Bolt mechanics validation help and guidance for others - RimfireCentral.com Forums

Go Back   RimfireCentral.com Forums > >

Notices

Join Team RFC to remove these ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 08-01-2020, 03:46 PM
22lrJohn is online now
US Army Veteran

Join Date: 
Feb 2020
Location: 
King County, Washington
Posts: 
68
TPC Rating: 
0% (0)
Bolt mechanics validation help and guidance for others



Log in to see fewer ads
I have really been enjoying my recently purchased model 43. But...

Last couple of trips to the range, after about 20 - 30 rds, the bolt handle became 'tightly bound' after firing. Unsafe to fire, after the second 'event,' I took it home, removed the stock and dismantled the action,step-by-step starting with the trigger assy.

The bolt still being bound in the fired position, I examined the firing pin, the bolt face / empty casing and the bolt gap in the receiver. Using the first principle of 'never' forcing anything, I took a jeweler's screw driver and inserted it between the firing pin and the bolt channel, which released the bolt tension allowing the cocking handle to rotate to remove the bolt.

Next, I examined the trigger bridge and the bolt guide and re-assembled to check for wear and misalignment (including tests with my spare bolt).

Long story shortened:

After drawing bolt pictures, several measurements, much cogitating and reading through some forum posts, I think I came to a conclusion.

The bolt handle is too loose, with the gap between the cocking handle and the firing pin guide (in the un-cocked position) of about .005".

What I learned:
1 - The loose cocking handle impacts proper bolt insertion; does not allow the bolt to ride along the trigger bridge guide correctly - at times preventing the extractor / ejectors from being properly aligned; affects headspace; and most importantly, can affect sear engagement, which is a serious safety issue.

2 - It is always good to draw and measure parts when things aren't quite right. The bolt handle is nominally 0.750". Mine shows un-even wear on the bolt cap side - up to 0.015" off-nominal.

Does this assessment make sense? Any other thoughts?

If so, is there any new guidance on shims? (Anyone have an extra unworn bolt handle they can PM me about?)

I plan to order Numrich part # 270850 - H & R shim kit, if this is still the preferred solution.

Look forward to any guidance from you all.
Reply With Quote
  #2  
Old 08-01-2020, 04:21 PM
'ol shooter's Avatar
'ol shooter
NRA Member - Click Here To Join! GOA Member

Join Date: 
Oct 2010
Location: 
So Cal
Posts: 
9,278
TPC Rating: 
100% (131)
Remove the bolt and stand the rifle on it's muzzle. Drop an unfired round into the chamber, does it "plop" all the way in on it's own weight? If not, that might be part or all of the issue. Clean the chamber vigorously with solvent and a bore brush and patches, then inspect the breech for evidence of firing pin strike. Many older bolt rimfires do not take kindly to dry firing. Good luck, tell us what you found out.
__________________
Bob B.
Reply With Quote
  #3  
Old 08-01-2020, 04:38 PM
22lrJohn is online now
US Army Veteran

Join Date: 
Feb 2020
Location: 
King County, Washington
Posts: 
68
TPC Rating: 
0% (0)
Quote:
Originally Posted by 'ol shooter View Post
Remove the bolt and stand the rifle on it's muzzle. Drop an unfired round into the chamber, does it "plop" all the way in on it's own weight? If not, that might be part or all of the issue. Clean the chamber vigorously with solvent and a bore brush and patches, then inspect the breech for evidence of firing pin strike. Many older bolt rimfires do not take kindly to dry firing. Good luck, tell us what you found out.
Thanks for the tip! I hadn't tried that test, yet... so, I just did. The round easily drops in.

That said, I am going to add that test when I clean my other rifles. I know my 1906 has a tight chamber.

I hope I can get this resolved as that Model 43 is my new favorite Mossberg!
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off




All times are GMT -5. The time now is 10:49 PM.

Privacy Policy

DMCA Notice

Powered by vBulletin
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Search Engine Optimisation provided by DragonByte SEO (Lite) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright 2000-2018 RimfireCentral.com
x