OzFclass

Hi guys,

I got some of the 80gr JLK porjies on the weekend and here is a pic of how they look like next to a 80gr amax. The JLK looks to need a longer throat to keep the same case capacity as the 80amax.



My chamber was cut with a 223 Wydle chamber by Rod and i dont know what the throat length it but i my opinion it isnt long enough for the JLK's. I have a 7 twist 223 being put together in a few months (Keith is out of the country) that will be throated for the 90gr projies so i think i will keep the 80gr JLK's until then unless someone thinks it will still be fine with a reduced powder charge? I am running ADI brass and gettign the 80gr amax to 2900fps in a 26" barrel.

Yep, by the pics you need a longer throat. The long 80 grain VLD bullets & the std 90 grain bullets require a similar throat length. If you supply me with 2 bullets I can cut a throat to suit. It looks like you need a #8 throat & this throat will still work with 80 grn sierra bullets with some jump, which will be O.K. I return to Australia 5/11.
Keith H.

seddo,
by the pics it looks like you need a longer freebore for the hornady bullet, if you want to get above the donut area. (assuming that is the length you load to.)
to my eye, the jlk looks like the point where the ogive meets the bearing surface is further back than on the amax. but my eye is very old.
keep safe,
bruce.

bruce moulds wrote:...to my eye, the jlk looks like the point where the ogive meets the bearing surface is further back than on the amax. but my eye is very old...

My old eye is telling me the same thing .

Keith,
I will wait for you to screw together my 7 twist 223 before i try the 80gr JLK's as there is no point with my current chamber. I have some Berger 80 & 80.5gr & 90gr projies on the way and should have some 90gr JLK's by the end of the year. I can see a fun christmas break shooting a lot fo 223's!!

Bruce,
The loaded round is what my 223 shoots as the moment. I thought about getting the throat lengthened but it shoots the 80's at 2900 and very accurately so i didnt want to touch it. You are spot on about the JLK having a shorter bearing surface, i will take a pic of them next to each other tomorrow.

Seddo what twist barrel are you running at the moment with the Amax's ?

Wakey,
I am using a 8 twist at the moment but have a 7 twist beign screwd together soon.

Forgot to take the pics yesterday, teh wife had me on a roller on sunday. As much as painting doesnt exicte me its a lot better than gardening!!

Don't worry Seddo, next year you can give the painting and gardening a miss and head up to Bendigo for the DRA teams match with the Gippsland contingent.

Norm wrote:Don't worry Seddo, next year you can give the painting and gardening a miss and head up to Bendigo for the DRA teams match with the Gippsland contingent.

I'll second that.

That sounds like a plan!!

seddo,
the more i look at that picture,
the more i think the jlk should be seated out longer to have the same throat relationship as the hornady.
keep safe,
bruce.

You obviously have a keen eye Bruce because you're spot on. Im in the process of playing with 80gn Berger and JLK VLD's also the Berger 80.5 palma projectiles. With all the bullets seated touching the lands in the same chamber, the JLK sits the furthest out because it has a very pointed secant ogive even moreso than the Berger VLD. Not sure how you've seated the examples in the photo Seddo but I can tell you unless thats two different chambers, something has gone awry ! The JLK should be seated MUCH further out. Andy.

the JLK is in the hornady OAL gauge and was taken straight from the chamber for the pic. i did it 2-3 times and kept coming up with the same length. I will have another look tonight.

Seddo,

The case you're using in the OAL gauge seems to have a rough mouth. In one instance, a similar circumstance interfered with a measurement I took.

It may be worth outside chamfering that case neck.

John

Seddo,

If you look closely at the photo there is a dark reflective line down the centreline of all 4 projectiles. This appears to be on the bearing surfaces only. Note that this line extends much further up the A-maxes, indicating their bearing surface to ogive junction is about 0.1" further out of the case. This doesn't necessarily say that the JLK will be jumping 0.1" compared to the JLK because it depends also on the angle where the ogive and lands meet. However, in this case, the ogives look quite similar in shape, so I reckon Bruce's comment is correct.

Alan