.223 keyholes...HELP!

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Mr White

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I got a great deal on some Hornady 53 gr match bullets, $8.50/100. I figured I could come up with a good load for 100 yd matches.

The loads: Winchester cases, CCI 400 primer, 24.0 and 25.0 gr H4895, Hornady 53 gr match bullet #2250,

The gun: Bushmaster DCM AR-15A2 service rifle. 20", 1:8 barrel.

Both loads shot OK. the 25 gr load shot a little bit better, but with both loads I had 2 of 10 rounds keyhole through the target. They stayed within the small group but pierced the target perfectly sideways.

Anyone else experience this? Any suggestions for better loads for this bullet or other reasons why this might be happening would be very helpful.

I'm kind of at a loss. I know the barrel is OK. Its only got less than 5000 rounds through it and I've never had a keyhole from this gun with any other bullets from surplus M193 to M855, to 60, 69 and 80 grain handloads. What gives???
 
What kind of velocity, what twist rate. Are they barely stabilized and some running out of gas and keyholing? Are they spinning too fast? Most likely. Strange. :)
 
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In barrel maker Lilja's twist chart, the 1:8 is ideal for 80gr bullets; Shilen says heavier than 70 gr; which means bullets of slightly higher and lower weights will perform well. The 1:14 is listed by Lilja as ideal for 50-52 gr; Shilen1:14 up to 55 and 1:12 up to 64gr.

Those bullets are being spun too fast and are probably starting to come apart.
 
Use a lighter load, the least that will function the action for rapid fire and see if that quits tipping them.

Less than 5000 rounds by how much? Target shooters of my acquaintance don't seem to get near the accurate barrel life that internet experts do.
 
Less than 5000 rounds by how much? Target shooters of my acquaintance don't seem to get near the accurate barrel life that internet experts do.
Click to expand...

Many Benchrest shooters consider "about" 3000 rds to be some sort of magic number for usable barrel life. The big dogs can probably tell the difference between their barrels between 2000 and 3000 rds. I have seen shooters trash a barrel at around 2000 rds because they thought it was "shot out". I would shoot mine till 4000 or a bit more because I am cheap and am not going to win the Supershoot anyway. I can tell when a barrel starts to lose its accuracy, I just shoot in denial for a while. (Clean harder and pretend it's OK.) :)

All that said, a "worn out" Benchrest barrel will still shoot mighty good, it just is not going to win against the big dogs. :)
 
Thanks for all the replies.

No, I don't have a chronograph... yet.

Walkalong, A service rifle barrel should be good for over 7000 rounds. We ain't benchrest shooters. And no, I probably wouldn't hold my own against the big dogs, but even with a brand new Derrick Martin-built gun, I wouldn't hold my own against the big dogs. :)

I kind of suspected that the twist and velocity were just too much for those light bullets. My buddy suggested dropping back on the charge. I loaded up some with 23.0 and 23.5 gr and headed to the range tonight. The 23.0's shot a little better and neither one keyholed. I think I'll just load them up for plinking with 23.0 gr H4895.

Even though they didn't shoot too bad, they weren't as good as my proven 100 yd load: Winchester case, CCI 400 primer, 25.0 H4895, Sierra 60gr HP Varmit. This load shoots GREAT in my AR. The first time I shot that load in a match, my score jumped about 25 pts from my average.
 
why are we talking about benchrest and # of rounds through the barrel. if he put 200,000 rnds through a barrel, it wouldn't cause keyholing. would it? i've never heard of anything like that before. and nobody shoots benchrest with an AR, or puts surplus M855 through their benchrest guns :)

Mr. White, there's no real reason to think your barrel's NOT 1:8 twist, but I once bought an upper that was supposed to be 1:7 and it turned out to be 1:9. I didn't find out until after I put 6000+ rounds through it and then tried some heavier bullets that wouldn't stabilize.

I'm just saying, it wouldn't hurt to check it yourself.
 
why are we talking about benchrest and # of rounds through the barrel. if he put 200,000 rnds through a barrel, it wouldn't cause keyholing. would it?
Click to expand...

No, it would not, but as often happens, we, or at least I, got off topic somewhat. :rolleyes:
 
heh, i've been scratching my head all last evening trying to theorize some sort of physics that would cause keyholding from a worn out barrel :)
 
I hope you did not lose any sleep. :) It would have to be some kind of seriously worn out/damaged.
 
As to barrel life, I saw a target shooter bring a rifle with a documented 4700 rounds of .308 through it to the range. He could not depend on hitting the 6x6' target backer at 1000 yards. Finished the match with a borrowed rifle.
I do not recall any keyholes, the barrel would probably have been acceptable on a military or hunting rifle for a good deal more use, but it was no longer a target barrel.
 
Mal H - The backer is 1/2" thick rubber. I staple an old paper target to the rubber and then 6" black paper plates over that. It works well. I get 5 bullseyes in the area of an SR1 target.

Taliv - I believe with about 5 9's of certainty that its a 1:8 barrel. I tested it by runing a patch thru it and the shaft of the cleaning rod did a complete revolution once every 8". It hammers the 80 grainers in at 600 when I get to shoot across the course. And like I said, it shoots 60s pretty damn good at 100.

Whatever was causing it, I'm not gonna worry about it. I'll load up the 53s for practice and keep shooting the 60s for 100 yd matches.
 
The reason I asked about the target is that bullets hitting materials such as copier paper or even paper plates like you're using will tear holes along the grain of the paper that look a lot like a keyhole problem. I wouldn't rule that out, especially since you said the hole was in the main group.

If a bullet is unstable, it will almost never hit where it is supposed to. Further, if one or two bullets keyhole and the remainder don't that is suspicious as well. Either the load/spin/bullet is incompatible or it isn't. You rarely see off and on keyhole problems with the same batch of rounds. If one or two didn't keyhole out of the group of 10, then that would be more like what I've found with keyholing loads.
 
It is not the twist. In theory it is better to overstabilize a bullet than not. It is the bullet length that the rate of twist is relevant to not so much the weight (though the heaver bullet is usually longer).
My HBar is 1 in 7 and will hold 10 rounds in an 8" circle using the Hornady 55gr FMJ and IMR 4895 (rested iron sights).
What data are you using to load that bullet with?
I would continue with the 55gr and start a new load using a different powder (IMR 4895 would be my next choice)
 
Try a heavier bullet and see what happens. A 1:8" twist is way too fast for the 53gr you are using. I shoot 62gr loads out of a 1:12" barrel using the same powder and also varget. .5" groups are normal with those components
The light bullets are possibly coming apart spinning that fast.
 
May I suggest looking at Hodgdon website?

http://data.hodgdon.com/cartridge_load.asp

-----------------------Start Load-------------Max Load-----------------
Bullet--Powder--COL---gr----Vel---Pressure----gr-----Vel---Pressure----
53SMK-H4895--2.200" 25.0 3166 37,400 CUP 27.0C 3383 48,600 CUP

Your loads of 24 and 25 grains are below or at the bottom of what they are recommending. I find it hard to believe that a 53gr bullet would fail to stabilize in a 1:8 barrel and I have not cross checked with other manuals, but perhaps your load is too light.

I shoot 52 and 53 grain bullets regularly through 1:9 and 1:7 .223 barrels, using 26.5gr 748, and get 1.25" or so at 200 yards.

CDD
 
Mal H said:
The reason I asked about the target is that bullets hitting materials such as copier paper or even paper plates like you're using will tear holes along the grain of the paper that look a lot like a keyhole problem. I wouldn't rule that out, especially since you said the hole was in the main group.
Click to expand...
I thought that too, but the holes in the rubber tell the tale.

Normal rounds leave a tiny little self-healed pinhole in the rubber. The keyholed rounds left a line, just about the exact length of the bullet. The lines lined up with the keyholes perfectly, and some of the KHs were very distinct.

I got the data from either the Lyman book #47 or from the Speer book that came with my Rockchucker kit, I forget which. The load was max 25.5 gr of I4895. If I can find another load that someone has proven in a 1:8 AR, I'll try it. Otherwise, I'll keep shooting the 60s for matches and shoot the 53s for practice. As cheap as they were, Its not like I feel I'm out anything if they don't shoot great.

Maybe I'll pick up a pound of 748 and try working up to the load you suggested NuJudge
 
BAD BATCH OF BULLETS..............!!!!

I've had a number of bad batches of Hornady's. If you have noticed some white powder on the bullets, kinda like some white "mold" growing on the bullets lead, It's quite possible the bullets have gotten damp at some point in their storage and oxidation has started taking place. This will take place under the jacket causing core-jacket separation. You'll probably notice some staining of the jackets- water stains instead of bright shiney bullets. Nosler avoids this by packing in plastic wrap. Speer by using Plastic boxes. Sierra's are also suspectable to the "dampness" here in the S.E. USA.

I had this occur in a batch of 117gr Hornady BTSP's back in 1993. About 1/2 of the bullets in a box had the "white mold", and would shed the jacket in flight. I had to switch to some Nosler 85gr BTSP's that I'd taken to Montana on a Mule deer hunt to use on pararie dogs after the deer hunt, to finish my deer season. After 7rds at 4 Mule deer at distances from 125-300yds and NO hits, I found the bullets wouldn't hit a 2.5'x3' cardbox at 200yds. Only one hit, and it was a full keyhole.

The second was a batch of Hornady 50gr SX .224"s. The whole box had the "white skim" and wouldn't shoot at all, except at subsonic speed (l loaded them up in a .22 Hornet over 3.0gr of Bullseye and shot them up on a "pigeon" shoot.

The last was a box of 1,000 55gr .224" w/cannulure. I'm down to about 200 so I'll soon be shed of them !!!!!
 
My 6.5 twist .223 will blow up 75 gr Hornady A-max at top load levels. (I was desperately trying everything after I found that 90 gr Sierras would not stand the load needed to get to 1000 yards supersonic.)

They shoot quite well loaded down a bit and I will use them up to 600 yards.
 
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