Sauer 202 6.5x55 Headspace Dimension

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deeangeo

Well-Known Member
Does anyone know their fired case headspace measurement with this cartridge in their Sauer 202 rifle please? If so, would you kindly tell me what you measure at.

I had good results with h/space sizing at 1.776" using a Nosler 120gn bullet.
At 1.776" locking the bolt on chambering the round was a bit tight...not much, but a bit.
But then measured the fired cases headspace at 1.772"

Sizing with headspace at 1.771" the cartridge chambers sweetly, but the group size opened up quite a lot - from 1/4" MOA to 1" MOA. @ 100yds
So, I'm looking for clues.
​Cheers, ATB
 
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cambsman

Well-Known Member
I have the exact same rifle. Are you trying to set the coal for your rounds? Is that what you mean by headspace? I use a Hornady OAL gauge to establish coal for each bullet type.
 

srvet

Well-Known Member
I have the exact same rifle. Are you trying to set the coal for your rounds? Is that what you mean by headspace? I use a Hornady OAL gauge to establish coal for each bullet type.

Im pretty sure he means from case head to somewhere on the shoulder as the measurements he is quoting are shorter than the 55mm case length. Trouble is determining where on the shoulder your headspace measuring device is contacting the shoulder. This may differ between measuring devices not to mention between rifles where chamber dimensions may vary slightly from rifle to rifle
 
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deeangeo

Well-Known Member
srvet is right...it's not the OAL of the round I'm after.

It is the headspace measured of a 'fired' cartridge case in a 6.5x55 Sauer 202. Measurement should be done with the correct headspace guage and will be from approx. mid-way on the case shoulder to the case 'head'.

I'm interested in seeing the comparison between mine & another similar rifles chamber. ATB
 

woodmaster

Well-Known Member
I might be missing something here but is it not strange that your cartridge came out shorter after being fired? They usually get longer hence the need to re-size. I to run Sauer 202's one in 6.5swed one in .308w. I have no head space gauge but will see what length my fired cases are coming out at. I've never played with head space too much I just make them load clean and then set col so bullet is at 20thou off lands and that's it. Would be good to improve my load though.
 

srvet

Well-Known Member
I would personally try not to set the shoulder back when resizing. If chambering the case requires a little effort then I may consider setting the shoulder back 1 thou or so but only until the bolt will close as you wish. Otherwise you will lose the benefit of fire forming the brass. I tend to neck size for most of my rifles and generally don't size the full length of the neck at that. To my mind this should minimise working of the brass and improve the alignment of the bullet with the rifling
 

deeangeo

Well-Known Member
The quoted 'given' headspace dimension in the Lee manual for 6.5x55 SM is 1.779".

Sized at 1.775" the cartridge just chambers & the bolt felt somewhat 'tight' locking down. Not rediculously tight, just tight.
When I measured the cases after 'springback' when fired the dimension is 1.772", so F/L re-sizing to 1.771" only works the shoulder/neck slightly and the cartridge chambers as sweetly as you like.

However, when reloaded with the same recipe, the groups opened up significantly. I'd just like a comparison measurement with a similar rifle of the same cartridge/cal. If anyone out there can help with this.

Nosler 120gn 49.2gns Vit.N160 3.051 OAL Hspce 1.775ins.JPG The groups have expanded from this to 1 MOA with just this dimensional change & I wonder why so dramatic a change. Things that make you go Hmmmmm! Cheers.
 

Ronin

Distinguished Member
Headspace - distance bettween bolt face and a datum line on the shoulder of the chamber

OAL - distance bettween rear of case (boltface) to Lands where bullet touches on ogive (point where it is touching the lands)


You cannot measure headspace using a fired case,,,it needs to be measured using a correct Headspace Gauge and shims.

OAL - easily measured using a comparator and dial gauge.


​Which one you mean??
 

deeangeo

Well-Known Member
Not OAL...don't require that measurement RM
Just the measurement using a headspace guage on the case fired cartridge case.
That's exactly how I would measure the case to F/L re-size the case....datum on case shoulder to base of case head.
Measuring the headspace in the rifle.......bolt face to internal datum on the shoulder is indeed a different & correct actual headspace measurement.

I don't know of a convenient to me gunsmith that might be able to take an exact measurement of the internal headspace.
​Cheers, ATB
 
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Sinistral

Well-Known Member
Oops my mistake. Sorry! Can't help with headspace I'm afraid.

Cambsman,

You can't be blamed for this. The Hornady (ex. Stoneypoint) bullet length comparator is wrongly advertised as a headspace gauge, which it's not.

BTW you need to introduce yourself as this is an open-access site - not requiring a Log-in to view.

HORNADY LOCK-N-LOAD HEADSPACE GAUGE TOOL | Sinclair Intl


Redmist has it right. It's a datum line taken as the midpoint on the shoulder precisely halfway between the shoulder and the neck/shoulder junction. There's no practical way to measure it on a fired or unfired case, unless you believe in the accuracy of the sort of gauge below .... the question is how you know exactly where the mid-point occurs.

Instructions for reloading with the Digital Headspace Guage



This is not an everyday bit of kit, so I think it's a bit anal for ordinary shooters to worry about this measurement, even if you have the technique to acquire it accurately.



'NO-GO' and 'GO' gauges are enough for gunsmithing tolerances in rebarrelling which Redmist is talking about, I think.

The quoted 6.5x55 headspace (Lee) which I assume is SAAMI differs from the German standard. This is exactly 1.776575" not 1.779" so the Sauer will have a 'shorter' headspace measure than a Remington, methinks
 
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Sinistral

Well-Known Member
Forgot to add that in practical terms it's unnecessary to twitter about measuring to get a close headspace 'fit'.

Your cases are fireformed to fit the chamber on each firing, so if you neck-size only from then on (recommend a Lee Collet neck-die!) your headspace is bound to be right.
 

deeangeo

Well-Known Member
Your cases are fireformed to fit the chamber on each firing, so if you neck-size only from then on (recommend a Lee Collet neck-die!) your headspace is bound to be right.

That's fine & readily accepted, however, I am curious to know what other users of 6.5x55 measure their fired cases at - that is, if anyone with this cartridge/cal. does measure the fired cases for resizing purposes using one of these guages.

I also accept the majority of people who do use the Hornady headspace guage in the absence of other manufacturers having their guages so readily available for purchase in the UK, simply have to go by the guage readings on their calipers. Those calipers may or may not be calibrated and I also realise that different brass - both batches and manufacturers will have varying 'springback' qualities...not to mention that brass with several firings behind it, will also lose some elasticity.

After neck sizing a few times, at some point the shoulder can & does interfere with smooth chambering of the cartridge as it 'grows' but setting up the F/L die so the shoulder is just nudged back .001" or so, can and does aid accuracy, smooth chambering & brass life IMO.

​Incidentally, just to be clear, I'm not talking about the use of a comparator here. Just the headspace guage & any findings other users of the tool might have.
Cheers, ATB
 

deeangeo

Well-Known Member
The quoted 6.5x55 headspace (Lee) which I assume is SAAMI differs from the German standard. This is exactly 1.776575" not 1.779" so the Sauer will have a 'shorter' headspace measure than a Remington, methinks

Although I had not realised there was a different German standard and am interested to learn there is, I also believe your thought is very likely. Cheers, ATB
 
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Julie

Active Member
.............I don't know of a convenient to me gunsmith that might be able to take an exact measurement of the internal headspace.
​Cheers, ATB

HS gauges for the 6.5 55 are not available is a series, only the usual g/ng/f

The only sets which are generally available are for the 308/7.62 series and derivatives, this is for two reasons:


  1. The rather obvious 308 vs 7.62 headspace difference - so OK to use 7.62 in a 308 chamber but not 308 ammo in a 7.62 gun etc
  2. Traditionally the custom target rifles tended to be based on 308 cases , so if you built a custom rifle, you would headspace down to the bottom end of the acceptable range – hence why 308/7.62 HS gauges can be obtained in a series.

This second point also guides you on the approximate HS your gun will have, if it is a custom target version, it will usually be headspaced around the bottom end – so typically a little over the go gauge (1.7794) – say 1.780 – 1.781, if however it is a general or stalking rifle, it would be headspaced towards the no go (1.785) to ensure it’s “less fussy about ammo or cases” – say 1.783 being a sauer 1.785 if it was Ruger etc

Of course this is when new – after manufacture when it has been used a lot, most guns headspace well above the no-go gauge – which is OK as long as it is below field (1.789) – so it depends on the gun and usage/age

These days custom target rifles don’t tend to be based on 308 cases anymore and are usually some wildcat derivative – in which case we use a different technique for headspace measurement – which you may use

Basically it is usual when building a custom target rifle in some odd wildcat based cartridge to only have the go gauge manufactured, and when chambering just ensure it goes, then for the no go just add packing – Rizla paper comes in various thicknesses, so if you use the silver it is around 0.8 mill thick – about 0.02mm – so using two silver Rizla papers on the head of the headspace gauge will change the 6.5 x 55 go (1.7794) to 1.781!

In your case, if you use a tight (ish) case and add packing – draw the paper over your jumper/trousers and it will receive enough static to stick to the case head – add pieces until you generate a situation where it will/won’t go - say three papers will, four won’t then use your current measuring method (I assume you are using the hornady Cart HS kit) – which will give you the range as say 1.7832 will go whilst 1.784 won’t.

Unfortunately there are a few downsides here – firstly the Hornady kit is designed to be used with a Vernier or digital calliper – the digital’s aren’t that accurate – only to 1-2 mill or so, and although verniers are available much more accurate they are very expensive and not the usual ones available, so you do need to use a micrometer to measure, and secondly be careful about the paper – it can stick to the bolt face (so when you measure it you miss a couple of thicknesses), or you fold it over and miss a thickness, or you can compress the paper with the bolt – so limit the number of papers to 3 or so

Julie
 

deeangeo

Well-Known Member
That's interesting Julie and certainly worth trying out to find an accurate HS dimension. I have no problem with vernier/micrometer tools and have them available, although for my loading I do tend to use digital calipers 'cos my eyesight just isn't what it used to be & I'll have to enlist the aid of younger eyes or a magnifying glass!

I shall have to use the Hornady HS bushings as they're the only tool I have, unless I make something very specific in the workshop.....but that really seems far too much effort for the data I want. Using rizla paper is a new one on me & I'll have a go with it.
​Cheers, & thanks a lot.
 
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