.260 pressure problems.

[Jason millichamp]

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?

 

[Rick Richard]

Not familiar with that powder, but yes to your question. However, if it is that much over pressure than I would look at charge weight, temperature sensitivity or maybe a carbon ring.

 

[johnnyk]

Very well could be the different powder lot, which can be hotter/faster (i.e. higher pressure) at the same weight or slower, requiring more to reach same level of pressure as before. It's a pain to have to start load development over each time you get a different lot of powder but it's the safest way to go.
Another thing to look for is a carbon ring just ahead of the chamber. These build up and cause all kinds of problems, mostly related to pressure. These (carbon build up) cause havoc on a known good load.
I got it once on my 6.5-284 Norma and used Sea Foam. It took a bit of elbow grease but I got rid of it. Now I use it at every cleaning and that seems to keep the problem at bay. Maybe others on here have another method for removing it.

 

[jjmp]

Don't shoot a 6.5 anything ,but checked my reload source ,24 bbl,R-P brass Rem9.5 lg rifle primer ,1/9 twist h4350 start 39.0 grns Max 42.0 with 140 grn bullet . I'd say your about 2 full grains to hot ,try dropping your powder charge 1 full grain to start ,not nocking your powder choice but any powder can spike in hot weather , cheers !

 

[Tank308]

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.

 

[MagnumManiac]

H4350/2209 is notorious for lot to lot variation in speed of burn. So yes, this is probably what you are experiencing.
This is why with certain powders, ie, 2209, 2208 and 2225, you need to buy 4kg lots at a time.
I know here in Australia this is VERY expensive, running close to $400 per keg, but if you shoot alot of the same powder this IS the cheapest option in the end.
I buy 4kg kegs for most of ADI powders, that way I don't have to re-do loads for speed variations for hundreds of rounds.

Cheers.

 

[Jason millichamp]

Thanks for your insight. The recommended max load for 2209 is 44.5 so I'm well under and their recommendations are pretty conservative. But I will drop the powder back until I get 2800 fps and go from there. Cheers.

 

[J E Custom]

Thanks for your insight. The recommended max load for 2209 is 44.5 so I'm well under and their recommendations are pretty conservative. But I will drop the powder back until I get 2800 fps and go from there. Cheers.

You might try seating the bullet a little deeper to lower the pressure.

All of the 260 I have built like some bullet jump(.015 to .020 minimum.

You might also try a Secant ojive bullet like the Berger or Eldx at the same COAl to give you some freebore/jump

J E CUSTOM

 

[ronstone09]

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?

I use a .260 for target shooting and use H4350 at 42.6 grains bullet is 140 berger match jammed into the lands and I do not get any pressure signs ! I use lapus brass with cci bench rest primers !

 

[hseII]

I use a .260 for target shooting and use H4350 at 42.6 grains bullet is 140 berger match jammed into the lands and I do not get any pressure signs ! I use lapus brass with cci bench rest primers !

What velocity are you experiencing?

 

[Hardshot]

The carbon builds up and my 6.5-.284 goes south. Bore tech cleaner every match

 

[Jason millichamp]

Ok thanks. I have carbon cleaner so will keep scrubbing with a bronze brush.

 

[gohring3006]

Over book max will sometimes bite you when it's hot outside. I'm guilty of it, but I hex boron nitride my bullets, and once the barrel is "seasoned" it smooths out the pressure curve and can make a picky rifle calm down. The other solution would be back off and work back up on the hottest day of the year.

 

[aushunter1]

Neck tension?
Did you change or do anything different in you process?
Use a different die maybe?
A change of neck tension can cause pressure spikes!

Eg, I have been doing LD for a new rifle & have been neck sizing, I used the FL die for the first time & noticed an increase in neck tension in the handle of the press, also I had super squeaky clean brass as well & as the projectile was being seated it just wasn't going in smoothly & felt graby.
I pulled the 6 I had loaded to have a look at the proj's( they were actually hard to pull as well0 & no marks.
I ended up lubing the projectiles with graphite lube & then they all seated smoothly & with half the effort previously needed.

Edit: I also just checked my reloading notes for my 260 & for 140gr SMK using 2209 & BR2 primers & my best load is 41.1gr & max being 42gr

***Not sure where you are getting your data from but ADI max load for 260 rem 140gr proj using 2209 is 42gr not 44gr!

http://www.adi-powders.com.au/rifle/260-remington/