JLK 90 grain 223 bullet Failure

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bigmedicine

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Recently I started shooting the 90 grain JLK bullets in my 223 caliber F class rifle, using a 1-7 twist and pushing them out at 2820 fps.
I have found them to have better accuracy and lower pressure signs than the Berger 90 grain VLD'S.
Unfortunately, I am having the JLK bullets fail, either blowing up or who knows what exactly, but they don't make it to the target and go off with a different sound!

Is anyone else having similar issues with the JLK bullets or is it just me doing something wrong?
I have shot over 1500 rounds through this gun using the Berger 90 grain VLD and have never experienced this problem although being less accurate but I guess that a couple of 4's is better than a "0".

These blow-ups have been witnessed by the RO at competition and not just a figment of my imagination
Anyways, let me know what you think!!
 
How old are your JLK 90 gr some of the older JLK where made from 6mm jackets and they where not very good, the new ones in klast year or so are made with J4 jackets like the bergers ?? what powder are you using for 2820fps
Manitou
 
just a speculation..

is it possible the JLK has a much thinnner jacked then the bergers and if your pushing them at the same velocity as u did with the Berg, that they arnt gonna take it and you may need to drop veloc. or go back to the Berg
 
bigmedicine said:
I have shot over 1500 rounds through this gun using the Berger 90 grain VLD and have never experienced this problem although being less accurate but I guess that a couple of 4's is better than a "0".

These blow-ups have been witnessed by the RO at competition and not just a figment of my imagination
Anyways, let me know what you think!!
Click to expand...

Is the throat a little rough or carboned. Try some JB in the bore and work the throat. It may help.

NormB
 
Had the bore checked with a bore scope, no problems there. The bullets are new. Using the same powder, primer and brass. Same bullet jump and die setting as before.
I will keep shooting them for now but will inspect the remaining bullets and follow up if it happens again with more info. I am going to test them at a lower velocity , and try to find an accuracy load at a lower node.

As I stated before, they are performing well but, after shooting only 150 rounds the percentages arn't impressive! One failure in a competition took me completely out of the running!!!!!!!!!!!
If it happens again with this lot of bullets then it is time to move on to something else.
I have been advised of an article in target shooter magazine referring to this problem in the 90 grain bullets, so the search for the ultimate 223 f/tr bullet continues!!

Stay tuned for further results as the summer competitions heat up!!V:I:V:I:
 
Here is what i would suggest. If you have a few to spare send them to a known 223 shooter to test if he gets the same results bullets blowing up then it is the bullets if he doesn't it is gun related.

The other option and this is less popular is to put a lubricant on them Moly or HBn. Randy Robinett spoke about a barrel blowing up bullets at a pretty decent rate he check the usual things, speed, worn out barrel,, and thin jackets; turns out it was a combinaton of the three. He moly'd his bullets and ran the same test he didn't have another failure.

good luck
 
I used to get the Sierra 80s blowing up in my 22-250AI. ((3200 fps). It only happened after the barrel was half worn (500 shots), so I assume barrel roughness is part of it.

I found moly helped delay the problem.
 
I have a friend shooting bullets from the same batch with no problem,so it might have been just one bad apple!If it happens again I will probably try something else. I am still going to try a lower velocity , trying to get the same accuracy! Still searching for the holy grail of bullets!
 
I had a similar problem some 3 years ago, with the 'old' issue of JLK 90s .Last year, I got some of the 'new' ones. I think I can honestly say that I have not (yet?) found the secret of using them! I've had a lot of pressure problems and have been reducing the charge (now 24.0 gr N150) to a level where the velocity is less than 2600 fps. Then at a practice before this weekend's shoot at Connaught on Friday, having trouble hitting the target at 800m, I had two helpful observers state that they saw bullets disintegrate on their way down range. I've set them aside for further study! The barrel is a 1 in 6.5" Krieger. One suggestion has been that the bullets are slightly oversize, so that in a tight bore with a fast twist, undue strains are placed on the rather thin jackets. The jury is still out! i used 90gr Bergers last year, with none of these problems.
 
It sounds like a bad batch. I recently had the same issue with 162 amax in my 7mm ultramag. Only 6 out of 21 shots made it to the target. I never had a problem with them before but at 3600 fps( 32 inch barrel)I was surprised I didn't lose any before this.
I switched over to 168 bergers and no problems so far.
 
Just to add to my previous note, I pulled out and measured with my micrometer five bullets of each of the following. The first number is the average diameter (the 5th and 6th decimal places are not really relevant since I was only measuring to 1/10 of a thousandth of an inch – the 4th decimal place); the second number is the standard deviation of the five measurements – in all cases it’s much smaller than the 4th decimal place!
Sierra 90gr: 0.224380, 0.000008
Berger 90gr: 0.223900, 0.000012
JLK 90gr: 0.224300, 0.000010
Sierra 80gr: 0.224140, 0.000005
Berger 80gr: 0.224200, 0.000007
JLK 80gr: 0.224230, 0.000004
I’m not sure what it all means, except that JLK 90gr are not larger in diameter than the others. Berger 90s are the smallest – I used them last year with none of the problems that I’ve been finding this year with the JLK 90s. I haven’t used the Sierra 90s much, but I don’t recall any problems with them either.
Jim
 
6mm 115gr bullets have similar issues:
  • jacket strength can be critical
  • exact barrel twist is very important
  • type and number of rifle grooves is critical (polygonal being the "best" for 6mm)

I learned all of this after ordering my barrel so I have to work around the issue.
The simplest and best advice is to buy exactly what is proven to work under all conditions if possible.

Many shooters have abandonned the 6mm 115gr DTAC bullet because of this issue but it performs perfectly with the appropriate twist/groove pattern.
I think that you've found a "incompatible" bullet - barrel twist/groove combo.

Alex
 
Jim,

Are you running a tight bore, or a standard constriction? I'm thinking the quicker twist, and possibly the tighter bore, are adding up to simply beign too much for the jacket to take.
 
The barrel is a Krieger 1 in 6.5" twist. I honestly don't know whether it's very tight or otherwise abnormal. It shot 90gr Bergers OK last year with none of these problems. But my experience with the 90gr JLK, of either the 'old' or 'new' stock, has been anything but happy. I may be having a 'fire sale' soon!
 
Any chance there's some carbon built up in the throat? Don't know if that would be enough roughness to chew up a thin jacket or not. Just thinking out loud...
 
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