Head space checking

NigelM

Well-Known Member
I'm no real expert, but the correct way to do it is with a proper set of go and no-go gauges. That's the definitive test and used by gun smiths and the proof house.

There is a bodgers way of half doing it, which a proper gunsmith wouldn't approve of, but it is done. Get some insulating tape Measure it's thickness with your verniers - it's probably about 2 thou. Put a layer on the base of a new or FL sized cartridge and trim around the outside. Then try to chamber.

If it chambers alright add another layer and trim. Chamber again and see if the bolt closes. Keep adding layers until you can't close the bolt without a struggle. Pull the tape off and measure the total thickness again with your verniers as it has now been compressed. If it's more than about 6 thou or 3 layers of tape you probably have too much head space.

Or you can buy a set of head space gauges. Or best of all take it to a gun smith and he will do it properly for you which is likely to be the cheapest option.
 

bobjs

Well-Known Member
Cheers nigel

I think its set to tight,

I fitted new ejector and extractor and on closing the bolt with brand new brass the bolt was hard to close and the ejector (sako type) made a grove in the head of the case, never seen this before so it looks like the gun will have to go to a smith for acheck up.

Bob.
 

Fosbery Holster

Well-Known Member
Hi Bob

The simplest way I find to check head space is to use your own fire formed brass from that particular rifle, or if none use unfired pulled round for safety’s sake.
Simply use a brass case with adhesive tape of a known thickness placed onto the base, say for instance your tape is 1.5 thou thick, chamber the case close the bolt extremely gently with just finger pressure, if the bolt locks easily remove brass and add another piece of tape now it’s 3 thou, try the bolt again as before gently, if you find it difficult to close the bolt ( don’t use any pressure other than finger pressure) you have almost found your head space, don’t forget to trim adhesive tape to slightly less than the diameter of the case base, refine the tape used, thicker or thinner until the bolt will close under just finger pressure, the layers of tape measured for thickness gives you your head space without spending vast amounts on head space gauges
 

Dalua

Well-Known Member
Cheers nigel

I think its set to tight,

I fitted new ejector and extractor and on closing the bolt with brand new brass the bolt was hard to close and the ejector (sako type) made a grove in the head of the case, never seen this before so it looks like the gun will have to go to a smith for acheck up.

Bob.
I'm not sure I quite follow: has the act of fitting a new extractor and ejector any potential to alter the headspace?

All my SAKOs have an ejector that knocks the empty out from under the extractor-claw at the back of the bolt's travel - so its ability to mark the case-head would not be affected by headspace at all.

If the ejector were a spring-loaded plunger in the bolt-face, then I guess if it (or its spring) are too long, such that the plunger is proud of the bolt-face even when it's maximally pushed in, then that would reduce the headspace in a very unhelpful manner - i.e. only over the area of the plunger, but not the rest of the face.
 

PKL

Well-Known Member
if it was fine before the new extractor and ejector, the headspace is fine..what your problem is, is ejector protrusion or oversize brass that's not been sized or fired.

a bolt can be tight to close and still well within headspace
 

bobjs

Well-Known Member
I'm not sure I quite follow: has the act of fitting a new extractor and ejector any potential to alter the headspace?

All my SAKOs have an ejector that knocks the empty out from under the extractor-claw at the back of the bolt's travel - so its ability to mark the case-head would not be affected by headspace at all.

If the ejector were a spring-loaded plunger in the bolt-face, then I guess if it (or its spring) are too long, such that the plunger is proud of the bolt-face even when it's maximally pushed in, then that would reduce the headspace in a very unhelpful manner - i.e. only over the area of the plunger, but not the rest of the face.

You got it.

Even fully sized fired brass used in the very same rifle is being marked with the new spring and ejector is fitted, tried new unfired brass and that was even tighter. And as you say the mark is only made on the small ark of the bolts closing motion so lets say from 12 o’clock to 3 o’clock

The ejector when fitted IS NOT Proud of the front of the bolt, the spring feels nice and strong so i thought it was strange for this to happen

Bob.
 

PKL

Well-Known Member
Bob,

did you shoot the rifle BEFORE the new extractor and ejector? or did you buy it and fit the new parts...ie, it 'could' have come to you with incorrect headspace?

what model is it may I ask?

also, does the bolt SN match the receiver?
 

Dalua

Well-Known Member
So is the ejector in this rifle a spring-loaded plunger protruding from the bolt-face?
 

Ttocs

Well-Known Member
Try removing the ejector spring and plunger then try a sized case. If the bolt cycles ok, it’s probably the ejector not compressing fulIly hence the mark on the case heads
If you think there’s too much headspace, partially insert a fired primer into the case and try again, progressively push in the primer and retry until the bolt will cycle to give an ‘indication’ of headspace.
 

bobjs

Well-Known Member
Hi Guys

the rifle has been used by me for some time and always had a soft eject (IE: the case just clears the ejection port of the action) I had sold the rifle but wanted to check it was ok with a new ejector and spring so ordered one with Neil Mc and Neil sent it to me,

when I removed the old one and compared the spring to the new on the new spring was shorter but thicker in in the fact that the spring was a heavier gauge metal than the old spring so I thought this has been the problem for a while (not that it bothered me but you cant sell on a rifle with a fault on it.

so I fitted the new spring and ejector and holy Fook it fits like a dream feels stronger is just below the rim of the bolt face ..... but it as mentioned leave a deep mark on the case head when you close the bolt with both full sized brass that has been fired in the rifle and the same with brand new lapua brass.

the rifle is a tikka 595 6mmbr and shoots like a dream but ejects the case like a pansy. and what is annoying is when I seen how my mates ejects his case (ejects the case about 3 foot) there has to be a problem.

I trimmed the new spring down by one leaf (don't know what to call it.) it now does not mark any of the cases but still ejects like a pansy.

sorry for the delay lads but I am in and out like a lost dog at the moment.

regards and thank you for the help.

bob.
 

PKL

Well-Known Member
yes that's a spring issue clearly..reducing the spring by a full coil may have been excessive as it's not necessarily the length that's the problem, but the diameter of the spring coils and how tight it's wound. sounds like you need some new springs to play with to find the perfect fit.

what's the spring length and diameter? I might have some offcuts in various sizes from my gun spring kit I could send.
 

Dalua

Well-Known Member
So this all relates to a new ejector and spring, rather than the extractor - and the ejector in this case is a plunger protruding from the bolt-face, as found on Tikka rifles (rather than SAKO)?
 

Heym SR20

Well-Known Member
Extractor marking case head will be due to sharp edges / burs on the new extractor. A few minutes with a stone or fine emery will sort this. Or just a bit of time.

A strong extractor spring will make the bolt harder to close as you have to compress the spring. Also if the plunger is not nicely polished, will also cause drag.
 

Sharpie

Well-Known Member
If the ejector plunger was marking the case head and making the bolt stiff to close, it sounds as if the new one couldn't have been being entirely pressed back into the bolt when closed. You could test this by trying to push it in all the way with something, and see if it still protrudes a little. You should be able to push it all the way in, even slightly under-flush.

So either the new plunger is slightly longer than the old one, and/or the new spring with the larger diameter wire was becoming coil-bound under compression.

Cutting off a full coil solved that, but left you back where you started. I'd guess that you cut off too much.

My guess is that the original ejector spring had just weakened with use. A new one, or even stretching the original out a little longer to stiffen it might have been all that was required.

I'm not sure a new extractor or ejector plunger were actually necessary, as long as the original parts were still in good condition. Just the spring.
 

bobjs

Well-Known Member
Cheers lads,

1, the old spring is thinner gauge than the new one and it ejects very softly.
2, the only thing that was different with the new spares was the new spring is a heavier gauge spring,
3, i have inspected all the new parts and they are just the same as the old ones just in new condition,
4, i did not try to compress the ejector while holding the bolt in a small vice i only found the fault when I closed the bolt.
5, the new spring may have become coil-bound as you say but why would GMK not notice this as it wouldn’t only effect me?
6, the spring thats in it is thinner gauge and is very soft and easy to compress and simply stretching it would distort it and it will only end up back where it was after a few days out on the estate with the rifle,

PKL. Thank you sire, i am not paying another £46 to gmk so i would like to take up your offer and i will post the dia and length of the springs i have here both the new one that i cut and the old one thats back in the bolt,

Regards to all

A miffed off 6mmbr case damager,

Bob.
 

PKL

Well-Known Member
Cheers lads,

1, the old spring is thinner gauge than the new one and it ejects very softly.
2, the only thing that was different with the new spares was the new spring is a heavier gauge spring,
3, i have inspected all the new parts and they are just the same as the old ones just in new condition,
4, i did not try to compress the ejector while holding the bolt in a small vice i only found the fault when I closed the bolt.
5, the new spring may have become coil-bound as you say but why would GMK not notice this as it wouldn’t only effect me?
6, the spring thats in it is thinner gauge and is very soft and easy to compress and simply stretching it would distort it and it will only end up back where it was after a few days out on the estate with the rifle,

PKL. Thank you sire, i am not paying another £46 to gmk so i would like to take up your offer and i will post the dia and length of the springs i have here both the new one that i cut and the old one thats back in the bolt,

Regards to all

A miffed off 6mmbr case damager,

Bob.
Just pm me so I don’t forget
 

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