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-   -   Mauser heaspace or gauges in sacramento (http://www.calguns.net/calgunforum/showthread.php?t=621183)

backstrap 09-16-2012 11:57 PM

Mauser heaspace or gauges in sacramento
 
Can anyone point me in the direction of getting a 308 Mauser headspaced in the sac area. Doesn't have to be a shop. If you have the gauge I'm sure I can return a favor.

kcstott 09-17-2012 6:20 AM

I hope you mean just "checked" as to "correct" the headspace on a mauser requires some serious work and would cost as much as having a new barrel installed.

jamesob 09-17-2012 8:25 AM

take 2 pieces of scotch tape, place it on the back of the case, insert the round onto the bolt. if it doesnt close all the way, your fine. if it does close your chambered to deep. its not the most precise way but it does work.

kendog4570 09-17-2012 9:21 AM

Quote:

Originally Posted by jamesob (Post 9342506)
take 2 pieces of scotch tape, place it on the back of the case, insert the round onto the bolt. if it doesnt close all the way, your fine. if it does close your chambered to deep. its not the most precise way but it does work.

Ammunition is not a guage, and neither is cellophane tape.

7.62x63mmUS 09-17-2012 10:11 AM

Just buy the gauges. Seriously it's worth it for the peace of mind alone.

kcstott 09-17-2012 1:22 PM

Quote:

Originally Posted by jamesob (Post 9342506)
take 2 pieces of scotch tape, place it on the back of the case, insert the round onto the bolt. if it doesnt close all the way, your fine. if it does close your chambered to deep. its not the most precise way but it does work.

I don't know how many times we have to go over this. On a cartridge that head spaces on the shoulder tape should never be used as a head space gage.
You have no base line dimension, you have no idea how far under or over size the case is. It's also a safety issues. If you did this as a professional gunsmith and something happened to the rifle. You are liable for any damages and or injuries.
$60 for a set of gages in the most common of calibers is cheep insurance

7.62x63mmUS 09-17-2012 1:35 PM

I've bought a lot of 30-06 and 8mm surplus rifles the last few years and have used a field gauge to check them all. All you really need for safety checks is a field gauge. A rifle that closes on a no-go gauge but won't close on a field gauge is usually considered "serviceable". My dad has a Turkish mauser that would have consistent problems detonating primers despite being clean internally and with a new firing pin spring. Well guess what? I checked it with my 8mm field gauge and the bolt closes. Basically firing the pin pushes the cartridge forward to the extents that the extractor claw allows causing light strikes. Theres a potential for a case head failure in these situations, although we had fired this rifle sporadically for the last 20 years. This rifle was purchased at Big 5, which surprised me. I had one 1903 Springfield that failed the field gauge as well. A new bolt head fixed that problem. Obviously Simpons LTD doesn't check this, or at least warn about it. You never can be too careful. For the last couple K98's I bought at Big 5 I asked the store employee/manager if I could check and they did let me.

backstrap 09-17-2012 3:00 PM

Here's the problem. The primers are swelling using steel case. Is this a headspace issue or case issue? Could brass cases ammo fix it?

7.62x63mmUS 09-17-2012 3:36 PM

I believe excessive headspace is part of it... probably not ALL of it though. Happens with all types of cases.

kcstott 09-17-2012 4:56 PM

Swelling?? How

Are they backed out and flattened? or just backed out?

Is the firing pin indent cratered or indented normally?

jamesob 09-17-2012 5:02 PM

did i say it was the best way or the most accurate? no. it will give you a general idea of whats going on without buying gauges.

kcstott 09-17-2012 5:36 PM

Quote:

Originally Posted by jamesob (Post 9345223)
did i say it was the best way or the most accurate? no. it will give you a general idea of whats going on without buying gauges.

Ok how's that??

I just measured a hand full of new ammo It headspaces .008" to .012" under a go gage dimension add .006" for the No go dimension

Two pieces of scotch tape is .004" so you're still .004" to.008" under a go gage and .010" to .012" under a no go.

If you are using a fired case. Well what was the original dimension of the chamber it was fired in? Was it long or short on headspace?? You don't know.
And thats where I take exception to this technique. If you have nothing to reference from how do you know where you end up.?

The point I'm getting at is you have no idea what the headspace dimension is of the cartridge you are stacking layers of tape on.
So if you don't know what it's headspace dimension is how will you know how many layers of tape to add?

You can do this on cases that headspace of the rim, case mouth or belt but not on a rimless case with a shoulder. It's not accurate at all and will not even get you in the ball park. I would only recommend this technique when you are building rifles during or just after the battle of Armageddon

CS Sports 09-17-2012 6:13 PM

Quote:

Originally Posted by jamesob (Post 9345223)
did i say it was the best way or the most accurate? no. it will give you a general idea of whats going on without buying gauges.

Actually, it is a terrible idea to use cartridges to measure headspace. Best case scenario it gives you meaningless info, worst case scenario it gives you dangerous info.

Gauges are precision ground for a reason, guessing, or approximating headspace measurement is a recipe for disaster.

OP, if you are ever in the Woodland area, you are more than welcome to swing by and we will measure properly with gauges.

kouye 11-02-2012 3:51 PM

Bringing up an old topic...how is a headspace (to much gap) fixed typically?

kendog4570 11-02-2012 4:29 PM

Quote:

Originally Posted by kouye (Post 9642028)
Bringing up an old topic...how is a headspace (to much gap) fixed typically?

It depends on what the reason for the excess head space is, and the type of action. Sometimes replace worn components with new, sometimes rebarrel or set existing barrel back, sometimes it is not "fixable", like setback in the lug seats.

kouye 11-02-2012 5:15 PM

In my case an FN Mauser, originally chambered for .30-06 then rechambered/barreled for 7.62 NATO. Fails with a .308 Field gauge.

As I understand it a military 7.26NATO chamber is deeper than a commercial .308 and that may be the reason for failure.

kendog4570 11-02-2012 5:49 PM

Quote:

Originally Posted by kouye (Post 9642602)
In my case an FN Mauser, originally chambered for .30-06 then rechambered/barreled for 7.62 NATO. Fails with a .308 Field gauge.

As I understand it a military 7.26NATO chamber is deeper than a commercial .308 and that may be the reason for failure.


Max .308Win/7.62 NATO is .010" over .308 Win minimum. You may be OK just need to check with the appropriate gage, 7.62 field (which is .308 min + .010"). .308 field is .308 min +.008". It would be nice if your chamber was tighter, but it is not unsafe (assuming it passes the NATO field gage). It could even be longer and not be “unsafe” (meaning you will not get head separations on new ammo), but that is another topic. Brass life will suffer, and it might be less accurate than a tighter gun. The good news it will take any ammo you can throw in it, along with a shovelful of dirt. It might be wise to check the bolt and receiver for signs of setback and lug seating, in case it was barreled correctly and something happened top it before you got it.

kouye 11-02-2012 6:18 PM

Yeah, I have a 7.62 NATO field gauge on the way. Hoping for the best. Visual inspection done by a gunsmith after the failure didn't show anything obviously wrong. He owns a couple of 7.62 Mauser's himself so he knows this gun.

Previous owner shot both 7.62NATO and .308 target loads, but I'm a big chicken. I want an okay from a qualified gunsmith before I shoot the thing with anything.

After I get my gauges, I'll take it back to the gunsmith for a more detailed analysis and if there's something that would need to be done to tighten it up. Cost is not the issue here either, I just want a good shooter that will eat .308 and 7.62NATO.

Next step is an M1A, but I needed an excuse to step up in cost/round and this rifle is it... :)

kendog4570 11-02-2012 6:35 PM

Quote:

Originally Posted by kouye (Post 9642995)
Yeah, I have a 7.62 NATO field gauge on the way. Hoping for the best. Visual inspection done by a gunsmith after the failure didn't show anything obviously wrong. He owns a couple of 7.62 Mauser's himself so he knows this gun.

Previous owner shot both 7.62NATO and .308 target loads, but I'm a big chicken. I want an okay from a qualified gunsmith before I shoot the thing with anything.

After I get my gauges, I'll take it back to the gunsmith for a more detailed analysis and if there's something that would need to be done to tighten it up. Cost is not the issue here either, I just want a good shooter that will eat .308 and 7.62NATO.

Next step is an M1A, but I needed an excuse to step up in cost/round and this rifle is it... :)

I am in Aptos if you need help. FFL Licensed and insured for gunsmithing. 25+ years experience.

kendog4570 11-02-2012 6:37 PM

Quote:

Originally Posted by kouye (Post 9642995)
... after the failure ...

What failure?

kcstott 11-02-2012 6:43 PM

Are you sure it's .308/7.62 nato?? Are you sure it's not 7.65X53mm Argentine?? Is the barrel appropriately marked as such?

kouye 11-02-2012 6:50 PM

Failure to pass the .308 Field gauge check. I didn't ask to have him check it with a 7.62 NATO gauge as there was a lot of people in the shop waiting for him at that time.

Barrel is stamped 7.62x51mm with a BNP proof also has an Israeli 7.62 stamp on the side of the barrel as well as burned into the stock. Receiver is marked as .30 and cutout in the front ring for the slightly longer .30-06 round when it was originally converted from 8mm Mauser to .30-06 for Colombia.

kcstott 11-02-2012 6:51 PM

Quote:

Originally Posted by kendog4570 (Post 9643111)
What failure?

I think he meant the failure of checking with the gages.

kouye 11-02-2012 7:02 PM

Does the data presented on this site look right?

http://www.303british.com/id36.html

If so, is it true that a commercial .308 chambered rifle can run either 7.62NATO surplus and commercial .308 but a military chambered 7.62NATO rifle might be able to run 7.62NATO but not commercial .308 ammo depending on the condition of the chamber?

kcstott 11-02-2012 7:28 PM

Not exactly
Nato is almost alway higher PSI then commercial. And the 7.62 nato is no different.

As to chamber dimensions. Yep that is usually the case. The real issue is using commercial loads in a military chamber. Military chambers are designed to take nearly anything. Dirty, dented, etc. It will chamber and fire nearly all of them with no issues.

The comercial chamber being more tight will not tolerate dirty dented cases like a military chamber will.

kouye 11-04-2012 7:42 AM

So I took the bolt apart and found the firing pin tip bent. Would this be a direct result of too much headspace?

kcstott 11-04-2012 10:55 AM

Nope. Separate issue. Cocking piece is probably not set up correct.

Don@Tahoe 11-19-2012 9:20 AM

Can anyone give me the dimensions of the go-no go gauges for a 30-06, I would like to turn my own.

kcstott 11-19-2012 1:58 PM

Quote:

Originally Posted by Don@Tahoe (Post 9751380)
Can anyone give me the dimensions of the go-no go gauges for a 30-06, I would like to turn my own.

Ok For one you don't turn a gage, they are ground to proper shape an length.
Two, you would need to be able to machine the gage to a tolerance of +/-0002"
Not something the average home shop is capable of doing.
Not to mention how are you going to measure it?? To make sure it's correct??

Just spend $60 and be done with it.

But if you think you can do it here you go.
http://upload.wikimedia.org/wikipedi...idge_30-06.png
Keep in mind you will have to indicate the 17.5 degree angle as a minor variation will create a to long or too short gage.
Should be made from A2 tool steel, rough machined, heat treated to Rc 57-60, and ground to final size with the angle being +/- 5 MOA, OAL +/-.0002" and gaging datum line +/-.0002"
Add .004" for a no go gage and .010" for a field gage.

If the barrel is off the gun and you have a .375" ball bearing and know trig you can measure the headspace.

Don@Tahoe 11-19-2012 5:36 PM

The tolerances are beyond my capabilities, the best I could do is +/-.001, I really appreciate your time, thanks.

kcstott 11-19-2012 5:47 PM

Well when the difference between a go and no go is .004" you can see how the tolerances will stack.
Lets just say you did make them to +/-.001 then you either have a difference of .002" or .006" between go and no go.
That's why I said .0002" because at the worst you have .0005" variance from your basic dimension

Wrangler John 11-20-2012 8:49 AM

Also, when purchasing headspace gauges, purchase the set from one manufacturer, there are variations between brands, that can stack giving false readings if mixed together. Here is the blurb from a Manson gauge entry on Brownell's site:

" . . . MIXING AND MATCHING BRANDS OF HEADSPACE GAUGES - Don't do it!! That's the short answer, here's why. It boils down to tolerance stacking. Each Headspace Gauge manufacturer works within a range specified by SAAMI. Manufacturer ''''A'''' may work at the high end of the range while Manufacturer ''''B's'''' gauges are in the middle of the tolerance range. Mixing the two could give an inaccurate [result]."

Here is a page with info about headspace: http://surplusrifle.com/shooting/headspace/index.asp

Just so you know, I have been a loader and cartridge wildcatter for 50 years, and build my own swap barrel rifles. Changing barrels and bolts to swap between cartridge head sizes requires adjusting headspace, which is easy, but must be done with precision gauges.

So, let's say I buy a rifle with safe maximum headspace, where the bolt will not close on a FIELD gauge, that is otherwise safe to shoot, or a lot of new brass is undersized for a particular chamber. This is not a problem for the handloader. What is needed is to adjust the headspace by forming the cartridge case to match the chamber, and this applies to belted, rimmed and rimless cases. It produces more accuracy and cases that stretch less on firing that last longer.

Sometimes the headspace difference is minor, where backing off the full-length sizing die a couple of threads when sizing new brass will prevent chambering. That’s good, because all that is needed is to turn the die down an eighth of a turn and resize, then checking if the bolt closes, and repeating until the bolt just closes, establishes headspace for that chamber. Then I set the die lock ring. Thereafter that die is adjusted for that particular chamber. If however, the chamber is too large or the brass too short, then the need is to neck the case up a caliber or two and reset the shoulder.

http://i274.photobucket.com/albums/j...3Headspace.jpg

The photo above shows how I accomplish this. The case on the left is a .223 Remington as it came from the factory.

The middle case has been necked up to .243 in a 6mm PPC F.L. die by running it over the expander ball, stopping short of actually sizing the neck. Almost any 6mm/.243 die that is short enough will work, my alternative is a .243 WSSM die. I don’t use Forester dies for this operation as the expander ball is just below the neck sizing chamber inside the die making it functionally longer. The other alternative is to purchase a dedicated neck expander die. Most manufacturers sell tapered neck expanders for cartridge conversions including RCBS and Redding.

The case on the right has been partially sized back down in a .223 Remington F.L. die. The double diameter neck can be seen that will become the headspace stop or double shoulder. To fit this case to the chamber, the die would be turned in no more than an eighth of a turn at a time, the case then resized, and the process repeated until the bolt just closed. On a bolt action I prefer just a bit of resistance as the bolt closes. The die lock ring would be locked down. Firing this case would establish minimum headspace and it could be either reloaded using the F.L. die or a neck only die adjusted out to avoid pushing the neck/shoulder back.

I use this same technique on rimmed cases, where the case is converted to headspace on the shoulder instead of the rim thickness. I used this method in forming cases for the Contender pistol and others, using bottle necked cartridges. It also works on rimmed bottle necked rifle cartridges such as the .30-30 and .348 Winchester, and wildcats based on them. I set the 7mm Remington Magnum and belted wildcats to headspace on the shoulder in the same way. The only disadvantage is that brass has to remain separated and marked for the rifle it was set for, and the die should be kept for use only for that ammo. This is not a technique to allow use of a rifle with excessive headspace outside of safe limits, rather it is a means of adjusting cartridge headspace to minimize case stretch and inaccuracy. If the rifle bolt closes on a FIELD gauge, do not use the rifle or this technique. If headspace is too excessive, the case head will not expand enough to seal the chamber, allowing gas to escape into the action, a very dangerous condition that can cause injury or death. This is a discussion of my experience only. Use caution and common sense, as I can not assume liability for individual judgement and interpretation.


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