Ever Seen This Before?

It looks to me like the crown of barrel has been nicked somehow. Try painting the crown with magic marker and shoot a few rounds. The residue around crown after the shots should be even all around the bore.
 
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According to the Greenhill theory a 1 in 10 twist would be ideal for that load. It sounds like bad bullets to me.



Raid...

The Greenhill formulas were based on the lead round nosed bullets of the past (FAR PAST /ubbthreads/images/graemlins/wink.gif ).

They cannot take into account things like plastic tips.

I don't think anyone has come up with a current formula that takes these things into account.

For example, the 30 cal, 155 Scenar bullet does NOT use a 14" twist, (which is recommended by Berger and the others)... because the entire front half of the bullet is empty airspace, and it is about as long as a 190 SMK, and thrives on a 10" twist.

So Greenhill is pretty much pase'

.
 
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"... It looks to me like the crown of barrel has been nicked somehow.."



"It looks..." Did you see pictures of the crown... somehow I missed them. Where are they posted??

Three weeks ago, I had targets like his with two sideways bullet holes, and they came from a $700 Schneider barrel with a perfect, recessed crown.

So how do you explain that??
 
Yes, I have seen this before with my 17 Rem. it would shoot 20 grain fine but would keyhole 25 grainers. It was caused by carbon and copper build up. The only cure was to clean it with JB Bore Paste.
 
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Barrel twist is good for a 55 grain bullet. Give it a good cleaning. there is an integrity issue going on with the bore or crown. If you can borrow borescope, it may give you a better idea.



+1
 
Are you putting a tight crimp on these bullets? Looks like the jacket is stripping off some times, that can be a sharp land or can be caused by a tight or inconsistant crimp fracturing the jacket. It may not show up all the time either since the V max is sort of inconsistant in ogive and profile some times
 
Lionhunterco,

"3rd keep in mind that a 1-12 1-14 is optimal for that weight not 1/9. I cant say with certanty that is the problem but I have never ran 4000 with a 1/9 barrel. assuming thats a .223 at say 3100 fps it would put it as some where around 20,666 rpm instead of the 13,287 rpm with the 1/14."

I believe you have the decimal point in the wrong place. The RPM is roughly 10 times what you listed.

Jack
 
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Yes, I have seen this before with my 17 Rem. it would shoot 20 grain fine but would keyhole 25 grainers. It was caused by carbon and copper build up. The only cure was to clean it with JB Bore Paste.



That is my guess as well. I've had it happen in my .17 and this summer a friend got some sideways bullet hits out of his 22-250. We spent a couple hours cleaning it and it was good as new. He now cleans it much more often.
 
"Three weeks ago, I had targets like his with two sideways bullet holes, and they came from a $700 Schneider barrel with a perfect, recessed crown."

"So how do you explain that?"
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Probably a defective barrel Amigo. You seem to be an expert on this subject, so it should be simple for you to solve the problem yourself. /ubbthreads/images/graemlins/smiliesmack.gif
 
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"Three weeks ago, I had targets like his with two sideways bullet holes, and they came from a $700 Schneider barrel with a perfect, recessed crown."

"So how do you explain that?"





I guess PFM (Pure F*ing Magic) god forbid the load was wrong or it was a MISTAKE!
 
My Savage had a similar K-holing problem when it was new. Straghtened right out after getting the copper fouling out. Guess the lands were real sharp still and grabed huge loads of copper till it was broke in. It shoots beautiful now!


Dave
 
Went to the range again today and guess what...same thing. Of 10 rounds, 3 keyholed.

I got a reply from Hornady on this issue:

"Well they aren't losing the tip and they don't appear to have a comet tail. I would conclude from this the bullet is physically sound. After that I would say there is either something grossly wrong internally with the bullet or there are some bullets that are undersize and not engaging the rifling."

They recommend I measure the diameter of the bullets I have left but all I have is a caliper.

If anyone else uses 55gr Vmax .224 and has an accurate way to measure them, please do and let me in on the results.

In the meantime, I am considering using different bullets.
 
Went back to the range. Same problem. Then, I shot Nosler 55grs and no keyholing.

Still haven't heard back from Hornady on the bullets I sent them.

If it were a barrel problem, wouldn't it keyhole everything? Especially another 55gr round?

I think my answer is to just use Noslers.
 
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If it were a barrel problem, wouldn't it keyhole everything? Especially another 55gr round?



No, A softer, thinner jacket can be damaged in a rough bore, causing this problem. Noslers have tougher jackets.

If the Noslers shoot, you have a winner. They are great coyote medicine.
 
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