Load for an AR-15

[TonyAngel]

OK, guys. I have questions about this new endeavor.

I built an AR using a 16" Bravo Company SS 410 1:8 twist barrel and it has a 5.56 chamber. The projectiles are going to be 77gr. Sierra Match King. The powder is going to be RL15. I got the brass from Scharch in the form of 500 once fired .223 casings in a mixed lot to include LC, FC and WCC. I got them already primed with CCI primers.

Now, to the questions. My biggest question is with regard to the brass. Scharch claims that the brass is fully prepped and that it is all uniformly trimmed to 1.75". Assuming that to be true, my question is whether I should sort all of the casings by manufacturer because of differences in case volume? I'm asking because if there is a substantial difference in case volume among the manufacturers, I can only assume that I'll have to work up maximum loads for each brand or at least segregate the different brands of cases to get the most consistent groups. Am I right or am I worrying about nothing?

My second question is with regard to the charge weight. I've searched here, other sites and read the FAQ at Sierra and the consensus seems to be that 24grs. of RL15 under a 77gr. SMK loaded to a 2.260 OAL is the "magic" load for most. I know that all loads should be worked up, but still, there has to be a floor where a load couldn't be an over pressure load inspite of the variances in components. I mean, can I just whip out a bunch of rounds with the above recipe or should I start out lower on the charge weight. If so, how much lower? 23gr? 23.5gr? Does the fact that my barrel has a 5.56 chamber affect any of this?

Lastly, I'm going with the 77gr SMK because I've seen guys shoot some really amazing groups with them using RL15. On the other hand, I've read that guys go with lighter bullets for closer ranges (100 yards), like 52gr hollow points. Why is that? Is it because of the cost of the bullets? I usually shoot at 100 yards and am now wondering if I just bought a bunch of the wrong bullets.

Your information and guidance is appreciated.

Thanks.

 

[rg1]

You'll gain some accuracy by separating the brass by manufacturer. The LC and WCC should be close by weight and internal capacity but the FC brass is usually heavier with less internal volume. I would recommend working up to 24-24.1 grains of Rel 15 but I wouldn't load very many test rounds. I'd start at about 23 and work up to 24.1 looking also for best accuracy. I'd also check all 3 case brands while working up. 24-24.1 is a time tested load with Rel 15 but just make sure with your lot of powder and primers. The irregular tips of hollow point bullets will cause some variation in overall length. Some rifles will have a little trouble with hollowpoints at the maximum of 2.260". I load mine to 2.255" maximum with most at near 2.250" and they feed in all my rifles. If you do load to 2.260" make sure the longest round you load is that dimension and that some don't end up longer. Check this site:
http://www.6mmbr.com/223Rem.html

 

[taliv]

i was talking to a 600 yrd benchrest shooter last week that told me they started on a new lot of R15 that changed the impact enough to be off the paper! that's pretty extreme, but it happens. not that big of a problem by itself, but you combine that with a new barrel/chamber that could be tight, and a couple different case sizes, and 95* summer temps and ammo you just started out at what you thought was max but was really just a bit over because your balance scale wasn't level... because you didn't want to take the time to work up... it could get to be a problem.

of course, odds are, any combination of that brass, those bullets and that weight of powder is going to be a good bit lower than mil-spec 5.56. and you wouldn't be the first one to just load it up and shoot.

77g will be plenty accurate at that range., and better suited to your twist

 

[TonyAngel]

rg1, thanks for the link and thank both of you for the info. I've always had the tendency to over think things. I think I'll go with 23.5gr to start. Unfortunately, since I ordered primed brass, I won't be able to take any volume measurements with water.

 

[Canuck-IL]

The 1:8 will probably be fine with the 52gr heads at 100.

Especially because of temperature variations, I'd work up but do it in just a few steps. I'll bet most of the ranch you end up at 24gr safely but not necessarily needing it - - that along with some Varget and 4895 loads are pretty universal in HP. Maybe try 23.2 and 23.6, with a chrono if possible, check for pressure signs and then if all is copasetic, try 24. Personally, I stopped at 23.8 as they're all 10 ring at 300 yds so why waste the grains and punish the gun? That's in both a 1:7 and a 1:8, 20" barrels.
/Bryan

 

[243winxb]

5.56mm

my question is whether I should sort all of the casings by manufacturer because of differences in case volume? I'm asking because if there is a substantial difference in case volume among the manufacturers, I can only assume that I'll have to work up maximum loads for each brand or at least segregate the different brands of cases to get the most consistent groups. Am I right or am I worrying about nothing?

If you want accuracy, buy new brass all of the same make, brand , lot, then weight and sort. Other wise , forget about it, dont load near maximum.

can I just whip out a bunch of rounds with the above recipe

NO Mixed brass, stay away from maximum loading, unless you like to use a bullet puller.

Does the fact that my barrel has a 5.56 chamber affect any of this?

Yes, its more forgiving pressure wise, not great for accuracy.

Lastly, I'm going with the 77gr SMK because I've seen guys shoot some really amazing groups with them using RL15. On the other hand, I've read that guys go with lighter bullets for closer ranges (100 yards), like 52gr hollow points. Why is that? Is it because of the cost of the bullets? I usually shoot at 100 yards and am now wondering if I just bought a bunch of the wrong bullets.

The 77gr has better sectional density & ballistic coefficients for longer distance. Good reading here , its old but still useful, click the 223 info page http://www.6mmbr.com/index.html

 

[BADUNAME37]

1:8 may not be quite fast enough twist to stabilize a 77g projectile.
I have 1:9 and the maximum I can comfortably load with any accuracy is 62g Barnes Triple X pills. Jumping to 77g just by one additional twist may be pushing it.

Also, realize that the faster the twist, generally the faster the barrel will wear out.

I am only going on what I have read, don't take what I wrote above as cast in concrete, just some things for you to possibly consider.

 

[dakotasin]

some more input for you...

i've done a lot of work with federal cases, including weighing many of them. the case weights range from 90.0 grains to 95.0 grains - that is a huge spread for a case that small. some fc cases are crimped, and some are not. the crimped cases are a royal pain the first time they are re-primed, but after that they are actually pretty good. the non-crimped cases develop loose primer pockets on the 2nd or 3rd firing and i pretty much treat them as throw-aways.

my accuracy load that works very well out to 600 yards is 23.4 grains rl-15 behind a hornady 75 grain bthp. i load them to 2.250 so they will work in p-mags. because of the extreme spread in case weight, only some of the time can i load hotter. once i reach 24.0 grains of rl-15 i will occasionally run into failures to extract. the fc cases are so inconsistent i think you can treat them as mixed headstamp cases, though i have not tried mixing headstamps yet to see what the difference will be. i'll do that this winter. i have mixed headstamps in other chamberings and the differences are huge and generally not a good idea, but given the inconsistency of fc cases, its gotta be about the same.

i've never loaded a wcc or lc case for any chambering.

based on my experience if i was in your situation i would start load development at 23.0 grains and load up 8 each in .3 grain increments from 23.0 to 25.1 and shoot those 8 as fast as i could accurately get on target. this will get things hot enough that if there is going to be a problem it will show itself here prior to you getting several hundred cases loaded, and then have to pull.

the load that is most accurate with no failures is your load.

i've standardized all my ar-15 shooting to be w/ 75 grain bullets. plenty of other guys will run 2 or even 3 different bullet weights in competition, but because i compete to be a better shooter and big game hunter and not to win trophies i run the same load at all distances.

i have also had very good luck with hornady 60 grain v-max in competition with 8-twist barrels, and many of my fellow competitors run those bullets exclusively. i switched because getting the v-max locally is sporadic while the 75 grain bthp's are easily available locally. you may want to take into consideration how available the bullet you want to run is locally.

 

[JimKirk]

I want to ask a related question, I think, being your discussing .223 brass differences.

I purchased some once fired, FC cases, some have a smaller headstamp writing than the other. They weight on the average about the same for a sampled lot of each. I did noticed that one has better primer pockets than the other.

Anybody know anything about the two different FC cases?

Jimmy K

 

[Eb1]

1:8 and the Sierra MK 77 grain will be fine. If it is a true 1:8. Use a cleaning rod with tape on it to measure the twist.
The length of the 77 grain will load in a magazine. Therefore will be fine with a 1:8 twist barrel. Remember it isn't weight as much as it is length of the bullet and velocity.

Use this http://kwk.us/twist.html

 

[TonyAngel]

Thanks for all of the info guys. I'm going to play it safe. I'll sort all of the cases, load up some of each and head to the range and make some observations. I was in such a hurry to get loading, that I think I made a bad choice of getting the Scharch primed brass.

Really, I went that route because my shooting/loading time is really hard to come by and I'd rather shoot than load. I thought I could save some time by going with the once fired, processed and primed brass from Scharch. It WAS my plan to make the once fired and primed brass a permanent part of my replaceables list and ordering them as components rather than something to be reused.

I'll just see how the "sorting the brass" thing works out in terms of group size.

Thanks for all of the info guys.

 

[Canuck-IL]

based on my experience if i was in your situation i would start load development at 23.0 grains and load up 8 each in .3 grain increments from 23.0 to 25.1

25.1 is too hot and, totally a waste of powder anyway.

1:8 is fine for 77s and even does 82s.
/B

 

[Wahoo95]

Don't forget to try some 75gr Hornady BTHP's over 24gr of Varget or RL15 when you get a chance. My gun loves 77gr SMK's over 24gr Varget and RL15....but it REALLY likes the 75gr pills! My best accuracy is right at max of 24gr for my gun, however I don't lose much by backing it down to 23.8.

 

[BikerNut]

1:8 may not be quite fast enough twist to stabilize a 77g projectile.
I have 1:9 and the maximum I can comfortably load with any accuracy is 62g Barnes Triple X pills.

You can go up to 68-69 grains with a 1:9. I've reloaded and shot 69-grain SMK's at 200/300/600 yard high power matches with very good results from my 1:9 barrel (results would have been better with someone else pulling the trigger, but that's against the rules).

A 1:8 barrel will accomodate 80-grain bullets with no problem.

 

[TonyAngel]

Thanks for all of the info guys. I tried out TAC and Reloader 15. I think the RE15 is a keeper. These groups were the last of 200 rounds. I was doing OK, but I screwed the pooch on the very last group at the bottom right.

These were at 100 yards and I used 77gr SMKs.

 

[dakotasin]

if you can pull that stunt again w/ the 23 grain load, you're gonna have an awful tough time finding a better load.

nice work!

 

[TonyAngel]

These groups weren't too bad either, considering that they were ten shot strings.

The groups on the left weren't too hot, but the ones on the right weren't bad, except for that one round in both groups at the 11:00 position. That first hand fed round on a new mag is making me crazy. I'm still working on my form.



I think this AR is a shooter. I'm going to play around with the crimp and such. Also need lots of work on my trigger control. You can see on the lower left, I forgot to hold my breath on the last rounds and I got that nasty vertical string.