View Full Version : Help with ocw please
Have a colt 6920. Was using lc brass 77gr nosler hpbt, cfe223 and cci41. Left to right was 23.5, 23.8, 24.1, 24.4 started to see pressure signs at 24.4 which is .1 over max according to hodgon. All shooting was with an aimpoint pro at 100yds prone. My question is, where would you guys go from here? Not looking for .5moa, just want to build a good reliable load. These rounds will be stored away. Their were 2 more targets but they aren't worth showing. I was thinking working around 23.6-24.1 but wanted your guys' opinion. Thankshttp://uploads.tapatalk-cdn.com/20161111/7667b6e6e44339e86bfdc2aa203cf10d.jpg
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To be totally honest you need to do the same test but shoot a minimum of a 10 shot group per load.
Too many variables in only 3 shots per load per target.
Looks like you are on to something but not enough to make a final decision.
Just my experience in load production.
Clarence
wilson1911
11-11-16, 18:30
23.8
Reshoot 23.7 23.8 23.9 groups of 3 still. This will confirm your node, or you might be a small amount better with an adjustment.
I actually like your last load, but its showing pressure and your brass will not live long.
After you are sure of your node, work on seating depth. How much you move is up to you. But I would try +/- 5 thou at a time.
You also need to chrono that load. Raise your dot up a few clks to bring the group more to the center of your target.
Good shooting btw.
23.8
Reshoot 23.7 23.8 23.9 groups of 3 still. This will confirm your node, or you might be a small amount better with an adjustment.
I actually like your last load, but its showing pressure and your brass will not live long.
After you are sure of your node, work on seating depth. How much you move is up to you. But I would try +/- 5 thou at a time.
You also need to chrono that load. Raise your dot up a few clks to bring the group more to the center of your target.
Good shooting btw.
Thanks. Yeah I liked the last one too, I might dabble a .2 below that one. With my astigmatism it's tough shooting prone, for minute accuracy. Scoped rifle I'm fine, red dot not so much.
I know that flyer on the second target from the right was a pulled shot.
I'd thought about the chrono but was already headed to where I was going to do this, it's all where I live, and figured piss on it ill chrono it after I have some data to work with. I hate setting up that chronograph. The first two targets that aren't shown were all a little high, so I dropped it 4 minutes to keep it from climbing off the target, guess I shouldn't have. But this way I reuse these targets.
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I would probably work 23.5, 23.6, 23.7, 23.8, 23.9, 24.
PERSONALLY after I find a node I go to the chrono. 5 shot groups +- 1% of where I think the node is in .1g increments. Shoot them over the chrono, dont worry about group size, read the chrono data. Look for lowest ES and SD. Thats your consistency load.
Last load development I did was for 6.5creed. 100yd OCW showed a node at 39.8 I think it was. I shot from 39.4 to 40.2, 5 shots each in .1g. Chrono data showed a CLEAR center with ES and SD. Started at say 10 SD, went to 8 SD, then 7 SD, then 6 SD, back to 7 SD, etc... 39.9 was my load. I then confirmed it out at distance. It bangs 6" steel gongs at 900y repeatably. This method of using the chrono for final tuning completely eliminates shooter error, called flyers(which you admit one of your groups had one), etc... Fire them into the berm at 10 feet, doesnt matter, you have good data.
I would respectfully disagree with messing with bullet seating depth. Nosler 77s aren't depth sensitive, and you're running a 5.56 chamber with a longer leade.... too long to get VLDish jumps, I'd guess.
I would respectfully disagree with messing with bullet seating depth. Nosler 77s aren't depth sensitive, and you're running a 5.56 chamber with a longer leade.... too long to get VLDish jumps, I'd guess.
yup, load em a little short of mag length so any variance in the tip is accounted for and load away. You arent going to get a 77g anything CLOSE to the lands and stay in the magazine in an AR15.
yup, load em a little short of mag length so any variance in the tip is accounted for and load away. You arent going to get a 77g anything CLOSE to the lands and stay in the magazine in an AR15.
One of the finer points of playing with seating depth is that you are altering the barrel time in milliseconds thus fine tuning the harmonic for your individual barrel.
That said I load as the above two posters suggest :-)
for anything other than a VLD, seating depth is not that important IMO and most bullets are way more jump tolerant than most people give them credit for. In a mag fed gun, not much you can do to get close to the lands in most cases, especially in the OP's case where he is shooting a 6920 that has fairly generous chamber dimensions.
If I was having a custom chamber cut for a gas gun I would pick a bullet I was going to shoot exclusively, load a round to mag length(minus a small safety margin), and have the chamber cut to that dimension. BUT in the gas gun world, nobody really does that. There are magazines that let you load longer than others, but its not a huge difference usually. Like in the big frame AR world the Larue mags allow you to load ~2.9 where as a LR-Pmag only allows you to load ~2.8.
So for the most part in the gas gun world we are simply loading to mag length and then we only have powder charge to play with the load. I cant imagine a scenario where I would want to load deeper and thus have a larger jump...thats me personally.
With ONLY playing with the powder throw I have a load in my 6.5c, as I stated earlier, that can hammer a 6" gong at 900 yards. While I cant say "this is a 1/2 MOA load" because 1/2 MOA of 900 would be 4.5", I am pretty sure its ~1/2 MOA load. Good enough for me.
I'm 67 with chronologically gifted eyesight and I put a 1-4 power scope on my carbine for load development. And a aimpoint with a 2 inch dot isn't something I would even try a OCW test with.
That being said a OCW test is to find where bullets hit at the same horizontal level or at a node and shot at longer ranges than 100 yards. And your red dot gives you a two inch error to start with, meaning a OCW test with a red dot is stretching things a bit. (old farts opinion)
Long Range Load Development
https://sierrabulletsblog.com/2014/07/03/long-range-load-development/
I know I'm stretching it using the red dot but it's what's on the gun, that's what the gun is getting shot with and that's start these bullets will be propelled from. I think I have them sitting a little to deep honestly. But I did load 5 of each weight 23.5-24 and will run them over the chronograph tomorrow.
I'm building this load for no more than 350 maybe 400 yds and there just want it minute of man
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Here are the results from the chrono. Not sure what the hell I was doing wrong for these big of swings. All lc brass, all charges weighed. Maybe I should of trimmed everything? I did taper crimp. http://uploads.tapatalk-cdn.com/20161115/e8adf03f10062ea18200cba72fa62854.jpghttp://uploads.tapatalk-cdn.com/20161115/55faf9bbae5eb9419d67b7ec24fa5bf9.jpghttp://uploads.tapatalk-cdn.com/20161115/82d499d93f1325d474e043229c8956eb.jpghttp://uploads.tapatalk-cdn.com/20161115/6b987d5d38c8d4c2f20e85866db7d94c.jpghttp://uploads.tapatalk-cdn.com/20161115/48fa4dc1ab90cd1f982e786169c484d9.jpghttp://uploads.tapatalk-cdn.com/20161115/6256a586db7bfe39ebc42b31f27cc5a8.jpg
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never crimp with accuracy ammo.
Although I cant imagine crimp vs. no crimp would throw your numbers that far off.
Man, I dont even know where to tell you to explore. That 23.9-24g range looks the most consistent, but each group has a couple of wacky numbers in them.
With good reloading practices you should be able to get into single digit SD's and low double digit ES's.
I really dont know anything about that CFE 223 powder. For 77g stuff in 556 I am using 8208xbr exclusively. 8208 is quite a bit faster than CFE223. CFE223 is slower than Varget(although not by much) and a lot of guys will call Varget the precision powder in a lot of different cartridges.
wilson1911
11-15-16, 12:56
How close are you to being mag length ? I assumed from your first post you were not that close, or you would have stated that.
You might as well post your loading routine/equip so you can chase down where your load is going wrong.
How close are you to being mag length ? I assumed from your first post you were not that close, or you would have stated that.
You might as well post your loading routine/equip so you can chase down where your load is going wrong.
On the length they were off a little ways
Tumble
Full length resize rcbs small base die
Clean primer pocket
Inspect cases
I then sorted for head stamp
Chamfer case mouth if needed
Prime cci41
Weighed each charge weight on Lyman 500
Seat with rcbs seater
Crimp with Redding taper die
I am bad about trimming and I know on 556 I need too.
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On another note this is a carry load I chronographed awhile ago. http://uploads.tapatalk-cdn.com/20161115/acc0a5cfdf418c9854e67da113a12141.jpg
I know it's a complete different cartridge, but I know how to roll precision ammo. I do it for bolt rifle.
How much should I be letting the rifle cool between rounds and should I keep it at slide lock while doing it?
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Here are the results from the chrono. Not sure what the hell I was doing wrong for these big of swings. All lc brass, all charges weighed. Maybe I should of trimmed everything? I did taper crimp.
If your cases were not trimmed to the same length the crimp pressure will vary a great deal and effect uniformity.
Buy some factory loaded ammo of the same type and bullet weight as a base line for velocity and accuracy testing.
The very first time I used my Magneto Speed Chronograph was on my AR15 carbine and I tested my reloads against factory loaded LC and Federal.
wilson1911
11-15-16, 13:21
On the length they were off a little ways
You need to measure this. Know your max length and where you are at now. Most load for mag length anyway
Chamfer case mouth if needed
I always chamfer, make them consistent.
Crimp with Redding taper die
I am bad about trimming and I know on 556 I need too.
So how long is your brass ?
Crimping and long brass may be where your erratic pressure is coming from. How many firings do yo have on the cases ?
They were loaded at 2.25.
Far as firings on the brass 5-6 I think.
I'll trim and load some to just below mag length tonight and see where that gets me.
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How much should I be letting the rifle cool between rounds and should I keep it at slide lock while doing it?
not that important when you are shooting over chrono, but be consistent. 5-10 seconds in between. Chamber heat wont affect them that much, but IMO you dont want 4 rapid fire and 1 that sits in the chamber for 30 seconds.
I'll trim and load some to just below mag length tonight and see where that gets me.
I wouldnt change your seating depth. 2.250 is fine and the 77g nosler and SMK's tip will vary a little due to how they are constructed. If you try to go longer, you may have some that dont fit in the mag. I think 2.250 is where I load 77g SMK's. Dont chase your tail on seating depth.
Trim and dont crimp and see where that gets you. Its all about getting consistent, even pressure on the projectile. Anything that upsets this(varying brass length or varying crimp pressure) will cause pressure changes and bullets going weird places.
You obviously know how to load if you can get single digit SD's and low double digit ES's out of pistol ammo and im guessing bolt gun. Semi gun is no different if you want precision ammo. Load like you do for a bolt gun.
Ok, so I went back out abdominal ran some more over the chronograph. All brass was once fired hornady, all trimmed to the same length, all bullets seated just below mag length all power charges weighed in a balance beam. 77gr nosler hpbt. This is what I got. Their are still a bunch of major deviations though. http://uploads.tapatalk-cdn.com/20161202/9abcba705946b97decac42bcaac5290c.jpghttp://uploads.tapatalk-cdn.com/20161202/b815ee8108bcfc04718f6adb774a8705.jpghttp://uploads.tapatalk-cdn.com/20161202/583208d6072c360972e7dea890b105c6.jpghttp://uploads.tapatalk-cdn.com/20161202/be33fe6798d741883d1edcf675e5e093.jpghttp://uploads.tapatalk-cdn.com/20161202/1693f011f658e93d0bd31269d92a5d1b.jpghttp://uploads.tapatalk-cdn.com/20161202/2e84567d01c9b661eccee70d4baf2553.jpg
This was 55gr fmj new ammunition from freedom munitions.
http://uploads.tapatalk-cdn.com/20161202/ffaa9f1daedfcb2b854a35316fd414d4.jpg
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im guessing your gun doesnt like CFE223. I didnt like it the few times I played with it.
I think quite a few of us around here are using 8208XBR with the heavies. 23.2 was where I ended up in an 18" stainless barrel. I dont know my SD numbers off the top of my head but its a solid 1/2 MOA load. I think MarkM clued me in on that load and it worked well for me.
waveslayer
12-01-16, 18:44
I use CFE with 77 gr. SMK's. Getting single digits on my SD. I also use XBR with 75 gainers with single digits.
Two things come to mind, how are you dispensing your powder?
How accurate is your Chronograph compared to a Magnetospeed or Labradar
My wife thinks I only have 3 guns
I use CFE with 77 gr. SMK's. Getting single digits on my SD. I also use XBR with 75 gainers with single digits.
Two things come to mind, how are you dispensing your powder?
How accurate is your Chronograph compared to a Magnetospeed or Labradar
My wife thinks I only have 3 guns
I dispense into the tray for the balance beam scale, then trickle to weight.
Have no idea how accurate it is. It's a chrony chronograph. This is the first chrono I've ever owned
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waveslayer
12-01-16, 19:14
I dispense into the tray for the balance beam scale, then trickle to weight.
Have no idea how accurate it is. It's a chrony chronograph. This is the first chrono I've ever owned
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What's your chamber and barrel twist? I use a Wylde chamber, that's why I ask
My wife thinks I only have 3 guns
What's your chamber and barrel twist? I use a Wylde chamber, that's why I ask
My wife thinks I only have 3 guns
It's a colt 6920, 556 chambering 1:7 twist
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waveslayer
12-01-16, 19:28
It's a colt 6920, 556 chambering 1:7 twist
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I'm running 23.7 grains on my gun. Have you tried SMK's
My wife thinks I only have 3 guns
No I have not. They're a little pricey for what I get the noslers for, and I have an un opened 1000 Rd box of the nosler.
Do have enough ar comp to load them all, maybe I'll that and my next batch I'll buy Sierra. This is mainly ammo that's going into storage and to be set aside.
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Nosler 77g CC's are clones of 77g SMK's. Dont waste your money.
I would see about a lb of 8208XBR or Varget. They are "known quantities" in the precision ammo game. Reloder 15 is also a "known quantity" as that is what is supposedly loaded in the Mk 262 ammo developed for the .mil SPR stuff.
Like I said, I personally didnt like CFE223 when I tried it in both 5.56 and 308 loads. Some rifles just simply dont like certain powders.
It's a caldwell pro chrony to be exact
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waveslayer
12-02-16, 10:21
It's a caldwell pro chrony to be exact
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I have sub 1/2 MOA loads using CFE, which isn't working in your gun, Varget and XBR
My wife thinks I only have 3 guns
Correlating the muzzle velocity and chrono data to the original targets in the first post, it seems like 23.9 is the best. To me anyways especially being as I was using a red dot. I'm not looking for 1/2moa accuracy. Looking more for accurate enough to 350 yds or so
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waveslayer
12-02-16, 14:21
Correlating the muzzle velocity and chrono data to the original targets in the first post, it seems like 23.9 is the best. To me anyways especially being as I was using a red dot. I'm not looking for 1/2moa accuracy. Looking more for accurate enough to 350 yds or so
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Using a red dot is hard if you can't see where you're aiming each time with any precision
My wife thinks I only have 3 guns
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