5.56 Tumbling/Keyholing??

[Hogdaddy]

I'm sure I'll get a wrist slapping for this but here goes:
Wan to use my TC Contender .223, 14" barrel as a stand gun for hog hunting.

Since I've got lots of 5.56 I figured I'd use it as practice/sight in rounds and get better .223 ammo for actual hogging. Did LOTS of googling, reading/studying on shooting the milspec round in a saami chamber. Weighed the various articles and pontifications and decided to go for it.

Went to range to shoot both rounds through my Contender. Used Hornady 55 gr TAP FPO and green tips.
Recoil and flash were noticeably greater with 5.56, also they keyholed in the paper on every shot at 25yds. The .223 made nice round holes. Both were pretty much in the same area of impact.

In my opinion there are only a few reasons tumbling could be happening:
Short barrel
Different leade
Twist.

Your comments will help.

BTW I'm not shooting any more milsurp in my Contender...

 

[Hogdaddy]

Just pulled a range target from May when I shot my AR 5.56 pistol at 25 yards and dang if they weren't all tumbling! I blamed it at the time on the ammo which was milsurp frangible. Barrel length is 8" and it's a 5.56 chamber???

 

[FrankT]

Is your Contender a 223 or 556 chamber? The 556 runs higher pressures than a 223 and that may be why you are keyholing also.

 

[TEXASLAWMAN]

May not be fast enough twist rate to stabilize. 55gr???

 

[Brian Shaffer]

I assume the barrel is not shot out, right? The only times I have had keyholing issues with 5.56 was after the lands were wore away.

 

[Hogdaddy]

New barrel, .223 chamber (but the AR pistol is 5.56), twist rate is a possibility - I measured it, think was 1x10. Leaning towards leades, that's definitely different between the two chambers and does create pressure issues from what I read http://www.rifleshootermag.com/rifles/ar-15/5-56-and-223-are-they-different/

 

[FrankT]

remember safe to shoot 223 in a 556 barrel, not so much a 556 in a 223 barrel.

 

[Ratdog68]

Yes, generally speaking, a .223 chamber isn't suited to handle the higher pressures of 5.56 loads.

 

[Hogdaddy]

Yepper

 

[rob072770]

My old DD M4 had a 1in7 twist rate and was rate 5.56. I am not an expert but is not 1 in 10 not enough to stablished the bullet

 

[TEXASLAWMAN]

Are you shootin 55gr or 62 gr? The older barrels will only stabilize 55gr.

 

[Shooter]

too many variables here. Try 77 grain Black Hills, and let us know what you think. The TC should handle it well and it is a better killer.

 

[TEXASLAWMAN]

If it's already tumbling a heavier bullet is not good I'm betting that the barrel twist is only enough for 55 gr.

 

[Hogdaddy]

The 5.56 I was shooting is SS109 - 62 gr
I'm going to check the twist and let you know.

In the target I posted, all the round holes are 55 gr Hornady TAP FPD. Interestingly, both 5.56 and .223 were shooting about the same accuracy. The cheap tasco red dot was only on the pistol to allow me to test the 5.56/223 compatability.

 

[pruhdlr]

Out of the things that you have listed in your OP,freebore and length of bbl would not have anything to do with the instability of the bullet in flight. As long as the velocity was kept up even a 1:12 bbl would easily stabilize a 223/5.56.

I used to have a 14" bull on a T/C pistol and it was super accurate with the bullets up to and including the 60's. If this is a OEM T/C Contender bbl I believe that the twist is 1:12. I know that it is not 7,8,or 9.

You CAN shoot 223Rem in 5.56 bbls however I do not think that T/C ever chambered that bbl in 5.56X45. Only in 223Rem and not even in Wylde. You also can shoot 5.56 in a 223Rem bbl just as long as the ammo is not loaded up to absolute max pressure.

Do have any kind of muzzle device on the gun ?? --- pruhdlr

 

[rgilbert]

Mine would not shoot anything above a 60 grain bullet. I got the same results with ss109. Mine was super accurate with 50-55 grain bullets. I don't remember the twist, but I don't think its fast enough for anything but the lighter bullets.

 

[Hogdaddy]

twist is 1:12 left hand - it that makes any diff.

The only reason I wanted to shoot the 5.56 in my TC is money. I've got lots of the SS109 I would use for as much target practice as I wanted, then buy commercial for hogging.

If I can't shoot those 109s I'll prob just buy some cheap commercial $7/box for practice...

 

[Hogdaddy]

No muzzle device

too many variables here. Try 77 grain Black Hills, and let us know what you think. The TC should handle it well and it is a better killer.

Curious - if it isn't able to stabilize a 62 gr bullet why would it stabilize a 77?

 

[pruhdlr]

Remember also Hogdaddy,they make some damn great hog/deer killin' bullets nowadays in the 50-55gr weights. If you choose one of the all copper ones make sure you are mindful of their LENGTH for the stability thing. --- pruhdlr

 

[Hogdaddy]

Remember also Hogdaddy,they make some damn great hog/deer killin' bullets nowadays in the 50-55gr weights. If you choose one of the all copper ones make sure you are mindful of their LENGTH for the stability thing. --- pruhdlr

Thanks, I will, but what length would be the longest you would recommend, stability in mind?