Is this an excessive lenght chamber?

[Davey Boy]

My .308 has a chamber length of 2.068 measured many times with a Sinclair chamber guage.

Sammi Trim length for the .308 is 2.015 . Where should I be trimming 2.020 or more, or never trimming until it approaches chamber length? Or just 2.020 so that it is consistant. Doubt that it will ever stretch to chamber lenght.

What would you do?

 

[gunsandgunsmithing]

My .308 has a chamber length of 2.068 measured many times with a Sinclair chamber guage.

Sammi Trim length for the .308 is 2.015 . Where should I be trimming 2.020 or more, or never trimming until it approaches chamber length? Or just 2.020 so that it is consistant. Doubt that it will ever stretch to chamber lenght.

What would you do?

If accurate, that does seem a bit long but, how does it shoot?
I'd fire the brass a few times and then uniform it all. If you're using Lapua, it may be close enough for the life of the brass. By close enough, I'd say if it's all within about .005", I wouldn't worry with uniforming it. Just my 2 cents. Is this a factory chamber by chance?

 

[fguffey]

What would you do?

I want to know the length of the chamber from the end of the neck to the bolt face. I want to cover the chamber with the case, I understand hot high pressure metal cutting can cut the chamber when the case does not cover the chamber.

I have forming dies, meaning I can form cases with long necks; when determining the length of the chamber to the end of the neck I trim the long neck until the case will chamber without crimping/closing the mouth of the case when the bolt is closed.

F. Guffey

 

[Davey Boy]

If accurate, that does seem a bit long but, how does it shoot?
I'd fire the brass a few times and then uniform it all. If you're using Lapua, it may be close enough for the life of the brass. By close enough, I'd say if it's all within about .005", I wouldn't worry with uniforming it. Just my 2 cents. Is this a factory chamber by chance?

This is a factory chamber CIL 950 C Same as the Savage 110C. And yes I measured several times using the Sinclair chamber tool. I can't even touch the lands without the bullet falling right out of the case. I does shoot sometimes under MOA if I do my part. Guess my best bet is to pick a case length and trim all to that length for consistency.

And sorry Mr. Guffey don't understand what you mean. The case with the Sinclair chamber gage measures 2.068 That is from the bolt face to the end of the chamber.

 

[#40Fan]

Don't mind guffey. If you can get the necks to grow, do so. Won't hurt a thing with all of that room.

With all of that extra though, be careful not to let carbon build up in the gap.

 

[boltfluter]

Duffy, the village idiot, needs to take a long walk off of a short pier. Just pick a length you like and trim all.

Paul

 

[Hummer]

What I would do is drill bottom of a fired case out, tumble clean it in stainless steel media to get it nice and clean. Put case in chamber and run a borescope in from the bottom, up through the neck and take a look at exactly what you have and how far you can go. Chamber drawings are not necessarily the way to figure much of anything.

When I chamber a new barrel I save the front 3/4" or so I cut off muzzle. I chuck it up and run the same reamer into it till the shoulder goes in back, then reverse it and cut the front back to where I can see where the chamber stops. That way you know exactly what THAT chamber is seeing. It also gives you a neck gage so if you are running a tight chamber you don't have to run your ammo into the chamber and out just to see if it is too tight in neck.

In the long run it pays to have one reamer chamber all your rifles of that caliber. My match reamers I order meet the 222 principle. Which means I don't want anything on that case moving over .002" when it is fired i.e. neck doesn't expand over .002, shoulder does not go forward over .002 and case .200" up from rim does not expand over .002. This will give you longest case life.

 

[JFrank]

My .308 has a chamber length of 2.068 measured many times with a Sinclair chamber guage.

Sammi Trim length for the .308 is 2.015 . Where should I be trimming 2.020 or more, or never trimming until it approaches chamber length? Or just 2.020 so that it is consistant. Doubt that it will ever stretch to chamber lenght.

What would you do?

2.10

 

[243winxb]

does shoot sometimes under MOA if I do my par

I don't see a problem. SAAMI CHAMBER.

 

[JRS]

Duffy, the village idiot, needs to take a long walk off of a short pier. Just pick a length you like and trim all.

Paul

That wasn't necessary, Paul.

 

[joshb]

Duffy, the village idiot, needs to take a long walk off of a short pier. Just pick a length you like and trim all.

Paul

Actually, that was a fairly good response. I understood it, tho he didn’t finish, per se.
If your brass is all short, trim it all to the same length and shoot it. Just keep an eye out for the carbon ring build up.

 

[JFrank]

This is a factory chamber CIL 950 C Same as the Savage 110C. And yes I measured several times using the Sinclair chamber tool. I can't even touch the lands without the bullet falling right out of the case. I does shoot sometimes under MOA if I do my part. Guess my best bet is to pick a case length and trim all to that length for consistency.

And sorry Mr. Guffey don't understand what you mean. The case with the Sinclair chamber gage measures 2.068 That is from the bolt face to the end of the chamber.

He is making a case with a longer neck for measuring purposes.
As always a long trip down memory lane by way of a circular motion around the barn ending up right back where he started from with total disregard for clarification therefore posing a separate question to confuse further discussion.
I'm on his ignore list so he won't read this.
SPJ

 

[Webster]

My .308 has a chamber length of 2.068 measured many times with a Sinclair chamber guage.

Sammi Trim length for the .308 is 2.015 . Where should I be trimming 2.020 or more, or never trimming until it approaches chamber length? Or just 2.020 so that it is consistant. Doubt that it will ever stretch to chamber lenght.

What would you do?

From everything I have read the case is made so it's impossible for the neck to reach the end of the chamber. The neck length in the chamber is always at least 0.025" longer than a factory case neck length, I assume for safety reasons. Your neck will never grow 25 thou or longer, so it can never touch the end of the chamber. Measure your case neck length and compare it to the space in the SAAMI drawing to accommodate the neck.

 

[fguffey]

I don't see a problem.

That is sad: I do not see you offering a remedy.

Again, I am a case former. I am the only reloader that can not move the shoulder back on a case with a die that has case body support: I understand you do not have a clue what that means but when I form a 30/06 case with a forming the shoulder of the case does not move back, when I form a case the shoulder is erased and becomes part of the shoulder and or neck and the shoulder that is formed is a new shoulder.

So I ask: (You do not see a problem), Who is the idiot? The diameter of the throat is smaller than the diameter of the chamber neck. If I do not trim the neck of the formed case the case neck will not chamber into the throat of the neck without being sized when chambered.

And then there are two lengths of the chamber, one is measured from the datum/shoulder to the bolt face and the other is measured from the beginning of the throat back to the datum. That little piece of information has been with us for over 70+ years.

F. Guffey

 

[grovey]

Is the chamber long as well, or is it just in the neck? Perhaps 7-08 brass could be necked up and sized to use the extra space.

 

[fguffey]

and case .200" up from rim does not expand over .002

I have cases with .260" thick case heads from the cup above the web to the case head. I understand that means nothing to members here but if my cases with thick case heads expand the diameter of the case head expands.. if the diameter of my case head expands the diameter of the primer pocket expands and the flash hole diameter increases; and then the bad news, the case stretches between the case head and case body.

F. Guffey

 

[Davey Boy]

If I let them all just grow without trimming, I will have an extra variable that will be all over the place as to a consistant trim length and accuracy. Yes I would like to avoid as much in the way of a carbon ring as possible, but will just have to deal with it in a more vigorous way. I'm thinking of letting the brass grow to 2.020 and keeping them at that for consistancy. It does leave a lot of room for carbon to build up but I use wipeout and wipeout patchout so that should keep carbon to a minimum. I have the time to let both sit overnight. Don't have a borescope and that won't be in the budget at anytime soon.
Thanks fellas for all the replies, and Mr. Guffey perhaps a picture along with your explanations. Sometimes a picture is worth a thousand words, and doesn't confuse as do words sometime.

 

[joshb]

I’ll add a little more advice here, based on personal experience. As I slowly got into this “game”, I bought what I thought I needed when I thought I needed it. I bought a borescope about three years in. That was a mistake on my part. I had used the products you mention and quite a few more. I’d let barrels sit overnight with those cleaners, too. I was VERY surprised at what I found when I used my borescope for the first time. Carbon and copper in every barrel!! I wish I hadn’t waited so long to get my scope. I feel that it should be one of the first purchases a guy should make, if he’s serious about “precision shooting”. I bought the Lyman on sale. I only use it to check for cleaning and new gun inspection. It’s the best money I’ve spent yet! Good luck!

 

[243winxb]

2.0488" + .015" tolerance = 2.0638" total..

chamber length of 2.068

So the chamber is long by less then .005"

 

[Davey Boy]

2.0488" + .015" tolerance = 2.0638" total..




So the chamber is long by less then .005"

Well if you put it that way, yes, not enough to be worried about I guess.