To bush or not to bush???????

[msinc]

Here are some photos {pi$$ poor, but the best I can do} of some primers and the respective bolt face they were fired with. The load is 24.0 grains of IMR 4198 behind a 50 grain bullet....not exactly my idea of hot, but maybe I am wrong. The primers appear cratered to me. Three different brand "small rifle" primers, the brass one obviously a Remington. Just to be clear, they are not "magnum" small rifle primers.
The bolt appears to have no damage or so-called "gas cutting" and the striker hole mikes out at .0745" {again, best I can do}. The actual striker mikes out at .0735" and I am guessing that the clearance or .001" or so is about right...I don't believe it necessarily needs to be any tighter in the interest of reliability. I would like to also point out that I have a new unfired PTG bolt and the striker hole mikes the same dimension.
The questions I have are: Given the bolt's striker hole to striker clearance, lack if any apparent damage {unless I am seriously missing something} and likely proper clearance and not a hot load with good condition ammo sized to zero headspace in the chamber.....

1. How is it doing this???

2. Will a firing pin bushing solve this????

3. What happens short or long term if you just do nothing and allow this to continue???

I mean, if I currently have .001" clearance I don't know that I would want or need less. I understand the grinding down of the pin and lengthening of the striker hole so the striker is now "guided", but I doubt guiding the striker will cure this and it seems like that is all that will change.
I should have gotten some chronograph numbers to report for additional info and I can certainly do that if needed. FWIW, in this rifle, the load seems to be very accurate, but that don't mean it's not still a problem somewhere.
Thanks in advance for any info, it is greatly appreciated.

Edit: it just occurred to me {I can be slow} that all the primer pockets were "uniformed and the primers sit down in the pockets some {will measure it shortly} can the primer flow be happening because it has this 'room to move"???

 

[dkhunt14]

From the picture, the bolt face looks a little rough. It also appears to have a chamber around hole. Could be the just the pic.

Was this new brass? I don't believe it will hurt anything as long as they don't get blanked. Matt

 

[Phil]

I bush mine, I`d rather have it and not need it than need it and not have it.......

Cheap insurance is how I justify it.....

 

[Alex Wheeler]

Its not about the clearance. Its about diameter. The larger the pin diameter the more force the primer can apply to it (pounds per square inch). What happens is, the primer pushes the pin back into the boltface. The smaller pins do not get pushed back into the bolt face.

 

[hogpatrol]

Only have a few Remingtons but all are bushed. Some Savages can be done also.

 

[hrlincoln]

Maybe try a primer with a harder/thicker cup and re-develop load...
CCI 450
CCI BR4
Rem 7 1/2

http://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

 

[SheepDog]

From the photos of the primers I don't see indications of excessive pressures. The primers still have radius on the outer diameter. The cratering is due to the larger than necessary firing pin hole. The firing pin hole seems to have a chamfer . That is not good but you don't reuse primers so having the ridge on them doesn't hurt anything.

 

[carlsbad]

I bush all mine before I even build them. Your craters are not good. As Alex said, it is about the diameter. The pressure inside is determined by the load. Force = pressure x area. so a larger firing pin with a larger area pushes out of the primer with a larger force causing more deformation of the primer. And area goes up by diameter squared so reducing the diameter will eliminate cratering.

--Jerry

 

[edw]

I had the same problem with no other pressure signs. Mine were so bad I couldn't get some of them in the shell holder to de-prime! I had Gre-Tan bush the pin and all was good. Now I too have all my rifles bushed as soon as I get one

 

[msinc]

Well, upon closer examination......at the direction of duckhunt14 and sheepdog.....it looks like the problem is at least found. Please excuse the schit for a photo...I have better guns than cameras...well not this gun, just sayin'



I cannot understand why anyone would want/need a bevel in the striker hole, but I guess they obviously feel the need. I guess this answers the ultimate question of to bush or not...looks like the only way to fix it. I agree, it could probably be left alone. The rifle is accurate and as suggested...the primers aren't going to be reused.

Its not about the clearance. Its about diameter. The larger the pin diameter the more force the primer can apply to it (pounds per square inch). What happens is, the primer pushes the pin back into the bolt face. The smaller pins do not get pushed back into the bolt face.

I watched the video from Gre-Tan Rifles about bushing the bolt...now I understand better what he was trying to demonstrate with the little shim of steel. I don't recall him mentioning a reduction in the diameter of the striker...I must not have been paying attention at that moment because why else would he demonstrate the shim thing??? He does demonstrate later turning the striker down for a longer distance than factory to facilitate the front being continuously guided, but it doesn't appear to be reduced in the video.
Next question of course, what is the final reduced dimension of the 700 striker???

 

[swd]

Well, upon closer examination......at the direction of duckhunt14 and sheepdog.....it looks like the problem is at least found. Please excuse the schit for a photo...I have better guns than cameras...well not this gun, just sayin'



I cannot understand why anyone would want/need a bevel in the striker hole, but I guess they obviously feel the need. I guess this answers the ultimate question of to bush or not...looks like the only way to fix it. I agree, it could probably be left alone. The rifle is accurate and as suggested...the primers aren't going to be reused.



I watched the video from Gre-Tan Rifles about bushing the bolt...now I understand better what he was trying to demonstrate with the little shim of steel. I don't recall him mentioning a reduction in the diameter of the striker...I must not have been paying attention at that moment because why else would he demonstrate the shim thing??? He does demonstrate later turning the striker down for a longer distance than factory to facilitate the front being continuously guided, but it doesn't appear to be reduced in the video.
Next question of course, what is the final reduced dimension of the 700 striker???

Wow quite a bevel there! Typically .062"

 

[carlsbad]

I believe your hole is beveled from lifting your bolt with the cratered primers. My guess is you have some hard bolt lifts and it is caused by the cratering. --Jerry

 

[msinc]

Its not about the clearance. Its about diameter. The larger the pin diameter the more force the primer can apply to it (pounds per square inch). What happens is, the primer pushes the pin back into the boltface. The smaller pins do not get pushed back into the bolt face.

I believe your hole is beveled from lifting your bolt with the cratered primers. My guess is you have some hard bolt lifts and it is caused by the cratering. --Jerry

The bolt clicks a little,but not much...I barely notice it. It maybe getting bigger as a result of lifting the bolt on the cratered primers, but wouldn't it have to have had some bevel for the primers to crater to begin with???

 

[carlsbad]

no. primers crater by pushing the firing pin back. --Jerry

 

[carlsbad]

Photo of a proper firing pin hole. No chamfer.

Click on hyperlink, it is working for me.

--Jerry

 

[AckleymanII]

We all have little things that just drive us as crazy as an out house rat, and crappy looking bolt faces with primers pouching out is one of those things for me.

It is a good idea to:

cci 41
BR-4
cci 450's

You are going to have the bevel on all the above primers, to what degree you can live with is up to you.

 

[carlsbad]

Here is a magnum load from that same bolt face. No cratering. Jerry

click on hyperlink. it's working for me.

 

[Uthink Uknow]

That firing pin hole appears to be huge. Bush it.

 

[gotcha]

I cannot understand why anyone would want/need a bevel in the striker hole, but I guess they obviously feel the need. I guess this answers the ultimate question of to bush or not...looks like the only way to fix it. I agree, it could probably be left alone. The rifle is accurate and as suggested...the primers aren't going to be reused

.............................................................................. There is one more issue that hasn't yet been addressed........................ That is the SHAPE of the firing pin tip as evidenced by the flow of the primer cup at the outer dimension of the pin. There is no need for your firing pin to be this "pointy". Changing your load to accommodate different powders, bullets, charge wgts. or jamming could easily cause your primers to be pierced before reaching best accuracy. Look closely at the firing pin tip in the GRE-tan youtube video and see it is rather flat as compared to the firing pin indent on your primers. A CAREFUL re-contour of the firing pin tip to a flatter contour can easily remedy this condition. ..... NO it won't remedy the excessive chamfer on your F/P hole. But Gre-tan can fix that problem. Ask Greg about these two completely different problems. I've re-contoured at home with 600 grit wet-or dry and solved the problem of primer flow/piercing from excessively "pointy" F/P's............... I'm as a guilty as the next guy of sometimes "not seeing the forest for the tree's"

 

[snert]

Have to admit, this subject matter was not what I thought when I saw the title. But personally, seeing what you have I would bush it.