.260 pressure problems.

[Jason millichamp]

Thanks aus hunter. I do get my brass annealed and the problems I'm having are with new lapua brass only been fired once. I haven't changed my dies and haven't been doing anything different. Which is why I think the advice re batch powder differences may be the problem.
The load info for 140 grn on the adi website is for nosler partition which are flat bottom straight sided projectile not the same as mine. They have more bearing surface on the barrel and subsequently more frictional resistance to going down the barrel. more pressure. If you look at the 142 grn hpbt bullet on that site you will see that the max is 44.5 grns. These bullets are the same profile as mine and heavier so it would be safe to use that as a max.
Cheers.

 

[Andrew Cowling]

Hi. I have a tikka varmint in .260 that I've been shooting in competition matches.its had probably about 1200 rounds through it. I shoot lapua scenar 139 with lapua brass and br2 primers. I load 44.4 grns of ADI 2209 powder which is the same as H4350 I've been getting about 2830 fps. At a match I went to it was drizzling and I got big pressure signs on the case. Brass flowing into the extractor position on the case. I thought it was the moisture that increased the pressure. Then I shot it again on a dry day and continue to get press problems. So I shot it over a chrony and it's now spitting them out at 2920 fps. I only buy powder as I need it and during that time I've bought new powder on the way. Would the change in powder batches cause the massive change in pressure and speed or would it be something else. Thoughts anyone?

Yes. ADI (HODGEN EXTREME) specifically state to check velocity of reloads when changing batches. They do thier best to get the burn rates the same. Age of the powder and how it has been stored can also have an impact on the burn rate.

 

[Andrew Cowling]

I bought 500 6.5 139 scenars. Had same problems. Measured bullets diameter .2642. Had to back off charge and increased jump. Gave up on them.

That is interesting. Oversize projectiles or even undersized bores usually give far better accuracy.

 

[Jason millichamp]

I bought 500 6.5 139 scenars. Had same problems. Measured bullets diameter .2642. Had to back off charge and increased jump. Gave up on them.

Hi tank. Interesting, guys in the club have measured ogive length and Weight of many projectiles. The lapua projectiles are the most consistent weight and ogive length of any of the other projectiles used. Including Berger. I've found them supremely accurate with the right charge behind them.

 

[Tank308]

That is interesting. Oversize projectiles or even undersized bores usually give far better accuracy.

I agree. I was only commenting. That primers where blowing out until I backed off charge.

 

[Tank308]

Hi tank. Interesting, guys in the club have measured ogive length and Weight of many projectiles. The lapua projectiles are the most consistent weight and ogive length of any of the other projectiles used. Including Berger. I've found them supremely accurate with the right charge behind them.

I agree It seemed a waste of time to weigh and measure, they where so consistent. I was only commenting on my blown primers when I tried them . . Backed off charge and it cured the primer problem in my gun. I didn't try them in my other 6.5's. Still sitting on the shelf.