6BR pressure signs low loads

[Kracken McGraw]

I’m pretty sure lighter fluid IS naphtha. Walmart, as much as I hate the place has ronsonol. I go there once a year to stock up.

Thanks, that is what I thought too.

 

[divingin]

I’m pretty sure lighter fluid IS naphtha. Walmart, as much as I hate the place has ronsonol. I go there once a year to stock up.

If you hate Walmart, you can get lighter fluid on Amazon (not that they're a whole lot better, but it saves a drive.) I had to do this as California has seemingly banned Naptha in hardware stores (not verified, just my experience.)

 

[Eraser]

On my second firing of Lapua Brass I'm getting high pressure signs heavy bolt lift, ejector swipes and partially flat primers.

Shooting virgin Lapua Br brass had no pressure signs same load 28.5, resized the brass and started load testing from 25 - 28.5 and every case had ejector swipe and heavy bolt lift. The chamber was dry and the barrel had 39 rounds down the pipe since the last cleaning.

FPS 2575 at 28 grains of varget

View attachment 1312321

I had this very same, almost identical problem with a Savage FTR in 6BR.
What happened was when I measured to the lands and then backed out 0.020 to start load development, I was having the same problems the OP was having at the 28.0 grn mark with a105grn bullet.
So I backed out more, same results, then more, now things are a little worse.
So, I went back to the 0.020 measurement, cut the powder charge down a little at a time and around 25gr of Varget everything got normal.
To make a long story short, what I found out was I wasn't any where near the lands when I was measuring to them. The bullet was sticking it the throat, there was no simple solution for me so I re-barreled, and all is well.

 

[Dolomite]

I had this very same, almost identical problem with a Savage FTR in 6BR.
What happened was when I measured to the lands and then backed out 0.020 to start load development, I was having the same problems the OP was having at the 28.0 grn mark with a105grn bullet.
So I backed out more, same results, then more, now things are a little worse.
So, I went back to the 0.020 measurement, cut the powder charge down a little at a time and around 25gr of Varget everything got normal.
To make a long story short, what I found out was I wasn't any where near the lands when I was measuring to them. The bullet was sticking it the throat, there was no simple solution for me so I re-barreled, and all is well.

Interesting thanks for sharing you experience…

 

[Eraser]

Interesting thanks for sharing you experience…

I even though the rifle just had its first 100 rounds, I scoped for a possible carbon ring, not there...... .

 

[novice]

I still doesn't see any sign of excess pressure on the displayed cases. Just sayin.'

 

[Dolomite]

I still doesn't see any sign of excess pressure on the displayed cases. Just sayin.'

Look good in one of the comments I posted close up pics of ejector marks all over the brass and heavy bolt lift but that’s hard to show in pictures.

 

[novice]

Let me add to my comment above. ​

In post #10, 243winxb uploaded a pic which shows an extrusion of the case head into the ejector tunnel, which is similar to what I experienced some years ago in a Rem700. In puppy's pics I do not see that boss created by pressure. Rather, it appears to me that a burr on the ejector tunnel is creating a circular impression during firing and that the case head is being rubbed or scraped by something on the bolt face.​

Also, there are several such circular impressions on each case.
Why are there ejector marks " all over the bass" after two firings?
Any interference between bolt face and case head can increase bolt lift.
(Aside: It is my guess that the four cases in Post #10 show four degrees of excess pressure created by hot loads.)

 

[Dolomite]

Let me add to my comment above. ​

In post #10, 243winxb uploaded a pic which shows an extrusion of the case head into the ejector tunnel, which is similar to what I experienced some years ago in a Rem700. In puppy's pics I do not see that boss created by pressure. Rather, it appears to me that a burr on the ejector tunnel is creating a circular impression during firing and that the case head is being rubbed or scraped by something on the bolt face.​

Also, there are several such circular impressions on each case.
Why are there ejector marks " all over the bass" after two firings?
Any interference between bolt face and case head can increase bolt lift.
(Aside: It is my guess that the four cases in Post #10 show four degrees of excess pressure created by hot loads.)

Ahh got it, thanks for the explanation.