6.5 129sst

[Sikadog]

I have a problem with my 6.5-284 it has a 26 inch barrel with a 1-8 twist I have been shooting sst's from the start, the barrel has had 80 rounds through it, and now they have started blowing up on the way to the target, the last 6 rounds never got there. I am pushing them with Ramshot magnum why would they start blowing up now.
Can anyone help

Keith

 

[Trnelson]

How fast are you sending them?
Copper fouling could also be a factor.
How much time between shots?

 

[Sikadog]

I am driving them at about 3100fps they have shot perfectly well previously, there is no copper fouling in the barrel, at the last range I fired about 20 rounds it was only the last few that were a problem.
Sorry 26 rounds the last six started from a cold barrel.
The only thin I can put it down to is as the barrel beds in its getting faster.

 

[Barrelnut]

I'm thinking a combination of barrel heat and jacket thickness on the bullet. I have heard of A-MAX bullets blowing up like this in competition where hot barrels were in use. You do mention it was the last shots in the string of 20. Was it a hot day?

It could well even have to do with the lot of bullets. If you get another box from another lot, it may not have the same issue at the same temps.

This is why Berger started using thicker jackets on their target bullets. Some would blow up coming from hot barrels. Bergers and SSTs are cup and core bullets. Doesn't take a whole lot of heat to separate the lead core from the copper jacket. Then they explode from the rate of spin.