Powder ?

[325wsm]

I was wondering if anyone could tell me the difference between H4350 and IMR 4350. Are the burn rates different or is it just basically same thing just different company. One is available at my local gun shop and one is not. Just wondering. Thanks!!

[Dingoboyx]

But I believe they are just different companies versions of the same thing

[sourdough44]

Similar powder but use the listed data for the brand you load.

[Slamfire]

There are differences between IMR 4350 and H4350. I have yet to detect a significant difference between AA4350 and IMR 4350 with the lots of powder that I have.

In this test squence, it took a grain more H4350 to create the same velocity as IMR 4350.

Understand that powders have lot to lot variances. If I had a slow lot of IMR 4350 and a fast lot of H4350, it is possible that I would see an insignificant difference over the screens.

It is always safer to use the manufacturer’s recommendations and develop your loads from there.

M98  26"  1-10   Wilson Barrel								
	
200 gr Sierra  Match 53.0 gr H4350 wt'd WWII Cases Fed 210S OAL 3.35	30 April 98
						T=72°F	
								
Ave Vel =	2509						
Std Dev =	20							
ES =	58							
Low =	2478							
High =	2536							
N =	15							
	
200 gr Sierra  Match 54.0 gr H4350 wt'd WWII Cases Fed 210S OAL 3.35	30 April 98
		 				T=72°F	
								
Ave Vel =	2575						
Std Dev =	10							
ES =	30							
Low =	2559							
High =	2589							
N =	9							
				
								
200 gr Sierra  Match 55.0 gr H4350 wt'd WWII cases Fed 210S OAL 3.35	30 April 98
						T=72°F	
								
Ave Vel =	2612						
Std Dev =	17							
ES =	48							
Low =	2590							
High =	2638							
N =	9							
								
200 gr Sierra  Match 51.0 IMR 4350 wt'd WWII cases Fed 210S OAL 3.35	30 April 98
						T=72°F	
								
Ave Vel =	2460						
Std Dev =	22							
ES =	68							
Low =	2427							
High =	2495							
N =	10							
				
								
200 gr Sierra  Match 52.0 IMR 4350 wt'd WWII cases Fed 210S OAL 3.35	30 April 98
						T=72°F	
								
Ave Vel =	2581						
Std Dev =	78							
ES =	205							
Low =	2481							
High =	2686							
N =	10							
								
								
200 gr Sierra  Match 53.0 IMR 4350 wt'd WWII cases Fed 210S OAL 3.35	30 April 98
						T=72°F	
								
Ave Vel =	2585						
Std Dev =	36						
ES =	129							
Low =	2546					
High =	2675							
N =	10	

[SL1]

From what I understand about the sources of these two powders, they are NOT one of those situations where the same company is making one powder and selling it under two different brand names. So, differences can be greater than you would expect for lot-to-lot variations in powder from one manufacturer. Still, the INTENT was to make similar powders for similar applications.

SL1

[Jim Watson]

IMR 4350 is made in Canada.
H 4350 is made in Australia.
I am sure Hodgdon's intent was to have a powder to use in "4350" applications but the source is different and the manufacturing process is different. Load data overlaps considerably but they differ at the maximum. You might also see differences in accuracy.

But if you need that burn rate and only one brand is available, you are pretty well stuck.

[Blue Grass]

I can't tell any difference in accuracy between the IMR and AA versions. Haven't shot enough H to tell. However, as stated several times above, don't interchange powders and load data just because they have the same number.If you're using AA-4350 data, don't use H-4350 or IMR-4350 powder. I don't know if or what the difference between them is but don't experiment.Good luck.