Gunsmithing FIXED excess headspace?

sobrbiker883

sobrbiker883

Lt. Colonel
Full Member
Minuteman
Sep 18, 2003
7,125
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Gilbert AZ
#1
My fired brass is .009" longer than factory, pretty sure my chamber's deep.

Can this be fixed by just pulling the tube (R700) and shaving the three faces on the chamber end? If so, would .008" be the number or is there springback involved that needs taken into account?

The guy that did the barrel's out of pocket for a month, but I have a machinist buddy or two and can size up brass "go"/"no go" gauges for it.
 
#4
Re: Fixing excess headspace?

Steve, yes it is easily fixed by just what you said. We pull the barrel and cut one counterbore dimension, the tenon length, and the barrel shoulder. Set them all back .008" or .009".

If its too deep, we can measure how deep it is with gauges.

There is "crush" when mounting a barrel, but since its already "crushed", we take off "X" if the chamber is "X" too deep.


Id be happy to take care of it for you



and Im sorry but the two comments above would not correctly fix the problem. They both do the same thing and dont take into account counterbore dimensions that would be screwed up in the process. <span style="font-weight: bold">Especially</span> when talking .008" or .009"
 
#5
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">My fired brass is .009" longer than factory, pretty sure my chamber's deep.

Can this be fixed by just pulling the tube (R700) and shaving the three faces on the chamber end? If so, would .008" be the number or is there springback involved that needs taken into account?

The guy that did the barrel's out of pocket for a month, but I have a machinist buddy or two and can size up brass "go"/"no go" gauges for it. </div></div>

new brass is pretty short. i'd check it with a hs gauge before i went any further. this is assuming by "factory" you mean factory new brass, not fired brass in a factory barrel.
 
#6
Re: Fixing excess headspace?

Didn't check it with a guage, but I have close to $500 worth of 1X fired brass and would rather have the barrel fit it than resize it all.

Everything was cool in my head until my stach of Creedmoor brass started rupturing on the third or so firing. My bad-assuming zero HS, but then again, .009" is a bit much from a guy that slold me on the Creedmoor chamber.

Keith, thanks, I think I have it covered, but if you have a 6.5CM reamer, sen me a PM with a price on a "mini setback", that may be the way to go in case the chamber's hinky from me firing through a match with ultiple case failures.
 
#7
Re: Fixing excess headspace?

We'll have our Creed reamer here in about a week. Besides Mike has one I used on his rifle.

It wouldnt take much time to do what you're asking. You could stand there and wait while I do it. I wasn't plannin on chargin ya. Maybe a lift to a match sometime. I dont remember where you live, I think you told me though.


Our bad ass lathe showed up today. Along with our mill.


Its a Kent. Weighs 2200lbs and is by FAR the nicest lathe Ive ever used. And we had quite a few to choose from at school. Im really excited to build on it. The feel of a heavy, quality machine cant be expressed. You just have to feel it then you go, "Oooooohhhh. wow." This thing will do great work.

We'll be cutting steel in about a week.
 
#8
Re: Fixing excess headspace?

Actually, I'll take you up on the gracious offer Kieth. Esp if I can watch
wink.gif
I will give you a call tomorrow, you number's the same still right?
 
#10
Re: Fixing excess headspace?

Creed reamer gets here in 3 more business days but, we're waiting on pilots.



Doing what we need to do, we may not even need a reamer.

If there's say, .008" excessive headspace PAST the No-Go, we can take .0010" off putting you at +.002 from Zero headspace, I'll then lightly polish the chamber because you said you were concerned about the ruptured cases.

That should make it good as new.


We'll gauge it and see whats up before we do anything.
 
#11
Re: Fixing excess headspace?

Sounds great! I defer to your measuring, I just know I have 500+ cases sized to 3.532" with a HS comparator and brass coming out at <span style="text-decoration: line-through">3.451-2"</span> 3.541-2" and splitting on the third firing!

Whenever works for you. Gotta run an errand or two and I'll give you a holler.
 
#14
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Didn't check it with a guage, but I have close to $500 worth of 1X fired brass and would rather have the barrel fit it than resize it all.

Everything was cool in my head until my stach of Creedmoor brass started rupturing on the third or so firing. My bad-assuming zero HS, but then again, .009" is a bit much from a guy that slold me on the Creedmoor chamber.

Keith, thanks, I think I have it covered, but if you have a 6.5CM reamer, sen me a PM with a price on a "mini setback", that may be the way to go in case the chamber's hinky from me firing through a match with ultiple case failures. </div></div>

if your chamber is correctly headspaced and you are sizing your brass back .009" after firing, having case head separation wouldn't surprise me at all. if your chamber is in spec, i'd rather change the resizing practices than make the chamber out of spec.

i'd gauge it.
 
#16
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">
if your chamber is correctly headspaced </div></div>

Therein lies the rub, but I pretty much think the odds are better for a buddy to cut a chamber deep than Hornady to put out 4 cases of 140 Amax Match and a case of 120 Amax MAtch ammo that are all .009" undersized.

When I had my POF 6.5CM, I did measure the fired brass and it was coming in at .002" over factory so I set my dies to that (factory).

I just trusted my buddy and never measured the fired brass out of the boltgun, which was built later.
The 1X fired stockpile was processed to match factory, and the amount I have would pretty much cost the same as a new Bartlein and install, but I'd kind of like to use the Bartlein I already have....

I've done stupider things, but the first thing we'll do is compare the "go" guage to factory brass (as a variance in guages could have caused all this), and the chamber.
 
#18
Re: Fixing excess headspace?

Yes he is.

Actually if the chamber works on a go and doesn't on a "no-go" I will probably just apologize for wasting anyone's time, polish the chamber if there's any hinky residue and fireform all the brass and return to a .001-.002" bump and rock on.

Hey Keith-maybe I can borrow the go/no-go guages tomorrow and find out?
 
#19
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">
if your chamber is correctly headspaced </div></div>

Therein lies the rub, but I pretty much think the odds are better for a buddy to cut a chamber deep than Hornady to put out 4 cases of 140 Amax Match and a case of 120 Amax MAtch ammo that are all .009" undersized.</div></div>

i'm not saying either way until you check it with a gauge. i can't remember the exact number but i do know that my factory new winchester brass is in the ball park of .008"-.009" shorter than once fired in a chamber cut to minimum headspace. after the first firing, i disregard what the factory new brass measured and bump it back .002" from the fired dimension. i haven't used hornady brass or ammo but i wouldn't find it hard to believe if they did measure that short.
 
#20
Re: Fixing excess headspace?

I would not put much faith into any of the headspace comparators that clamp on to a pair of calipers.
I use the RCBS precision mic for comparing fired and sized cases.
In the case of the 6.5 Lapua or Creedmoor where one does not exist, I have made an insert to install into the unused bullet length part of the precision mic.
Barring that, make a chamber gauge with the same reamer as the barrel and make it deep so you can use a depth micrometer to measure.
 
#22
Re: Fixing excess headspace?

Our Creed gauge actually shows up next week sometime. Mike (my buddy Mike) has the GO and NoGo I used on his rifle. He lives down the road from me about one mile. Im sure he'd let you or I barrow his till the next match we see you at.



I meant to go to the match this month but I didnt know when it was and didnt plan for it. I really hope to make the August one.





And thanks Mechanic. I enjoy doin this shit so a quick one hour job for someone I shoot with sometimes is no prob.
 
#26
Re: Fixing excess headspace?

I'll be getting to it later this week. Like Friday I hope.

Just got the lathe and mill turned on today for a few seconds. tomorrow we go over the machines and start getting them ready. Before I can even use the lathe I need to spend about 3 hours milling the bottom part of the new tool holder down so it will fit. Getting rid of the 4 way and going to a good quick change. I don't mind the 4 ways but I like the easy and accurate height adjustment that the quick change offers.

Anyways, Steve your rifle is the first project this lathe and new tooling will see.
 
#28
Re: Fixing excess headspace?

Well, I believe my rifle busted the cherry on Phoenix Custom Rifle's new lathe...

Keith had my rifle for a few days and now the chamber has had the gas checking cut out and has been slightly setback to a proper "go guage" plus .002" headspace.

I'd imagine it can only improve the rifle's shooting, but its going to be hard right away to objectively check-my recoil lug was not timed correctly either, and the barreled action now has some stress on the lug. The McM A3 its in was bought used and had the pillars originally installed a little skewed so its always pointed right of centerline, but now it is worse.

I think I'll shoot it tomorrow as is, and then hog out the stock and rebed it adn do the best I can with the pillars.

Thanks again Keith, I think PCR is off to a good start and from talking to you it sounds like you are headed in the right direction!
 
#30
Re: Fixing excess headspace?

Ummmmm, just a c-hair late-I was in the garage with the Wile E Coyote end mill (Dremel)
crazy.gif


I took material away from everything but where the lug butts up to the bedding, to include the barrel pad and any Devcon that was "fit" to the lug.

Everything's cleaned and retorqued, we'll see how it does in the morning. Looks pretty much like it did before I think.

Time to make a few chrono rounds for the 6XC and I gott get to bed!!
 
#31
Re: Fixing excess headspace?

If anyone (other than myself) has actually seen how a piece of brass is manufactured they will instantly appreciate the weight of 300 Sniper's advise.

A cartridge (fired, new, old) should never be used as a gauge. It's a foolish practice with far more potential for consequences than reward.

A gauge costs $30 bucks. $30 rarely covers the Emergency Room Co Payment on most policies.

Buy the GO gauge. Stick it in the chamber. Strip the bolt of anything operated by a spring and see if it closes. IF it closes snip off a piece of small diameter solder and use it as a "crush" shim between the gauge and bolt face with everything clammed up. Measure that thickness and you KNOW beyond any shadow of doubt exactly where the headspace is. If your under .006" then your well inside of SAAMI for most cartridges. If you not reloading the FIELD length is typically GO+.01"

If you are a handloader then it doesn't hurt to stay inside of GO+.004"

As mentioned you need to compensate for crush. Crush largely depends on the quality of thread fit between barrel tennon and receiver. It also has a lot to do with how square the faces are and how parallel the recoil lug is.

One way to tell (laymans) is to screw the stuff together by hand. If it sucks up real quick with little/no perceived "squishy" feeling then chances are its pretty good. If things are like mashed potatoes then something is prolly out of whack a bit.

Hope this helps.

BTW with Ackley stuff you should have .004" crush on the parent case when initially fire forming. this ensures case growth ONLY at the body/shoulder and mitigates issues at the web.

Good luck.

C.
 
#32
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Keith at PCR</div><div class="ubbcode-body">300,

I agree.

We'll be checking the chamber before doing anything.

I wouldn't headspace a rifle to a piece of brass. </div></div>

Looks like we agree.

youdeserveit.jpg
 
#33
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C. Dixon</div><div class="ubbcode-body">... A cartridge (fired, new, old) should never be used as a gauge.... </div></div>

Agreed - unsupported, all you'd be doing is setting the shoulder back on the case.

However, I've heard that you can use a case as a custom HS gage provided that you fill up the case with something solid, such as epoxy or lead.

On another note, I feel a gage such as this when used with a dial caliper is very helpful for comparing new/fired/re-sized cases (ignore the seated bullet):

DSCN0979.jpg


DSCN0980.jpg


You can make one with a barrel stub and chamber reamer, I actually made that one on a mini-lathe using the crossfeed....

Cheers,

Bill
 
#35
Re: Fixing excess headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Keith at PCR</div><div class="ubbcode-body">WRM, among other reasons, you cant headspace with brass for legal reasons. Not because it crushes the brass. </div></div>

Keith, please forgive my ignorance - I'm not a professional gunsmith or FFL, and was not aware of any such law. Could you please provide a link to this statute that I may educate myself?

Thank you,

Bill
 
#36
Re: Fixing excess headspace?

There's no specific law against it. But if you are taken to court and you tell the judge you headspaced the rifle that blew up with a $.30 piece of shit brass, you lost the case.

If you prove you used the industry standard for headspace measuring, and the barrel WAS headspaced to a SAAMI Gauge set, you are fine. In that aspect anyways.


I would think not headspacing to a piece of brass is common sense(for gunsmiths) because of worrying about lawsuits.
Thats what those precision ground SAAMI headspace gauges are made for that only cost $30.
I can see how a customer would want it done. But the smith has to worry about court.

 
#38
Re: FIXED excess headspace?

Just wanted to update that the rifle now sports a chamber that is +.002" over a PTG (I believe) "go" gauge, and all future brass will be sized to fired minus .002".

It seems Keith did well on making the cuts and not abusing my Bartlein, I had 11 rounds and took six to get zeroed and then shot a group over the chrono (data on left was this group, right is a different rifle).

Maybe I've gotten better, but the best group it ever put on paper before was just over .5moa and usually ran around .7-.9 moa consistently-so I'm inclined to say Keith's work made a difference. Needless to say I'm happy:
65cm081111a.jpg

<span style="font-size: 20pt">

Thanks PCR!!</span>

 
#40
Re: FIXED excess headspace?

Sweet deal, should solve the problem of the splitting the cases! And the thing is shooting lights out! Still need the 6XC? (kidding)
 
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