I’ve got 120 pieces of brass for my 600 Overkill…

The first hundred I bought with my rifle from AHR…

The other twenty were given to me by a friend…

All are Jamison…

My standard load is 150 – 152.5 grains of H4350 (new version of powder, older version yielded slightly higher velocities) over a 900 grain bullet (Woodleigh, Alaskans, or Dead Toughs)…

The velocities are in the 1950 – 2000 fps range with all of the above listed bullets…

When loaded in the brass from the batch of 100 there are no extraction problems (they practically fall out of the chamber)…

When loaded from the odd batch of twenty I have very sticky extraction…

Here is the catcher; identical loads from either batch chronograph the same…

Initially I assumed some difference in the case dimensions (capacity) were causing some higher pressures, but most of the time with higher pressures don’t you get higher velocities?

Anyway, what’s wrong with my batch of twenty?

Too soft maybe…

I dunno…

What do you guys think…

Either way the odd brass is going to be retired to use as dummy rounds…

weigh the cases and see if that is the problem. Could be thicker case walls. I assume you have trimmed them all after the first firing...?

Rich
DRSS

Are you sure all the cases were made by jamison? There is alot of .600OK brass out there from the two different batches made by Horneber. If the headstamp says RG ( me) .600ok its Horneber. There is even some un- headstamped brass around thay I or Fritz454 made and gave away. Yes case wall thicknesses did vary, however the earlier stuff was thicker. I've personally never used the Jamison stuff and never had the problem. Ask AHR if they had Jamison make any changes to his case dimensions. I vaguely remember something about this but could be wrong. Let me know what you have.-Rob

Rich…

I did trim them…

I’ve never weighed them though…

Rob…

I’m pretty sure they are Jamison…

I’ll weigh them and check the head stamps tonight and let you guys know tomorrow…

Does the sticky extraction mean higher pressure and wouldn’t that mean more velocity?

Thanks

Matt V

quote:

Originally posted by trophyhunter5000:
Rich…

I did trim them…

I’ve never weighed them though…

Rob…

I’m pretty sure they are Jamison…

I’ll weigh them and check the head stamps tonight and let you guys know tomorrow…

Does the sticky extraction mean higher pressure and wouldn’t that mean more velocity?

Thanks

Matt V

Higher pressure doesn't necessarily mean more velocity. Or to be more correct, significantly more velocity.

John

Ditto- Sticking brass does not necessarily mean higher pressures. I'd be more worried about soft brass sticking at those pressures. Again, Jamison brass is a complete unknown to me.-Rob

Ok…

Rich,

The odd batch on average weighs about five grains more…

Rob,

It is Jamison brass…

The head stamps on both batches read 600 OVERKILL, RG, JI…

I spoke with AHR and apparently there was an old batch of Jamison that did the same thing…

That batch is now out of circulation and apparently I’ve got some of it, must be too soft…

On the other hand my 100 count batch of JI brass that I bought from AHR has held up extremely well…

I may have pushed the envelope but I’ve got some cases that I’ve reloaded close to twenty times with the 150 grain H4350 load…

Thanks all for the clarifications…

Matt V.

You could load up the soft brass with light loads and use it for head shots on grouse. Just wouldn't try a body shot

They could be soft, but also it could be a difference
in the inner corner radius. Could you get me three,
one of the good ones and two of the odd ones and I'll
check them out.I'll send you some more 700s in trade.Ed

Ed,

I'll send you some...

I'll call or PM you Monday...

Matt V.