AR15 - temp sensitive powder = cook in chamber?

[CA_Shooter]

I am new to loading for the AR15 and because I have a bunch of brass and found 1000 55gr FMJ bullets...so why not?

I tried 2 different sets of loads:
Load 1 set: Hornady 55 FMJ, frontier brass, AA2230
Load 2 set: Hornady 55 FMJ, frontier brass, N540

I shot slowish fire, around 1 shot every 7-15 seconds.

With the N540, I tested a smaller range of powder charges because there wasn't any published data for the 55 FMJ. Groups seemed to move relatively consistent.

With the AA2230, I had published data so I went wider with my charges. With AA2230 the trend I saw was the more I shot, the worse the groups seemed to open up. I didn't see any of the normal bolt action trends of groups going from small to big and then back to small again. But then again, I only have use temp stable powders in the past.

For AA2230, would the groups possibly be opening up because they were cooking in the chamber at different rates? And if that is what is happening, then that means temp instable powders are a no go for the AR platform (unless you don't care about group size)

 

[markm87]

For AA2230, would the groups possibly be opening up because they were cooking in the chamber at different rates? And if that is what is happening, then that means temp instable powders are a no go for the AR platform (unless you don't care about group size)

I quit using W748 long ago due to temp instability. I used it in the past for FMJ "blaster ammo" with a "cushion" in the load for pressure increases in hot temp shooting.

I'd imagine that the round sitting in a warm chamber would be just like the round heating up in our desert sun. So yeah... unless you run a single feed mag for slow rates of fire, and keep your ammo cool, you're probably better running a more stabile powder.

 

[darkangel_r2]

I am new to loading for the AR15 because I have a bunch of brass and found 1000 55gr FMJ bullets...so why not?

I tried 2 different sets of loads:
Load 1 set: Hornady 55 FMJ, frontier brass, AA2230
Load 2 set: Hornady 55 FMJ, frontier brass, N540

I shot slowish fire, around 1 shot every 7-15 seconds.

With the N540, I tested a smaller range of powder charges because there wasn't any published data for the 55 FMJ. Groups seemed to move relatively consistent.

With the AA2230, I had published data so I went wider with my charges. With AA2230 the trend I saw was the more I shot, the worse the groups seemed to open up. I didn't see any of the normal bolt action trends of groups going from small to big and then back to small again. But then again, I only have use temp stable powders in the past.

For AA2230, would the groups possibly be opening up because they were cooking in the chamber at different rates? And if that is what is happening, then that means temp instable powders are a no go for the AR platform (unless you don't care about group size)

Well first off standard 223 remington load data has a max charge of 25 grains. And wylde and 556 chambers can do low 26 grains. So you might just be a little slow. Run another test with 24 as your bottom and go up to 26. Bet you find something better in there. A number of ball powders like to be run at higher pressures. Be aware that these can speed up with an increase in temp so either leave plenty of room above for pressure or load when it is scorching hot out.

540 is also a very slow powder for 55 grain 223. Its unlikely to produce the best results. n133 and n135 from the vv line work much better for that weight. But honestly id stick to ball powders for 55 fmjs. 2230, 2460, h335, w748 tac, and pp varmint are all excelent powders for 55 fmjs. So you already have one of the best.

https://ramshot.com/wp-content/uploads/2020/08/WesternPowdersHandloadingGuide8.0_WEB.pdf

 

[Ned Ludd]

I would say the take-home message from your test is that N540 is the better powder in your setup across the charge weight range tested. The cause(s) of the larger groups with the AA2230 might be harder to determine with certainty. It could be that your setup is much more finicky with AA2230, as 22.6-22.8 gr seemed to work much better than the higher charge weights you tested; it could be that seating depth tolerance is lower with the AA2230; temperature (i.e. "cooking" the rounds) may have had an effect; it could be a lot of things. How did the velocity at 22.6-22.8 gr AA2230 compare to that obtained for the best groups with N540? Were they even in the same ballpark? Although not everyone considers collecting velocity data an important part of the initial load development process, this is a case where it may have either supported or ruled out your hypothesis regarding temperature stability of the powder.

Sometimes it is not possible to easily determine why a given powder/bullet/primer/etc. didn't work well, without a significant amount of further load development/testing. In fact, sometimes it may not ever be possible to ever get a certain combination to shoot well, in which case you'll always wonder why it it didn't work. In such cases, the better solution may be to try something different, so as not to throw away too much time, effort, barrel life, and reloading components at a combination that is not going to work, or to try understanding why it didn't work. The good news here is that the N540 seems to be giving you much better results. I would suggest focusing on further development with the N540, rather than the AA2230, or consider trying some other powders in the appropriate burn rate range.

 

[Walt Krafft]

I suggest you get some better bullets before spending a lot of time trying to improve accuracy. 1 to 1.5 moa is what those bullets are usually good for. And, an AR15 is difficult to shoot well from a bench. It can also have accuracy robbing mechanical problems. Welcome to the sport!

 

[SKWERLZ]

I suggest you get some better bullets before spending a lot of time trying to improve accuracy. 1 to 1.5 moa is what those bullets are usually good for. And, an AR15 is difficult to shoot well from a bench. It can also have accuracy robbing mechanical problems. Welcome to the sport!

I think this is great advice.

For bulk 55fmj I just load near the top of 223 pressure with a ball powder like W748 or cfe223 and 1-2 moa is peachy.

If I want accuracy it’s 55 ballistic tips or 69 SMK’s and 8208 or other extruded powder.

 

[6bra1k]

fmj is a blasting bullet not a target bullet.
no issue off a bench
scope ???
frt and rear rests ??
2230 is almost a copy of the mil powder for 55's
lots of stuff to look at..the bullet is first and pass on 540

 

[Coyotefurharvester]

Did you crimp the rounds, I'm guessing not since 1.8925 would be seated with all the cannelure(+) out of the case(with my comparator). I would try a light taper crimp with an aol between 2.200-2.210(should be on the cannelure at that length). Just because some AR (ramps,magazines) can reposition bullets during cycling. Revisit 26.0/540 and 23.0 of the 2230, with the light crimp. If the group's hang 1 moa and less occasionally you are gtg.

 

[CA_Shooter]

I quit using W748 long ago due to temp instability. I used it in the past for FMJ "blaster ammo" with a "cushion" in the load for pressure increases in hot temp shooting.

I'd imagine that the round sitting in a warm chamber would be just like the round heating up in our desert sun. So yeah... unless you run a single feed mag for slow rates of fire, and keep your ammo cool, you're probably better running a more stabile powder.

Temp instability is my biggest concern. Because then all bets are off and even consistency with an inconsistent bullet is out the window.

Well first off standard 223 remington load data has a max charge of 25 grains. And wylde and 556 chambers can do low 26 grains. So you might just be a little slow. Run another test with 24 as your bottom and go up to 26. Bet you find something better in there. A number of ball powders like to be run at higher pressures. Be aware that these can speed up with an increase in temp so either leave plenty of room above for pressure or load when it is scorching hot out.

540 is also a very slow powder for 55 grain 223. Its unlikely to produce the best results. n133 and n135 from the vv line work much better for that weight. But honestly id stick to ball powders for 55 fmjs. 2230, 2460, h335, w748 tac, and pp varmint are all excelent powders for 55 fmjs. So you already have one of the best.

https://ramshot.com/wp-content/uploads/2020/08/WesternPowdersHandloadingGuide8.0_WEB.pdf

I would say the take-home message from your test is that N540 is the better powder in your setup across the charge weight range tested. The cause(s) of the larger groups with the AA2230 might be harder to determine with certainty. It could be that your setup is much more finicky with AA2230, as 22.6-22.8 gr seemed to work much better than the higher charge weights you tested; it could be that seating depth tolerance is lower with the AA2230; temperature (i.e. "cooking" the rounds) may have had an effect; it could be a lot of things. How did the velocity at 22.6-22.8 gr AA2230 compare to that obtained for the best groups with N540? Were they even in the same ballpark? Although not everyone considers collecting velocity data an important part of the initial load development process, this is a case where it may have either supported or ruled out your hypothesis regarding temperature stability of the powder.

Sometimes it is not possible to easily determine why a given powder/bullet/primer/etc. didn't work well, without a significant amount of further load development/testing. In fact, sometimes it may not ever be possible to ever get a certain combination to shoot well, in which case you'll always wonder why it it didn't work. In such cases, the better solution may be to try something different, so as not to throw away too much time, effort, barrel life, and reloading components at a combination that is not going to work, or to try understanding why it didn't work. The good news here is that the N540 seems to be giving you much better results. I would suggest focusing on further development with the N540, rather than the AA2230, or consider trying some other powders in the appropriate burn rate range.

Good call on the Chrono @Ned Ludd I'm going to run it back with a chrono and more rounds at each charge to see what is happening with velocity. This is a curiosity thing.

I suggest you get some better bullets before spending a lot of time trying to improve accuracy. 1 to 1.5 moa is what those bullets are usually good for. And, an AR15 is difficult to shoot well from a bench. It can also have accuracy robbing mechanical problems. Welcome to the sport!

I think this is great advice.

For bulk 55fmj I just load near the top of 223 pressure with a ball powder like W748 or cfe223 and 1-2 moa is peachy.

If I want accuracy it’s 55 ballistic tips or 69 SMK’s and 8208 or other extruded powder.

fmj is a blasting bullet not a target bullet.
no issue off a bench
scope ???
frt and rear rests ??
2230 is almost a copy of the mil powder for 55's
lots of stuff to look at..the bullet is first and pass on 540

I have had these 55 FMJ lying around for a while now, and with the component shortage this seems like a fun thing to mess around with. I bought these for 7 cents a round previously. I find it difficult to spend 30+ cents a round for an AR bullet when I could spend around 10 cents more for a 6mm. I'm not looking to do any more than use them to experiment on at 100 yards. If 1 MOA or .5 MOA is all I can get then that's fine.

I'm using an Atlas Bipod and a rear gamechanger bag. I could try to stick this on my Seb Mini though as I do have a front rest attachment for the rail. That sounds like fun

I have some SMKs I'll be using for better shooting.

 

[darkangel_r2]

Temp instability is my biggest concern. Because then all bets are off and even consistency with an inconsistent bullet is out the window.

You can't expect long range performance out of 55gr fmjs or any fmjs. So as long as the temp swings don't cause high pressure I would not be too worried about it.

I have had these 55 FMJ lying around for a while now, and with the component shortage this seems like a fun thing to mess around with. I bought these for 7 cents a round previously. I find it difficult to spend 30+ cents a round for an AR bullet when I could spend around 10 cents more for a 6mm. I'm not looking to do any more than use them to experiment on at 100 yards. If 1 MOA or .5 MOA is all I can get then that's fine.

Unless its a match quality barrel I would not expect much better than moa. FMJs are not prone to great accuracy due to how they are made.

I'm using an Atlas Bipod and a rear gamechanger bag. I could try to stick this on my Seb Mini though as I do have a front rest attachment for the rail. That sounds like fun

I would suggest you do your load dev as close to the style of shooting the rifle is to be used in as possible. Though that is less important for semis since they recoil internally. So I suppose whatever position you feel most comfortable with is likely the best.

 

[SKWERLZ]

You can't expect long range performance out of 55gr fmjs or any fmjs. So as long as the temp swings don't cause high pressure I would not be too worried about it.

^^^^^^^