6.5 prc pressure issues.

[Foster_65]

Hey folks. I’m having a problem with my Christensen titanium ridgeline with pressure signs. Every time I shoot, even with a load weeelll below max, below a known load, I get very hard bolt lift and all the typical pressure signs. I’m currently shooting 57.5 h1000 under 140 eldm. I have taken this load up to 58.5 grains and that is where I hit slight pressure. My velocities are in line white what I would expect. Maybe even a touch slow. Around 2860-2985 with a 22 in barrel. I anneal after every loading and bump should .0015-.002 from chamber dimension. haven’t run this brass hard at all but am now getting this pressure. I will say this brass has 11-14 ish loadings on it. I thought maybe I was getting a carbon ring even though bore scope didn’t show anything. cleaned the piss outta it anyway and still same issue. Does anyone have any ideas? Could the brass be shot? I thought brass life was gone when it would t hold a primer? Again I’ve taken it easy on this stuff. Thoughts ?

 

[Foster_65]

To add to this, my brass length is between 2.025-2.029. So on the longer side but still under max. Could brass length cause this? Also note that the chamber has been reamed with the aw2 reamer as I was getting clickers. My mind tells me this is a brass issue not rifle since this is recent. Can’t think of anything that would have changed over time other that case length.

 

[Weldor]

Get a chamber length gauge from Brownel's and see how long your chamber freebore is. Sinclaire's are like $6 bucks

 

[Harvey_NW]

To add to this, my brass length is between 2.025-2.029. So on the longer side but still under max. Could brass length cause this? Also note that the chamber has been reamed with the aw2 reamer as I was getting clickers. My mind tells me this is a brass issue not rifle since this is recent. Can’t think of anything that would have changed over time other that case length.

My gunsmith said even the AW2 reamer doesn't always permanently fix the solution depending on sizing die. IMHO you might just be at the end of case life and it's hardened up and springing back too much. I also think 57.5gr H1k isn't necessarily taking it easy on brass, I get pressure signs around 58-59 in an AW2 chamber as well on formed brass. If you did your initial pressure test on virgin brass it can give you false results and pressure up when it's formed. I usually shoot a quick check ladder and drop my charge accordingly.

 

[Foster_65]

My gunsmith said even the AW2 reamer doesn't always permanently fix the solution depending on sizing die. IMHO you might just be at the end of case life and it's hardened up and springing back too much. I also think 57.5gr H1k isn't necessarily taking it easy on brass, I get pressure signs around 58-59 in an AW2 chamber as well on formed brass. If you did your initial pressure test on virgin brass it can give you false results and pressure up when it's formed. I usually shoot a quick check ladder and drop my charge accordingly.

Yea with fire formed brass I took this combo up to 58.5 where I just started getting a heavy bolt lift so I backed down a grain and it shot well for a while. So maybe taking it easy isn’t the right term but def never had so much as an ejector mark then went right or very stiff bolt lift and heavy ejector marks. You could very well be correct about being at the end of usable brass life. And that’s ok. I got nearly 15 firings out of it so I’d say I got my monies worth is that is indeed the problem. I’m wondering if I missed something or if anyone else has experienced this and what the culprit was. I have a few virgin adg brass loaded up to test this. I also loaded a few with the shoulder set back another .002. I’m going to trim a couple down and shoot them and see if that makes a difference also. I will report back.

 

[Bater]

Order a mandrel die from Eric Cortina, cheaper than SAC sizing die and very affective. I'll bet this fixes your issue, though you may need to start with a new batch of brass. I've had so so results in reviving brass that has started "clicking".

 

[TaperPin]

If you brass is lasting 14 reloads, it’s definitely not pressure causing the hard bolt lift. That brass life would be associated with rather mild pressure by many.

Personally I’d cover 5 cases in blue sharpie to get a better understanding of what part of the case is sticking in the chamber. It might act like a lubricant and none of those will actually stick, but it should show tight spots on the side of the brass where it has the hardest contact with the walls. It might even show how rough the chamber walls are where it is making contact. It would probably show contact near the case head in a rather normal way.

I’d be concerned if an area closer to the shoulder showed more than normal scuff marks. I’ve never seen it myself other than in photos, but if the reamer caught a chip and scratched the chamber walls, then that area was polished out to not draw attention, the chamber could have somewhat of a “bulge” or reverse taper if too much material was taken out.

Not all full length dies are the same - some have such sloppy large dimensions it’s not really squeezing the case dimensions down far enough near the case head when the shoulder is pushed a little. The chamber is larger with the new reamer, but the dies might be allowing the brass to start off very near or touching the chamber walls so spring back is slightly less than ideal when fired.

Since you have a bore scope I’d look at surface finish of the chamber - nobody wants a super rough chamber or things stick, or a polished chamber or bolt thrust goes up because the case isn’t being locked onto the chamber walls with pressure.

That’s a long winded way to suggest small base dies have a high likelihood of solving the problem.

 

[wind gypsy]

What pressure signs are you seeing?

How many rounds on this rifle/barrel?

Was the brass shot in a different chamber previously?

 

[Foster_65]

If you brass is lasting 14 reloads, it’s definitely not pressure causing the hard bolt lift. That brass life would be associated with rather mild pressure by many.

Personally I’d cover 5 cases in blue sharpie to get a better understanding of what part of the case is sticking in the chamber. It might act like a lubricant and none of those will actually stick, but it should show tight spots on the side of the brass where it has the hardest contact with the walls. It might even show how rough the chamber walls are where it is making contact. It would probably show contact near the case head in a rather normal way.

I’d be concerned if an area closer to the shoulder showed more than normal scuff marks. I’ve never seen it myself other than in photos, but if the reamer caught a chip and scratched the chamber walls, then that area was polished out to not draw attention, the chamber could have somewhat of a “bulge” or reverse taper if too much material was taken out.

Not all full length dies are the same - some have such sloppy large dimensions it’s not really squeezing the case dimensions down far enough near the case head when the shoulder is pushed a little. The chamber is larger with the new reamer, but the dies might be allowing the brass to start off very near or touching the chamber walls so spring back is slightly less than ideal when fired.

Since you have a bore scope I’d look at surface finish of the chamber - nobody wants a super rough chamber or things stick, or a polished chamber or bolt thrust goes up because the case isn’t being locked onto the chamber walls with pressure.

That’s a long winded way to suggest small base dies have a high likelihood of solving the problem.

This is some good information and ideas. A couple notes to some of the comments. I used the the aw2 to hand ream from factory. After I “polished” the chamber with 400 grit sand paper. This was under the instruction received on long range only. It worked very well up until this last batch or reloads. It bid rifle and brass has shot hundreds of rounds that way. Maybe a small base die is in order or maybe I just retire this lot of brass and move on to new.

 

[Foster_65]

What pressure signs are you seeing?

How many rounds on this rifle/barrel?

Was the brass shot in a different chamber previously?

Pressure signs are very hard bolt lift after shot and significant ejector marks.

Rifle has 7-800 rounds fired. Was cleaned pretty religiously until last year I kinda quit with all that unless it’s needed. That was not the problem in this case.

The brass has never been shooting another chamber other than the first 3 or so loadings on the saami chamber before it was opened up. I kept using the same brass and it solved all problems until this last couple of firings and sizings.