Bolt Bushing, Reduces SD?

[memilanuk]

So I have bushed a ton of bolts for Savage Rifles and a lot of the friends I do them for are now telling me it reduced their SD considerably. I never thought that would be a result and I can't really rap my head around the science of that. Anyone have an idea of why it would help?

Never really did a 'before' vs. 'after' test with the same load in the same gun. Usually when I've gotten a bolt bushed, it was between barrels. So I can't comment on the reduced ES/SD numbers per se.

That said, my 'lay person' understanding of some of the benefits of having the firing pin hole bushed - besides stopping cratered primers - was that the 'cavity' behind the firing pin hole in a factory bolt (or bolt head) was somewhat larger than the actual pin diameter, and that while traveling forward the pin would rattle and bounce around a bit before finally lining up and coming out the hole. Somewhat of an exaggeration, no doubt, but the point was that the bushing would support the firing pin more fully, and the tip would never fully leave that sleeve... therefore less wasted energy and/or bad harmonics during firing pin fall.

Having never seen a bolt head sectioned to where I can actually *see* how much of the pin is supported in the bushing 'after' vs. 'before'... I may be completely talking out my wazoo. But that was what I was given to understand.

 

[Dusty Stevens]

 

[memilanuk]

I presume that is the 'un-bushed' version... so it kinda looks like I thought, if that is the tip of the firing pin just outside the cavity there. Any pics of a bolt or head that has been bushed for comparison?

 

[Grimstod]

View attachment 1053261

Yes Rem bolts have an unsupported firing pin. Savages however do not. It is beneficial thing to fix for REM bolts. With the savages. I make sure the firing pin is straight and does not hit(rub) the sided by modifying the firing pin and just making sure it straight since it is supported.

 

[memilanuk]

Yes Rem bolts have an unsupported firing pin. Savages however do not. It is beneficial thing to fix for REM bolts.

Just curious... is this something that is addressed on some of the more 'bespoke' custom actions? I've had a bad experience with one of the '700 clone' actions that used a PTG bolt... which at the time copied the Remington bolt, right down to the big sloppy firing pin hole. Really kind of twisted my knickers to have to send the bolt off to get the firing pin hole bushed, on my first 'custom' action...

 

[Grimstod]

Just curious... is this something that is addressed on some of the more 'bespoke' custom actions? I've had a bad experience with one of the '700 clone' actions that used a PTG bolt... which at the time copied the Remington bolt, right down to the big sloppy firing pin hole. Really kind of twisted my knickers to have to send the bolt off to get the firing pin hole bushed, on my first 'custom' action...

I am curious about this too. Only custom I have on my shelf at the moment is a Borden Alpine. The firing pin hole on it is not to big but I have not sectioned it to see if has internal issues like a Rem 700. Knowing Jim I would think he would have corrected this design flaw in the Rem 700 when he design his actions.

I do know that PTGs Savage bolt head does have this problem. The entire firing pin is unsupported like a Rem 700. One reason I do not recommend them. Sorta like downgrading your rifle.

 

[memilanuk]

I do know that PTGs Savage bolt head does have this problem. The entire firing pin is unsupported like a Rem 700

Huh. i could have gone a while longer without learning that little tidbit

Not the first unpleasant surprise I've gotten from PTG bolt heads, though

i presume a bushing job will 'fix' that part of it, yes?

 

[carlsbad]

Yes, easy fix.

I don't think PTG Remington 700 BR bolts have this problem but I'm still looking into it. --Jerry

 

[Grimstod]

Huh. i could have gone a while longer without learning that little tidbit

Not the first unpleasant surprise I've gotten from PTG bolt heads, though

i presume a bushing job will 'fix' that part of it, yes?

It can be fixed but it is a pain. Easier to Jost get a regular Savage bolt head and true it up while bushing it.

Another not, some people when they bush a bolt they put in a threaded rod and then finish of the face. This I do not lake as you must block the gas port on the side of the bolt. Seams unsafe to me. I personally do not block any gas ports when I bush a bolt.

 

[Alex Wheeler]

Worse than an unsupported firing pin like a Remington is one that is supported for part of the travel but no cone like a Remington. Some pull out of the bolt face and have to smash their way back in.