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Does a bolt head need to overclock?

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Bear43 View Drop Down
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    Posted: August 08 2019 at 7:32pm
I have been working on a Savage No 4 Mk 1* that belongs to my dad. He wanted a micrometer rear sight (thanks again, Canuck), a cheek rest removed (that went to britrifles) and to have it cleaned. Well, just out of curiosity I checked the head space and it failed on the milspec field gauge. So, I measured up what I needed and got a couple bolt heads. The second one clocked in exactly on the spine of the bolt. It does not overclock at all. I put the bolt in and the headspace is fantastic, it chambers a round with no problems and the bolt closes completely with no issues. I think it is good to go but I was wondering if there needs to be any overclocking on the bolt head or is it fine as is? I honestly have never seen a bolt head line up this perfectly before.
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Goosic View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 7:53pm
I have the same thing going on with my Long  Branch. I though it weird too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:01pm
Bear, that is a good question.  My first thought is that you would not want the bolt rotational travel to be limited by the bolt head.  I don’t know if there would be any condition that this would occur on this rifle as you have described. 

Is the bolt head shoulder hard against the bolt front face when bolt head is aligned with the spline?  Not just on the striker stop (collar)?  

 I don’t think I would want to grind anything off the end of the bolt or shoulder on the bolt head to get that over travel.  Wear over time should achieve that.     
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bear43 Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:02pm
Goosic, I have seen how that shoots so I have my answer Thumbs Up  I guess I am so used to seeing overclocking that I found it strange it was so perfect. Even better that I only had to try 2 bolt heads to find one that worked.

britrifles, the bolt head shoulder is snug against the bolt front face. Firing pin protusion is good, rounds chamber fine, bolt closes completely and easily. Everything I see says "go" but it just made me think if any overclocking was a requirement or not.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:15pm
You won’t have to worry about wear on the bolt head threads!  Thumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bear43 Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:19pm
So very true, that stress point is gone for sure LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Canuck Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:28pm
My two Parker Hale (#1/mk3-#4/MK1*) rifles have negligible bolt head rotation. Maybe a few degrees but hardly noticeable. I also have a Long Branch exhibiting the same lack of rotation and that rifle cycles with no issues at all. When I take a rifle apart, after cleaning thoroughly, I take a 6 power magnifying lens to the wear surfaces of the bolt head. That practice gives me a solid idea where that rifle 'is'. I also check the wear on the sear to trigger interface surfaces.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bear43 Quote  Post ReplyReply Direct Link To This Post Posted: August 08 2019 at 8:33pm
Thanks, Canuck, that info makes me feel a lot better and puts my mind at ease. I am just overthinking again.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: August 09 2019 at 4:02am
A 'correctly' fitted bolt head should have zero overturn.
This is rarely achieved so a tolerance of overturn is allowed.

You have a 'rare' well fitted bolt head. No overturn and correct headspace.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote englishman_ca Quote  Post ReplyReply Direct Link To This Post Posted: August 09 2019 at 6:46am
There is an armourers' tool that fits over the bolt head and acts as a wrench to crank on the assembly to align the bolt head with the rib, if too tight.

I have fitted bolt heads and they don't turn enough, so the bolt head goes into the padded vice jaws and I crank on the bolt handle to align things and may be give a coontair of overturn. Just enough to let me insert the bolt into the receiver. Sometime I have had to really crank it hard.

So the short answer is, as you have found out, no, you don't have to have any overturn.
If it will fit in the bolt way and function, it will break itself in and eventually give itself a slight overturn. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: August 09 2019 at 7:01am
Its fine the spec is "less than 20 thou at the ridge." they picked that number because of the amount of backlash in the threads. Anything under 20 is OK because the threads have that much linear backlash.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: August 09 2019 at 7:31am
Originally posted by englishman_ca englishman_ca wrote:

There is an armourers' tool that fits over the bolt head and acts as a wrench to crank on the assembly to align the bolt head with the rib, if too tight.

I have fitted bolt heads and they don't turn enough, so the bolt head goes into the padded vice jaws and I crank on the bolt handle to align things and may be give a coontair of overturn. Just enough to let me insert the bolt into the receiver. Sometime I have had to really crank it hard.

So the short answer is, as you have found out, no, you don't have to have any overturn.
If it will fit in the bolt way and function, it will break itself in and eventually give itself a slight overturn. 


This one ?
(this is No1 Mk3 variant)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote englishman_ca Quote  Post ReplyReply Direct Link To This Post Posted: August 09 2019 at 8:03am
Yup, that is it!
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