load data vs yardage

[shoots45s]

I'm loading for 223 with a 55 gr SP bullet using BLC-2 powder. Trying to find the best load for accuracy I did some load testing. All brass was new Lake City. Carbine is a Carbon-15 Bushmaster with a Nikon M223 1-4x scope set at 4x. Shot from shoulder, seated, with front sling mount resting on sand bag (barrel was free to move).

I first tested powder charges from the min of 25.5 to max of 27.5 in 0.5 gr increments, 10 rounds at each. I found that 26.0 gr gave best accuracy at 50 yds (actually 43 yards - a friend had a laser rangefinder). Then I tried different seating depths - from 2.20 to 2.26 in 0.015 increments, 10 rounds each. Same distance. I found that 2.23 had the best accuracy. Grouping was about 2" circle

So I loaded up 80 rounds at 2.23 in and 26.0 gr. Went to the range. At the supposedly 50 yard range, I got similar grouping as before. I also tested with some factory Prvi ammo and my loads are far more accurate than the factory stuff.

But when I went to 100 yards, my bullets were all over the place. No grouping that I could discern. They were more accurate than the factory Prvi stuff at that distance though judging by the number of holes on the target (the range gives two 1 foot paper targets - I used one for the factory and the other for my loads).

So do I need to determine a different load for 100 yds vs 50 (43) yds?

Thanks,

 

[rcmodel]

No.

Probably need to practice more.

Not trying to be sarcastic.

But almost any AR-15 should do better then that with any loads and a 4x scope.

What bullet brand, weight, and type are you using?

At any rate, if a load is only 4MOA accurate at 50 yards, it should be equally only 4MOA accurate at 100, 200, etc.

Or 4" at 50, 8" at 100, 16" at 200, etc.

rc

 

[shoots45s]

I won't dispute that the shooter needs more practice.

I'm shooting these bullets - http://www.wideners.com/itemdetail.cfm?item_id=8950&dir=278|281|1081|1141

RE your comment on yardage - that's what I thought - if I'm 2" at 43 yds, then it should be about a 5" at 100 yds.

For the last ten rounds, I took very careful aim and finger control to let the round fly aiming at the center of the lower left 6x6" corner that was clear of holes. Not a single round hit that area. I'm sure the scope was aimed within an inch of the aim point each time when the round fired. There was some wind but at the speed of the 223 it should not have much effect. And the trajectory is rather flat out to at least 100 yards so there should not have been much bullet drop.

I'd like to understand what's going on before I load up a couple 1000 rounds...

Thanks,

 

[rcmodel]

Any chance there is a more experianced rifle shooter around you could get to shoot your rifle for groups?

At any rate, I'd not worry about seating depth / OAL until I figured out what the problem is. There is no point in chasing the rifling leade with a 5.56 NATO chamber cause you can't reach it.

That bullet, seated to standard length of 2.250" should easily shoot 1" groups or less at 40-40 yards.

Here is my old Colt Carbine at 100 yards with and an EoTech holosight.

Same loads 26.3 W748 - standard 5.56/.223 seating length 2.250".
Nosler Ballistic-Tip vis Win FMJ-BT bullets.


rc

 

[shoots45s]

Nice shooting. I was considering getting a shooing vise to take the shooter out of the equation.

I know it's not the most accurate means of measuring the jump distance but using a bullet in a casing and carefully chambering it and ejecting it, repeat 10 times, I found that the lands were about 2.315" based on the COAL. Obviously with a spec of 2.26, no way to get to the lands.

I'm a bit concerned that with this rather short 55 gr bullet that it's mostly out of the case mouth before it gets to the lands. I was considering trying a 69 or 75 gr bullet set to a COAL of 2.25. The longer bullet should allow it to get closer to the lands straighter before it leaves the case mouth. A 75 gr bullet is at the upper range of weight for the 1:9 twist of the barrel (depends on the source).

I'll check into a shooting vise and see how that goes.

 

[Greg Mercurio]

You might try shooting with sand bags under the front and the rear. I shoot BLC2 almost exclusively and the rifle is capable of near moa accuracy with nothing special loads. But when shooting for accuracy checks I use bags front and rear to eliminate the big variable which is me.

 

[shoots45s]

The range supplies heavy metal stands and sand bags. The front of the rifle is rested on a sand bag on the stand at the far end of the rails (not the barrel). The rear end is on a sand bag and also pulled into my shoulder. I'm trying to shoot from a two point position - shoulder and hand. I do hold my breath and slowly pull the trigger back until it fires. If the gun starts to waver too much, I stop take a couple of breaths, relax and start again. No hurry.

I should mention that there was a metal pole at my right shoulder that kept getting in the way - so some of this might have been me scrunching up to avoid the pole. Should have moved to a new spot. Next time, I'll double check the station they put me at.

 

[Lost Sheep]

Parallax

No one has mentioned the 'scope as a potential source of the problem.

Parallax can become a factor when changing distances. It should be easy enough to adjust out.

http://en.wikipedia.org/wiki/Telescopic_sight
http://www.6mmbr.com/parallax.html

This simple "poor man's" parallax correction is found in this web page
http://bullshooter.blogspot.com/2006/03/parallax-in-rifle-scopes.html

Set up to shoot from your rest as normal. Now, move your head backwards, away from the eyepiece of the scope. You will see that the circular image becomes smaller than the ocular lens. Centralize this image in the ocular lens, making the black band a perfect circle. If you sight each shot like this you will ensure your eye is in exactly the same place, eliminating the parallax error.

but you should read the whole article before charging ahead with just this one excerpted paragraph.

Good luck

Lost Sheep

 

[kutter]

Lost Sheep that occured to me as well, I was also thinking that his bullet weight might be too light if he has a heavy twist barrel. I know my 1:7 twist Sig does not like the 55gr pills. About the lightest I can go with is a 62gr. Not sure if that would mean a geometric increase in error though.

 

[shoots45s]

The barrel twist for this AR is 1:9. I've considered using a heavier bullet to also get a longer bullet to span the jump distance before it completely gets out of the case mouth.

 

[shoots45s]

Thanks for that info. I'm using a Nikon 1-4x20 scope with the parallax set for 100 yards, so it should not have been an issue in this case, assuming the scope is not at fault.

I will check out trying using a more stable shooting platform and sighting as suggest above. I have admit I have not been very careful about ensuring that my eye is along the optical axis.

 

[x_wrench]

i do not want to sound mean, or anything of the like. but right now, until you get to be a better shooter, you might want to consider something like this, http://www.midwayusa.com/product/394466/caldwell-lead-sled-solo-rifle-shooting-rest . it will take much of the shooter error out of working up a good load. after all, you can never really improve, until you know the ammo you are shooting is accurate. once you know that your ammo will group 1" or less @ 100 yards (my personal standard), then you will know that anything over that is you. and you can start fixing your shooting problems.most shooters that are having accuracy problems (at least that i have seen), the problem can be traced to trigger control. one thing that i have done, and still do during the winter when i can not get out, is to mount something like this to the gun, and dry fire practice. the constant beam will allow you to see how much the gun moves when you pull the trigger. set your scope on 1 power, and watch the beam. if it wiggles around when you pull the trigger, you will see it. you can start out aiming across the room. as you get better, go for longer distances. i can see a curve reflective sign out of my window about 80 yards up the road. and the laser really makes it glow. i am sure you can find many self help books on the subject as well. but the best investment may be to do a couple of sessions with an expert. the ideal set up, would be one of these, http://www.midwayusa.com/product/51...ng-system-fits-all-9mm?cm_vc=1978BrandPopProd . but i do not see one in 223.

 

[788Ham]

There was a guy at the range this past week, shooting an AR .223, using factory ammo, 55 gr. Shooting at 50 yds., he couldn't get them to group worth a hoot, I think too, he was afraid the scope would nick him, he was pulling away from the rifle just as the round went off. I shot 9 rds., adjusted his scope about 12 clicks LFT, moved to center of bull. He shot it several times, still pulling away. I told him I thought he ought to go to a heavier bullet, 60 or 62 gr., see if this didn't help, I thought with the AR twist, this might be causing the problem too. Just a curious thought, but maybe this will help in your case too.

 

[brickeyee]

The barrel twist for this AR is 1:9.

Or 1;7, or 1:7.5.

It depends on what the gun was set up for.

 

[shoots45s]

It's a Bushmaster Carbon-15 and it's stamped on the barrel as 1:9

 

[Walkalong]

A 1 in 9 twist will shoot those Hornady bullets just fine.

Most rifle scopes with no parallax adjustment (Like the Nikon M 223 1X - 4X scope the OP mentioned) are adjusted for zero parallax at 100 yards. The parallax at 50 yards would be negligible. The closer to center you have your eye, the less parallax is as well.

I have that scope, and the reticule isn't exactly the best for very fine shooting. Fast, accurate shooting yes, but not precision shooting.

 

[shoots45s]

I'm the OP...

I went to the range today with some rounds that shot well at 43 yard and poorly at 100 yards. I used a plastic MTM shooting rest (picked up from Academy for $35) that was far better than the sandbags supplied by the range. And I took very careful care to ensure that my eye was aligned along the scope axis. They still shot poorly at 100 yards but better than the factory Prvi Partizan stuff. THis was with BLC-2 powder.

That said, I picked up some CFE223 powder yesterday and loaded 10 round each of 55 gr SP at 26.0, 26.5, 26.9, 27.4 to max of 27.8 with the COAL to the Hodgdon spec of 2.200". I wasn't able to get the targets but the low one shot about an 8" circle. The next two were about 3" and next to highest was about 6" and highest even larger and I think I had one keyhole bullet. I think the middle load was the best - the pattern was about 3" or less and mostly circular. They all shot low 3" and right 2" of the aim point. I want to get a smaller shot pattern first and then adjust the scope zero.

So two questions:

1) should I do a seating depth ladder test on this bullet with this powder now to see if the pattern tightens up?

2) Should I redo the powder ladder test on the BLC2 powder for 100 yards since I'm still getting poor groupings at 100 yards. The original was done at 43 yards. I wonder if the barrel vibrations/harmonics are affecting the accuracy between the 43 and 100 yard shots.