IMR 4895 / 80 SMK / 1:7 twist

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BobCat45

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CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

Do any of you have experience with IMR 4895 in .223 with 80 grain Sierra Match King bullets?

Been using Varget, almost out, but have plenty IMR 4895 for Garand.

Been told, "if it works in Garand, will work in AR-15" so I went looking for data.

IMR website / load data redirects to Hodgden site, says 20.0 grains min, 23.0C max for IMR 4895 / 80 grain SMK, but 1:12 twist, WIn SR primer. My barrel is 1:7 and I use CCI BR4 primers.

Sierra 5th Edition (on accurateshooter.com) lists 24.5 grains Max for 69 grain SMK, no listing for IMR 4895 for any heavier bullets, but shows 22.9 grains H4895 Max for 80 SMK. The consensus seems to be that IMR 4895 and H4895 are different enough that loads are not interchangable.

John Holliger at White Oak says (old save from his website) 22.5 - 23.2 grains of H4895 - (H not IMR).

Searched here and in this thread http://thefiringline.com/forums/showthread.php?t=442032 Unclenick says "IMR 4895 does quite well with heavy bullets, like the 80 grain match bullets" so at least I know I'm not totally barking up the wrong tree.

Decided to load 5 rounds at 22.0, 22.5, and 23.0 grains. The 23.0 was not compressed, bullet loaded long, about 0.015" from lands, longer than mag length for Slow Fire Prone.

All shot fine, no pressure signs, primer cups not flattened or corners squared at all. Cases obdurated fine. All rounds went into little knot (but only 100 yd). Happy enough, decided to load 23.0 for match.

But before I got around to that, ran into a guy at the range who is a very high-scoring shooter, reloading sage, and pretty good gunsmith. He has been shooting rifles a lot longer than I have, is even older than I am - and he didn't get that old by being stupid or careless. He tells me to start at 24 grains and work up from there. Verified bullet weight and all relevant parameters, he is adamant, start at 24, sweet spot will be near 24.5 grains. Ok.

So - other than cutting flight time / wind drift, any benefit to pushing the load higher than 23.0 grains?

I'm not here "asking permission" to exceed book maximums, just looking for opinions and any anecdotal data anyone wants to share. Looking for insight - if I knew it all, there would be no point in reading more, right?

Thanks in advance for your thoughts.
 
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I tested the 80 SMK with AA2495, which is a copy of IMR 4895. Accurate Arms told me they blend the stuff to the same pressure curve as IMR 4895. You will find that any of the 4895 powders, such as IMR 4895, H4895 or AA2495 will produce excellent groups with any of the heavy bullets (69, 75, 77, 80 grain) in the 223.

Developing loads is easy in the 223. You stop increasing the powder charge when you pierce or blow a primer. Then you cut that load by 1/2 grain. Then you continue cutting the load by 1/2 grain every time you pierce or blow a primer. Six hundred yards is a long way for a 223, even the 80 grain bullet. At that distance competitive shooters are doing everything they can to get the velocity up, because the cartridge is so wind sensitive back there.

As for powder charge differences, understand that lot to lot differences within the same powder brand is around 10%. Powder lots are blended but they can't make each blended lot exactly like all the others. So you will see discrepancies between maximum charges. This variance in powder lots is how vendors were able to hide the fact that Hp-38 and W231, and H110 and W296 were the same powders in different cans. Load manuals always showed different maximum loads, but that was only due to lot to lot variance.

Other people's load data, their barrels are different, their brass is different, their primer lot is different. Someone else's best load may blow primers in your rifle, may do nothing at all. Each rifle and load is different.

I found that velocities close to 2600 fps eventually pierced primers in my AR's. I think you will find a maximum load between 22.5 and 23.0 grains IMR 4895 with a 80 SMK. But then, maybe not.


Code: 
[SIZE="3"]
M15A2 Armalite 20" 1:8 Stainless Wilson Barrel							
11-Apr-98  T = 68 °F
		
		
80 gr Sierra Match  22.0 grs AA2495 wt'd  WCC91, WSR, OAL 2.500"		
							
Ave Vel =	2535						
Std Dev =	17						
ES =	59						
Low =	2515						
High =	2574						
N =	9						
							
80 gr Sierra Match  22.5 grs AA2495 wt'd  WCC91, WSR, OAL 2.500"		
							
Ave Vel =	2562						
Std Dev =	14						
ES =	39						
Low =	2541						
High =	2580						
N =	8						
							
80 gr Sierra Match  23.0 grs AA2495 wt'd  WCC91, WSR, OAL 2.500"		
							
Ave Vel =	2637						
Std Dev =	15						
ES =	46						
Low =	2606						
High =	2652						
N =	9						
							
							

							
80 gr Sierra Match  23.5 grs AA2495 wt'd  WCC91, WSR, OAL 2.500"		
							
Ave Vel =	2689						
Std Dev =	26						
ES =	73						
Low =	2663						
High =	2736						
N =	8	[/SIZE]
 
Thank you!

23.0 shot fine, no sign of anything questionable. I'll try 23.5 to see.

In my White Oak barreled SR 24.5 grains of Varget shoots very well at 600 - every shot that is not a 10 is me snatching at the trigger or missing the wind shift. Same load (but new brass - LC 11) shoots very well in new WO Match rifle, but I'm running out of Varget.

In the SR for standing practice I tried 24.3 -24.5 grains of IMR 4895 and bulk 55 grain IMI bullets, and it seems like a good load. Need to try it with the 69s and then work up for the 80s.

Anyway, thanks for your reply and wealth of data.
 
23 grains of IMR4895 is the Maximum load that Hodgdon lists using a COL of 2.550". They also show it compressed. Their H4895 load has a 24 grain maximum. These are in Winchester cases fired by a Winchester SR primer. So you are going up in pressure and may exceed the standard maximum pressure doing it. For that reason I added the board's required warning to your post.

I doubt that Hodgdon 12" twist barrel even stabilized the 80 grain bullets they fired in it. People complain that a 9" twist isn't consistently good with the shorter 77 grain SMK's, so the 80's would be a bad bet with 9", much less with 12".

Hodgdon and Western powders both claim to hold burn rates to ±3% these days. I know Hodgdon went through some issues with variation in the then-new Varget powder in the mid-90's. I was told they revamped their whole QC system since then, so variation from lot to lot should be tighter now than it once was. Same for the IMR powder they distribute. When I went through the old data on .30-06 National Match ammunition, I found about 14% variation in burn rate for their IMR4895, but it was bulk grade, not a blended canister grade.
 
I think that your range buddy gave you bad advice, possibly confusing Varget for IMR4895.

24.5 grains of powder under an 80gr projectile is always a pucker factor moment in my load workup for an AR. I know one High Master who swears by 24gr of Re15 under any match bullet 80gr or less (Alliant's max is 24.1gr w/ 80gr bullet) and plenty who use 24.5gr of Varget for the same purpose.

I ended up using PowerPro 2000-MR for my 75 (BTHP) and 80gr (Hornady Amax) match loads. Ended up with 24.4 gr of powder with no pressure signs or issues, using a Wolf KVB 5.56M milspec primer in LC brass. Alliant's max charge is 25.1gr under an 80gr SMK, but I didn't see any accuracy benefits over 24.4 which was an easy charge to throw through from the Lee powder measure.

That load has been used in 5.56 chambers and Wylde chambers, not in .223 chambers.

Anyways, if 23 gr of IMR4895 shoots good in your rifle, and more importantly shoots SAFE in your rifle, by all means keep shooting it. When you are hitting all the 10s except your called flyers just keep loading and shooting that load. High Power is all about getting to be a better shooter.

Jimro
 
Unclenick, thanks! Didn't mean to post anything "over the line."

Jmro, thanks too. My friend knew what powder, but he is known for spinning .223 bullets to dust just off the muzzle, shooting a .223 bolt gun at 1,000 yards.

My rifles are both Wylde chambers.

23.0 grains of IMR 4895 shot great at 100 yards, didn't take it to 600 since I was nervously looking for pressure signs, not accuracy so much. But it behaved perfectly at 100 and that's one reason I asked here - whether anyone sees any point in going higher, except modestly shorter time of flight if the velocity is modestly higher.

I need a chronograph - but it would be just one more piece of "stuff" for my wife to liquidate after I'm gone. And the proof is on the target, not necessarily in the velocity. Except I've read that approaching real maximum powder charges, velocity stops increasing while pressure starts to go wild.

I think I will shoot the 23.0 grain load at 600 and if it is good, I'll leave well enough alone.

Thanks again.
 
I had an "aha!" moment when you mentioned your friend was shooting a bolt rifle.

I have a friend who does the same thing for F T/R. He loads 75 and 80gr Amax and 82gr Bergers way hotter than is safe for a service rifle. Custom chamber so he can seat the bullets longer in order to get the max case capacity to fill with powder.

But, because of the way his rifle is set up, those loads shoot safe for him. A lot of the F T/R class shooters are shooting 308 or 223 in name only, and really shooting "wildcats" that happen to have the same brass head stamp :p

Anyways, I expect that you'll have no issues at 600 yards. Id recommend picking up a bunch of Hornady 75gr BTHPs for the 200 and 300 yard line. I used the Prvi Partizan 75's and from a service rifle they are great for starting out. Buy 5,000 of them from Wideners, then rebarrel once you've shot through the lot :D

Jimro
 
Jimro, Thanks for your thoughts and advice.

I also failed to mention that these are moly coated bullets, which may lower pressures somewhat.

At 200 and 300 I've been shooting the 69 grain SMKs like most people at my club, and the 80 SMKs at 600. I guess I'm a follower, not a leader.

As I said, both rifles shoot the 80 SMKs fine at 600 using Varget. If I could get more of that I would not be asking all these questions here.

Thanks again and I'll post an update once I've tried 23.0 IMR 4895 at 600.
 
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