Working up loads for a AR.  need input

Here are a two targets with 5 round groups at 100yds, cause that is all I have, going up at .2 grain increments. You can certainly see when you see an accuracy node.

77 gr MK with n140 started at 24 gr. and went to 24.8 looks to me that it is just hitting an accuracy node at 24.8

24.8 load av vel 2826 ES 10.57 SD 3.87



69 gr MK with CFE223 started at 25.2 gr and went to 26. I see an accuracy node at 25.6 and it looks like another starting at 26

25.6 LOAD AV VEL 2837 ES 26.52 SD 10.90

Yeah it looks like your 2 bottom right corner loads are in there. I would go with those.

2826  seems awful fast for 77's

Try 23.0 grains of N140 working up to no more than 24.0 grains. Most reloading sources, including VihtaVuori's list 23.5 grains as maximum with 77 grain bullets in .223. You started .5 grain over maximum.

What length barrel?



 

Actually the vihtavorire loading guide shows 24.7 as a max load for the 77 gr sierra MK.

I have no pressure signs other than slightly flattened primers, Their test barrel was a .223 with a 1:12 twist. I have a .223 wilde chamber. We all know that .223 loads in 5.56 chambers produce lower pressures. I think there is room to go up.

I am going to try two 10 shot strings at 24.8 and see if that SD holds

also going to load two 5 shot loads at 25 gr and 25.2 gr

20"  I have a shooting croney so it would not suprise me if it were reading a little high. It said I was pushing 69 gr mk at 3000 last weekend. I was expecting about 2750 with the 77 MK

here are the specs on the gun

CMT billet upper and lower receiver
Geissele SSA-E trigger
Vltor A5 Extension, spring and buffer
Magpul ASC stock
Shilen 20" match 1 in 8 twist wilde chamber ratchet rifling barrel
Spikes bolt carrier with shilen bolt
Vltor gas block
Raptor charging handle
Precision Reflex 15" Delta forearm

Kind of strange they would do their load data with a twist rate that will not work with the 77. ( 1 in 12 )

The longer twist may cause lower pressure too.

you see a lot of .223 load data with 1;12 twist barrels. most .223 chambered bolt guns that all this load data was really developed for use the light varmint type bullets.

A few loading manuals have both AR and regular .223 loads. Compare them. Usually they drop the heavier bullets in the .223 section and drop the light bullets in the AR section.

the publishers of reloading manuals have to be careful to make sure all their .223 loads are safe in a standard .223 chamber. 5.56 chamber is a different animal.

Seems my rifle likes them hot. At least to .223 standards.

Again, try lighter powder charges just to see if accuracy improves. I have 5.56mm, Wylde and Noveske Mod 0 chambers and the loads I posted work best in all three of them. You're going in the wrong direction safety wise. I always reference the bullet makers load data, never the powder manufacturer's. The bullet maker has the most experience with their own products.

You lose nothing by trying slightly lower powder charges.

I have a lighter load for my favorite 69 gr mk and a super accurate load for 52 gr MK.

I won't be using the 77 gr mk often. We have a 600 and 800 yrd range at my gun club. This load is only for it

I also have worked up a low power accuracy node and a long range node for berger 70 gr. I want to compare the 77 mk and the berger. It is all about the velocity between these two bullets at these long ranges. I have 1000 bergers ordered. Unfortunately they are out of stock. That is why I am working on the 77 MK.

You are right. No need to put unnecessary wear and tear on your rifle. Really the lower power loads are more accurate at the shorter ranges.

I am just checking out the limits of my toy.

What I was really getting at with this post was how those groups change with different powder charges. It facinates me. You are thinking holy cow this powder is just a waste and then .2 lof a grain ater the group you are looking for is there.

It is hard with this barrel to find a load for the 77 MK. I have heard they really don't straighten out for about 200 yrds but that just doesn't make sense to me. Wish we had a 200 yrd range to test that theory

every barrel is a little different. you have to find what your gun likes.

Don't see how anyone could be happy with factory ammo

but I have had guns that just shot everthing well

kind of the luck of the draw

Some of those loads are very good. You can see them pull in vertically which shows the load improving but horizontal stringing shows in all of them which is most likely not the load. Would have to question what you are shooting off of as it looks like it is pulling to the side.

yeah that is me.

but try to put in 10 perfect 5 shot groups at a public range with a mosin on one side and some guy on the other side bouncing mini 14 brass off your head.while the guy with the .308 with the compensator is sending shock waves down the line.

Sometimes I just have to stop and walk away till things calm down.

I am actually using a lead sled fcx for load development

Don't take me wrong you and the load are not doing bad the vertical grouping shows that. If the load was off it would be all over like the 77s. The FCX looks like a decent rig although the front bag is not an exact match to the wide flat bottom tube you are running. For horizontal stringing like that make sure the upper doesn't rock side to side in the lower. Try a different optic to make sure the windage isn't jumping around. Make sure to follow thru the same each shot on recoil. Definitely need to fire some 10 round strings to make sure the horizontal stringing isn't from barrel stress. That would start with POI on one side and steadily move across the target in a line until it eventually pulls into a smaller group. Usually takes more than 5 shots to get it to stop walking. That barrel should not have that problem but you never know. I had one do that and the only fix I could think of was to have it cryo'd. The AR would shoot under 0.2" groups at 100yds after the barrel heated up. So sent it off and had it frozen and when I got it back the group was locked in dead solid. At 1 1/2" @100yds. Even my hottest handloads wouldn't budge it. Total waste of barrel and money. Starting to ramble again so better stop typing

Something else here at play too. You should not see a significant difference in group size with only a .2gr powder change not even in a small capacity case like .223

A good load will print a good group +/- .5gr of the target weight charge. Something as simple as the temperature change caused by a cloud blocking the sun rays could do the same as a .2gr difference in powder charge.

In .308 Win capacity cases my good loads will tolerate +/- 1gr in charge weight and still shoot good. In magnums this margin gets wider. It just makes sense.

You need a load that will tolerate some change and still be accurate for use in the "every day, real world".

yeah

This is the kind of input I need. You made me think about my shooting technique. I cheat and put pressure on the stock with my cheek or shoulder to get that last bit of alignment rather than taking the time to adjust the rest where all I have to do is relax and squeeze the trigger. Usually I do this because I am hurrying the shot because of the activity around me. When I do get everthing aligned properly and squeeze off a shot the groups are better.

I started with a larue removable mount and that sucker moved. Now I have a Leupold vx-6 4x24 tmoa and a fixed leupold mount to match. Scope is stable.

Upper/lower fit is snug. There is an adjustment screw on the back takedown pin where you can adjust the tension and snug up the fit. Can't get it too tight or you can't push out the takedown pin. I have thought about drilling a hole in the grip where you could access that screw without removing the grip and tighten it for shooting and loosen it for takedown. So much I read says that a tight fit is really not necessary but with my experience with bolt guns this just doesn't make sense.

the FXC comes with two front bags. One is a wide flat bottom that fits the forearm well. the other is a v shape for normal forearms.

this barrel is very picky. Many times I have thought about retiring it to the dust bin.

then I get a group like this, 10 shot string over crony es 20 sd 8, and again there is hope. this was shot off sand bags when I was developing my 69 gr mk and varget load.

The groups in the second pic at the beginning of the post show the most promise. Middle and bottom right target. Anytime the point of impact is in a fairly straight line the load is pretty good there is just something else at work making it spread across the paper. If you could pull them in horizontally the same as vertical you would be looking at 0.25 moa. I would stick with the 69gr SMK and load a few more around those charges and see if it continues to stay tight vertically. If so stick with the one that prints the best vertically and then try to figure out what is giving the horizontal shift. For target shooting off a rest keep your body off the stock as it should be resting almost dead on target by itself. Just slight stock and trigger control is all that should be needed. You should have to only concentrate on vertical crosshair alignment. If you have issue with horizontal alignment off a rest then you need to change something. If you feel you have a hard time getting in around the rest to control the rifle then change to a lightweight BR rest with separate tall rear rabbit ear bag and save that one for the high recoil stuff.

*edit*

For an AR it is usually the mid to tall bag depending on the type stock that is used. I have yet to find any AR stock that ideally uses the standard height rear bag.

Good advice! thanks

Again I want to thank you for your input. The horizontal stringing I never really noticed until this. Today I really concentrated on trying to eliminate it. As you will see in the pic below it is still there. What I found is that my ear protection was making me put undue pressure on the stock to get a cheek weld and proper sight picture. I was wearing ear muffs. Tried everything to make it work but the results are below. I shot two ten shot groups over the croney to verify my av. velocity. ES and SD.

Both of the loads below were the bottom right pictures from my post above

this is Sierra Match King 77gr with 24.8 grains of n140



Went up .2 grains and the group came apart



Now I decided to get rid of the ear muff and use regular ear plugs. Luckily the rangemaster had some. What a difference. Perfect cheek weld and sight picture. Going to take a while to adjust but you can already see a change in horizontal dispersion.

Sierra Match King 69 gr  26 grs of CFE223 ten shots over croney





Went up .2 grains and got this

You are certainly welcome and hope some of it is of help. Everyone's setup is different. The main thing is consistency. From the way you make your loads to the way you hold the gun. Consistent from one shot to the next. Take a breath, let it partially out, squeeze the trigger smoothly and decisively. You know the gun is going to go bang, you know it is going to recoil, you know a bullet is going downrange. All of it is good. Keep working on your technique and load till you are satisfied. Last thing I will say since this is about reloading is that die instructions are how to use them in general. For sizing don't just turn the die down until it touches the shell plate. Turn it down only as far as needed to get the case to chamber. For target shooting I size them so they go in the chamber smoothly but do not fall back out freely when you point the muzzle in the air. Again this is for target shooting and not fast fire.

thanks again

I am going to try that 77 mk load by dropping it .1 of a grain. See if the group holds together and if the ES and SD improve. Right now the two 10 shot groups I shot have a ES of 35.89 and a SD of 11.95 and an ES of 42.09 and a SD of 13.37.

Saturday I shot one group .2 lower and it had an ES of 6.51 and a SD of 2.64 but the group wasn't that great.

my croney says average velocity of 2839 reloading manual says it should be around 2650 or 2700 with that load. I assume its reading high but consistently. Shouldn't really effect the ES and SD should it?

I am going to take your advice and ditch the lead sled till load development when I get my .308 back.

time to start hunting for a rifle rest and a tall rear bag. before the lead sled I was using a regular bag and a little rear bag. Problem with that was the shooting bench was so low you just about had to lay dowing across it to get in position. one thing I like about the lead sled is I can sit up erect and get a proper sight picture. Need a pretty tall rest.


actually the pic I posted above for the 69MK was an old pic

this is today's

Don't let the numbers lead you by the nose. The chrony bases all of them solely off the velocity it calculates but it can't see what the velocity is doing to the bullet. The numbers can be terrible but if the little holes are closer together then that is what counts. I can't recommend any particular rest other than say I use a Sinclair lightweight BR rest and Protektor bags (Caldwell also) and have been happy. For your triangle front handguard you would be better served by a platform that has the adjustable wings that pivot at the bottom and fold in at the top. They will fold in at the top pushing the bag in forming a triangle shaped bag around your handguard.  Helps with control.

You know that is funny. I went to brownells and Midway yesterday and that is the exact rest I picked The Sinclair Benchrest (B/R) Lightweight Rest is for shooters who prefer using Protektor or Edgewood owl ear style front sandbags  . I picked the number 2 Protektor bag for the rest and the Protektor Deluxe Double Stitched Mid-Ear Rear Shooting Rest Bag with Heavy Doughnut Bottom Leather Black and Yellow rear bag. Is that doughnut really that important in the rear bag? Is that what you would recomend?

Neither had the stainless foot pads. I shoot off a wood bench and it looks like those sharp points will tear up the wood. Have you used those foot pads? Guess I will have to get those from Sinclair. Wonder what size.

Sounds right but then it depends a little on stock design as to which rear bag. The points on feet are specifically for shooting off wood. They keep the rest from sliding. I have the discs just in case I shoot off something smooth but most of the time it is off wood. The mods have been very generous allowing the discussion of equipment/technique but perhaps that should be saved for another thread in the general AR-15 forum. You can post a link if you get one going. Finishing up a fluted bull 4 groove 1:10 match upper now for the 52gr SMK load so should be putting in some time using the bench rest myself. Could be a hole puncher or it could be a sprayer. Time will tell.