Plunger ejector and bolt wear

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Plunger ejector and bolt wear

Post by pierre » 15 May 2020, 2:58 am

Hello all,

I've been wondering about the way the way the bolts lock in firing position when there is a plunger ejector.

Unless I'm mistaken, when the bolt is going forward, first it will put the ejector spring under tension, go on moving forward and straight, and then it will be allowed to turn, locking into firing position.

Given the shape of the bolt carrier, in the part where the bolt is going forward with the ejector spring under pressure, the tension will be redirected as a rotary tension (the bolt tries to rotate early)

As the string is very stiff (if you're trying to lock it by hand, you can't lock the bolt without some momentum, it's too strong to overcome), this means that at the instant before the bolt is allowed to turn, there's quite a lot of tension trying to turn the bolt. Isn't that prone to rounding off the edges of the locking teeth, possibly lowering the life span of the rifle? (maybe it is intended to be rounded off, without altering the action?)

Thanks!

Pierre
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Re: Plunger ejector and bolt wear

Post by straightshooter » 15 May 2020, 7:27 am

The amount of wear will be negligible even if no maintenance is ever performed.
The locking lugs (which is what I presume you mean by teeth) generally have a bevel to ease lockup and provide some 'cam forward'.
People who shoot a large volume of rounds such as target shooters generally apply a very thin smear of grease to the back of locking lugs to minimise wear.
The strong spring on some plunger ejectors is believed to be a source of misalignment of a loaded round in the chamber by benchresters so in many cases the spring is considerably softened or removed completely in competition rifles.
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Re: Plunger ejector and bolt wear

Post by SCJ429 » 15 May 2020, 7:54 am

Here is some advice from Mr Salazar.

https://www.accurateshooter.com/technic ... materials/
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Re: Plunger ejector and bolt wear

Post by pierre » 15 May 2020, 6:09 pm

Yes I meant locking lugs, but I couldn't find the word. I'm no native english speaker. So I learned a new english word, lug, thanks. :)

Thanks both for the answers.
About the link: they mention to use grease for bolt action and oil for AR. Why this difference?
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Re: Plunger ejector and bolt wear

Post by Larry » 15 May 2020, 8:24 pm

Normally grease is used where there is some pressure between the surfaces involved and oil is used where there are just two surfaces sliding against each other. But in the firearms industry there are just too many opinions most not from people with a engineering background.
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Re: Plunger ejector and bolt wear

Post by pierre » 20 May 2020, 5:32 pm

So I replaced the oil with grease in the bolt, that's operating better, thanks
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Re: Plunger ejector and bolt wear

Post by Oldbloke » 20 May 2020, 6:23 pm

pierre wrote:So I replaced the oil with grease in the bolt, that's operating better, thanks


That will be fine.

Can I just add. The wear and pressure applied by you closing the bolt is about 1 zillianth of what is applied when u pull the trigger.
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Re: Plunger ejector and bolt wear

Post by pierre » 20 May 2020, 9:42 pm

Oldbloke wrote:That will be fine.

Can I just add. The wear and pressure applied by you closing the bolt is about 1 zillianth of what is applied when u pull the trigger.

Obviously, however that huge pressure is applied on a very big surface... but yes on a 308 there's some power in there :)
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