2 heavy bolt lifts and dirty cases

[stello1001]

Just tested some loads today. Had 2 cases on my last (highest charge) that had heavy bolt lift and they came out dirty. Specs below:

6.5 GRENDEL (howa mini bolt action)
Virgin starline
RUAG primers
107 TMK
benchmark powder

Cases were chamfered & deburred prior to running a mandrel through them.

I then primed with frankford hand primer seater.

Dumped a charge using chargemaster.

I will say though, these were new primers I was experimenting with. They went in super tight. It was pretty bad I almost thought they were going to perform so poor by how bad the fitment was. Mostly everything shot with extreme consistency as far as chrono numbers go.

I did 3 different charge weights with 5 rounds per with 107 SMK.
I also did the same with 107 TMK. The only 2 rounds with the issue were with the TMK on the last charge.

Charges went in the order below:

27.6
27.9
28.2

All 15 rounds with the 107SMK had insanely low ES & SD. The 107TMK had higher numbers but not too bad.

At the end, I fired 5 rounds with 107SMK and CCI450 as a control group since this was the first time trying the RUAG primers. The CCI450s did worse.

Below are the cases in question. I also noticed the top right corner case (this is also on the set with 2 cases in question) had what appears to be a micro crack right through the primer. I do not believe it leaked though.

Anyone had this happen before?

Thanks

 

[Dolomite]

It normally happens on lower charges. I do love the exotic lighting on the pictures.

 

[stello1001]

It normally happens on lower charges. I do love the exotic lighting on the pictures.

I shoot under a pink tent hahaha.

I thought so too, I figured on low charge cases where the brass does not fully expand to seal the chamber we get some gas leaking back out between chamber wall and case. However, do you believe this to be the case? I don't think it was too low a charge, and it only happened on the highest charge too. A bit strange.

 

[Dolomite]

I shoot under a pink tent hahaha.

I thought so too, I figured on low charge cases where the brass does not fully expand to seal the chamber we get some gas leaking back out between chamber wall and case. However, do you believe this to be the case? I don't think it was too low a charge, and it only happened on the highest charge too. A bit strange.

try reshooting those cases, maybe it’s just isolated to those pieces of brass or shoot that load again. I never had luck with Starline, primers pockets were jacked up with a raised section around the primer hole and they said that’s normal. I had to cut out so much brass from just the center of the primer pocket and not the edges.

 

[stello1001]

Yup, I plan on reloading that brass...

I'm wondering if anyone else has experienced something similar to this?

 

[DHDeal]

I have found RUAG SR primers to be softer (for lack of a better word) than 450's, GMM AR, or 7 1/2's.

Not sure why you are seeing dirty cases with a heavier charge. Benchmark is not a powder I use so I can't help there. I have shot a few thousand of the 107 SMK in the Grendel and I use 8208 and mostly 450's with them.

Suppressor used?

 

[stello1001]

I have found RUAG SR primers to be softer (for lack of a better word) than 450's, GMM AR, or 7 1/2's.

Not sure why you are seeing dirty cases with a heavier charge. Benchmark is not a powder I use so I can't help there. I have shot a few thousand of the 107 SMK in the Grendel and I use 8208 and mostly 450's with them.

Suppressor used?

Yup, I was shooting suppressed. I primarily use 450s too. However this entire outing I wanted to try the RUAG. All three 5 shot charges with the SMK had single digit ES & SDs. My "control" group with 450s had higher numbers. I will continue testing more when I get the chance. Maybe spife will chime in later. He's usually very knowledgeable and spends time in this forum.

 

[spife7980]

The hottest loads starting to show heavy extraction is normal.
The dirty cases, I’ve had it sometimes and I contribute it to the hot gases post firing mixing with the cooler maybe more humid air and immediately condensing onto the chamber, which gets transferred to the case body when it’s fired and pressed it the chamber walls.
Fold and wrap a paper towel around a jag so that it doesn’t jab through and jam it into the chamber and spin, I bet you see lots of soot come out of that chamber.

No idea on the primer crack.

 

[R_A_W]

Just to rule something out... what do the unfired & fired cases measure base to shoulder datum?