Can't explain 6.5 Wby PLEASE Help

[Terry Scott]

This has to be the strangest problem I have ever had reloading.
Last year I built a 6.5 Wby. (257 WBY necked up yo 6.5)
The load developement went as you would expect, the Wby case liking loads on the warm side. It is shooting 140 bergers @ 3350 fps into less than a half inch at 100 yds.
I put the rifle away for hunting season, and picked it up recently to do some more loading and took it out to the range with some of the handloads I had from last year.
This is where it got interesting. The exact loads I was using last year are blowing the primers out now... Thinking I loaded too much powder I went back to my notes, no this is the load that shot well in my developement. Checked the powder, out of the same bottle, checked seating depth, same as last years, same primers too.
Obviously I have to go back to the drawing board and start over with my load developement.
My next move is to start with some fresh cases, and give the rifle a thorough cleading.
Got any ideas why this is happed???? Or what to do?

 

[Truc]

sounds to me like the load is temp sensitive, did you work up the load when cool and is now warmer? That will do it if you were close to max. What powder were you using, if it was the Reloader powders I would expect this to be the problem, or switching primers from standard to magnum will certainly cause problems.

 

[Terry Scott]

I agree however I shot the loads in warmer temps before an I'm using h1000 which is not very temp sensitive

 

[Chase Curtis]

I have the exact same round except with an improved 35* and i load 142 smk with about 70gr h1000 im at 3250fps

Might just be a hot load... Not sure why the change but 3350 is cookin

 

[Terry Scott]

I'll just back it down and see what happens, what brass are you having the best luck?
I've also put in 50 thousands of free bore to help alleviate pressure.

 

[Chase Curtis]

Im 15/20 thou off... Norma brass.. Im on 4 reloads and going strong. You tried any Retumbo?

 

[Terry Scott]

H1000 and vit 560 seemed to work the best
I have a lot of retumbo did it work for you?
If so how much?

 

[Chase Curtis]

No.. It gave good velocity but did not perform accurate enough.. I was using 72gr of retuumbo.

I tried n570.. It worked good velocity wise but again ES was all over the place and failed in accuracy.

I've had good luck with H4831.. You probably won't achieve max velocity.. Well you might with the 140.. I used it wi 130 Berger.. It was not a great speedster.. At all.. Like 3050 fps it's a snail load.. but it will shoot under 1/2" at 300. With a single ES...

 

[Popapi]

Are you using magnum primers???? If so I wouldn't SLEEP on using LR primers.......

 

[ICANHITHIMMAN]

Is there any chance the powder you had loaded was from two different lot#?

 

[Shooter264]

Is it possible you have developed a carbon ring? I have seen it happen with 6-284's in the past.

 

[Buano]

My first thought would be a fouled barrel. Try stripping all the copper and see what happens. My bet would be the pressure will immediately go back where is belongs. (This isn't a wild guess — I had exactly the same experience.)

 

[MNbogboy]

You mentioned that it was the same powder...Are the bullets from the same lot?...Berger changed dies on their 6.5 140s VLD hunting bullets sometimes between last summer and this spring....If I remember correctly the base to ogive measurement increased by .046 or .047 towards the tip(at least in the lot I received)...If you were measuring by COAL and not CBTO then that could possibly account for a rise in pressure especially if you were near the lands to begin with...The new bullets do however average approximately .030 longer so in actuality you you might only be .015 or so closer to the lands with a COAL measuremnt the same as the old ones...

Just another thing to think about.

My $.02,
Randy

 

[HuntFarther]

I was told on the 6.5 wby with a 27" barrel you should not expect 3200-3250. I would try and get in that ball park and see what happens.