Christensen Ridgeline headspace changed?

[HighCascadeHunter]

Is it possible for a rifles headspace to change?

I have a Christensen Ridgeline in 6.5 creedmoor. I had this rifle rebarreled once by christensen. I measured the jam point for my handloads with the hornady gauge at 2.89 oal.
I’ve been loading and shooting all summer a couple different bullets typical around 2.85 oal with no issues other than minor pressure and basic load development work.

I began having chambering issues this week. This looked like difficulty closing the bolt ( some rounds would chamber and others I didn’t feel safe chambering as it required significant force) and when ejecting the round the bullet was marred from jamming into the lands. I became concerned about this so reevaluated my loads, checked brass sizing, remeasured everything. Cleaned the rifle. Everything I know to do I’ve done.

I rechecked my oal with the hornady gauge again with a variety of bullets and I am jamming bullets into the lands at about 2.79 inches. 1/10 inch less than previously measuring and well under spec for ammo.
So again my questions, am I missing something obvious here or is it possible for a rifles headspace to change that drastically ?
Thanks all, would really appreciate any help here besides the obvious answer of sell the turd and get another Tikka.

 

[SDHNTR]

Distance to the lands and headspace are two different things. I’m not even sure what you’re asking, other than it’s clear some of your ammo isn’t chambering.

Measure brass that chambers easily and brass that won’t at the datum line on the shoulder. What’s the difference?

Then do the same with loaded cartridges measuring cbto, not oal. Bullets have different ogive locations. Measuring oal across different types is likely your problem.

Make sure you aren’t mixing brass and/or bullets as you measure. Keep your measurements consistent. You’ll find your answer.

But to answer the question, can headspace actually change? Yes, if a barrel shoots loose, but it won’t shrink. Things don’t shoot tighter, ever. Lots of other things can cause a rifle to act like short headspace though. Usually the ammo is the culprit, sometimes gunk or carbon can also build up in the chamber, but that takes lots of shooting usually.

I can almost guarantee you, your issues have nothing to do with the headspace of your rifles chamber.

 

[HighCascadeHunter]

so I guess I had a couple questions wrapped up there. Yes, I wanted to know about headspace changing. You answered just as I would suspect, a barrel can loosen but won’t tighten.
My resized brass all chambers fine, so probably not a headspace issue.

The distance to lands appears shorter, that is what I’m measuring with the hornady oal gauge. 1/10 inch less than when barrel was new.
I am jamming rounds into the lands and unable to close bolt on both factory 140eldm and 143eldx, as well as handloads.

Averaging about 2.190 base to ogive with hornady comparator on 143eldx factory ammo

I’m showing a measurement of 2.056 with 143eldx bullet in a hornady modified case and same comparator. ( this is off the oal gauge, bullet seated at jam point.)

Photo shows marring of the bullet, I assume from jamming into lands as all my measurements seem to confirm.

What am I missing here?

 

[SDHNTR]

Well throats don’t burn shorter either. Something has changed with your measuring process, your seating process, or your bullets.

Slight chance at a carbon ring buildup, but in my experience that concern is largely overblown. Worth a look though.

 

[SDHNTR]

Wait, factory ammo is jamming now too? And didn’t before?

 

[Ice-kub]

I've been having a similar issue with my 7wsm, I'm wondering if the reamer throat was under spec possibly? Might drop it at the smith after the season. Only problem is it shoots lights out, worried it's going to change

 

[HighCascadeHunter]

Wait, factory ammo is jamming now too? And didn’t before?

Correct,
So i was able to shoot some precision hunter 143eldx this evening. 2650fps, no pressure signs or other issues, bolt close was a little snug but Seemed to function okay. After checking a couple boxes they seemed to close the easiest.

I cannot close the bolt on match 140eldm. That is factory ammo.
Can’t close the bolt on hand loads that have been previously used from same batch of reloads.
Very strange to me, so I’ll be hunting elk this week with the precision hunter.

 

[SDHNTR]

Stick a patch soaked with carbon remover into the throat and leave it overnight, muzzle down. Then twist a brush around the throat a few dozen times. Swab out. See if that helps.

 

[BRTreedogs]

What are you attempting to measure here?

That comparator insert looks to big to me. Way to far down on the bullet.

 

[Caseknife]

Yep, sounds like carbon build-up. Clean the bore real good and should get better. Real easy to see with a bore scope, and see if you get it clean.

 

[Wapiti1]

See doctored photo. There should be no major marks on the bullet at all from chambering and removing. Only minor scratches from the chambering process. Your photo says one of two things: Your lot of bullets are out of spec (possible, easy to check). Or your rifle throat has carbon buildup.

Do what SDHNTR suggests. You may need to get western with it. Put the cleaning rod in a drill and scrub the throat at low medium speed. A bronze brush cannot damage the barrel. Old wives tale.

 

[greyghostnw]

I would keep on hand a good nylon brush like ones from iosso one or two calibers larger than your rifle caliber for cleaning carbon ring and or preventing it all togather every time you clean rifle as part of your process use it to twist in area with carbon remover and mop it out then as always inspect with bore scope. Any rifle owner should own a bore scope there fairly cheap considering now days, teslong are great. Ive never had a carbon ring in doing so. One less thing to worry about. Hope as others posted that could be problem. Good luck….

 

[SDHNTR]

About how many rounds down the tube?

 

[HighCascadeHunter]

What are you attempting to measure here?

That comparator insert looks to big to me. Way to far down on the bullet.
View attachment 782324

It’s not far down on the bullet, the bullet was seated that deep into the case. That was as long as they were able to go with the carbon buildup.

 

[HighCascadeHunter]

About how many rounds down the tube?

I’m about 200 into this barrel.

 

[HighCascadeHunter]

Okay, I got the carbon ring in the throat cleaned out and rifle is working excellent again. I feel a little dumb for jumping to head spacing and serious issues. Thank you @SDHNTR and @Wapiti1 for the feedback and the picture was particularly helpful. No issues with headspace or lands, it was purely carbon buildup in the throat that prevented the cartridge from chambering. I had been cleaning every 50 or so rounds but clearly not breaking up that carbon. This is my first suppressed rifle and 20” barrel. I’m guessing that combo led to more buildup than I’ve seen before.
Leaving soaked patches in the throat, and scrubbing with bronze brush got it clean.
Thanks everyone! Ready for elk in two days
Shooting the 147 eldm hand loaded. Should be a killer

 

[Mike D Texas]

I’m about 200 into this barrel.

There is no reason to have a carbon ring within 200 rounds on a 6.5 CM. Unless it’s possibly a crappy chambering job and is rough in that area….but even that’s a stretch.

Is this factory ammo or reloads? Have you checked a random lot of bullets for consistency and correct measurements?


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[HighCascadeHunter]

There is no reason to have a carbon ring within 200 rounds on a 6.5 CM. Unless it’s possibly a crappy chambering job and is rough in that area….but even that’s a stretch.

Is this factory ammo or reloads? Have you checked a random lot of bullets for consistency and correct measurements?


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Interesting, I have no experience with a carbon ring preventing rounds from chambering. This was the first time I’ve run into this. Cleaning resolved it and it chambers just fine now. It is 20” barrel and suppressed so maybe that contributed?
Haven’t measured any bullets they all worked fine before and do again now.
I’ve shot hornady match and precision hunter, handloads with eldm and hammer hunters using staBALL and 4350 as powders. Might be more like 200-250 through it.

I definitely did not think I could have such a significant issue with so few rounds either.

 

[wind gypsy]

Yeah, that is very fast carbon build up to be causing those types of issues that fast! wonder if the freebore diameter is tighter than normal or something.