Bushing the firing pin ????

[bobinpa]

How does bushing the firing pin hole help to improve accuracy? I know this is a broad question but ........ I know that it helps to reduce or even eliminate cratering but how does it improve accuracy? I am getting ready to do another build and I just want some opinions.
Thanks in advance
Bob

 

[BoydAllen]

If a pin is bushed so that its tip does not come out of the bushing during the normal cock and fire cycle, there is the potential for improving accuracy if there was a problem related to the alignment of the pin with the the unbushed hole in the bolt face. Greg Tannel once told me that he had a problem with a rifle throwing a shot now and then. After trying everything else that he could think of to solve the problem, he bushed the firing pin so that the tip stayed in its hole throughout its full travel and the fliers stopped. On the other hand, if you are getting excellent results, perhaps your action would not see an accuracy improvement.

 

[wapiti25]

It may have to do with where the pin hit's the primer/anvil if it is off center.

 

[CatShooter]

It may have to do with where the pin hit's the primer/anvil if it is off center.

If you take a primer apart, you will see that there is actually a LOT of leeway to where it is struck, for the pellet to fire completely.

Once it goes off, no matter where it is hit, the pellet is consumed in less than ¼ of a millionth of a second - so it either goes or it doesn't.

 

[BoydAllen]

Actually, I was not referring to how the pin is centered on the primer. On an unmodified Remington, in the cocked position, the firing pin tip is out of the hole that is a close fit with its tip, and depends on the fit of the shoulder that acts as a stop for the front of the striker spring, inside the bolt. If this fit is not close enough, the tip of the pin may make glancing contact with the cone shape that leads into the hole that is a close fit with the tip. It is this slight and inconsistent rattling around as it goes forward that evidently was causing the occasional unexplained flyer that I wrote of in my previous post. By making the tip of the pin longer, and the hole that fits it deeper, it never comes out of that hole, and the potential problem is avoided. One thing that buying a Remington clone can do is avoid having to make this modification, if like Jerry Stiller, the manufacturer has taken pains to specify his bolts so that they work in a more enlightened manner, no additional work in this area is required. I suppose that I should add that not all rifles display this problem, and if yours shoots as well as you need it to, and does not pierce primers, though it may make prodigious craters, I would leave it alone, as I have with several of mine. If it ain't broke...

 

[Old Navy]

Besides all the things Boyd mentioned mine had a hole so big it cratered almost every load I shot. The pin was approximately .007" smaller than the hole. Since having Gre-Tan bush the bolt absolutely nothing I try will crater the primers. Later! Frank

 

[dooley]

I don't remember seeing any posts that claimed bushing the the firing pin hole made a rifle shoot more accuratly, all the posts I have read on here have stated only that firing pin hole bushing helps reduce cratering and piercing primers, it has done this successfully with the 2 rifles I have had bushed, it hasn't made my rifles shoot more accurately, but also it hasn't made them shoot less accurately either, just more effiently. dooley

 

[Old Navy]

I don't remember seeing any posts that claimed bushing the the firing pin hole made a rifle shoot more accuratly, all the posts I have read on here have stated only that firing pin hole bushing helps reduce cratering and piercing primers, it has done this successfully with the 2 rifles I have had bushed, it hasn't made my rifles shoot more accurately, but also it hasn't made them shoot less accurately either, just more effiently. dooley

I had mine bushed back in Feb. I went back through my notes to see if my groups changed. Group size didn't change but I experienced a heavy bolt lift with my #1 load of a 105 hybrid over 33 grains of #15 with CCI-450. All shooting conditions were the same except the temp was up to 36 from the previous session of 32. I had to back down to 32.5 grains to get a normal bolt lift. Later! Frank

 

[Uthink Uknow]

I fail to see how or why a bushed bolt face will improve accuracy short of preventing blown primers with a Rem 700 or it's clones. Also, the pin is held in alignment with the bolt face by the collar on the assembly that is back from the tip of the firing pin. One can bush and machine that portion of the assembly. The assembly is not supported by the tip of the firing pin.....or it shouldn't be.

 

[BoydAllen]

I find your screen name particularly interesting, given your answer. Multiple gun smiths that I know of bush the hole in the face of the bolt, and more than one of those grind modify the pin and install the bushing so that the tip of the pin stays in the bushing throughout the cock and fire cycle. The story that I related about why one smith does that came to me from the most popular smith for doing this modification. You are free to ask him about it yourself. I suggest that you also ask Speedy Gonzales about this point, as well as Jim Borden. I am pretty sure that more than one custom action manufacturer builds their action this way, Stiller for sure, most likely Farley, and I am pretty sure that BAT does as well. This is not to say that good shooting actions cannot be made so that the largest diameter of the pin centers it in the hole in the bolt face. It can, but often it is not.

 

[John Beauchamp]

If you start bad cratering and piercing primers below what would be considered a max load and just as the verticle is starting to come out then bushing could allow you to increase the load enough to reach the point of no verticle. Had this happen on a couple 204 savages

 

[Old Navy]

IMHO seriously cratered primers translates to inconsistent ignition. My reasoning is I saw some cratered and some not within the same five shot groups. Later! Frank

 

[joecob]

This is not to say that good shooting actions cannot be made so that the largest diameter of the pin centers it in the hole in the bolt face. It can, but often it is not.

IMHO, bushing is more often than not a waste of someone's time and another's money.

 

[Greyfox]

This is not to say that good shooting actions cannot be made so that the largest diameter of the pin centers it in the hole in the bolt face. It can, but often it is not.

IMHO, bushing is more often than not a waste of someone's time and another's money.

Interesting POV. Mistaken, but interesting anyway.

Rick

 

[BoydAllen]

Lest we forget, in factory actions, barrel threads can be considerably off center from the bolt raceway. When you see off center primer strikes, there may be more than one cause.

 

[audredger]

My rifle may have been an extreme case however; having had the firing pin bushed and turned has helped with accuracy.

Prior to being bushed; I always had cratering even with light loads. I would also have the odd misfire (FTF). If I rotated the round 90 degrees and re-fired it would often go off. Since having the pin bushed I have not had a mis-fire. I am getting lower ES & SD's and I attribute that to a more consistent pin to primer strike. Note: the firing pin spring was replace ( it needed it ) and that may account for some of my results.

I believe that having the pin bushed has helped my rifle. What happen between my ears is often a greater contributor to accurate shooting than anything else.

 

[ebb]

I cant believe all the answers here about some thing so essential to a consistent ignition in 700 actions. If you look at the way a firing pin works in a 700 bolt you will see its like dropping a nail down a funnel it isn't centered till the very end of its travel. The firing pin isn't even touching the front of the bolt at full cock. When the bolt is bushed it rides in a tube and is captured the whole way of its travel. If you cant see or understand this is an improvement something is seriously wrong with you. This is one of the biggest problems with a Remington action, when Greg Tannel does a firing pin bush job he precisely sets the firing pin protrusion which can be a big problem with primer ignition. I had Greg do 2 of mine and the pin setting was a major improvement to accuracy in the one rifle and was worth a the price of both bolt jobs. I am seriously considering doing all of the 700 bolts I own, if for no other reason as the waters wont be muddy I will know I am getting good ignition.

 

[Robert]

I cant believe all the answers here about some thing so essential to a consistent ignition in 700 actions. If you look at the way a firing pin works in a 700 bolt you will see its like dropping a nail down a funnel it isn't centered till the very end of its travel. The firing pin isn't even touching the front of the bolt at full cock. When the bolt is bushed it rides in a tube and is captured the whole way of its travel. If you cant see or understand this is an improvement something is seriously wrong with you. This is one of the biggest problems with a Remington action, when Greg Tannel does a firing pin bush job he precisely sets the firing pin protrusion which can be a big problem with primer ignition. I had Greg do 2 of mine and the pin setting was a major improvement to accuracy in the one rifle and was worth a the price of both bolt jobs. I am seriously considering doing all of the 700 bolts I own, if for no other reason as the waters wont be muddy I will know I am getting good ignition.

ebb ,
Absolutely right, and not only for the model you mention…

I do presume bushing also induce reducing the F.P diameter? Reducing tip diameter from .080’ to .065’ requires some 33% less energy.

To maintain the FP tip centered, I took an other approach, with a seoarate ‘floating’ firing pin tip, .065 at front and guided by its larger (6mm) rear diameter at close fit in the corresponding bolt bore. The front diameter of the moving mass sliding also in the same bore, so then the two parts are always perfectly centered, ensuring a constant linear blow. The FP tip has a slightly larger fit in its bote, thus ensuring it is never subjected to lateral friction. This play hovever is very minimal to prevent cratering caused by exvess of gap between FP and its hole, this allowing primer cup metal extruding around the FP tip.

R.G.C

 

[fdshuster]

Bought a very nice, used Remington 700 receiver & stock (no barrel), and using the identical 6BR loads that I've been using in my other Remington 700's, this one was blowing primers, about 3 for every 5 rounds fired.

Sent the bolt to Gre-Tan for the firing pin modification & the bushing. That was 2 years ago, the rifle has seen a lot of rounds fired & no more blown primers.

So impressed with the work, and had another Remington 700 bolt with burn holes in the bolt face from ruptured primers. Sent it off to be bushed also. Bolt face cannot be told from new.

 

[Phil]

I bush them all,kind of standard operating procedure for me.

I have no idea if it improves accuracy.