Do I have a Headspace Problem?

[Desert Dan]

I'm pretty new to hand loading and could use some help. Brief background - I've been shooting my 6.5 PRC with factory and basically factory-copied length hand loads with moderate charges and have had no issues. A little bolt sticking but nothing that caused concern. Now that my suppressor is in I decided to start working on some loads so I can get it optimized and zeroed for fall. Started to measure the max base to ogive using the hornady modified case and gauge with the comparator. My measurements to the lands were significantly shorter than I was expecting. So short that by the measurements even factory 143 ELD-X cartridges are getting jammed into the lands. Looking at the bullet seated in the modified case there's no doubt it's sitting really deep.
I don't know if this is at all common or if I have to get my rifle checked out but it was definitely not what I expected. I ran that gauge in there about 30 times figuring I wasn't doing something right but after all that I had to accept that it was just coming up short. Thoughts are appreciated. Thanks.

dan

 

[Wrench]

Who reamed it? Sounds like it is more a throat issue than headspace. If you were as shy on headspace as you're describing, you'd have a hard time closing the bolt on a case.

I'd sharpie or candle smoke a factory round and chamber it and then pull it and read the marks.

 

[WeiserBucks]

That's not headspace, it's a short throat. You either need to shorten your CBTO or have the throat lengthened. If you're experiencing a heavy/sticky bolt lift after firing a round, that's definitely an indication of over pressure.

 

[Desert Dan]

(Sigh...)
Okay assuming that's the issue what the hell do I do now? It's a factory rifle so do I contact the manufacturer? Is getting the throat lengthened expensive? And more importantly have I damaged my barrel or action already? Thanks for your help.

 

[WeiserBucks]

You likely haven't damaged it, but I'd stop shooting it until you address the issue. Any competent gunsmith should be able to lengthen the throat for a very reasonable price.

If it was shooting well you can always just handload your CBTO shorter but itll likely compromise a bit of velocity. Up to you.

 

[Low_Sky]

(Sigh...)
Okay assuming that's the issue what the hell do I do now? It's a factory rifle so do I contact the manufacturer? Is getting the throat lengthened expensive? And more importantly have I damaged my barrel or action already? Thanks for your help.

Have you ever tried unloading a round after chambering it? If not, load a dummy round with no powder to those factory specs. Do as suggested and mark the bullet with a sharpie or candle smoke. Measure the CBOL and chamber it. Extract the round. Look for rifling marks on the bullet. Measure the CBOL again.

This should tell you pretty conclusively what’s going on.

If it’s short throated that’s an easy fix. You could probably send it back to the manufacturer if the the throat really is too short for off the shelf ammo. But I’d probably take this as an opportunity to get the throat reamed to my specs by a gunsmith. Load three dummy cartridges to the length you want and take them and the gun to a smith. They’ll ream the throat to fit the dummies you loaded for them. If you’re feeding this gun from a magazine, don’t load your dummies all the way out to magazine length. Leave yourself some margin to chase the throat as it burns out.


Sent from my iPhone using Tapatalk

 

[packer58]

Good advise above, first identify your issue by painting the bullet on one of your factory rounds with a sharpie and chambering it and read the marks if there are any. SAMMI spec COAL should fit in all factory chambers without jamming into the lands.

 

[Don Qui Puncher]

What method are you using to measure to the lands? This is the best I’ve found

 

[Desert Dan]

Thanks for the replies. They're appreciated. I made a few phone calls and spoke with the manufacturer who was very helpful. I ran and re-ran the bullet test with the Hornady comparator and I'm going to load a sharpie painted factory round tomorrow to check for markings. SAAMI specs are 2.755 to 2.955, factory rounds in the box I have are averaging 2.9455 (those are overall lengths) and to the lands mine is measuring 2.865 for a difference of .080. It's within SAAMI specs so now I'm considering what I should do.

 

[JRMiller]

If you had excessive headspace your brass would grow excessively in the chamber upon firing.
If you have a body comparator, measure some new or sized cases then compare to a few fired in your chamber.
If your case shoulder length grows by something like .010-.020"+" then you have excessive headspace.
Most reloaders shoot for .003" or less shoulder bump. some guys prefer as little as .001"

 

[Desert Dan]

If you had excessive headspace your brass would grow excessively in the chamber upon firing.
If you have a body comparator, measure some new or sized cases then compare to a few fired in your chamber.
If your case shoulder length grows by something like .010-.020"+" then you have excessive headspace.
Most reloaders shoot for .003" or less shoulder bump. some guys prefer as little as .001"

I was using a borrowed body comparator previously and have one on the way right now so that is the first thing I will do. I also suspect my FL sizing die is a little off since today I tried to load an empty sized case and a dummy round into the chamber and neither would fit. In fact it wasn't even close so I just stopped until I can measure it and get it right. That's an easy check tho and as soon as I get the body comparator I anticipate that will get fixed.
As for the throat, I looked up the SAAMI specs and mine is measuring right about in the middle of the SAAMI range.

 

[Cahunter805]

Does a fired not sized case chamber easy? If so it’s certainly your FL die setup incorrectly.

 

[Sobrbiker]

Does a fired not sized case chamber easy? If so it’s certainly your FL die setup incorrectly.

.....what?
Just how does a fired case indicate FL die setup?

Dan-when you say “body comparator” are you talking headspace comparator? If so you have to be sure the insert is the correct diameter to hit the shoulder’s datum line at the right point.
If a FL sized case that is within trim spec won’t chamber, that says your die setup is indeed incorrect.
You could always size a case, chamber it-if bolt won’t close screw die in 1/16 of a turn at a time until bolt barely drags closing (should be at zero headspace at that point). I like .002”-.003” headspace for a field gun, .001-.002 for a match gun. These can be verified once you get a headspace comparator (I usually set die to push shoulder back .002” from an average of a few fired cases’ measurements.
You may need to help case under extractor and push against ejector tension for neck to guide into chamber straight on a 700 style bolt.

 

[Cahunter805]

.....what?
Just how does a fired case indicate FL die setup?

Dan-when you say “body comparator” are you talking headspace comparator? If so you have to be sure the insert is the correct diameter to hit the shoulder’s datum line at the right point.
If a FL sized case that is within trim spec won’t chamber, that says your die setup is indeed incorrect.
You could always size a case, chamber it-if bolt won’t close screw die in 1/16 of a turn at a time until bolt barely drags closing (should be at zero headspace at that point). I like .002”-.003” headspace for a field gun, .001-.002 for a match gun. These can be verified once you get a headspace comparator (I usually set die to push shoulder back .002” from an average of a few fired cases’ measurements.
You may need to help case under extractor and push against ejector tension for neck to guide into chamber straight on a 700 style bolt.

The OP stated a FL sized piece of brass wouldn’t chamber hence my question.
You can size the case to much causing the shoulder to bulge at the shoulder/body junction and thus not chamber. You can also bulge the case while seating bullets if your seating die is setup incorrectly.
I do agree with your shoulder bump of .002 also.

Dan what brand/model rifle is this?

 

[Desert Dan]

Well here is what happened when I loaded a factory cartridge into my chamber this morning. The bolt closed a little stiffer than normal but I almost couldn't get it lifted out. It was that tight which is clearly not the way it was the last time I shot a few months ago. The round was colored from just under the tip to just above the casing. It's obvious where it was contacting. The pics below are from different sides of the bullet. You can see one side was contacted significantly further up the length of the bullet than the other sides.
So what could cause this change? This rifle has approximately 350 rounds through it - mostly factory rounds with the last 50 or so shots fired being hand loads to factory length, starting with a light charge and working up to mid range where I started to see extractor marks. No issue until now. I keep my rifle clean, checked the lug recess for gunk, ran a chamber mop through it with almost nothing coming out and visually inspected the bore and barrel, and finally ran a lightly oiled patch down the barrel followed by the bore snake. Nothing unusual. The bolt closes normally on an empty chamber. An issue with the bolt rather than the chamber maybe? I don't know how a rifle could go from acting normal to this without me doing anything that I'm aware of. Smart people, chime in.

 

[Cahunter805]

A few possibilities
More than likely carbon build up or a rough throat/neck area. What cleaning products and procedure do you normally use?

Could be an out of round chamber or the factory ammo is not very concentric either.

What brand/model of rifle is this?

 

[Desert Dan]

A few possibilities
More than likely carbon build up or a rough throat/neck area. What cleaning products and procedure do you normally use?

Could be an out of round chamber or the factory ammo is not very concentric either.

What brand/model of rifle is this?

Christensen Arms Ridgeline. A normal cleaning after firing consists of running patches of either Hoppes solvent or if it's been awhile I'll use Bore-Tech copper solvent. Rarely I will use Sweet's 7.62 to clear out any copper fouling. I run patches of whichever I'm using until the fouling stops coming out on the patch. Then I dry patch until the patch ends up clean. Finally I run a well-oiled patch down and follow up with a dry patch and followed up with a lightly oiled patch before it goes back into the safe.
I'm going to give it a good cleaning. I think something stuck in there since I shot it last.
Thanks man. The rifle was fine up to the last firing so something changed recently and now it's just finding what it is.

 

[Cahunter805]

I’d recommend a nylon brush and scrub the neck/throat with the boretech and let it sit 5 minutes then repeat again and then patch it out. Also Iosso bore paste or JB bore paste on a undersized brush wrapped with a patch and some Kroil/oil really can get carbon removed easily.

 

[KD32]

Agree w/ Cahunter that it could be carbon buildup. Here’s my why:
Started w/ my 6.5 PRC last spring, worked up different loads/bullets. After a couple hundred rounds, the next bullet I decided to test (127gr LRX) seemed like it had to be seated much further into the case than I expected. Had me scratching my head, measured everything I could think of. Decided to check my dummy rounds that were loaded to Hornady factory ammo specs. Those rounds were tough to chamber & extract, which hadn’t been the case when I had first put them together & used them to check function (I built gun also). Inspected them, and found scratches on the bullets. Checked my loads w/ 147 ELDM, 156 Berger, same thing, drag on chambering & extraction (both were .030 off when worked up). Did some reading, and found where guys were saying that the 6.5PRC can be prone to carbon buildup. Re-cleaned rifle using my normal procedures, nothing on the patches. Read some more, general consensus was once there was a hard carbon ring, something like JB Bore Paste was the only way to get it out. Patches came out filthy after using JB. Kept cleaning till patches came out white. Dummy rounds chambered & extracted with no effort afterwards. Rechecked the 127 LRX, and the max length to ogive was noticeably longer than before.
Sounds like certain cartridges are more prone to develop a carbon ring at lower round counts, relative to others. I’ve begun cleaning the 6.5PRC more frequently & haven’t had another issue.
Hope you get your issue figured out soon Desert Dan!

 

[Low_Sky]

Well here is what happened when I loaded a factory cartridge into my chamber this morning. The bolt closed a little stiffer than normal but I almost couldn't get it lifted out. It was that tight which is clearly not the way it was the last time I shot a few months ago. The round was colored from just under the tip to just above the casing. It's obvious where it was contacting. The pics below are from different sides of the bullet. You can see one side was contacted significantly further up the length of the bullet than the other sides.
So what could cause this change? This rifle has approximately 350 rounds through it - mostly factory rounds with the last 50 or so shots fired being hand loads to factory length, starting with a light charge and working up to mid range where I started to see extractor marks. No issue until now. I keep my rifle clean, checked the lug recess for gunk, ran a chamber mop through it with almost nothing coming out and visually inspected the bore and barrel, and finally ran a lightly oiled patch down the barrel followed by the bore snake. Nothing unusual. The bolt closes normally on an empty chamber. An issue with the bolt rather than the chamber maybe? I don't know how a rifle could go from acting normal to this without me doing anything that I'm aware of. Smart people, chime in.

Based on the long mark on one side I'm guessing you did this with a fully assembled bolt. When trying to gauge contact with the shoulder or lands, you should be taking out the firing pin and ejector, and hooking the rim of the cartridge under the extractor so that you are only feeling contact between the round and the chamber. Your pics are a little fuzzy, but I'm not seeing rifling marks on the round. I'd investigate a carbon ring as others have suggested.