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Bump on bolt
Posted: Thu Sep 22, 2022 9:19 am
by JimCunn
The .357 Mag has a 'bump' on the bottom of the bolt that drives the hammer back and down by about 1/8 inch, then lets it back up again as you operate the lever. I've not attempted yet to analyze the purpose of that function.
Anybody know offhand?
20220922_080802.jpg
Re: Bump on bolt
Posted: Thu Sep 22, 2022 9:33 am
by GFK
Looks as though to assist with cocking the hammer.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 9:37 am
by JimCunn
Well, yeah - but is that it's only purpose?
Why does it release the hammer forward again after driving it back?
Re: Bump on bolt
Posted: Thu Sep 22, 2022 10:56 am
by GunnyGene
JimCunn wrote: ↑Thu Sep 22, 2022 9:37 am
Well, yeah - but is that it's only purpose?
Why does it release the hammer forward again after driving it back?
My .41 BBSC has that same little bump, I think to make sure the sear is fully engaged. It does not release the hammer back to the fired position when the bolt is in battery if that is what you meant. If it does, you have a serious problem.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 11:17 am
by JimCunn
That wasn't what I meant.
It releases it back to the position it was in immediately before the bump contacted it.
I agree about assuring the sear engages - I am curious about whether it also involves the transfer bar, but have not examined it to determine if that might be the case.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 12:20 pm
by GunnyGene
JimCunn wrote: ↑Thu Sep 22, 2022 11:17 am
That wasn't what I meant.
It releases it back to the position it was in immediately before the bump contacted it.
I agree about assuring the sear engages - I am curious about whether it also involves the transfer bar, but have not examined it to determine if that might be the case.
That's possible also. I never really gave it any thought, until you brought it up. Interesting question tho.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 12:50 pm
by JimCunn
I thought so too.
Especially since it isn't ubiquitous on Henrys.
My curiosity is what is driving the question.
Since the bolt is not a snug fit in the receiver, it also slightly tilts the bolt when the bump is in contact.
But I doubt that that is significant.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 4:04 pm
by GunnyGene
JimCunn wrote: ↑Thu Sep 22, 2022 12:50 pm
I thought so too.
Especially since it isn't ubiquitous on Henrys.
My curiosity is what is driving the question.
Since the bolt is not a snug fit in the receiver, it also slightly tilts the bolt when the bump is in contact.
But I doubt that that is significant.
My .41 is a pre-gate model (2018), so the bump has likely been standard for quite a while. Don't recall anyone else mentioning it. Doesn't interfere with function at all so I reckon it's all good.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 5:02 pm
by JimCunn
"Doesn't interfere with function at all"
True, but it sure does grate and grind when it is in contact with the hammer.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 6:03 pm
by GunnyGene
You could polish the rubbing surfaces. I did mine, and also use a tiny dot of Slip 2000 grease there occasionally.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 7:02 pm
by GFK
JimCunn wrote: ↑Thu Sep 22, 2022 9:37 am
Well, yeah - but is that it's only purpose?
Why does it release the hammer forward again after driving it back?
Well, you can contact Henry, for a more exact answer.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 8:24 pm
by GFK
JimCunn wrote: ↑Thu Sep 22, 2022 11:17 am
That wasn't what I meant.
It releases it back to the position it was in immediately before the bump contacted it.
I agree about assuring the sear engages - I am curious about whether it also involves the transfer bar, but have not examined it to determine if that might be the case.
The transfer bar rises as the trigger is pulled. I suspect that hammer is pushed back that far to ensure that it is fully cocked. By it retracting some, one can see that the hammer moves freely and is set, and ready to be released.
Re: Bump on bolt
Posted: Thu Sep 22, 2022 9:46 pm
by JimCunn
Waiting on my new Arkansas stone to arrive.
I'll have to cold blue the top of the hammer after.
Re: Bump on bolt
Posted: Sat Sep 24, 2022 1:02 pm
by jstanfield103
I believe that it is there for the positive sear engagement. You have to pull the hammer a little past the sear engagement. When you pull the trigger you will also see that the hammer moves back just a little before release.