quick question before i send a nasty-gram to T/C...

I have a 6.5 creedmoor barrel for my T/C dimension that was short throated, such that my coal was almost 1/4" under spec.

I sent the barrel back to T/C and they appeared to polish the chamber. so now i'm testing again with my hornady guage...

with a 130gr nosler accubond...

the bullet clearly engages the lands still very short. however, if i give the back of the gauge some force, i can ease the bullet in a bit more until it really stops, getting me close to the 2.825"...not quite all the way, I can get the coal out to 2.780"

so my question is, how hard should i have to push on the gauge in order to actually find my c.o.a.l.? I normally use very light pressure until i feel the bullet stop and engagement.

Even if i shove the damn thing in there it is still short by a bit...

I think i may ask T/C for a new barrel instead of sending this one back and waiting another month on it.
Thank you

You must push hard enough for the gauge cartridge’s shoulder to touch the chamber shoulder. If it’s not touching the shoulder you’re not getting the measurement.

Light pressure on the bullet. I use a small dowel down the barrel so you can push the bullet back and forth.

https://www.youtube.com/watch?v=WCPgKNp8i7o

Maybe that is the TC chamber spec; does it chamber factory loads? Chamber throats aren't subject to random lengths in production.

quote:

Originally posted by dpcd:
Maybe that is the TC chamber spec; does it chamber factory loads? Chamber throats aren't subject to random lengths in production.

Na ha

The throat is built into the chamber reamer. If the throat is short, TC made it that way intentionally. I don't put a lot of faith into those commercial throat length gauges. If it's a female gauge made with the reamer used to cut the chamber and a piece of the barrel that was used to barrel the gun, then yes. Those are very accurate. Short of that I use a felt pen on the bullet and slowly increase the seater depth a turn at a time until the bullet impacts the lands and grooves.

thank you for the replies.

toomany, i need to be clear. I am pushing the gauge cartridge very firmly into the chamber. what i have to put a lot of pressure on is the bullet pusher.

when using the bullet pusher, with very light pressure i can clearly feel contact at the very short mark. i can give it more pressure (quite a bit more), and the bullet will move up to the 2.78" mark.

so it appears the throat is very tight...at least to my dumb ass.

the reason i'm questioning this is this does not happen on any of my other rifles i use this gauge on. it is very clear, seat gauge cartridge firmly, push bullet until it clearly is engaging the lands, measure, repeat a few times for consistency, done.

at this point i'm not exactly sure what to do. i do not like it the way it is...if i can't seat the bullet out as far as i'd like, why have this cartridge?

if i build the cartridge to the 2.825" length, or shoot factory norma ammo, i feel resistance when closing the bolt, it is engaging the lands a good bit.

Ok, your throat is tight, not necessarily short. Different animal.
Measure your bullets.
I do not use any fancy gauges; I use bullets in cases lightly sized so the bullet will be pushed back and give the max length.
What to do now if TC won't fix it; have it chambered with a known SAAMI spec reamer.
But again, does it chamber factory ammo? If so, then TC probably will say it's ok.

gotcha, thank you. it does chamber factory ammo, just with resistance.

next time i'm downstairs i'll get my partially sized case and check it that way.

Like Rod said, if the chamber is the correct depth the throat is cut correctly. No way a production rifle throat is cut with a dedicated throating reamer.

Substitute a FL sized case for a go gauge (guessing you don't have one...). Strip the bolt, chamber the empty case...the bolt handle should fall without resistance, or just the lightest of contact.

My money is on a short chamber.

Far as the gauge, I "tap" the rod firmly a couple of times- middle finger "flick", like the old days of paper football in the classroom

Do NOT use a lot of pressure. Bullets are malleable (duh) and you'll get an incorrect datum. Nothing wrong with jamming vld's into the lands where desired, but you need to know point of " contact" so that you can accurately measure how much you're jamming (or jumping).

If it was mine I would get a 6.5 throater and run the throat as deep as I liked (and it will be .0005 over bullet diameter too); that $50 is less than all the shipping back and forth will cost. And the reamer is still worth 35 when you are done. And if it is really tight on factory ammo, run a SAAMI spec reamer into it a couple of thousandths.
Short chamber? How can that be; it chambers factory ammo, he said; that wouldn't make the 1/4 inch difference in seating depth. even with the slight resistance the OP says has.

Yeah sending it back to TC is just going to get you the (BOVINE STARE)! I'm sure they won't cut a custom throat in it for you. You have already determined that headspace is correct, at least as far as a GO is concerned when you chambered a factory round. Like Tom said, buy a throater and have it punched out to fit whatever you are trying to chamber. Probably cheaper still would be to check the local gunsmiths and see if one of them has a throat reamer in that caliber. If it's a break action, all they have to do is set the depth on the throater and run in the reamer until it hits the breach face. They might even do it for $40 or $50. I notice that American gunsmiths like to give work away. I guess they get a lot more glory and respect down there than we do up here. We're all in it for the money here because everyone HATES us! But then again, all of the gunsmiths up here are assholes! LOL

quote:

Originally posted by speerchucker30x378:


Yeah sending it back to TC is just going to get you the (BOVINE STARE)! I'm sure they won't cut a custom throat in it for you. You have already determined that headspace is correct, at least as far as a GO is concerned when you chambered a factory round. Like Tom said, buy a throater and have it punched out to fit whatever you are trying to chamber. Probably cheaper still would be to check the local gunsmiths and see if one of them has a throat reamer in that caliber. If it's a break action, all they have to do is set the depth on the throater and run in the reamer until it hits the breach face. They might even do it for $40 or $50. I notice that American gunsmiths like to give work away. I guess they get a lot more glory and respect down there than we do up here. We're all in it for the money here because everyone HATES us! But then again, all of the gunsmiths up here are assholes! LOL

Rod, every American shooter, or any American who comes to these chat boards and reads through them, thinks he's a gunsmith! Now, to the OP, go buy a throating reamer for $50-$60 and see how deep you can make that throat!

quote:

Originally posted by cooperjd:
quick question before i send a nasty-gram to T/C...

I have a 6.5 creedmoor barrel for my T/C dimension that was short throated, such that my coal was almost 1/4" under spec...

C.O.A.L and throat datum are two very different things.
Mark the bullet with a sharpie at the point where the ogive meets the cylinder portion, set a micrometer .002" under groove diameter for the caliber you are working with and scribe a line around the bullet at the point where the mike touches it, and breech seat the bullet in the clean chamber with a case whose neck has been modified into a three fingered collet. Measure the case from the base to your line with some calipers, and that dimension is your seating depth for THAT bullet in THAT chamber, at THAT point in time. The dimension will grow as the throat wears.
Probably best to check this stuff before running cutting tools into the chamber.

quote:

Originally posted by slivers:

quote:

Originally posted by speerchucker30x378:


Yeah sending it back to TC is just going to get you the (BOVINE STARE)! I'm sure they won't cut a custom throat in it for you. You have already determined that headspace is correct, at least as far as a GO is concerned when you chambered a factory round. Like Tom said, buy a throater and have it punched out to fit whatever you are trying to chamber. Probably cheaper still would be to check the local gunsmiths and see if one of them has a throat reamer in that caliber. If it's a break action, all they have to do is set the depth on the throater and run in the reamer until it hits the breach face. They might even do it for $40 or $50. I notice that American gunsmiths like to give work away. I guess they get a lot more glory and respect down there than we do up here. We're all in it for the money here because everyone HATES us! But then again, all of the gunsmiths up here are assholes! LOL

Rod, every American shooter, or any American who comes to these chat boards and reads through them, thinks he's a gunsmith! Now, to the OP, go buy a throating reamer for $50-$60 and see how deep you can make that throat!

Well, the simple fact of the matter is, if he wants to seat the bullets out farther, he has to lengthen the throat, somehow. Polishing the chamber won't do it. Running a chamber reamer in to lengthen the headspace wont do it (unless he runs it in 1/10th of an inch and that would be BAD, or buys a chamber reamer with the throat length that he wants and runs it in). A lot of guys do recut their own throats by hand. They also cut chambers by hand or in cats heads by indicating the barrel and using floating reamer holders. I don't recommend those practices either. But some guys even ADVERTISE that they do things that haphazardly and call it better. So he can cut it by hand if he wants. The truth of the matter is, while it can bell the throat or make the throat to long, neither of those conditions is dangerous, the British used to paradox rifle barrels. The proper way, as I also indicated, is to send it to a gun plumber and have him put it into the lathe and do it properly between centers and as I said, it would probably be the same price as the reamer. In my own stuff and bench rest stuff I NEVER cut chambers and throats separately. It risks building in alignment error. But to some it's common practice.

Those are his options and he has to govern himself accordingly.

I have no problem with amateurs running throating reamers into their barrels. He can't hurt it, and when one ends up with a 3/4 inch bullet jump, then I get to install a new barrel for him. So everyone wins.

Sounds like a novel business model, give questionable advice on the internet and hope they bring it to you to fix. Only problem with that is, if I get bad advice from the HVAC guy, or the auto mechanic or the Dr., I go elsewhere! 9 7/8 out of 10 of those, that manage to screw something up like that, take it to the gunshow and try to make it some one elses problem. After 40+ yrs of job shop machining experience and a diploma from an accredited gun smithing school with 27yrs of bench experience says to me, any novice should stay away from things they don't know anything about, other than what they have learned on the "mis-information super hi-way".

Good advice but I assure, they don't, and won't. Men, like to think they can do everything,, and they will try no matter what you say to them. I find.
And note that I did not tell the OP to ream it; I said, "If it was mine"....That is not advice.

thanks guys. this is very helpful.

i have a masters in mechanical engineering and have spent some time in a machine shop; so i have a pretty decent grasp of how all this stuff works. (i'm an a-typical engineer, i wrench on my truck, build furniture, remodel stuff, i actually use my hands).

for these barrels, they do not thread onto the receiver, they slide into the receiver to a certain point such that the action screw locks the barrel and action together, and then is held on with a barrel nut.

so, it is not like my r700 that i recently had to have the barrel set back one turn and have the chamber recut to correct a headspace issue.... if you touch the chamber in this one and make it too long, the barrel is scrap, or i'd have to rechamber to a larger 6.5mm with the .308 boltface.

so as handy as i may be, i will not be running any tools into my chamber/throat/bore. I'll check with my local smith, or message one of you guys on here and see what i can have done.

The wife just gave birth to our first son last week, so I'm not likely to do a lot of shooting right now anyway...