Printable View
After reading over Peter Laidlers "fitting rifle bolts" (more than once) I have a question regarding bolt head fit.
I understand the least amount of bolt head over turn is desirable, but is there any advantage to a very light under turn?
Would this help give a tight fit to absorb recoil down the bolt body and evenly onto the locking lugs?
With this underturn the bolt locks tight with even contact on the lugs..
Thanks in advance,
Jon
The brunt of the recoil forces are not carried on the threads, in fact, they have a slight clearance. The force is transmitted through the anuli of the end of the bolt body and on the back of the bolt head. These areas will appear as shiny rings when you inspect your bolt.
A sloppy fit with lots of bolt head over turn isnt good, but my belief is that the thread fit being tight isn't that critical. As long as the overturn is within limits, good to go.
Thank you Englishman, but if the bolt head overturns and there is no contact between it and the bolt body, as Peters article states, the recoil is taken up on the threads, which to me makes sense. Please correct me if i am wrong!Quote:
Originally Posted by englishman_ca
Less over turn helps accuracy as the recoil is taken up on a square bolt body, as opposed to angled threads giving a straighter axis of recoil.
I'm wondering if this tight bolt head will help get maximum accuracy, or at least eliminate one of the many variables to achieve max accuracy.
Jon
Or am I just out to lunch on this and the extra tightness does nothing but make a stiffer bolt throw?
You are not wrong with your concept, Jon.
The time when you wont get recoil transfer thought the bolt body anulus is when a new replacement bolt head is fitted on an old bolt and there is too much overturn.
An old sloppy bolt head and with its long time mated bolt will always bear on the body, not threads. I guess that the worn bolt threads allow more axial movement and the slack is taken up by the extractor pushing on the ramp on closing.
I've seen bolt heads so worn that they were wobbly on the bolt, 45 degree overturn. But the bolt head would bear on the body.
The rest of the rifle was also tired, I don't think a new new tight bolt head would have helped unless accompanied by a new bolt and receiver.
Tight is good, I agree.
If the bolt head sits tight with a slight under turn, one would have problems installing it into the receiver bolt way. Bolt head and lug have to be able to align.
Great information thank you!Quote:
Originally Posted by englishman_ca
My current bolt does VERY slightly under turn but i am still able to install it in the body, It gives a tight lock up, is this an accuracy advantage over if i were to relieve it a bit to over turn by 1 degree or less?
Personally, and maybe it's just me, but why not just fit the bolt head into the bolt body as per the instructions passed down from my old and wise apprentice masters to me in the 60's and passed on to the flock so that the correct way isn't lost in the future
I was curious to see if this was something you had encountered or ever tried?Quote:
Originally Posted by Peter Laidler
I just have a tight bolt head and was wondering what the general consensus is on the matter.
All you are achieving with a tight bolthead, is excessive wear on the bolt guide channel, excess load on bolthead threads and a stiffer operation, requiring excess force to operate.
Go with Petes recommendation, he's correct.
I think that you will find that once you start shooting the rifle with your super tight under turned (out of spec) bolt head, after a few rounds it will start to break in as things get hammered by recoil and no longer be super tight, it will likely then have a slight overturn.
In selecting a bolt head, it is always nice to have a bin full from which to choose as it is critical to get not only the thing to head space correctly, but also to have a correct overturn. The difference of fit between bolt heads is due to something called 'tolerance stacking'. There is an armourer's tool that fits over the bolt head to get leverage to allow one to crank on it to turn the head into the bolt with force when it bottoms out and it doesn't align with the bolt lug that last wee bit. Your bolt head would be one. The tool lets one run the head backwards and forwards and in effect starts the break in of the two parts to each other. It allows you to align an under turned bolt head with the bolt lug.
A different rifle, but I did hear something once about Lithgow replacement bolt heads for Sht.LE that were produced for fitting to used bolts, and the bolt head threads had the thread timing indexed a little to allow for thread wear. Sounds like a great idea, but I think it might be just another folk law. I have never seen such a bolt head and am not sure how I would recognise it if I did.
I'll shut up now and defer to the experts, I'm just a hobbiest who has worked on a few rebuilds in my garage behind the shade tree. But carry on Jon, you wont hurt anything other than feelings. I know that you are giving your rifle loving attention to detail, but just get it within specs and call it good.
As an apprentice in the machine shop it was explained to me that with a fit between parts, sometimes it was pointless to be measuring with a micrometer when I was marking with chalk and then cutting with an axe. ie, sometimes fine precision is overkill.
In your case within spec is good, at the tight end of the spec is also good but not necessarily gooder.
And don't be put off asking questions because you are curious. You will find the members here quite candid. They might seem blunt, but are to the point, they won't steer you wrong with bad advice. There is a lot of experience and a wealth of knowledge to tap into here. Its just that some here are crusty old farts, some crustier and fartier than others. :)
It's not really about a consensus...Quote:
Originally Posted by jonh172
The EMER specifies no more than 1/8" overturn. If it comes up even at 12:00 you're good to go.
The OP asked if there were opinions on if having a tight bolt head would help with accuracy. Now that we have flogged him with a wet lettuce, I think that the answer might be ...no, no opinions. But a tight bolt head can cause other issues if out of spec.
My tuppence worth is that it probably doesn't have a measurable effect on shooting accuracy, but it certainly wont hurt it.
The simple answer on accuracy is "no".
How is he flogged with wet lettuce? The EMER specifications are the bible. There simply isn't much to add to it. If he can screw it in to install with zero overturn, there's no problem. It will eventually loosen and have a bit of overturn anyhow with use. I'd say it's perfect.
I guess the EMER's on the Lee Enfield line are the product of over a 100+ years dealing with the Lee Enfield design and testing finding what works and what doesn't then throw in a few wars untold skirmishes with more learning all the while the armourers are compiling data to eventually be turned into the bibles for the 303 line.
The fountain of knowledge on these little jems is superb here and it is with honesty and integrity the advice is offered not only for the one asking the question but for all of us wanting to learn. TIA
Bullsh*t, no such thing. We all told him not to do it. NO!Quote:
Originally Posted by englishman_ca
As one who shot the 303 in target comps for a number of years to tight in head space is as bad if not worse than too loose. You will need a rim thickness gauge to make sure all the rims are the same then as the action heats up your ammo wont fit. The head space setting of minimum .064 max .074 allows for all variations of rims and heat expansion. Be aware some cartridge rims are much thinner than other manufacturers. There are other things more important than head space for accurate shooting in the Lee Enfield.
IMHO agreeing with #17 that the most important thing with the 303's is the bedding it has to be correct, a good barrel, careful handloads and lots of range time to find the elevation settings as the reloads will never have the same trajectory as the MkVII round, mind you it does help if your a reasonably good shot..........
Thank you Englishman for ALL of your helpful insight!!Quote:
Originally Posted by englishman_ca
I was in fact just referring to accuracy advantage/disadvantage, you have more than answered my question.
---------- Post added at 12:17 AM ---------- Previous post was at 12:16 AM ----------
Little off topic but big thanks for the information! Never enough good to have going into a project!Quote:
Originally Posted by Bindi2
---------- Post added at 12:22 AM ---------- Previous post was at 12:17 AM ----------
Although I appreciate all information I get on this topic, there's no need to get hot under the collar about it.Quote:
Originally Posted by browningautorifle
Just a couple guys talking here....
Not hot at all, just stating a fact. We said NO, don't do it. He tried to chastise...and has no right. Just speaking in print, you read it wrong.Quote:
Originally Posted by jonh172
More sound advice from BAR and the forum brethren based on the bleedin' obvious. Jonh, it's called 'the wisdom of the crowd' but this time the wisdom of the crowd based on solid fact and backed up with experience
I'll not mention flogging with a wet lettuce ever again!
Which says nothing...Quote:
Originally Posted by englishman_ca
Well I got the info I was looking for plus a little extra, thanks everyone for the insight, opinions and experiences!
Let me see if I have this right: when the bolt head is screwed tight up against the shoulders on the head and bolt body, the recoil forces are transferred through the shoulders.
If the bolt head is so loose that when in the closed position in the rifle the shoulders do not touch even when the bolt head is pushed backward by recoil, then the recoil forces would transfer through the threads.
There must exist a few thou of clearance between the individual male and female threads, so when the bolt and bolt head shoulders are done up tight against each other, the thread faces that would transfer the recoil forces were the bolt head to have gross overturn, are actually not in contact with each other at all.
And I thought EVERYONE enjoyed a good flogging with a wet lettuce first thing in the morning.............................perhaps I have a problem.
Depends on the type Roger Iceberg or Cos I'd take the Cos not as hard hearted as an iceberg if I was into a flogging.......:p
Kudos to you for being a good sport. ;)Quote:
Originally Posted by jonh172