Any Idea

[nemasis243]

A mate of mine has just got a 20 cal ,when he bought the rifle he was given some Hornady once used brass so full resized and found a load that had plenty of grunt and grouped well but wernt to hot on the crono.

These were working really well leaving big exit wounds and no runners.

He has just bought some new Hornady cases preped them as he did the last lot ,has loaded the same load but for some unknown reason is getting to much penetration of the bullet before it starts to expand so the exit wound is quite small ,he tends to go for shoulder shots but is finding the bullet is going right through and smashing the leg bone on the other side and is having to put another round into most of the charlies he is shooting.

We have wieghed the two batches of cases and they are very close ,same batch of bullets,powder and primers.

As these are new cases and not once fired as the others were even though they had been full length resized , is it possible that you would get a pressure difference in the case?

Unfortunately the crono was lent to someone and come back in bits so we are waiting for it to be replaced, if anyone has any ideas on the subject would love to hear from you as at the moment were both head shot .cheers Andy

[Guest varmartin]

You really need to check the velocity of this second batch...

Or if you have any of the others left, shoot the 1st then 2nd lot at 300 yards and check for elevation changes ??

 

Martin

[craigyboy]

What bullet is he using? I found the 39g seirra bliztking to be a bit hit and miss, sometimes penetrating real deep and exiting other times just doing its job well, similar results with the 40g v-max, they still killed 100% though. If he isnt already I would try the 32g v-max I have found 10 out of 10 times it to drop the fox on the spot no messing around, it penetrates well leaving no entry wound that I can ever find and there is never an exit wound but the fox is usually a bag of mush which indicates perfect bullet performance, if he is already using the 32g v-max then I dont have an answer for this one, maybe try the 35g berger but personally I dont like it, it penetrates well but the surrounding tissue around the bullet is virtually undamaged so bullet placement has to be spot on. I cant see changing the cases would affect velocity by very much, especially considering they are from the same manufactuer and it would take a massive velocity change to alter the bullets performance like that, take a serious look at different bullets.

[silentsoulsleave308holes]

I wouldnt have thought that it would have made that much difference in terms of penetration BUT

 

there is a size difference between FULL length sized fired brass and NEW brass

 

on the first firing of new brass the brass expands then doesnt fully contract and looses some elastice and this repeats after every firing

 

on the first firing tiny little imperfections are hammered out making the brass appear smoother outside and inside and also the brass grows out to the shape of your neck/throat

 

even when full length sized the neck/throat area will never again be the shape of new brass not even if the shoulder were to be bumped back

 

this ironing out of imperfections and change in the shoulder and neck amount to quite a difference in internall volume

 

this difference only normally supports about 50 to 80 feet per second difference but can on occasion, with an abnormally large/long neck area of the chamber, cause larger variations

 

your fired full length sized brass will have a larger water capacity than the NEW brass and because of this the NEW brass load will have a more compact load with less internal volume giving increased pressure and more velocity

 

hope this helps and sorry if its teaching egg sucking

[Andrew]

Unless we're talking about a gross change in velocity here, I would think it's a bullet issue as well. I have shot the 32 ain V-Max as low as 2600 ft;/sec and had expansion on vermin-sized critters. Unfortunately, the initial post is lacking in details! Did the same bullet (LOT#) get used? What caliber rifle -I'm assuming it's a 204 Ruger.

 

Interesting bit about case capacity. I have seen it in my .222 Remington. I have now gotten into the habit of FL sizing even new brass. It comes from the factory only in various stages of uniformity anyhow.~Andrew