I have just purchased an old Brno model 21 in 7x57. The gun is in excellent condition and has hardly been fired. I had the headspace checked and it will go on a no go guage but will not close on a field gage. My gunsmith says that the factories would still consider this within spec. I have never heard of this before. Is it correct or is there a problem.? Would appreciate your advise.

A field gage is the absolute max headspace dimension. So while its within the total tolerance, it is the absolute upper end.
So, yes, the gun is safe to fire with factory ammo, but you will get case stretch and head separations if you reload to a factory spec cartridge gage. Accuracy may also suffer.

Do you reload?
If you do, the headspace is a non-issue as you can set the shoulder of the case back as much or as little as you please and set the cartridge to the correct length for this rifle's chamber.

These rounds would be too long for a min. spec headspace 7x57, so if you have more than one in the stable, make sure you segregate the ammo for each.

added latter...
No Company that I have worked for would except a chamber that closed on a NO-GO gage. Feild Gages are essentially for checking guns that have seen many many rounds, think military. All guns will see a growth of headspace over years of use, from wear on the locking surfaces, wear from diry brass working on the breech face and the chamber, microscopic setback from firing and eventually a gun that closed on a NOGO will also close on a Field gage. Its just a matter of time.

If you don't reload I would recommed that you have the barrel set back one turn, and recut the chamber to min. headspace.

If you do reload, its a non issue, simply make "custom" ammo for that chamber.

quote:

Originally posted by Rusty Marlin:
If you do reload, its a non issue, simply make "custom" ammo for that chamber.

bbell, yes, if you reload you can dance around the problem my manipulating your handloaded ammo, however, be very careful selling a gun with a headspace problem... I would fix it!

"Headspace" is a little understood non-issue in most instances.

There is essentially no such thing as "dangerous" headspace when firing a new factory load because (1) the new brass will stretch a very long way without any head separation, and (2) if the headspace exceeds the amount that new brass will safely stretch, then it is unlikley that the primer will be held sufficiently against the bolt face for the firing pin to ignite it. The exception might be in a controlled-feed action like a Mauser where the extractor claw holds the case head to the rear, but in this instance there is still no danger in that essentially all of the case stretch would be forward in the chamber. I suppose if you point a gun with grossly excessive headspace straight up so that the primer is held against the bolt face by gravity, then you might be able to induce a case head separation on first firing.

There are various reloading methodologies which have been discussed at length elsewhere to properly adjust the brass to fit the chamber with handloads. I would never hesitate to purchase or shoot a gun which won't close on a field gage (unless its excessive headspace is a result of abuse) as its headspace is well within the managable range.

That's a helluva gamble you're offering up..........

I'd fix it, whether I was going to keep it or sell it. At the very least, let the new owner know that it was in that kind of condition.

We've had three different rifles in our posession that have had the first factory rounds seperate due to excessive headspace. Two of them would barely close on a no-go gauge and the other was even more sloppy. All 3 were 30-06's and if memory serves me correctly, they were all using Remington factory ammo.
Two of them happen to be post-64 push feeds and the other a Remington 721.
Fortunately for the shooters, they only suffered minor powder burns and good flinch.

Headspace is nothing to play around with.

quote:

Originally posted by triggerguard1:
That's a helluva gamble you're offering up..........

I'd fix it, whether I was going to keep it or sell it. At the very least, let the new owner know that it was in that kind of condition.

We've had three different rifles in our posession that have had the first factory rounds seperate due to excessive headspace. Two of them would barely close on a no-go gauge and the other was even more sloppy. All 3 were 30-06's and if memory serves me correctly, they were all using Remington factory ammo.
Two of them happen to be post-64 push feeds and the other a Remington 721.
Fortunately for the shooters, they only suffered minor powder burns and good flinch.

Headspace is nothing to play around with.

Please enlighten me in my total ignorance.
Why is excessive headspace such a problem,
Why is a headspace from 0,1mm- 0,15mm a problem, when factory ammo often varyes more than 0,5mm, and reloaders often makes it mutch worse.

If a rifle that barely closes on a no-go gauge, expierince caseheadseparation, i can guaranty you that it would have hapened, also with a rifle that would close easily on a go-gauge, but not on a no-go.
In that situation, i would look at the brass.
And if it had been a CRF rifles, you would have been mutch worse of.


best regards
Jørgen
Schultz & Larsen Rifle Company

One of those lunatics who actualy has done a lot of practical tests on the issue. Along with multiple blowup tests, on manny diferent actions types

quote:

Originally posted by triggerguard1:
We've had three different rifles in our posession that have had the first factory rounds seperate due to excessive headspace. Two of them would barely close on a no-go gauge and the other was even more sloppy. All 3 were 30-06's and if memory serves me correctly, they were all using Remington factory ammo.
Two of them happen to be post-64 push feeds and the other a Remington 721.
Fortunately for the shooters, they only suffered minor powder burns and good flinch.

I would be willing to bet that these three examples had more to do with the distance between the breech of the barrel and the bolt face, than headspace. The push feed Winchesters that I see usually have too large a bevel or chamfer at the mouth of the chamber which does not fully support the brass in the critical web area. This deep bevel coupled with a bolt face that is a bit too far away from the breech exposes too much brass to the open air which WILL cause head separation or blown case.

When I set back, or, rebarrel a gun, I pay as much attention to the distance between the nose of the closed bolt and the breech of the barrel, as I do the distance between the case head and the bolt face. Too much of a gap spells trouble.

I've seen the same chamfers and that doesn't help either, though your average Remmy has more case protrusion than Winchester push-feeds I've measured, to say nothing of CRF's or Mausers.

After thoroughly inspecting the rifles, the only factor amongst them all that was consistent and out of tolerance was indeed the headspace.
Chamber casts proved to be normal in terms of diameters or concentricity issues.

These were not all from one user, nor were they brought in at one time, but rather 3 seperate incidents with different users, brass, and guns over a span of about 10 years.


Now please enlighten me as to what makes a firearm go bang.........

quote:

Originally posted by triggerguard1:
Now please enlighten me as to what makes a firearm go bang.........

Is this directed at me?

Mauser 96-------apx 70.000 psi casehead blowout and breach failure, bolt stopped after 2"
Mauser 98-------apx 70.000 psi casehead blowout sever lug setback, action cracked at tumbcut boltface fractured.
CZ--------------apx 70.000psi casehead blowout lug setback. boltface fractured.
The 3 abowe were all CRF with 0 headspace, chambered in 6,5x55
Tikka -------apx 80.000 psi primerblow, causing flying plastic boltcap, and flame 10" backwards. no action defects. heavy boltlift
Tikka ------apx 100.000 psi. bolt stuck, casehead deformation, action still intact
Tikka ------apx 120.000 psi. Caseheas blowout. boltface rim cracked, extractor blown. 1mm lugsetback, boltstop blown away, and huge flame backwards.
Varberg ---apx 80.000psi tight boltlift, but could be opened without force
Varberg----apx 100.000psi heavy boltlift
Varberg----apx 120.000 psi casehead blowout lugsetback. Boltfacerim cracked, extractor blown,
Remmington--apx 100.000 psi tight boltlift
Remmington --apx 120.000 psi heavy boltlift
remmington --apx 145.000psi casehead blowout. lugsetback, boltface cracked
S&L----apx 80.000 no indications
S&L----apx 100.000psi no indications
S&L ---apx 120.000psi tight boltlift could be opened by hands
S&L----apx 145.000psi casehead blown, boltface cracked,reciever split, bolt mooved ½", No flying particles more than 50cm, no flame or splinters backwards.

All tests were made with identical 6,5x55 barrels, with minimum headspace, chambered with the same reamer.
All loads were made with 160grains hornady RN, Powder Norma 200, Starting at 42 grains, ending at 48grains(if possible)

The 2 actions that handled highest preasure had both a 100% caseheas support, and with build in extractor.

Prior static tests in hydraulic press showed that the CRF actions withstand the same static preasure at the PF actions.
All actions handled static boltface preasures from 14ton to 18 ton.

I belive that some manufactures use a long caseprotrution, as a type of safetyvalve.

I would like to thank everyone who replied. There is obviously a great deal of knowledge on this forum. Although I purchased it I can send it back until tomorrow. The sellor is a reputable dealer. The reason I am reluctant to return it is It is a brno model 21 F (full stock) made in 1955. It is the round bolt version with a factory single trigger. Very rare. Additionally the stock is so slim and delicate. Fits me better than any other gun I have with iron sights. Havent yet found rings to test it. The negative is that headspace. Following the discussion I was wondering about chambering to a 280 remington or 7x64 as setting back the barrel would leave a gap in the stock. Not sure if I should return or keep. It is not a collector item as the stock has been shortened and a recoil pad added. I paid $850 cdn. Thoughts from our experts?

Well, around here the action alone is worth that. The magazine on that model is long enough for either cartridge you are considering rechambering to.

Were it a clean gun, I'd be inclined to keep it and if I was really concerned about headspace I'd simply form cases from some longer parent cartidge like the .280 for example. Adjusting the die so that the formed case is a tad long in the shoulder and you get a slight crush fit on the case. Zero headspace.

quote:

Originally posted by z1r:
Well, around here the action alone is worth that. The magazine on that model is long enough for either cartridge you are considering rechambering to.

Were it a clean gun, I'd be inclined to keep it and if I was really concerned about headspace I'd simply form cases from some longer parent cartidge like the .280 for example. Adjusting the die so that the formed case is a tad long in the shoulder and you get a slight crush fit on the case. Zero headspace.

+ 1

At one time I spent several years buying guns at auction in Europe. Believe me, after the war headspace in guns of unknown history & provenance was not something you could count on.

Still, I had no insurmountable problems shooting those guns safely, regardless of their headspace dimensions. I just followed advice similar to that quoted above and everything worked out very well.

bbell,
You might check your gunsmith's choice of headspace gauges. The 7X57 seems to have been one caliber that has had mention of different versions. Some early 7X57s show maximum to excessive headspace.
For example:
Forster even has two different Go gauges for the 8X57. In the US the 6.5X55 headspace guages are shorter than the original Swedish ordinance guages so Swede rifle may show long headspace with US gauges and will be intolerance with Swedish ordinance gauges. This is documented on the internet. I have a like new M70 Winchester in 6.5X55 that chambers tightly on Norma factory ammo. It will not completely close on a go gauge. My Swede rifles gauge properly and accept factory loaded ammo.
I also have loading dies that vary .03 in headspace for the 7.65 Mauser. One set produces ammo .030 too short. Yet Norma ammo matches my guages and 3 of my rifles and the Kynoch drawing. The 4th rifle is about .030 too long. Matching it to the short die would give close to .060 excess headspace.

I have a mint like new M95 Mauser in 7X57 that appeared to be unfired when I bought it. It drags on and will almost close on a No-Go.
I don't know where you are located but there is a chance that there is some variation in 7X57 specifications and gauges. You might get a second opinion with another set of gauges.

quote:

Originally posted by Westpac:

quote:

Originally posted by triggerguard1:
Now please enlighten me as to what makes a firearm go bang.........

Is this directed at me?

No it wasn't...........sorry for the confusion.

quote:

I also have loading dies that vary .03 in headspace for the 7.65 Mauser. One set produces ammo .030 too short.

This could only be the case if in a novice move, you simply screwed the die into the press until it bumps the shellholder. Different shellholders, depending on the thickness of their lips, will also give different "headspace". Surely with a moniker like "ireload2" you are familiar with how to adjust the headspace properly on your die set up and the reference above is erroneous.

quote:

Originally posted by Stonecreek:

quote:

I also have loading dies that vary .03 in headspace for the 7.65 Mauser. One set produces ammo .030 too short.

This could only be the case if in a novice move, you simply screwed the die into the press until it bumps the shellholder. Different shellholders, depending on the thickness of their lips, will also give different "headspace". Surely with a moniker like "ireload2" you are familiar with how to adjust the headspace properly on your die set up and the reference above is erroneous.

The reference is not erroneous in the hands of a newbie. I guess that you don't get it. Suppose I just give you the dies and let you sell them on ebay. Would you really do that?

quote:

I guess that you don't get it. Suppose I just give you the dies and let you sell them on ebay. Would you really do that?

You are correct that I don't get it.

You can adjust either set of dies to resize to the proper headspace. The exception would be if your chamber is very short, then the deeper die may not be able to set the shoulder back enough. I've had this experience and it can be addressed either by grinding some thickness off of the shell holder or off of the bottom lip of the die.

I have a set of dies for a .264 Winchester which I chopped about a half-inch off of in order to load some 6.5 Remington ammunition. If I wished to reload some .264 Winchester with these abbreviated dies, all I would need do would be to back them off of the shellholder approximately a half inch and go at it. Does this explain why I am puzzled as to your reference to two sets of dies producing different "headspace"? So might two different shellholders, for that matter. It's all in the adjustment of the dies in the press.