Finally shot my AR I built earlier this year

[Rdlningcltchdmpr]

I mess with AR's a good bit. Couple of questions:
- what twist is your barrel, maybe I just missed it?
- what size is your gas port?

If you gas port is the proper size, and they are usually oversize, undergassing can be due to not getting the hole in the gas block centered over the gas port. If you remove your gas block now, you will be able to see exactly where it was vs the gas port.

There is a secret trick to getting the gas block absolutely perfect, it's what i use when i build. It's called the spaghetti trick.

 

[Loudcherokee]

Clearer understanding now. I see your 24.2gn load looks very promising but I would get away from the LC brass and try Winchester or Lapua .223 brass. Your waterline with this load looks good but the horizontal might just be inconsistent body placement behind the gun. if your applying intermittent cheek pressures, and I assume you are a "righty", you could be driving the shots to the left.

I planned to try some quality brass but the LC and some RP is all I had on hand, and I won't use RP for precision stuff.

I am actually a lefty, and tried my best to get a positive grip and cheek weld on the gun, but its been a long time since I've done any serious shooting. I probably weigh about 60 pounds more, have smoked a lot more cigarettes (gave those up in 2016 except occasional) and drink too much coffee. When zoomed in at 24x, I can see my heartbeat in the scope throwing the cross hairs off about 3 inches either side, normally left. Couple that with the excitement of getting to shoot a brand new rifle after building it 7 months ago, and being just a tad pressed for time, it wasn't the best circumstances but its what I had available.

Hence the comment about ordering a lead sled to take as much of "me" out of the equation as possible before I do any further load development. After that I will work on my technique and try to get back to how I used to be. I was once able to shoot one hole groups with my .308 all day at 100 yards but couldn't even manage a 1 inch group with that gun yesterday.

LC

 

[jepp2]

it's what i use when i build. It's called the spaghetti trick.

Please share. I always make a drawing showing the gas port start end end relative to the step in the barrel and the same for the gas block. Then I calculate how far off the step the inboard end of the gas block needs to be.

 

[mdram]

Please share. I always make a drawing showing the gas port start end end relative to the step in the barrel and the same for the gas block. Then I calculate how far off the step the inboard end of the gas block needs to be.

its simple
get a short piece of spaghetti put it in the gas block hole
slide gas block inplace, move until spaghetti falls into barrel.
tighten block down
use a cleaning rod to break off spaghetti and let it fall out of barrel
repeat as need until no more spaghetti remains

same principal as the little plastic things they sell for doing it

 

[jepp2]

get a short piece of spaghetti

Probably best to use it uncooked....

 

[mdram]

Probably best to use it uncooked....

might be, but if you cook it and add butter it slides better

 

[Rdlningcltchdmpr]

Please share. I always make a drawing showing the gas port start end end relative to the step in the barrel and the same for the gas block. Then I calculate how far off the step the inboard end of the gas block needs to be.

I used to do that, spaghetti was what was recommended to me to use but it was too loose for my liking. So i cut a steel pin that fits just right in the gas port hole, not to tight, not too loose. Make it long enough so it is flush when you insert it into the gas hole. Then slip the gas block on and turn the barrel upside down as you look in the end of the barrel. Now move the block back and forth, and left and right until the pin drops into the block. Then mark the block with white marker to retain proper location. Turn barrel right side up and make sure pin drops back into barrel. Then remove block so as to remove the pin and then put the block on permanent in the perfect alignment. One of my barrels was a Krieger and my colt milspec gas block would not line up so after close exam/ measure i had to grind off .025" from the end of the block in order for it to go on far enough for the pin to drop. It now works perfectly, cycle's everything.

 

[Rustytigwire]

i tried looking inside the bore for gas block line up with my Lyman borescope last night but could not see in the hole.
test fire soon. hoping it works.

 

[jepp2]

hoping it works.

If it doesn't you will have a "left" approved single shot rifle. But the good news is, when you take the gas block off, you will be able to see where the gas port was.

 

[jelenko]

The bolt not locking back can come from the gas system or something in the lower.
WOA has a simple test that allows you to determine which is causing the issue. https://www.whiteoakarmament.com/resources/faq.html#short

On brass - there is nothing wrong with LC brass, assuming it's been resized with good neck tension and the mouths have been deburred/chamfered, it will support 1/2 MOA groups. Of course, with tuning the powder charge, match grade bullet. Even for mag length loads, the groups can be fine tuned with seating depth less than 2.260.
Deburring the flash holes and/or uniforming the primer pockets seems to have little effect at the 1/2 MOA level.

 

[Loudcherokee]

The bolt not locking back can come from the gas system or something in the lower.
WOA has a simple test that allows you to determine which is causing the issue. https://www.whiteoakarmament.com/resources/faq.html#short

On brass - there is nothing wrong with LC brass, assuming it's been resized with good neck tension and the mouths have been deburred/chamfered, it will support 1/2 MOA groups. Of course, with tuning the powder charge, match grade bullet. Even for mag length loads, the groups can be fine tuned with seating depth less than 2.260.
Deburring the flash holes and/or uniforming the primer pockets seems to have little effect at the 1/2 MOA level.

I will have to give that a try. I did at first think it may be a mag issue, but they're brand new 10 round pmags and they fed all other ammo flawlessly. It was only the frontier that presented an issue with short cycling.

As for the LC brass I used, it was all trimmed, chamfered, deburred, flash hole deburred, and primer pockets reamed to remove the crimp, not swaged. Then it was weight sorted and all cases used were between 91.6 and 91.9 grains empty.

I'm going to go back and try some additional charges at .10 grain increments around 24.2 and 24.8, also 25.2. So my next tests will be 24.1, 24.2, 24.3, then 24.7, 24.8, 24.9 and 25.1, 25.2, 25.3.

Those seem to be the best groups if the horizontal spread is taken out of the equation. Then once that is locked down I will start playing with seating depth, although I'm at max mag length. Interestingly enough, when measuring this chamber, I find that 2.250 OAL is only .025 off the lands. Not sure if this is an effect of the 223 wilde chamber or not. I measured multiple times with the Hornady OAL gauge because I thought that seemed short.

LC

 

[Loudcherokee]

Got some scope pictures of my gas port. It appears to be lined up properly.

LC

 

[Loudcherokee]

Here's some more pics. Anyone know what those diagonal marks might be? Its near the throat.

LC

 

[JEFFPPC]

Windflags will help the horizontal .

 

[2506]

Those are tool marks in the crappy BCA barrel. Good luck trying to find consistent accuracy. Been there done the BCA barrel thing and have the tee-shirt and hat. You get what you pay for I learned. You can't expect to get quality out of a cheap barrel. With all the ruff tool marks in their barrels they foul easy and consistent accuracy goes out the window. By the time I found this out I had fired enough ammo and made enough trips to the range burning my gas to have payed for a high quality barrel that will shoot right out of the gate.