is hunting rifle. I think I will leave it until cooler weather again to try that load again. Like I said it was fine earlier this spring. Rifle is cleaned after everytime out. I suppose its possible there may have been a bit of oil in then chamber, but I had fired a few rounds with the RL26 previously with no indications of a problem.
I could also seat the bullet out further as I have room I just hadn't got to that point in development.

Thanks for the suggestions
Click to expand...

Seating the bullet closer to the lands would probably increase pressure. In a bottleneck case, seating depth does not make much difference, until you get close to the rifling.

Your load is currently too hot. It might be fine in colder weather, but if it was me, I would drop it a full grain.
 
Ganderite said:
Seating the bullet closer to the lands would probably increase pressure. In a bottleneck case, seating depth does not make much difference, until you get close to the rifling.

Your load is currently too hot. It might be fine in colder weather, but if it was me, I would drop it a full grain.
Click to expand...

Thanks for the advice, much appreciated
 
You must log in or register to reply here.
Back
Top Bottom