Whats going on here?

[Dmay]

Looks like severe under-pressure?

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7 RUM in Rem Sendaro. Factory barrel/chamber.

168g Berger VLDs......86g H1000......3290 fps.
180g Berger VLDs......83g H1000.......3121 fps

Those powder charges and velocities don't seem low to me?

(Color looks a little funny in pics, but its black powder residue, brass was clean before firing.)

 

[maynard]

For 168's Hogdon website has a starting load of 85.0 gr of H1000 to produce approx 2988 fps. Max load is with H1000 is 90.0 gr to get 3116 fps. So your numbers are not adding up as your velocities are way higher than max loads. Might want the check your scale.

The soot around the extractor rim is scary. What do the primers look like.

 

[personal_aviator]

Check your scale or check you chrony with a known good load.

 

[Eagleye]

Those are very definitely low pressure loads displayed in the picture.
Since these chambers vary a bit, you may need to up your charges a bit to get rid of the smoky/collapsed cases.
Regards, Eagleye.

 

[finstr]

I think I'd be getting a smith to look at the headspace...

 

[mossyhorns]

Diddo. See a smith,
Don't mess around with that!

 

[Bigbubba]

The shoulder is collapsing because of low pressure. The pressure is not building up fast enough to seal the shoulder of the case against the chamber and hot gases are flowing back past the case towards the bolt face which pushes the case in, as well as blackens it.

So yes, these are low pressure loads and there are several reasons why this could be occurring. These are 2 of them
1) head spacing
2) your scale is not accurate

Try a factory load and see if this occurs. That will help narrow it down (to the scale being the issue)

 

[bearhunter]

X2 Eagleye, Bigbubba. Low pressure for sure.

Good call OP.

H1000 can be finicky, depending on which batch you get. Are you using magnum primers??

That particular case is very long and getting good consistent ignition, with anything other than near maximum loads can be very difficult.

It's one of the reasons I stay away from those cases. Not only that but I'm getting to be a bit of a wuss as I get older.

When they work properly, like all magnums they require loadings as close to maximum as possible, therefore recoil is usually substantial.

 

[Dmay]

Thanks very much guys.
Rifle ain't mine, was shooting with a friend. Appreciate the opinions, supports what I diagnosed, but wanted back-up.
Factory rounds looked normal, so he's checking his scale, and gonna up the charge.

 

[Bigbubba]

Might be a good idea to borrow a 2nd scale and see what's going on there.