Single or Double Base.

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   Honestly, I don't think many shooters think of this (single base NC vs double based NC/NG); much depends on what is available.  
I initially picked a double based powder for the AR because I liked how well it flowed thru the measure, every charged weighed the same, to within the accuracy of my digital scale and perfectly suited to volume loading.   The ball powders are double based to obtain the needed ignition reliability.  Some ball powders will not ignite reliably with minimum or reduced charges. 

Not many competitive shooters (Service Rifle, Match Rifle, F-Class or Vintage categories) I know use double base powders.  For the AR Service Rifle, 8208XBR has been "the" powder for some time now, but it's been unobtanium for several years. H4895 (ADI AR2206H) and Varget (ADI AR2208) are also popular as is CFE and N135/N140, several other NC stick powders too.  I picked up a jug of IMR 4166 a few years back but not tried it yet. 

Of course, not all double based powders are made equal.  I'd be OK using those with low NG content if I could not get a suitable single based powder.  And I'd minimize how much rapid fire I did as much as possible.  Although we consider barrels as a consumable, I hate to burn up the throat in a "correct" grade vintage military rifle.  My M1 shooter has a Krieger barrel and my No. 4 shooter has a Criterion barrel on it now, so not as worried about it.  My 1903a3 has the original two groove, but it's pretty rough, and it will soon get replaced with a Criterion barrel.  My No. 4 T will never see rapid fire stages, the Vintage Sniper Match is slow fire 10 round strings over about a 5 minute period.  

Most double based powders are more temp sensitive than the stick powders.  Varget is very stable for example and my tests show this.  I found AA 2520 (double based) is not very stable, my 600 yard zeros seemed to constantly change with temperature.  My current 600 yard load with the AR is with N140, and at most, I may see 1 MOA change from summer to winter. 

Cordite in the .303 had a high NG content, and we all know what that did to the throats.  

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britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Topic: Single or Double Base. Posted: April 03 2024 at 11:32am
	Honestly, I don't think many shooters think of this (single base NC vs double based NC/NG); much depends on what is available. I initially picked a double based powder for the AR because I liked how well it flowed thru the measure, every charged weighed the same, to within the accuracy of my digital scale and perfectly suited to volume loading. The ball powders are double based to obtain the needed ignition reliability. Some ball powders will not ignite reliably with minimum or reduced charges. Not many competitive shooters (Service Rifle, Match Rifle, F-Class or Vintage categories) I know use double base powders. For the AR Service Rifle, 8208XBR has been "the" powder for some time now, but it's been unobtanium for several years. H4895 (ADI AR2206H) and Varget (ADI AR2208) are also popular as is CFE and N135/N140, several other NC stick powders too. I picked up a jug of IMR 4166 a few years back but not tried it yet. Of course, not all double based powders are made equal. I'd be OK using those with low NG content if I could not get a suitable single based powder. And I'd minimize how much rapid fire I did as much as possible. Although we consider barrels as a consumable, I hate to burn up the throat in a "correct" grade vintage military rifle. My M1 shooter has a Krieger barrel and my No. 4 shooter has a Criterion barrel on it now, so not as worried about it. My 1903a3 has the original two groove, but it's pretty rough, and it will soon get replaced with a Criterion barrel. My No. 4 T will never see rapid fire stages, the Vintage Sniper Match is slow fire 10 round strings over about a 5 minute period. Most double based powders are more temp sensitive than the stick powders. Varget is very stable for example and my tests show this. I found AA 2520 (double based) is not very stable, my 600 yard zeros seemed to constantly change with temperature. My current 600 yard load with the AR is with N140, and at most, I may see 1 MOA change from summer to winter. Cordite in the .303 had a high NG content, and we all know what that did to the throats.

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 11:35am
	I should have stated, I'm speaking of US NRA and US CMP sanctioned matches here. I don't specifically know what others are using, perhaps some of our members in other parts of the world will chime in.

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 12:29pm
	I go with the powder that has certain features I look for regardless of type. I want a powder that will mostly (85%+) fill the case when its loaded to the velocity I've decided I want when its being used in with the bullet I'm using. If there's more than one type that is suitable for those specs I go with the one that has the widest range of applications & runs over the widest range of velocities for that load. This triage usually brings me to just one or two of the many theoretically available.
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 12:49pm
	Yes, that’s a good approach. There are indeed some unique specialty applications. I developed a long range load for my DCRA No. 4 7.62 conversion. The overriding factor was the need to attain at least 1200 fps at 1000 yards to work the electronic targets. That lead to a search for a bullet with a very high ballistic coefficient and a powder that could deliver that bullet to the needed velocity with the lowest possible chamber pressure. Searching thru powders, this lead me to Varget. I could have also got there with AA 2520, but I knew I might be loading close to max pressure and did not want to suffer the throat erosion issue on this barrel by using a double base powder at or near to max pressures. As it turned out, I was able to achieve the 1200 fps at just over a mid range load of Varget with the 168 TMK bullet. That’s pretty respectable out of a 25 inch barrel.

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 12:56pm
	Yeah, burn rate & maximum velocity possible is a big thing even if I don't drive it that hard. If you look in a decent reloading manual, or set of them you'll see that different "suitable" powders sometimes have rather large variations in available velocity ranges. I actually like the ones that collect data from several makers of components & instead of the usual one maker's preferences for many calibers, lists several different data sets for one specific caliber. Its a great comparison tool.
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 1:40pm
	The Sierra Manual for example seems very conservative typically having the lowest maximum charges. And they publish load data in steps of 50 or 100 fps, so you know it’s not likely going to correspond to the max chamber pressure for the cartridge. I’ve settled on using the powder manufactures data as my primary source, but always check all the data I have (Sierra, Hornady, Lyman and others). There are some handy little cartridge specific publications that have just about everyone’s data for that cartridge, so you get a full perspective of the data out there.

Mayhem Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 06 2016 Location: Australia Status: Offline Points: 335	Post Options Post Reply Quote Mayhem Report Post Thanks(0) Quote Reply Posted: April 03 2024 at 4:22pm
	For me (and almost everyone else in Australia) it is about powder availability! Currently, that is mainly ADI and I use AR2208 in my .303.
	.303 - Helping Englishmen express their feelings since 1889

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 04 2024 at 4:37am
	This discussion got me to review load data for Accurate 2520, a double base ball powder. I came across an article in Handloader a magazine that stated the Nitroglycerin content is 10%. This powder has been manufacture by several different plants, which may account for some differences in burn rate etc. My short range load for the .223 Rem in the AR-15 was 24.0 grains with the 69 gr SMK. The Western Powders website had listed max at 25.9 grains. Sierra 5th Ed manual lists 25.5 gr as max (Colt AR-15). So my load was 1.5 - 1.9 grains below max, well in the comfort range for .223. Well, now that Hodgdon has taken over distribution of the Accurate line of powders, they now include load data on the Hodgdon Reloading Data Center site. Max is now listed at 24.4 grains with the 69 SMK and 24.9 gr with 80 gr SMK. Seems counter intuitive that the heavier bullet has a higher max charge, but it may be because the 80 grain bullet is seated out longer past magazine length (COAL at 2.38”). So that load I used that burned out two barrels is now close to max per the new data published on the Hodgdon site. Reloading data is prone to changes. So, it’s good to review your loads against new published data from time to time. At $600 a pop for a new Bartlein or Krieger barrel for the AR, I’m leery to go back and use AA 2520 again. These barrels should last 5,000 to 6,000 rounds before accuracy falls off at 600 yds. Button rifled barrels like CBI or Wilson, perhaps half that. But a 1500 round barrel life gets expensive if you’re shooting 3000 plus a year. They say the definition of insanity is doing the same thing over and over again expecting a different result…

slowindown Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: January 16 2024 Location: MS, USA Status: Offline Points: 108	Post Options Post Reply Quote slowindown Report Post Thanks(0) Quote Reply Posted: April 04 2024 at 5:41am
	What powder are you using for 223/5.56. I started using 2520, mostly on 69 and 77 smk. But you have me worrying about my barrel. I have a 20” Wilson combat barrel on a rifle I finished a few months ago. I’ve probably only put a couple hundred rounds through it so far but most of those were 2520 loads.

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(1) Quote Reply Posted: April 04 2024 at 7:01am
	My load with the .223 used to be 24.0 gr AA 2520 with 69 SMK. But I shot two Wilson barrels out in just 1500 rounds. I’m sure a big player here with Service Rifle is the rapid fire strings we shoot in matches. I then changed over to 23.5 gr H4895 with 69 SMK for the 200 and 300 yd stages and both my Bartlein barrels are now over 3000 rounds and still holding X ring at 600 yards (23.5 gr N140 with 80 gr SMK for 600 yd stage). My newest load for the short line is 23.5 N135 with 69 gr SMK, but not shot much of that yet. I changed to N135 because I can’t find H4895. I’m going to hazard a guess that if you limit your rapid firing to say 10 rounds and then let the barrel cool for say 10 - 15 mins before resuming slow fire, you will be OK. Avoid back to back rapid fire sessions. By rapid fire, I mean 10 rounds in 60ish seconds. The NRA and CMP High Power 80 round match has two back to back rapid fire stages, two strings of 10 rounds in each stage.

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 04 2024 at 9:29am
	Yes, I agree. I read an interesting article by a chemical engineer working with small arms propellants that described the action of double based powders as creating surplus oxygen after combustion that accelerates the erosion whereas NC powder consumes all the oxygen. The other thing is what level of accuracy the shooter is satisfied with. Both of those barrels I burned out still shot perfectly well at 200 yards, but 300 and 600 were producing about 3 to 4 MOA groups in prone. If you only shoot at 100 yards, you would never notice the problem. Application (type of shooting) and desired accuracy can to some degree enter into this equation on what powder is most suited. And, here’s my last thought. In my experience, accuracy falls off rather suddenly at mid to long ranges (500 yds and beyond) and more gracefully at short range (out to 300 yds). Probably not in all types of barrels and cartridges, but many competitive shooters I know have experienced this.

britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Offline Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: April 04 2024 at 11:16am
	Here’s an interesting perspective I found on another forum from an experienced competitive shooter regarding ball (which are all double based) powders: I would say that StaBALL, or ANY ball powder for that matter, in NO WAY is going to compete with H4895, or N135, or N140, or Precision Rifle, or Varget, or XBR8208, or AR Comp. for example. However, it could be handy replacement for powders like CFE223, or AA2520, or AA2460, or H335, or W748, and a few other ball powders. Maybe PP MR-2000 too. I would not buy StaBALL to replace H4895. I would buy XBR8208 or N135 to replace H4895. I actually had many lbs of H4895, and I went to my club swap meet and sold them all, only to replace with N135, which I believe to be superior. Load data is practically identical too. Of course we know you can’t believe everything posted on the internet! But, so far, this seems to be consistent with my .223 AR experience.