keyholing

S

shadyoaks

New member
Hi All-First post under this username, but I've been lurking and posting on this site for about ten years. I'm having a problem with a gun that I recently acquired (used)and since it's a varmint caliber I'm seeking help on this site.
In order not to tweak a bunch of personal biases, I'm going to withhold info on make, model, bullets, powder, etc. I will divulge that info later but first of all, what would you suspect to be the cause of keyholing? Not every round, but it will-all of a sudden-throw one of three shots for three or four groups and then settle down. Most of the keyholers go about 6" to the left. General grouping is inconsistant--fair to good for the caliber. What are your thoughts--where would you look first for the culprit?
Thanks, Steve
 
Quote:
Hi All-First post under this username, but I've been lurking and posting on this site for about ten years.



What name did you use to post under?

As for your problem, bore scope the barrel. A friend had a Remington 17 rem that did the same thing. New tube and all was better.
 
As Dan Carey said, too slow a twist rate for a particular bullet. If it is marginal, then a little more velocity, if you can get it, may overcome the issue.
 
I had a .22 Hornet in a TC Contender that would do the same thing with 50 grain bullets. I was told by a TC rep. that the twist was 1 in 12 (which seemed to me to be fast for a Hornet), but, regardless, it should have stabilized the 50 grain bullet. I slugged the barrel and found the bore was .224" at the breach end and .225" at the muzzle. I sent the barrel back to them and they replaced it. No more keyholing was experienced with 50 grain bullets.

I would expect if the barrel crown was very bad, you might get keyholing when using a bullet of marginal stability.
 
All of the above and one more possible. Shooting thin skinned jackets from a 17 Rem. that was fouled caused a problem for me. Then this last summer I had the same thing happen with a 17 HM-2. Again a good cleaning stopped the problem.
 
A short bullet or bullet with a very short bearing surface (like a light boattail) making a long jump to the rifling lands. My .270 keyholed with 135 Matchkings loaded to magazine length and making a .125" jump.
 
Quote:
As Dan Carey said, too slow a twist rate for a particular bullet. If it is marginal, then a little more velocity, if you can get it, may overcome the issue.


+1
 
Withholding chambering, bullet type and wt, and firearm make, adds a lot to what if. Check the crown for a small burr, check twist rate against bullet type and wt and vel. all these things can contribute to keyholeing and since it is intermitent i would hazzard that it is a monor issue that can be easily fixed.
 
If It has a muzzle break that would be my first choice of where to look.

I had a custom .17 Rem and it keyholed everything except one particular load. The entrance to the break was eroded and yawed the bullets.

Cut off the break Viola! back to 1/2 inch groups.

Dave
 
WOW!!! I didn't expect this much responce so quickly--Thanks to all who answered. First off-Crapshoot-I used the name durango before. When we moved from California and I tried to change the Email addresses it got so messy that I just gave up and started changing everything.
Back to the problem at hand, I'm going to the range tomorrow and have been busy reloading, so I'm not going to try to cover all the parameters in this post. The rifle is a Savage model 10 'package gun' and the scope is now a Tasco variable target/varmint. The stock is synthetic and will be replaced with a Boyds thumbhole when all this other foolishness is resolved. Caliber is .204 Ruger. I can't find a borescope within a hundred miles, but a friend who claims to have a 'good eye' has looked it over and couldn't find any thing with a 20X loupe(sp?). Bedding is suspect, but I don't want to make changes for now since both the dealer and savage are willing to "make it right". I know--just send it back!!--probably will, but it's driving me nuts and I want to make sure it's not me. Up to now I've been playing with 32 and 34 grain bullets in front of Benchmark (26.0 to 27.5 grains) and have gotten sub 1/2" groups at times and then up to 1" with factory and Midway's Dogtown bullets. Tomorrow, I"ll burn up the last of my Hornady 40 grain bullets and see if they will make a difference. I'm thinking that Colorado Pete may be close to the problem--I can't even get the little bullets to touch the lands and I'm not real sure that the long ones are very close but I rechecked my first targets with the 40 gr Vmax and not one keyhole until I switched to the smaller bullets.
Anyway, thanks for your indulgence, we'll see what tomorrow brings. Steve
 
I am new to the 204. From the others I have talked to about what bullets to shoot thru it, most have mentioned the 39gr Blitzking over the 40gr V-max. I have not tried the 40gr V-Max but I did get the 39BK to shoot a 5 shot .374 group today, after that I think I will just stick with BK's.
 
Quote:
Shooting thin skinned jackets from a 17 Rem. that was fouled caused a problem for me...... Again a good cleaning stopped the problem.



I had the same thing happen to me.
 
Shadyoaks,

Same thing happened to me with the password. I posted here for several years as "bacova", unfortunately for me I let my 'puter "remember" my generated password. Last Fall I moved and had to switch ISPs. When I tried to sign on as "bacova" I couldn't remember my password because my 'puter had been doing it for me. PM would email me something or other when I clicked the "help" button, but it went to my old email addy, which was defunct. As a result I had to do the same as you, come up with a new name/password and start over again.

Moral of this story, if you're signing on here with a 'puter generated password be sure and write it down somewhere where you can find it years later if necessary, otherwise you'll be starting over like Shadyoaks and myself.
 
Have the same problem with my 12 VLP in 204 ruger using 32 gr blitz kings. 100 yd group looked more like a shot gun pattern unless I kept the loads at the lower end. All other bullets worked fine. The 40 gr V-max was not the greatest for accuracy. A 1 in 12 twist is right on the edge for stabilizing the 40 v-max. The 39 gr bk's are very accurate.
 
Since barrel twist is within + or - a half twist my guess is your factory rifle is not a one in twelve but perhaps a 1 in 12.5. Lots of guys that rebarrel 20's go to a 1 in 11 barrel to take care of that issue.
 


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