The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old May 24, 2006, 12:33 PM   #1
Clayfish
Senior Member
 
Join Date: May 19, 2005
Location: Valdosta, GA
Posts: 953
Heat sensitive H4895?

Ok, so I've worked up an ultra accurate load for my savage 10fp using 25.5g of H4895 under a 68gr match hpbt with a cci small rifle primer, winchester case. I worked these up when it was cooler and had no pressure signs. Now that the weather is getting hot here in S. GA (last weekend was 95 degrees) I'm getting blown primers. No other signs of pressure just a firing pin sized hole in the primer. How heat sensitive is H4895? I'm going to back off just a bit to see if I can still get the accuracy without the primer problems. What do you guys think?
Clayfish is offline  
Old May 24, 2006, 02:54 PM   #2
djl4570
Junior Member
 
Join Date: May 22, 2006
Location: Northern California
Posts: 9
The modern "Extreme" line of Hodgdon powders are less sensitive than others I have used. I don't have much experience with H4895 but I have loaded a fair amount of Varget and IMR4064. I found 4064 to be more heat sensitive than Varget but neither were as heat sensitive as AA2520.

If your load is at the edge of maximum pressure then even mild heat sensitivity could push your loads over the edge. You didn't say which cartridge but I am going to assume .223 Remington which puts your load about half a grain over the max listed in Hodgdon #27.
djl4570 is offline  
Old May 24, 2006, 04:14 PM   #3
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,175
Caution!

Edit: Lengthy diatribe about .308 low pressure loads removed for irrelevance.

Nick
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member

Last edited by Unclenick; May 24, 2006 at 07:20 PM.
Unclenick is offline  
Old May 24, 2006, 06:01 PM   #4
Jim Watson
Senior Member
 
Join Date: October 25, 2001
Location: Alabama
Posts: 10,840
Uh, Nick, I think he's shooting a .223.
Something about "a 68gr match hpbt with a cci small rifle primer"
But he should have said so.

In 1964 Hodgdon said of 4895 (then army surplus made by DuPont)
"Reduced loads, as little as 3/5 of maximum, still give target accuracy."
Jim Watson is online now  
Old May 24, 2006, 06:31 PM   #5
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,175
Jim,

Well, look at that: I wrote a solution in search of a problem. I looked at "68" and read "168". That coupled with my 10FP being in .308 and . . . I think that's the sound of gas escaping my brain. I always forget that Hornady makes their match bullet in 68 grains instead of the more usual 69 grains.

Well, this is a horse of a different color. In the Winchester case this .223 load this is about 104% full and thus is highly compressed. It will run about 2500 PSI over SAMMI max, according to QuickLOAD, so the temperature change can indeed spell trouble. The Hodgdon Extreme powders are not totally immune to temperature change and are not as good as some of the Vihtavuori powder, if I recall correctly? The details are in this Denton Bramwell article.

Thanks for catching my blunder. And yes, 3/5 (60%) is still what they stick to, even in the Extreme series variant of 4895. At least, that is what their tech said today. Nothing about accuracy; just that it is a minimum.

Nick
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member

Last edited by Unclenick; May 25, 2006 at 09:49 AM.
Unclenick is offline  
Old May 24, 2006, 09:50 PM   #6
Clayfish
Senior Member
 
Join Date: May 19, 2005
Location: Valdosta, GA
Posts: 953
Thanks guys. Sorry I didn't make myself clear that I was shooting a .223.
Clayfish is offline  
Old May 25, 2006, 09:57 AM   #7
30Cal
Senior Member
 
Join Date: December 3, 2002
Posts: 1,093
Is H4895 one of the "extreme" powders? I know it's been around for a while and I would expect to see a fair increase in pressure with temperature. Not as bad as ball powder, but certainly some. Varget is very good in this respect.

Ty
30Cal is offline  
Old May 25, 2006, 11:34 AM   #8
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,175
Yes, H prefix stick powders are now all in the "Extreme" series, I believe. Made in Australia employing proprietary methods of that reduce temperature sensitivity over their IMR equivalents - at least, that's the claim. Check out the Bramwell article I linked to above.

Nick
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member
Unclenick is offline  
Old May 26, 2006, 09:08 PM   #9
P-990
Senior Member
 
Join Date: May 2, 2002
Location: Only1/2WayThere
Posts: 1,051
H4895 is temperature sensitive, in my experience. I noticed major accuracy changes in my batch, tossing 77 and 80gr .223s through my AR-15. On a cool day, it would hammer. Warm up and I noticed a drop off in X-count.

It is not nearly as tempermental as say, Winchester 748 ball powder, but it is less stable than Varget, IMO. I've left Varget in a car trunk for 8 hours before shooting it in the evening (accidently, I assure you) and noticed no difference in on target performance at practice. X-count was right where it normally is.
__________________
NRA Master, Highpower Rifle, Across-the-Course
NRA Expert, Highpower Rifle, Mid-Range Prone
P-990 is offline  
Old May 26, 2006, 09:15 PM   #10
Ruger4570
Senior Member
 
Join Date: April 3, 2005
Location: Rochester, New York
Posts: 2,136
If your loads are riding the safety "edge" I sure wouldn't count on Hogdons claim of not being effected by heat. If you are getting pressure signs, what does that tell you?
Ruger4570 is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:39 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.08253 seconds with 7 queries