Random Sierra GameKing keyhole

Hey guys, this is like my second thread ever on THR, so go easy please.

I tried doing a quick search but could not find any threads.

I recently loaded up some 65gr. GameKings for whitetail. I got one deer with it, left brain all over the field, absolutely no meat lost.
I know head shots aren't encouraged, but it was about a 75yrd. shot, so easy pickings.

However, I used the very advanced form of sighting in my 1/9 twist AR-15 by shooting small (smaller than a baseball) rocks beforehand and all seemed well. However afterwards when we went plinking again I figured taking along a few targets was a good idea. Most of the shots seemed dead on, but one was a perfect keyhole about three inches low and an inch left at 40yrds. or so. No one I ask has any explanation.

I've shot many 69gr. MatchKings before with sub MOA results, and never anything resembling a flier or keyhole. I believe the 65gr. SGK is shorter as well as lighter than the SMK, so I would think that my barrel should be able to handle it.

In summary:
RRA 1/9 twist 16" chrome lined barrel
65gr. Sierra GameKing
26.0 grains of H335
Lake City Brass
CCI primers
Only one shot out of dozens keyholed about two inches to the five o'clock on the target at a distance of 40yrds. with the rest performing about MOA or better.

Any thoughts?

It was about midday in central Texas a couple weeks ago, so I would say probably mid 50's to lower 60's and sunny. Warm enough to be out in shorts and a tshirt.

Yeah, I load mostly Sierra bullets because I can't find anyone to say a bad thing about them and I've never really had an issue with one until now. Just wish it wasn't with a hunting load.

WNTFW said:

A long shot: Could the key hole be from a ricochet? I had it happen once.

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Good call WNTFW. A ricochet is something I definitely did not think about. I guess technically I was shooting at a rock, so ricochets are definitely a possibility. It was a large flat rock leaning at about a 15 degree angle with one end buried in the ground and dirt on the sides creating a little cave of sorts. I stuck a target on a wooden board and leaned the top of the board against the top of the "cave" so that I was shooting into what looked to me like a natural bullet trap. Plus, we were shooting slightly downhill into it so most round should have been going directly into the ground. However, in retrospect, perhaps it wasn't as smart an idea as I originally thought...

We never heard or saw any ricochets in the few dozen rounds we put downrange, so honestly I never thought about that. I don't know how hard bullets grab at targets when ricocheting through them, but the wood I stuck the target on was just some old dusty lumber I found lying around so the glue didn't work very well and took a couple tries to get it to stay. I presume, a ricochet coming from the other side after traveling through the wood once on the way there, bouncing off the rock, and traveling through the wood again with at least part of the journey sideways would be slow enough to just rip the target off the plank or possibly even knock the plank over.

At any rate, ricochet is better than any theory I've been able to come up with.

Jasper1573 said:

+1 for NCsmitty

Rare occurrence of a bad bullet. Maybe the center of gravity of the bullet was off causing it to wobble severely? Either way, at such a short distance as 40 yds, it shouldn't have keyholed since velocity hadn't diminished yet.

Could it have nicked a twig or something that caused it to wobble? I have had this happen before at 300 yds and the round impacted target at 6 inches low and a couple of inches left.

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Whoops, didn't see your post earlier.

I like the twig nicking theory since we were shooting over a pond with plenty dry twiggy bushes, but I think we were pretty thorough in clearing out all the weeds in sight with our .22s before shooting for real. We got really competitive seeing who can cut off all branches in their dried up shrub first....lots of rematches.

longdayjake said:

You may want to check that load. It seems a little hot to me. By like 2 grains.

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It's over max load in the Sierra book by 0.4 grains of powder, still well below the max charges I've found in a few other manuals and definitely within the safe zone. Again, I'm using H335. I usually load right around max charge of the Sierra book and I've never had an issue. A buddy of mine usually loads 2 or 3 grains over and has never had anything like this happen.

918v said:

Are you crimping the hell out of them? If so, don't crimp and retest.

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I don't think I've ever crimped a round in my life. I'm lazy: lube, deprime, tumble, load, shoot, repeat.

918v said:

I think the only way to solve this mystery is through the use of a Juenke machine.

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Got one handy that I could borrow indefinitely?

Ah well, saves me the hassle of having to go find that bullet.

WNTFW said:

XM855,
When my ricochet came back through the target it was indoors with a .270 after mounting& bore sighting a scope. I would shoot a round, spot it, readjust. After the 4th shot I had 5 holes. 1 was way high & looked funny. I double checked everyone on the line was OK & let them know happened. When I pulled the target in it was keyholed and the paper tears faced us.
I never had it happen before or since. Scary at the time.

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Wow, at an indoor range? I'm assuming the target was as far out as the range allowed, did they have a proper bullet trap? I always feel more nervous about shooting at an indoor range than shooting outdoors...

chrome_austex said:

WNTFW has a good point. The direction of the paper tears would indicate if it was a keyhole or ricochet.

With a rock as a backer, you're going to get some splash back. Its not uncommon for some ricochet shrapnel to tear a hole that looks like a keyhole at first glance.

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The target did not tear and was not lifted off the plank I stuck it to, which is the main point leading me to believe that it was in fact a keyhole and not ricochet. I am almost 99% sure that the hole was an actual keyhole and not a tear in the perfect shape of the bullet going sideways through the target. Could fragments of jacket and lead splatter go through over an inch of wood?

IM391 said:

Food for thougtht. It was documented about 5 years ago that Game King bullets de-stabilize very easily is many different calibers and will also shed their copper very easily at maximum speeds. That is one reason why Sierra came out with the Pro-Hunter series bullet. I had similar problems with .303 and .30-60 and .223 rem. I went with pro hunter in .303 and Nosler Accu Bond in .223 and '06 and problems disappeared that that.

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I did not know that. Does the copper jacket come off mid-flight?? That definitely can't be good for accuracy. However, I don't know the definition of max speeds though, I'm only using a 16" barrel so I hope that should give me some leeway.

lizziedog1 said:

Were you shooting at a rock or a paper target?

If your keyhole shot was at a rock, how you could you tell how the bullet impacted?

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Your confusion is probably my fault for being so long winded. I was shooting at an adhesive backed target (like a Shoot-N-C) stuck on a wooden plank which was propped against a rock, but not directly in front of it. I think a picture would be best. Below is a picture I drew in Illustrator (sorry it's so bad, I'm doing this from my laptop without a mouse); the red arrow indicates the direction of fire, the grey is the rock, and the brown is the plank.

popper said:

Ricochet. Paper plate 25 ft at the base of a good sized post oak tree. Cheap Gamo pellet rifle, flat-nosed lead pellet. Hit the plate, tree and the wall of the house behind me. Paper plate never moved. I heard it hit the wall, picked the pellet up off the porch. No, I didn't look to see if the paper was punched from the other side. Base of the pellet was still round, nose looked like tree bark. Moral of the story, don't shoot at trees, they CAN shoot back. Still have the pellet in my souvenir box of other dumb things I've done.

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Hmm, I hope a piece of lead moving at a couple thousand fps faster than your pellet would hopefully bury itself into the wood at least.

RainDodger said:

One of the posts above got me thinking about your load. I have, sitting right in front of me, a Sierra reloading manual page, for the .223... specifically noted to be for the AR-15, not to be confused with "civilian" .223 loads.

The closest bullet to yours is 63 grains. With H335 powder, it suggests starting with 22.8 grains for 2600 FPS, and a max of 25.6 for 2950 FPS.

I don't know that your keyhole problem is a symptom, but I submit that longdayjake has a point. It's my opinion that your load is hotter than it should be.

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In the updated Sierra handbooks, the 65 and 63gr loads are both listed on that page with the same load data. I recall reading somewhere that someone called Sierra and they say it has something to do with the bearing surface or something causing it shoot similar to the 63gr.

This is the handbook I usually use for my loads, but honestly like I said in an above post, all their loads are a little on the light side and well below the max charges I've found in a few other manuals for similar bullets. I usually load just around max charge or a little above, much less than some people I know... We like slightly warmer loads for hunting
I figure if it's the load causing instability then there shouldn't be just a single bad round.