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Bolt closing force.

Printed From: Enfield-Rifles.com
Category: Enfields
Forum Name: Enfield Gunsmithing
Forum Description: Submit any how-to's or other gunsmithing suggestions here.
URL: http://www.enfield-rifles.com/forum_posts.asp?TID=10128
Printed Date: October 22 2020 at 8:43am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: Bolt closing force.
Posted By: Frameman 1
Subject: Bolt closing force.
Date Posted: November 22 2019 at 2:46am
Can anyone tell me how to measure the force normally required to close the bolt.without a round, on a Ishapore 2A?
What would that measurement be?


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There are no Americans in Baghdad!!



Replies:
Posted By: Long branch
Date Posted: November 22 2019 at 2:49am
If you're talking about the force required to turn the bolt down, it shouldn't take much.


Posted By: Frameman 1
Date Posted: November 22 2019 at 3:32am
Not exactly. I’m asking about the force required to push the bolt forward against the cocking/firing pin spring.

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There are no Americans in Baghdad!!


Posted By: Shamu
Date Posted: November 22 2019 at 7:17am
According to the service manual:
The weight required to pull the cocking
piece to the half-cock and full-cock positions shall
be 3.2 to 4.1 kilograms (7 to 9 pounds), and
5.9 to 7.3 kilograms (13 to 16 pounds)
respectively. These weights are checked with a
trigger test scale engaged on the head of the
cocking piece. Weak striker springs shall be
replaced.

This should be the same to close the bolt.


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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: Frameman 1
Date Posted: November 22 2019 at 9:39am
Thanks so much !
That’s exactly what I needed.
I’ll look for a service manual of my own.


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There are no Americans in Baghdad!!


Posted By: Shamu
Date Posted: November 22 2019 at 11:42am
Send me a PM with you e-mail & I'll send you a set as .PDFs


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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)


Posted By: Frameman 1
Date Posted: July 27 2020 at 5:32pm
Thanks for the advice.

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There are no Americans in Baghdad!!


Posted By: Goosic
Date Posted: July 27 2020 at 5:54pm
Originally posted by Explosive Explosive wrote:

A bolt that needs force to close on a round is what you want, it eliminates head space.... Headspace bad, no headspace good.Big smile
No no Explosive. When the bolt is closed and force is used to close it,be it minimal force, headspacing is way off. An example of correct headspace would be for the bolt to not close with a .074" NoGo gauge in a 303B Enfield.  Now, for the sake of argument you use a cartridge with a rim thickness of exactly. 060". You will have an air gap of .014" between the boltface and the cartridge.  If your boltface contacts the cartridge in such a way that force is required to close the bolt,you can cause excessive pressures to build in the chamber during firing and put undue stress on the bolt itself.  


Posted By: A square 10
Date Posted: July 27 2020 at 7:18pm
yes , but actually rotating the bolt to locked after its forward should only take your thumbs pressure 


Posted By: Goosic
Date Posted: July 27 2020 at 9:23pm
Originally posted by Explosive Explosive wrote:

I'm not suggesting hammering the bolt handle, but if it's a firm fit it's good.

  I had a case just this morning that was too hard to close, I disgarded it.
I am not suggesting that you are.
Opening and closing of a bolt should be smooth as glass with no noticeable resistance, especially with the Enfield rifles.  Those should cycle like there is no ammunition being used at all. I have a brand new Remington M700P that cycles rounds so smoothly, I actually have to visually check to make sure a round has been chambered.  Same goes for  both my No4Mk1* T and my No4Mk1* Long Branch rifles. Headspace is as they were when they left their respective factories and I can cycle a fired and spent round with just my index finger and thumb. 


Posted By: Goosic
Date Posted: July 28 2020 at 12:02am
Originally posted by Explosive Explosive wrote:

Originally posted by Goosic Goosic wrote:

Opening and closing of a bolt should be smooth as glass with no noticeable resistance.

In your opinion.,,, In my opinion headspace is bad.
This not just my opinion.  Any reputable Armourer or Gunsmith will tell you that as well. Head space NEEDS to be adjusted using the necessary tools/gauges to get a true adjustment.  Simply changing boltheads to achieve what you can only assume is the correct fit is a very haphazard approach to an issue that can be readily taken care of when using the proper tools and procedures. 


Posted By: WilliamS
Date Posted: July 28 2020 at 12:03am
Originally posted by Explosive Explosive wrote:

Originally posted by Goosic Goosic wrote:

Opening and closing of a bolt should be smooth as glass with no noticeable resistance.

In your opinion.,,, In my opinion headspace is bad.

It's not opinion though. While having a tight chamber can be good for accuracy, that is only within the bounds of good headspace. A rifle in headspace should close the bolt on a go gauge with the same amount of force it requires to close on an empty chamber.  Any extra force required to close the bolt means you are compressing some part of the cartridge and thus will have higher than expected chamber pressure.  That's just physics.


Posted By: The Armourer
Date Posted: July 28 2020 at 12:38am
Originally posted by Goosic Goosic wrote:

Originally posted by Explosive Explosive wrote:

Originally posted by Goosic Goosic wrote:

Opening and closing of a bolt should be smooth as glass with no noticeable resistance.

In your opinion.,,, In my opinion headspace is bad.
This not just my opinion.  Any reputable Armourer or Gunsmith will tell you that as well. Head space NEEDS to be adjusted using the necessary tools/gauges to get a true adjustment.  Simply changing boltheads to achieve what you can only assume is the correct fit is a very haphazard approach to an issue that can be readily taken care of when using the proper tools and procedures. 


Explosive - if you would care to have the opinion of the UK's most Senior Armourer who served his Apprenticeship on Lee Enfield's, and, has written a number of books on the subject it is :


It’s important here to remember the often said phrase among Armourers of ‘DON’T OVER CHS’. Here’s another thing to remember during this. Because there is a camming action operating while OPENING the bolt, called ‘PRIMARY EXTRACTION’ this action also operates when closing the bolt. And the same primary extraction forces that will enable the infantryman to force the bolt closed and unlock and extract a possibly distorted she!! case, covered in wet silt and mud in the saltwater magrove swamps of Johore in Malaya that’s caused the case to stick hard to the chamber walls will also enable the butchers or bubbas to close the bolt hard against the gauge. NO-GO on the .074” gauge is when, using the lightest finger and thumb action on the knob causes a slight feel of resistance.

The next question you’re going to ask is ‘….where during the bolt closing movement is this slight feel of resistance acceptable --- Is it almost closed or, hardly closed or in between’? Good question and the answer in the bible reads thus: ‘…with a 0, 1 or 2 bolt head, there must be resistance onto the .074” gauge prior to there being a minimum of .050” from the underside of the bolt lever to the contacting point of the body socket’. Then it goes on to say ‘…….With a No3 bolt head the left edge…………..’ But I want you to forget this because the statement was too ambiguous. I suggest that you use my maxim of ‘WITH ANY SIZE OF BOLT HEAD FITTED THERE MUST BE RESISTANCE OF THE BOLT ONTO THE .074” GAUGE PRIOR TO THERE BEING A MINIMUM OF .050” FROM THE UNDERSIDE OF THE BOLT LEVER TO THE CONTACTING POINT OF THE BODY SOCKET. I want the master Masons among you to learn that by rote!

Using this criteria, if a No3 bolt head starts to resist half way closed and a No2 resists at .051” from the body side, then use the No2 bolt head. Remember DON’T OVER CHS

There are a couple of reasons for this. Firstly, it is from a point when the underside of the bolt handle is approx .15” from the sharp curve between the top of the body and the side of the butt socket, that the bolt effectively ceases to move any further forwards and is effectively locked.
The second is that prior to the point of fully locking, a feature called ‘mechanical safety’ comes into operation and (it’s getting technical now……….) the stud on the cocking piece will strike the stud between the short and long cam groove at the rear of the bolt causing a diminished force of blow to the striker, resulting in a mis-fire! Phew!

You will understand that this is a highly condensed précis of events taking in months of learning, investigating and examining undertaken by apprentices and I’m trying to cram it into a 40 minute lesson!




Posted By: Goosic
Date Posted: July 28 2020 at 12:47am
Originally posted by Frameman 1 Frameman 1 wrote:

Thanks for the advice.
Frameman.
 
Do not take the advise from Explosive.  The man is misinformed and his assertions,if taken solely from his comment,could have negative consequences...


Posted By: The Armourer
Date Posted: July 28 2020 at 12:52am
Originally posted by Goosic Goosic wrote:

Originally posted by Frameman 1 Frameman 1 wrote:

Thanks for the advice.
Frameman.
 
Do not take the advise from Explosive.  The man is misinformed and his assertions,if taken solely from his comment,could have negative consequences...


Frameman, 

I'd go a little further than Goosic and say "this guy is giving potentially dangerous information" given this thread, and, his thread about 'overloading' the 303 cases with unknown powder.


Posted By: Frameman 1
Date Posted: July 28 2020 at 4:31am
I will respond to any advice received from the web with the same degree of caution I use when looking at political parties. 
Trust but verify.
Thanks again everyone. Very interesting subject and solutions.


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There are no Americans in Baghdad!!


Posted By: Shamu
Date Posted: July 28 2020 at 7:07am
There is one more possibility I'll mention. then this thread is done as its gone off the rails.
IF I repeat IF a case is blown out in the shoulder/neck area there will frequently be some resistance to the last part of chambering.
This mainly applies to reloads, but it is worth mentioning & it has absolutely nothing to do with headspace.


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Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)



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