keyholing .223

[George Mabry]

I have a Ruger Mini 14 in .223 that is keyholing at about 50 yards. I can only think of three reasons for a bullet to keyhole. 1. underpowered load for that design of bullet. 2. undersized bullet. 3. the bore is shot out/damaged crown.

I've eliminated the first two possibilities. That is the same bullet and same load I've used for 20 years. However, before taking any action I do intend to run some factory ammo through it just to make sure it's not my reloads.

Does anyone know of anything else I can check before replacing the barrel?

George

 

[rcmodel]

If you have never used Copper Solvent to remove jacket fouling in 20 years, that would be the first thing to do.
Severe copper jacket fouling can completely fill the rifling grooves, and key-holing will most surely follow.

Other then that, inspect the crown for cleaning rod damage or dings from a rock, etc.
Use a Q-Tip swiped around the muzzle both directions. Any small hard to see dings should pick up cotton fibers so they are easier to spot.

No mention of what bullet weight you are loading, but a 20 year old Mini-14 will have a fairly slow rifling twist and will not stabilize heavy .223 bullets now so common. I think maybe 1/12 back then but I'm not sure. If it is, you can't shoot bullets heavier then probably 60-63 grains.

rc

 

[Dave P]

I would vote for wrong bullet weight (which really means the bullet length) is wrong. I forget which way you should go (heavier or lighter) ...

RC must be right - try 55 gr bullets.

 

[George Mabry]

Thanks for the advice RC. I'm sorry to say that copper build up never occurred to me. I'll pick up some copper solvent tomorrow and I'm betting that that is the problem. Although that barrel has had a few thousand rounds put through it over the years, I would be surprised if it was enough to shoot out a barrel.

Dave, all I've ever used was a 55 grain bullet. That rifle use to hold a pretty good group together at 100 yards with the 55 grains.

 

[ngnrd]

If you haven't changed bullets, fouling may certainly be the issue. But, if you have changed bullets, you need to remember that bullet weight isn't the issue, but rather bullet length. And there are several long-for-weight bullets on the market these days. I'm specifically referring to all the lead-free varieties available now. And the twist rate in the Mini has changed several times over the years. Could still be a long bullet/slow twist issue.

 

[Sunray]

After a really good bath and a close inspection of the crown, slug the barrel. Hammer a cast bullet or suitably sized lead fishing sinker through the barrel(normally done from the chamber end, but from the muzzle will do.) with a brass rod and a plastic mallet(won't bother the crown) then measure it with a micrometer. Much over .223", it is shot out. Isn't likely to be shot out with just a few thousand rounds though.
To find out what its twist is, put a lubed patch on a cleaning rod and put it in the muzzle. Mark the top of the rod at the muzzle and at the handle end. Push the rod through for one complete turn of the handle end mark. Mark the muzzle end again. Remove and measure the distance between the muzzle end marks. That'll give you the twist. Early Mini-14's had a 1 in 10 until 1985, 1 in 7 until 1994, currently 1 in 9.

 

[Trent]

Most crown damage can be seen easily. Some crown wear won't be visible to the naked eye. If one "side" is worn (oblong shape), sometimes you'll only find it with very careful measurement and magnification.

I'm assuming your rifling / throat isn't worn to hell and gone... if your throat has eroded enough, "short" 55 gr bullets can yaw even before engaging the rifling, and travel the length of the barrel, leaving with run out. Bore scope it and see what your lands look like and how much feed (gap) you have.

Mini-14's are cleaned from the muzzle end, so it's a 100% certainty that if you don't use a rod guide (crown protector) on the end of the barrel when you clean the rifle, that the cleaning rod itself rubbing along the interior lip of the crown WILL wear it over time. The majority of crown damage I saw when running a gun shop was caused by improper cleaning; you MUST use a rod guide to protect the crown when you clean from the muzzle, or you WILL damage the rifle, period.

Take it to a competent gunsmith with the proper measuring equipment. If the crown is worn, get it recrowned, and it'll shoot good as new. If the throat is worn and your bullets are jumping for longer than .25" before engaging the rifling, might be time to consider a new barrel... or perhaps a trade on a new model.

 

[W.E.G.]

Its your reloads.

Use different ammo.

 

[GunDungeon]

What is keyholing?... i have heard the term used but never been explained.

 

[x_wrench]

another possability is that the twist rate of the barrel is to slow to stabilize the bullet you are shooting. that is a much more common thing in these small bores than you can imagine. when i started shooting small bores (223), i had a rude awakening to this fact. try shooting a light weight projectile like 40-50 grain bvullet, and see how it reacts. it will probably cure your problem.

 

[NCsmitty]

That is the same bullet and same load I've used for 20 years.

x_wrench, the quote is from the OP, so something else is going on.

As rcmodel mentioned, probably a buildup in the barrel causing the bullets to hit sideways.



NCsmitty

 

[x_wrench]

What is keyholing?... i have heard the term used but never been explained.

keyholeing is when the bullet hits the target sideways instead of straight on. so instead of leaving a nice round hole, the hole is eliptical in shape. there can be several causes of this.

That is the same bullet and same load I've used for 20 years.

x_wrench, the quote is from the OP, so something else is going on.

yes, i didnt read all of the posts. my bad. sorry.

 

[ngnrd]

That is the same bullet and same load I've used for 20 years.

Wow... I don't know how I missed that, either. :banghead: