Bolt Bushing, Reduces SD?

[Grimstod]

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?

 

[Grimstod]

If you don't know what Bolt bushing is here is a video on how you can do them. For Savages at least.

 

[Drop Port]

Consistent repeatable ignition, often overlooked.

 

[carlsbad]

Smaller cross sectional area, same firing pin spring, more firing pin pressure on the primer. Resulting in what Drop Port posted above.

I too bush all my firing pins up through 338 LM and do a lot of bushing for others. Probably second behind gretan.

I bush to .062 unless a customer requests something else. Most custom actions use .070 and I've had manufacturers say that .062 is too small but have thousands and thousands of rounds of experience to the contrary. Very hot loads can still crater a little at .070. I haven't seen cratering at .062.

--Jerry

 

[dsculley]

Grimstod does good work as well, with very fast turn-around. He recently worked on one for me and his work was top shelf!

 

[rwk]

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?

How much

 

[Grimstod]

rwk I do them for 49.99 I sent you a PM with more details.

 

[Grimstod]

Consistent repeatable ignition, often overlooked.

I agree. There are usually a host of things I correct when I do these things. All of it works together I am sure. I personally though it would affect harmonics more then anything. Perhaps with a smaller pin there is a faster penetration of the primer?

 

[Grimstod]

Smaller cross sectional area, same firing pin spring, more firing pin pressure on the primer. Resulting in what Drop Port posted above.

I too bush all my firing pins up through 338 LM and do a lot of bushing for others. Probably second behind gretan.

I bush to .062 unless a customer requests something else. Most custom actions use .070 and I've had manufacturers say that .062 is too small but have thousands and thousands of rounds of experience to the contrary. Very hot loads can still crater a little at .070. I haven't seen cratering at .062.

--Jerry

By default I do them to 0.064 but have done many at 0.062 and even a few at 0.060 with no problems. Usually I tailor them to the task at hand sorta like you are doing. Good to know someone else is doing the same. I by all means do not know it all. Maybe someday in a hundred or so years I will know it all Usually I ask if they expect to get their gun dirty or expose it to harsh circumstances.

 

[carlsbad]

PT&G sells bolts and firing pins nominally .062 for benchrest. Here is a thread where I talk about it and even show a couple of photos of my bushed bolts.

http://forum.accurateshooter.com/threads/bushing-bolt.3933878/

 

[ebb]

On a Remington when cocked the firing pin tip is unsupported. When bushed it is supported and doesn't have to rattle around in the bolt body and find it way to the primer. This is just a long winded way of saying the same thing as Drop Port

 

[msinc]

rwk I do them for 49.99 I sent you a PM with more details.

Fellas, this is a steal.....I wouldn't do it for twice that much, it's a lot of work when done right. In fact the ones I have done {for me} warranted a bottle of single malt Bushmill's and two Cuban cigars....gifted to myself!!!!
That said, it don't necessarily mean the rifle will shoot that much better, but I felt good afterwards. Admittedly, I did not check SD/ES numbers either, but now I will.
I am not familiar with Savage bolts, but when you bush a 700 and set it up so the reduced diameter firing pin is also full time guided captive in the bushing then it has to be a way more consistent ignition as opposed to the striker or firing pin flopping around loose in the bolt.

 

[carlsbad]

I've recieved some PMs about bushing Savage bolts. Grimstod is the guy for Savage. I do Remington 700 and similar. I set up in 3 dimensions and make sure the bolt face is perpendicular to the bolt body. I have a lot of references on the forum and I've posted a lot of photos. I charge $80 shipped. --Jerry

 

[Grimstod]

I've recieved some PMs about bushing Savage bolts. Grimstod is the guy for Savage. I do Remington 700 and similar. I set up in 3 dimensions and make sure the bolt face is perpendicular to the bolt body. I have a lot of references on the forum and I've posted a lot of photos. I charge $80 shipped. --Jerry

$80 for a Rem bolt is a great deal. I did one once and had to set it up in 3 dimensions as well. Lots of work. I applaud you for being able to do it profitably. I can't, so I stick too Savages. They are what I know inside and out. The Rem bolt maybe someday (10years) I will have to pick your brain on how to do them efficiently. Saw your work on the other thread. Looks really good!

 

[Grimstod]

Fellas, this is a steal.....I wouldn't do it for twice that much, it's a lot of work when done right. In fact the ones I have done {for me} warranted a bottle of single malt Bushmill's and two Cuban cigars....gifted to myself!!!!
That said, it don't necessarily mean the rifle will shoot that much better, but I felt good afterwards. Admittedly, I did not check SD/ES numbers either, but now I will.
I am not familiar with Savage bolts, but when you bush a 700 and set it up so the reduced diameter firing pin is also full time guided captive in the bushing then it has to be a way more consistent ignition as opposed to the striker or firing pin flopping around loose in the bolt.

Thanks msinc, you are very kind. I try to keep the price fair considering how much time it takes me to do one.

 

[spclark]

Perhaps with a smaller pin there is a faster penetration of the primer?

Not so much faster (we can discuss that under the topic heading "lock time" some other time) but a smaller FP tip imparts more energy per unit of surface area than a large FP tip.

 

[Grimstod]

Stronger firing pin would probably do that too. However I do not like to use the hard springs. Makes bolt lift to hard.

 

[spclark]

Stronger firing pin would probably do that too. However I do not like to use the hard springs. Makes bolt lift to hard.

Exactly, and one of the motivations behind using a stack of Belleville washers for FP actuation rather than a coil spring. Thru careful attention to washer characteristics one can achieve both greater energy upon release as well as lighter bolt lift.

 

[Bart B.]

I personally though it would affect harmonics more then anything.

The harmonics, or frequencies the barreled action vibrates at, won't change any significant amount with a couple grains weight change at the area near the hole in the bolt face. The vibration amplitude may change a little.

Anything that makes primers flash more consistent helps powder charges burn more repeatable making pressure curves more repeatable. It all adds up to smaller velocity spreads and smaller spreads in line of fire angles to the line of sight. All contributing to better accuracy.

 

[carlsbad]

Agree with bart.