Pressure?

[dougduey]

I had hand loading issues with my CA in 338 Lapua Mag. I learned that Christensen has very tight tolerances and their chambers are tight. They pressure out early (like others have said), and you typically end up with a load short of book max.
Check your brass. I ended up neck turning all of my Lapua brand brass but not my Nosler brass. Check and see if a bullet will freely slide in and out of a fired piece of your brass. If not, neck turning may be your answer or try another brand of brass.

 

[emp1953]

The above issues are simple to solve. Velocity of load will probably answer this question. Over book charges without velocity is not very wise. Just lot to lot differences can cause pressure issues. There are other things that could be happening, but I would start here. While waiting on chrono data I would recommend reading the Primal Rights blog linked above. And use a good chrono. If you don't know what a good chrono is buy Bryan Litz's book and go by his test results. Labradar, Oehler or Magnetospeed.

There is a common misconception on this sight that reloading data is usually way under pressured. This is where most don't understand lot to lot differences. Hodgdon data I like because it will show primer, bbl length and PRESSURE. If you equal their velocity then you will be at their pressure no matter what the charge. How do I know this?? Oehler 43PBL use for the last 25 years. My Oehler used with Quickload is always very close to Hodgdon pressure and velocity.

I have a Lyman, Hodgdon, and Nosler loading manual. All say they used a 26" barrel for their testing. Since most rifles that the readers here will buy will have a 20" to 24" barrel length their chronied velocities will seldom approach those in the manual. Usually lower velocities with a shorter barrel. So reloaders attempt to match the book velocies by increasing their powder charge and end up with pressure issues. I will look at 5 or 6 different load recommendations or more, from manuals and online forums and will see where others are finding max load values. I'm never chasing velocity anyway, I'm only looking for accuracy and only use a chronograph to make up my ballistics tables and make sure I have the energy needed at range for the bullet to expand and perform as needed. It has worked for me since 1969.

 

[emp1953]

Hello everyone. Need some help here. I have shot 3 loads today at the range, and all three caused some sticky boat lift. I don't feel like the power charge is that high, and I'm not good at telling pressure signs by looking at the bottom of the case. In my 7RM. Thanks

After reading through all the comments it just looks like these rifles are more "finicky" than others. I have a Cooper Backcountry, Tikka, Sako, Remington700 (pre 1970), Winchester70 (pre-64). All these in .270win. None of them shoot the same loads well. But all shoot their own loads excellently. The max-load in the Cooper gave me pressure signs in the Sako. Flattened primers and cratered firing pin marks. (bolt was never hard to cycle). I always use CCI200 primers. So go figure, rifles are like women, all different, different personalities. You need to get to know its personality and cater to it. 50 guys at the range can have the same rifle, at the range, and yours could be a bit different, better, or worse.

 

[Philward]

I didn't look these all up, but your 69gr of H1000 & 160gr Accubond load is 3 grains over maximum according to Hodgdon load data for that weight copper/lead bullet (see attached).View attachment 463176

Nosler data lists 70g H1000 max with 168g bullets. No data for H1000 and 160g bullets. Also this is partition bullet not Accubond.

 

[The_Whitetail_kid]

Nosler data lists 70g H1000 max with 168g bullets. No data for H1000 and 160g bullets. Also this is partition bullet not Accubond.

That's why it was a little harder to start loading this bullet. Very little load data. I went with what I could find on the internet, forums, previous experience.

 

[M1A1ABRAMS]

That's why it was a little harder to start loading this bullet. Very little load data. I went with what I could find on the internet, forums, previous experience.

Perhaps this may help. Hope pictures load.

 

[Bob Wright]

I think that is because I need to use a FL die vs just a neck sizer. I am still fairly new to the reloading game.

Yes, FL size. If you're neck sizing only, that's probably why your bolt is hard on closing. Your head space is .000 at best and you're having to force it into the shoulder to squeeze that brass into your chamber. It's hard on bolt lugs too.

 

[WYO300RUM]

Sorry for being vague. Fired brass, and clean chamber. Christensen arms ridgeline 7mm rem mag. One load 69 grains h1000 160 accubond. One load 70 grains h1000 with 160 accubond, one is 71.6 grain retumbo, 168 Berger. The bergers were seated 30 thousands off and accubonds 20 thousands off. Not that it matters but the 70 grains h1000 with accubond and 71.6 retumbo both shot half inch groups.
Norma brass, cci 250 primers.

I use 73.0 grs. Retumbo with 168 Berger with no pressure signs at all. It's a Ruger MK. II though. My C.A. Ridgeline 6.5 PRC does the samething to my cases even with factory ammo. Stiff bolt also with ejector marks.

 

[The_Whitetail_kid]

I use 73.0 grs. Retumbo with 168 Berger with no pressure signs at all. It's a Ruger MK. II though. My C.A. Ridgeline 6.5 PRC does the samething to my cases even with factory ammo. Stiff bolt also with ejector marks.

Haven't noticed the stiff bolt and marks yet with my 6.5 PRC but I'm sure it's coming.

 

[scpaul]

Does anyone know someone at C.A.? If so could we get him/her to chime in on what appears to be a chamber problem? It may not be a problem. We could atleast get their take on it. It seems to be too prevalent to be a problem. If it's a problem are all or these rifles from 1 time period or batch?

 

[coyotezapper]

Does anyone know someone at C.A.? If so could we get him/her to chime in on what appears to be a chamber problem? It may not be a problem. We could atleast get their take on it. It seems to be too prevalent to be a problem. If it's a problem are all or these rifles from 1 time period or batch?

Someone has, but with all of the noise it has been missed.

 

[WoodPecker Hunter]

REMEMBER. Guys. Loading manuals -data are just guide lines !
as you ALL should know a safe load in one brand of rifle could be a primer blower in another - not often but it happens as some powders top out FAST and over pressure FAST . Even a bullet brand change can make a Big difference . JMHO

 

[The_Whitetail_kid]

Got the 160 accubond chronographed. Averaged at 3207. However, since I full sized the brass have had 0 issues with bolt lift or anything feeling like pressure or anything. 2 more range trips have shown this. 3207 seems high, but with no pressure signs, should I continue shooting the load?

 

[scpaul]

I've shot 7Rm quite a bit and 3200 with a 160 gr. bullet seems real high. I can't get to my manuals right now, so am I right thinking 2900 is on the upper limits by the book with std. length barrels or am I wrong? If it works go with it. Barrel wear would be the only thing.