Pressure issues reloading for Christensen

[1yotedog]

I'm looking at, perhaps, a similar issue today. Christensen 6.5PRC handloads, 124 gr Hammer Hunters with RL-26. Getting right at 3200 fps with 10-20 ES except some random shots that are out there about 40 or so fps. After firing, some cases will show ejector marks or give "bolt click" while most don't. Cases are turned to 14 mils, once fired, annealed, bump sized 4 mils, and mouths expanded for neck tension of 3. What I am seeing this morning is that fresh bullets often seem to "hang" on the mouth of a fired case but slide in after that. On those cases, mouths measure only 2 mils over loaded diameter while the main part of the neck is more like 6. Since SAMMI shows cartridge length of 2.030, I've trimmed to 2.025 but many once fired cases don't actually measure more than 2.022 and don't get trimmed yet. I was going to let them grow a bit on next firing and catch up to the longer cases. My thoughts on this may apply to the OPs original question: the case mouth, not the entire neck, may be getting crimped at the front of the chamber. Depending on how bad, that shot will show pressure excursions while the shorter cases don't. Today, I'll devise a testing strategy to verify.

 

[skinnyjk]

I've got a Christensen in 6.5x284, 26" bbl. that I started working up hunting loads for. The problem is that I experienced very high pressures approaching max loads. Very tight bolts and extractor marks on cases. Those were still only at 2800-2900 fps. I've tried RL22, RL25 and 4831SC with both Berger 140 and 156 gr. Elite Hunter and Fed 215 primers. I spoke with Berger and they said that Christensen barrels and actions had very tight tolerances and most people had to adjust down to starting loads. The folks at Christensen are no help at all.

I've cut my loads and came up with the best accuracy being 47 gr. of 4831SC but now I'm only pushing 2575 FPS. My COAL is 3.275 which I think is about .035 off the lands. Question is, what can I do to get more velocity while staying away from the pressure issues? This rifle should easily shoot 3000 fps, but i can't get close. I'll be using this for LR elk and mule deer. Out to 800 yards.

Sounds like my experience exactly with a 300 win mag Mesa. The dealer was great to work with it's going back to Christensen. I started at.20000 off the lands all the way to.60. I could get it to around 2750 fps with a 180 scirocco

 

[shooter7]

I have a 300 RUM. It's from when they still used Rem 700 actions and screwed on their barrel. I get pressure signs below book loads. Christensen barrel is going down the road.

Waiting on a Carbon Six now...

I had a CA Mesa 300 Win Mag. When following the exact data that Barnes listed in their manual, I blew a primer 2.1gr below listed max. It was also the most picky rifle I've ever loaded for.

 

[Lazyace]

I haven't read through all the posts, but what brass are you using? I have noticed in a couple rifles that i will see pressure signs earlier with different brands of brass. Seems I find earlier signs with nosler brass more than others.

Lapua brass

 

[Accuracyman]

Sorry to hear about your problems. I can share my load data and chronograph readings at different charges on my hunting 6.5-284 so you have a comparison. As always these are loads shot in my rifle and found to be safe. Please work up based upon your own rifle and pressure signs.

Rifle chambered with a JGS reamer in 6.5-284 with a .297 neck and .188 freebore
Barrel is a 3B Bartlein 8 twist 5R cut at 24"(Might be 25" I'll check after work)
Lapua brass with a loaded round measuring .294" (I do neck turn just enough to true them)
CCI 250 primers
H4831SC powder
Hornady 143g ELD-X bullets seated at 2.489" on a Stoney Point gauge (Hornady now).
The cartridge overall length is 3.125"
That equates to a .020" jump from a touch point that was found using a fired case modified to fit the Stoney Point tool.
Redding competition dies with a .291 bushing (.003" under loaded round)

Charge Muzzle Velocity (LabRadar)
50.8g 2810 fps
51.0g 2823 fps
51.3g 2853 fps
51.6g 2870 fps
51.9g 2902 fps
52.2g 2908 fps

I started to get a slightly tight bolt with no ejector mark at 52.2g so I stopped there. My rifle really liked 51.3g and 51.6g. Both were sub 1/2 MOA with 51.3g under 1/4 MOA. I have not shot this load any further than 300 yards so I cannot answer performance questions beyond that yardage. I wanted to give you actual hunting rifle speeds so you can compare your results.

I have not tried other powders because I am more concerned with accuracy and temperature stability in my hunting rifles than muzzle velocity. I can always click up a bit more to compensate for velocity.

Kris

 

[Rexby4]

I am having mine rebarreled with a proof barrel because Christensens are junk.

If I may ask, what the cost of doing that? I have a CA Mesa in 6.5 PRC

 

[30BR]

I'd definitely turn the necks and try again.

If using Lapua brass, that neck seems too tight to use un-turned brass...

 

[Jmedical]

Ran into similar issues with a cooper. Had to switch powders retumbo, RL-26 and VV n565/570 was able to get that extra 100-150fps but h4350 was probably the best temperature/overall load. You could consider have a gun smith re do the chamber.

 

[dougduey]

Had the same issue with a CA Ridgeline 28 nos.
See if a bullet will fit in a fired case. If not you need to either neck turn or find a brand of brass with thinner neck walls because your throat is probably a little undersize.
Another issue could be carbon build up.
Have you shot any factory loads to see if they have pressure and what the velo. is on them.
Shooting reloads will NOT void your warranty. I told CA that I had shot reloads and they had me send the gun in for warranty work (not the high pressure issue).

Axl is dead on here. I have a Christensen in 338 Lapua and hit pressure early on some loads. A bullet would not fit down a fired Lapua brass case. Nosler cases didn't have issues. I neck turned all my Lapua brass and the issue went away. Christensen rifles have tight chambers.

I have the same issue with my 6.5-284 with a Savage action and Krieger barrel. Neck turned the Lapua brass and also had to buy a small base body die because any fired brass would not get sized enough down to the web area to allow me to chamber it. So, it's not just Christensen chambers

If you can get any RL23, buy some for it's my go to powder for the 6.5-284 and 140 gr bullets.

 

[Rexby4]

I've got a Christensen in 6.5x284, 26" bbl. that I started working up hunting loads for. The problem is that I experienced very high pressures approaching max loads. Very tight bolts and extractor marks on cases. Those were still only at 2800-2900 fps. I've tried RL22, RL25 and 4831SC with both Berger 140 and 156 gr. Elite Hunter and Fed 215 primers. I spoke with Berger and they said that Christensen barrels and actions had very tight tolerances and most people had to adjust down to starting loads. The folks at Christensen are no help at all.

I've cut my loads and came up with the best accuracy being 47 gr. of 4831SC but now I'm only pushing 2575 FPS. My COAL is 3.275 which I think is about .035 off the lands. Question is, what can I do to get more velocity while staying away from the pressure issues? This rifle should easily shoot 3000 fps, but i can't get close. I'll be using this for LR elk and mule deer. Out to 800 yards.

Are you using a full length resizing die?

 

[greatwhitehntr]

Dmagna is correct send it back my buddy had to send his back twice first time was the problem you are having stupid tight chamber even virgin lapua brass wouldn't fit and crap accuracy the second was it was putting a line about 5/8" up from the base of the case all the way around the case when fired. The 3rd barrel was the winner 147 eld M at 2999 fps and 1/4 moa all day long. Also check the crappy spot bedding they do. I had to fix that for him.

""(DO NOT TELL THEM YOU ARE RELOADING FOR THERE PRODUCTS! )"" It just becomes a bigger can of worms tell them you are using HSM ammo it is known to be faster than most with 140 class bullets.

 

[greatwhitehntr]

Oh also forgot you have to neck turn lapua brass for there chambers want about .003" clearance for fired case

 

[Dmagna]

If I may ask, what the cost of doing that? I have a CA Mesa in 6.5 PRC

The barrel was around $800 then the smithing will be around $1000. But I am having some other things don't too.

 

[Lenny Foffa]

If it were mine, To Start , I would find the best BENCH REST GUN SMITH I could , and ask him to do a chamber cast . Then carefully measure every dimension vs your loaded ammo. Do not forget Neck Dia. I hope not, but if the neck is that tight, you may have to turn necks. Knowing every exact dimension will get you 90% of the way there. Just my 2 cents , Lenny