Headspace and bolt heads |
Post Reply |
Author | |
mausernut
Groupie Joined: March 11 2017 Location: Manitoba Canada Status: Offline Points: 46 |
Post Options
Thanks(0)
Posted: July 21 2018 at 7:11pm |
Recently came across No. 4 Mk 1 supposedly for parts, however there wasn't much needed to make it shoot. Have some gauges and 2 other No 4 Mk 1 rifles here.
So I decided to see which bolt head I needed. The bolt with the No 1 bolt head (measuring .637) does not close on the no-go gauge in all three rifles. The bolt with the No 3 bolt head (measuring .640).
In the rifle it belongs to it will almost close on the no-go and in the new rifle it will close on the field gauge. Bow I'm not sure what bolt head to buy. |
|
if you can't be an example, be WARNING
Hunter Safety Instructor Canadian Firearms Safety Course Istructor Canadian Restricted Firearms Safety Course Instructor |
|
britrifles
Senior Member Joined: February 03 2018 Location: Atlanta, GA Status: Offline Points: 6539 |
Post Options
Thanks(0)
|
I might not have understood this right. Your saying that the No. 1 Bolt Head works fine in the new rifle (does not close on the No Go gage) but a No. 3 Bolt Head closes on the field gage? And the No. 3 Bolt Head measures longer than the No. 1 (as it should)? Your not changing bolts between rifles, right?
|
|
mausernut
Groupie Joined: March 11 2017 Location: Manitoba Canada Status: Offline Points: 46 |
Post Options
Thanks(0)
|
Since the new rifle came without a bolt, yes I was just changing bolts between rifles to figure out which bolt head I need. Apparently it matters what bolt body you have.
|
|
if you can't be an example, be WARNING
Hunter Safety Instructor Canadian Firearms Safety Course Istructor Canadian Restricted Firearms Safety Course Instructor |
|
Goosic
Senior Member Joined: September 12 2017 Location: Phoenix Arizona Status: Offline Points: 8792 |
Post Options
Thanks(0)
|
It matters immensely. You cannot simply swap in a different bolt then what was in it from the factory. The variations in where the lugs on the bolt mate to the channels in the receiver can be immense. So much so that you can experience what you just described. The other thing would be a lack of contact between the lugs,one or both,and the receiver channels the lugs engage when the bolt us fully closed, preventing lockup. There is a procedure done with hand lapping a new bolt into the receiver body. Another gentleman will arrive shortly and explain the process to you.
|
|
Shamu
Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 17603 |
Post Options
Thanks(0)
|
Yes, absolutely. One of the biggest aims of the various bolt heads was to deal quickly & cheaply with manufacturing tolerances in things like bolt bodies. Also you will need to check for things like over clocking out to 15 degrees & locking lug engagement. Fixing locking engagement may alter headspace as well! Definitely not a fully interchangeable plug & play part.
|
|
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
|
|
mausernut
Groupie Joined: March 11 2017 Location: Manitoba Canada Status: Offline Points: 46 |
Post Options
Thanks(0)
|
First thing I need to do is get another bolt for the one gun and go from there.
|
|
if you can't be an example, be WARNING
Hunter Safety Instructor Canadian Firearms Safety Course Istructor Canadian Restricted Firearms Safety Course Instructor |
|
Post Reply | |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |