View Full Version : Bolt Action Headspace Symptoms?

September 3, 2000, 11:01 AM
Recently bought a Yugo rebuilt K98 from the local "Big 5" sporting goods (non matching, excellent condition)and picked up some surplus 8mm ammo at a local gunshow. I don't recall but I think the ammo was either Yugo or Greek 1953 production military. The "Big 5" guns are supposed to be checked, headspaced and ready to go (except for some cosmoline cleaning) At the range the gun turned out to be an excellent shooter (1.5" groups @ 100yds) however every 4th or 5th round the bolt was very hard to open and when I did get it open I found the primer blown out of it's seat. :eek: As I said only some rounds did this others would eject fine. A blown primer would certainly indicate high pressure of some sort.

So... is this excessive headspace? Bad ammo? or something else im not thinking of?
Any input would be appreciated.

H. Meyer

September 3, 2000, 09:41 PM
Could be either headspace of bad ammo.
Have the gun headspaced by a gunsmith you trust.
If O.K., fire a box of American commercial ammunition through it. They say that some of this surplus 8mm ammo is very high pressure, so I wouldn't be surprised if this were the cause. I would not fire any surplus ammo as a first test of one of these rifles: soft cases, misfires, hard primers, high pressures, wierd original specs, maybe corrosive: too often, the ammo does not work right and then you don't know if it is the rifle or the ammo.
Also, make sure the barrel has been cleaned with a broinze brush until patches come out clean and you know it is not full of rust. This too causes high pressure and can even burst a barrrel.

Juan Hunt Greer
September 3, 2000, 10:18 PM
Check the condition of the firing pin tip. It should end in a neat little hemisphere. If it has been chipped or in any way narrowed or deformed, it could give just the symptoms You describe. Also check the hole in the boltface where the firing pin protrudes. It should be round and barely larger than the firing pin tip.
paranoia is a good thing to have when they actually are out to get You!

James K
September 3, 2000, 11:52 PM
Check for any other signs of headspace problems, like a bright ring around the rear of the case which would indicate case stretching. Popped primers may be an indication of several problems, but I think that the ammo is suspect rather than the gun.

I have been shooting Sellier and Bellot 8x57 JS stuff and it is accurate, non-corrosive and Boxer primed (reloadable) to boot.

The ammo you have been firing is probably corrosive and if so, a good barrel cleaning is required after use.


Joe Portale
September 5, 2000, 09:22 AM

Considering that you stated that every fourth or fifth round gave you problems, I agree with Jim Keenan and say the ammo is the problem. Go pick up a box of Federal, S&B or other better quality ammo and see what happens. I bought some surplus ammo that did the same thing. I even han primers fly out when the case was ejected.

As fast and dirty check for headspacing goes as follows:

Legal stuff first. The below IS NOT TO CONSIDERED SCIENTIFIC OR STANDARD OF THE INDUSTRY. TAKE YOUR GUN TO A SMITHY EVEN AFTER THIS TEST. This test will give a very rough idea about the condition of the head spacing. It is no substatute for a set of guages.

1. Place a piece of masking tape on the face of the end of the bullet. Close the bolt. The round should chamber, if not your headspacing is too tight.

2. Add another piece of tape and rechamber the round. You should not be able to close the bolt. If the bolt closes, your head- spacing is too loose.

Good luck.

Joe Portale
Tucson, Arizona Territory

"Those who turn their swords into plow shears,
end up plowing the fields of those who didn't"
Thomas Jefferson

September 5, 2000, 09:46 AM
Thanks for all the info guys! I suspected the ammo, considering it didn't do it all the time. But I think the collective wisdom is right, I'll take it (and the unissued M48 I just bought)to the local gunsmith this week.

H. Meyer
Carson City, NV.

James K
September 5, 2000, 12:34 PM
I suspect the primer problem is not caused by excess headspace but by head expansion, allowing the primer to fall out when the bolt is opened. This indicates soft cases and could be an indication of bigger problems down the line. I would stop using that ammo and see what happens with better ammo.