Chamber question

[Caleb85]

help me make sense of this:
A guy was talking to me about how he was going to chamber his barrel, he was talking about "go +.003 or .004" or just chamber it to the no go. What would be the advantages of this? And why is the world would he want to do that!?

 

[JasonT]

That sounds ridiculous unless it's a military semiautomatic/autoloader.

 

[Caleb85]

That sounds ridiculous unless it's a military semiautomatic/autoloader.

He talking about a bolt gun for PRS

 

[Ggmac]

Maybe for a project down the road , long chambered , so all he has to do is clean it up ? Just a guess .

 

[Steve Ladino]

Not ridiculous but probably based on a theory He has about extra case volume or maybe contending with brass flow to an advantage possibly, anyway after Fire forming all will be mute once the case sizes up to the chamber. Of course overdoing with FL resizing after firing would be detrimental to ignition/accuracy and case life. Its his baby.

 

[JasonT]

It won't likely be dangerous, but if he goes more than the "no-go" length, he'll definitely contend with a shorter case neck after the brass "blows-out" to the chamber walls. This will impact his barrel life and ability to hold a bullet.

 

[gat]

Many precision shooters ask us to chamber their barrels this way. It gives them the ability to "feel" headspace. You see they simply take the go gauge and apply a piece of masking tape to the rear of it. The bolt is very hard to close this way but not impossible. With the tape removed the bolt falls effortlessly on the go gauge. The tape measures around .004 and crushes to .0025-.003 . This way they know that their brass has room to grow but only slightly and they still chamber easily for quick feeding during tactical matches! Never had anyone ask to chamber to no go then stop.

 

[Danny1788]

I just started using 1/2" round disc shims .001" and .002" to check this and my go gauge. It makes it really easy, I like it better than tape as your just guessing with tape. Plus cutting the tape in a small circle on the end of a go gauge is a pain. I try to shoot for .003" plus gauge before the barrel is torqued down. that leaves me about .001 to .0015"

I bought them from Mcmaster Carr product #2904T38 and #2904T31

O I guess it matters what your chambering, I use them for magnums

 

[hoz53]

I just started using 1/2" round disc shims .001" and .002" to check this and my go gauge. It makes it really easy, I like it better than tape as your just guessing with tape. Plus cutting the tape in a small circle on the end of a go gauge is a pain. I try to shoot for .003" plus gauge before the barrel is torqued down. that leaves me about .001 to .0015"

I bought them from Mcmaster Carr product #2904T38 and #2904T31

O I guess it matters what your chambering, I use them for magnums

I'm glad to hear about these discs being available . Mabie you can get bigger diameters. I have been thinking about doing this to measure my lug to barrel dimension on chamber jobs. Also bolt nose to counterbore bottom on Rems. Thanks

 

[hoz53]

Many precision shooters ask us to chamber their barrels this way. It gives them the ability to "feel" headspace. You see they simply take the go gauge and apply a piece of masking tape to the rear of it. The bolt is very hard to close this way but not impossible. With the tape removed the bolt falls effortlessly on the go gauge. The tape measures around .004 and crushes to .0025-.003 . This way they know that their brass has room to grow but only slightly and they still chamber easily for quick feeding during tactical matches! Never had anyone ask to chamber to no go then stop.

I am fairly new to clambering but I am skeptical of this idea or mabie I am just not grasping it. What you are describing is the same as guys do that only have a go gauge then use the tape to check their no go setting. I chamber so the stripped bolt just falls on its own with a go gauge and then check to make sure the bolt doesn't close on the no go. That is within .003 on a 6br. I could "feel my headspace" with tape to if I wanted. If a guy wants more shoulder clearance to insure easy feeding Its as simple as sizing the shoulder on your brass back a little farther. I'd rather do that than make my chamber extra long. Even if your brass is only blown out one time to the longer dimension it's still stretching it more than I want and to me contributes to shorter brass life. Of Coarse prs guys probably lose it before that's a factor anyway. Just my2cents

 

[savagedasher]

Most dies will only move the brass back to were a loose go gauge fits . Tape on a firm go gauge you end up where you don't have to use special shell holders or shorten the dies. Larry

 

[gat]

Sorry that this leaves you skeptical but it works. I always work off both sets of gauges but I also do what my shooters ask, especially when there are no safety issues involved. Headspace usually exists over .003 to .004 and my shooters use primarily Lapua brass ,when we chamber and use the tape method their brass usually grows around .001 or less in length. I still check with a no go gauge before calling it good. Perhaps I was a bit skeptical too at first, however 3" groups a 1000yds don't lie. Neither does Lapua Brass surviving 12-14 trips to the old press before being scrapped. Just answering Caleb85's question.

 

[hoz53]

Sorry that this leaves you skeptical but it works. I always work off both sets of gauges but I also do what my shooters ask, especially when there are no safety issues involved. Headspace usually exists over .003 to .004 and my shooters use primarily Lapua brass ,when we chamber and use the tape method their brass usually grows around .001 or less in length. I still check with a no go gauge before calling it good. Perhaps I was a bit skeptical too at first, however 3" groups a 1000yds don't lie. Neither does Lapua Brass surviving 12-14 trips to the old press before being scrapped. Just answering Caleb85's question.

Ok Thank You for that explanation--Im just trying to understand here and hoping it all helps Caleb. So really you are chambering within the "normal" range just at the long end of it. I realize as long as a person fits their brass to their chamber they will be ok. I just wonder how far past go you could cut a chamber before brass life gets cut short significantly. Apparently its more than .oo3 to .004. Thanks Again for providing this info

 

[DaveTooley]

Much to do about nothing.

 

[gat]

Re-read my post and it sounded a little belligerent, I did not intend it to be. Please accept my apologies. As for the how much is too much question It would greatly depend on neck and shoulder thickness etc.

 

[Danny1788]

I'm glad to hear about these discs being available . Mabie you can get bigger diameters. I have been thinking about doing this to measure my lug to barrel dimension on chamber jobs. Also bolt nose to counterbore bottom on Rems. Thanks

Yes they make them larger sizes too, but i don't know why you would need to check that? if your measurements were right from the start you should have added the clearances in when cutting the CB and tenon length.

When its all torqued down i have found that i get around .002" for crush fit.

 

[hoz53]

Much to do about nothing.

That's what I have been thinking.

 

[hoz53]

Re-read my post and it sounded a little belligerent, I did not intend it to be. Please accept my apologies. As for the how much is too much question It would greatly depend on neck and shoulder thickness etc.

No need to apologize, I should have worded my post different. I like to hear about different thinking and I've learned a little from your post. I should have just posted--why make the chamber longer when you can just make the brass shorter ?-- I wonder if sizing your brass back to far effects concentricity or something like that. There must be some reason these guys are doing this I'm not seeing. Mabie it just is as Larry says they can't get dies to size the shoulder back far enough. A week or so ago I re chambered a factory barrel in .223 and I messed up and got my headspace .005 over go. I now wished I would have left it that way and shot it some to see wat would happen. Thanks

 

[hoz53]

Yes they make them larger sizes too, but i don't know why you would need to check that? if your measurements were right from the start you should have added the clearances in when cutting the CB and tenon length.

When its all torqued down i have found that i get around .002" for crush fit.

thanks for the info about the shim stock sizes. Yes I know about the clearances to add to your measurements. I just would like the ability to measure the clearances cause I'm curious,anal or something like that. Another thing--I'm going to fit a Savage small shank barrel to a Rem 783 (nut jobs) and I want to make sure about the clearances. That .002 dimension is good to know. Thanks