H4350 lot variations to temps?

[BsChoy]

I ran a bunch of 180 nosler partitions in my 30-06 over the chrono a little while back when it was cooler out and got an average of 2690 fps with 55.0 grains. Went out with some new loaded rounds from a new lb of the same make powder and all components the same and got 100fps slower in warmer weather? Anyone seeing any temp swings in their H4350 lately?

 

[rcmodel]

Seems very unusual it would get slower in warm weather.

All I have ever experienced is just the opposite, with any powder.

rcmodel

 

[MMCSRET]

Some of the Hodgdon line of powders are identified as extreme and are less affected by temp change. I don't remember if H4350 is one of them, give it a check, may help i.d. the difference.

 

[taliv]

maybe you were shooting the same brass and it was new when you shot the first can and once-fired when you shot the second can of powder?

 

[Ifishsum]

H4350 is in the "Extreme" line if it was purchased in the last few years. I have not found it to be temperature sensitive, but all powders can certainly vary from lot to lot. Differences in brass as Taliv mentioned can also make a difference.

 

[Slamfire]

All powders vary by lot to lot. Powder manufacturers blend different burn rate stocks in an attempt to deliever a uniform product to us civilians. I heard from Accurate Arms that the industry standard was 10% variation per lot.

This is also why you cannot exactly duplicate factory ammunition. When factories buy powder, they do not buy blended powder. They buy about 90,000 lbs at a wack, and with that lot comes the burn rate characteristics. They load up some ammo, run it through their pressure guns, adjust if necessary, and load up a gazzillion rounds and sell the stuff. Either to the military, or to us!

 

[BsChoy]

Update***

I handweighed 5 rounds with the same recipe as above (55.0 of H4350) and put them into 1.1 inches at 100! I think my Pact did throw some low weights so I am going to pull the bullets on the remaining rounds and start over. Average speed was 2633 btw.

 

[Zak Smith]

My .260 REM load using H4350 changed less than 10 fps from about 10F to 90F.

 

[BsChoy]

I was hoping you'd chime in Zak. I was picking H4350 for the 30-06 cuz sooo many guys seem to use it with awesome results. I have read alot of the articles you have penned and take what you suggest with a great deal of confidence. Thanks fella's I'm off to pull bullets and weigh charges!

 

[Clark]

I bought 8 pounds of H4350 and used some of it Friday.

Honady bullets were within 0.3% weight.
Honady bullets were within 0.1% diameter.
New Win 243Win brass was within 0.6% in OD at the extractor groove.
New Win 243Win brass was within 0.5% in ID of primer pocket
New Win 243Win brass was within 12.0% of PMC weight
I cannot measure brass hardness directly at this time.
I cannot measure H4350 grain size accurately at this time.

I found the threshold of any change in the brass was at 45 gr.
Vernon Speer in 1956 said to reduce the powder charge from there by 6%.
Vernon would then want to use 42.3 gr. [I actually used 43 gr and averaged 2975 fps, becuase I take chances]

I looked in the Sierra load book for 243, 100 gr IMR4350, for data taken 40 or 50 years ago, but it is where I always wind up anyway.
That book says 42.3 gr 3000 fps.


I must add up the above errors and split the remaining error between my unknowns:
1) H4350 canister blend accuracy
2) Win brass hardness accuracy

Oh wait, there is no error

Does that mean that H4350 has no canister blend error?
No.
It means that it is so accurate that the error is down in the noise.

What powder does have errors?
I bought 8 pound jugs of surplus IMR4895 from Hi-Tech.
It is bulk powder, and gives pressure and velocity results more like H322.
That is a 7.7% error.
That is not down in the noise.
That is the trouble that bulk powder has, to offset it's low cost.


What does it all mean?
AA can say canister powder varies by 10%.
AA can say a bag of dirt varies by 100%.
Real canister powder is better than that.

 

[BsChoy]

So if I'm correct Clark you are saying that not to worry about cannister powder cuz it's sooooo accurate there is no fluctuation worth a closer look

 

[Slamfire]

I found the threshold of any change in the brass was at 45 gr.
Vernon Speer in 1956 said to reduce the powder charge from there by 6%.
Vernon would then want to use 42.3 gr. [I actually used 43 gr and averaged 2975 fps, becuase I take chances]

I looked in the Sierra load book for 243, 100 gr IMR4350, for data taken 40 or 50 years ago, but it is where I always wind up anyway.
That book says 42.3 gr 3000 fps.

Go buy a lotto ticket, because you have the luck. Copying a 50 year old load, shooting it in your gun, and you get the exact same velocity as someone else did, in a different gun, is luck.

Does that mean that H4350 has no canister blend error?
No.
It means that it is so accurate that the error is down in the noise.

I have blown enough primers, where the only known change was a lot number, and I have shot enough bullets over my chronographs that I believe I have seen differences in powder lots.

What does it all mean?
AA can say canister powder varies by 10%.
AA can say a bag of dirt varies by 100%.
Real canister powder is better than that.

Of course I could be mis quoting AA, maybe I heard wrong. But Accurate Arms has a calibration lab, which calibrates their barrels, pressure gages, and chronographs. They will measure things that a guy with a rifle and an off the shelf chonograph will never see.