Thread: Pressure signs with factory ammo

I just set up a Sauer 100 and sighted it in yesterday. Cleaned the barrel before shooting and then fired 3 lots of 2 rounds cleaning between each 2 round string using boretech eliminator and leaving it to soak in the barrel for a few minutes before wiping out with 3 clean dry patches.I use a bore guide and do not saturate the patches, they are probably around 75% wet with boretech. After those 2 round strings I cleaned between every 4 shots.
The ammo used was Hornady superformance and Fiocchi, both with 129gn SST's. The Fiocchi is a milder load and is rated at about 100fps slower than the superformance. I have used these loads extensively in my Tikka with no issues. In fact on the same day I fired these same round through the Tikka with no issues.
However in the Sauer I was getting pressure signs with both loads. Shiny spots on the rear of the case and brass shaving on the bolt head. The rifle seemed to behave itself for about the first 4 rounds and the I noticed the bolt was tight to lift and the pressure signs appeared. I was also getting quite significant flyers. After the first 4 shots I was pretty much on target and then shots were going wide of the zero by around 150mm.
The only thing I can think of at the moment is the chamber being a little wet with boretech. However this should have been minimal considering the cleaning procedure. I have added some images of the case head and the bolt head. Looking for some feedback on possible causes.

My Mauser M18 (same action) does the same thing (6.5prc) with loads I would expect to be not too hot. The primers look ok but I get the ejector marks. I have been wondering if it has something to do with the bolt face having 2 ejector pins and nothing really to do with pressure?

Your primers look ok don't they?

Originally Posted by Tahr

My Mauser M18 (same action) does the same thing (6.5prc) with loads I would expect to be not too hot. The primers look ok but I get the ejector marks. I have been wondering if it has something to do with the bolt face having 2 ejector pins and nothing really to do with pressure?

Your primers look ok don't they?

I get the same thing with my Christensen Arms rifle which also has two ejector pins.

A wet chamber (oil or water) is the cause of the problem as it prevents the case sealing against the chamber wall and the full pressure is exerted rearwards. Make sure the chamber and bore are dry, and scrap the brass that has the pressure marks.

Yep primers do look Ok. I cant really see why the 2 ejector pins would cause excess pressure. At the moment I'm leaning toward a wet chamber causing the issue. Having said that, if there was some bore cleaner left in the chamber it would have been minimal, maybe this rifle is fussy in this regard. I will be going back to the range with a clean dry chamber, hopefully tomorrow to test the theory.

Originally Posted by zeropak

Yep primers do look Ok. I cant really see why the 2 ejector pins would cause excess pressure. At the moment I'm leaning toward a wet chamber causing the issue. Having said that, if there was some bore cleaner left in the chamber it would have been minimal, maybe this rifle is fussy in this regard. I will be going back to the range with a clean dry chamber, hopefully tomorrow to test the theory.

I wasn't suggesting the 2 ejector pins cause pressure, I was suggesting that their spring pressure or some other mechanical phenomena associated with the twin ejectors is causing the marks.

Originally Posted by Tahr

I wasn't suggesting the 2 ejector pins cause pressure, I was suggesting that their spring pressure or some other mechanical phenomena associated with the twin ejectors is causing the marks.

Oh Ok. I think there is more going on than that. Considering the hard tight to lift bolt and shots going wide of the group.

hornady superpreformance said it ALL before reading anything else...you cant make n omlet without breaking eggs,these are one of the hottest factory lodings on market and after seeing results through mates brand new top end .308w there is no way in hell I will use them... you have swipe marks...dont be surprised if you get FLAT primers and/or popped primers as well..and its not consistant either.3-4 out of 20 showed extremely hot and others were fine ish

Originally Posted by Micky Duck

hornady superpreformance said it ALL before reading anything else...

If you read the rest, he said it does it with the other fiocchi loads aswell, and that both loads are fine in a different rifle.

and if you had seen what this shit ammunition did in brand new high end .308w you would shit your gruts..... in nearly 40 years of using centrefires ,other than one rifle ending reloading fuckup Ive never seen anything as bad or inconsistant.

Originally Posted by Micky Duck

and if you had seen what this shit ammunition did in brand new high end .308w you would shit your gruts..... in nearly 40 years of using centrefires ,other than one rifle ending reloading fuckup Ive never seen anything as bad or inconsistant.

I have seen it first hand with one of my own rifles and factory superformance so i 100% agree with you. just pointing out he must have something else going on with the rifle with his current situation

You didn't mention drying the chamber between each two shot and clean cycle. So probably the wet chamber causing issues.
I dry mop the chamber and a dry patch down the bore each time I take a rifle from the safe to fire it. Guarantees no oil in there.

Greetings,
I would have a good hard look at the edges of the ejector holes in the bolt. If the edge is rough this could be part of your problem.
GPM.

Is this a new rifle or new to you ?

If it's new to you , it may have carbon and or copper build up adjacent to the throat which would need a borescope to see .

The barrel may just require a really deep clean .

Brand new rifle so carbon/copper buildup will not be the issue. Not the ammo because the milder Fiocchi was giving the same pressure signs. Good point regarding the edges of the ejector holes but the tight bolt lift and the some shots going wide of the zero point leads me to think the most logical explanation has to be a wet chamber. I am going to give it another try tomorrow and will report back.
The comments about the Hornady superformance surprise me. I have put around 200 rounds of that through my Tikka 6.5 Creedmoor with very consistent performance and nor issues at all with pressure.