Ring on Primer

[timeout]

Not going to argue with your pictures or your personal method of solving your rifle's firing pin clearance issue. For myself, if I can't shoot a normal load without cratering the primers I find that problematic. Like you, I've been there and did that. I have had primers that looked exactly like the OP's. Following a bolt bush job, shooting the exact same brass/bullets/powder charge, the cratering is gone. I find it foolish to have to tune my load to cover up a botched machining job on the rifle bolt. The OP's next problem will likely be pierced primers if he doesn't have the real problem corrected. I've been there and did that also. Then there is the cost of buying a complete PTG bolt assembly and gettting sub par quality. Have you priced one of those? At their prices I find it unacceptable to have cratered primers on a safe charge weight load. Nuff said.

 

[Dusty Stevens]

Not going to argue with your pictures or your personal method of solving your rifle's firing pin clearance issue. For myself, if I can't shoot a normal load without cratering the primers I find that problematic. Like you, I've been there and did that. I have had primers that looked exactly like the OP's. Following a bolt bush job, shooting the exact same brass/bullets/powder charge, the cratering is gone. I find it foolish to have to tune my load to cover up a botched machining job on the rifle bolt. The OP's next problem will likely be pierced primers if he doesn't have the real problem corrected. I've been there and did that also. Then there is the cost of buying a complete PTG bolt assembly and gettting sub par quality. Have you priced one of those? At their prices I find it unacceptable to have cratered primers on a safe charge weight load. Nuff said.

It is unacceptable, but not everybody knows. On top of that they work for most customers and its an easy fix. Sending it back or even calling is an exercise in futility, so to keep the stress level down you consider them a kit (which is what it is- not a drop in part) then spend a week and some cash and itll be perfect. Most things in our industry are the same way, they work for 99% of the customers

 

[STS]

Hold on here for just a minute. I'm not the biggest fan of PTG for several reasons, but there is no evidence presented in this thread to slam the gavel down and pronounce them guilty. The OP ordered a .075 pin and bolt. He has measured the pin at .074 which is exactly what I would expect for a pin hole of .075. He tried a Remington pin that measured .0748 that went in the hole, but it would fit in a .075 hole. The firing pin hole has not been accurately measured with a gauge pin which I would certainly do before sticking my neck out and accusing the manufacturer of making an error or "botched machining." The fact of the matter is that the bolt may be manufactured to specifications. I certainly wouldn't accuse them of anything unless I could prove it by accurately measuring the parts.

 

[bobm]

I do not have a firing pin clearance issue at all. The rifle of mine that the photos represent has "normal" mass produced fabrication dimensions for a hunting rifle. The M700 is an A prefix from the later 70's. My firing pin mic's at .0754. The sharp corner pin hole will barely accept a #49 drill shank. I'll call it .079 diameter. That leaves a .0018 clearance gap per side. Hardly any room for pressure squeezed brass to get in. If you think that is a serious problem, there are seven million 700's out there with that same problem.

The mild load that left the minor raised condition was 36.0 grs. IMR4895.... Speer 145 gr. SBT. Light recoil for offhand practicing and very accurate in that rifle. I have fired a thousand of this load. They always
have the same primer appearance with Remington or CCI. No big deal, in trash they go.

The stiff load with a more flattened primer and no cratering was 44.5 grs. IMR4064....120 Hornady VMax. Easy bolt lift, shorter case life with laser accuracy. Again, a thousand fired. No cratering with either primer brand.

Again, both loads from the same rifle.

My other "go to" load for this rifle uses any decent 150-154 gr. bullet pushed with 40.0 grs. IMR4064. Primers never have any cratering at all. There is just something about lower pressures causing the mild raised ring.

Certainly there must be some more scientific minds here that can weigh in on this.

 

[Dusty Stevens]

I do not have a firing pin clearance issue at all. The rifle of mine that the photos represent has "normal" mass produced fabrication dimensions for a hunting rifle. The M700 is an A prefix from the later 70's. My firing pin mic's at .0754. The sharp corner pin hole will barely accept a #49 drill shank. I'll call it .079 diameter. That leaves a .0018 clearance gap per side. Hardly any room for pressure squeezed brass to get in. If you think that is a serious problem, there are seven million 700's out there with that same problem.

The mild load that left the minor raised condition was 36.0 grs. IMR4895.... Speer 145 gr. SBT. Light recoil for offhand practicing and very accurate in that rifle. I have fired a thousand of this load. They always
have the same primer appearance with Remington or CCI. No big deal, in trash they go.

The stiff load with a more flattened primer and no cratering was 44.5 grs. IMR4064....120 Hornady VMax. Easy bolt lift, shorter case life with laser accuracy. Again, a thousand fired. No cratering with either primer brand.

Again, both loads from the same rifle.

My other "go to" load for this rifle uses any decent 150-154 gr. bullet pushed with 40.0 grs. IMR4064. Primers never have any cratering at all. There is just something about lower pressures causing the mild raised ring.

Certainly there must be some more scientific minds here that can weigh in on this.

Nobody is saying it wont work. Its for the 99% that dont have an issue with it. The op asked if it was an issue and should it get fixed. It doesnt bother that 99% and i think thats where you are at.

 

[bobm]

Agreed.

Dusty, take a look at this crude drawing. I can use my eye loupe and accurately use the caliper jaw tips to measure the OD of the mild raised crater in my left side pictures. I repeatedly get .092 dia. feeling the outer raised ridge. My pin hole measures at .079. I feel that this raised brass is not entering the hole at all and is being formed over the pin nose during the lower than normal pressure rise.

Do you agree that most high pressure cratering should be forming in the red shaded zone on my drawing? The pin is shown in the return to battery position at the end of the pressure cycle. Why do I measure raised brass bigger than what could fit in the hole? I am assuming high pressure cratering can and will occur even with a bushed bolt.

Close up of .092 OD raised ring using the Teslong.

 

[Dusty Stevens]

^^^^^^^^This is a fine example of taking that next step toward perfection

 

[Texas10]

I had a new stock Savage model 12 that would crater and blank any load I shot. I disassembled the bolt and found I had .008 clearance between the firing pin and bolt head. I ordered a half dozen firing pins from Savage and cherry picked one that measured a total of .0025 clearance. No more cratering or blanking.

On a second action, I had the bolt head bushed. The firing pin diameter was reduced from .070 to .065 and bolt head bushed to reduce clearance to under .002.

Smaller firing pin, tighter fit, better ignition, no cratering.

You can fix it with a firing pin swap, or send it out for repair as Dusty suggested. Having gone down both roads, I'd recommend the bush job.

 

[bobm]

^^^^^^^^This is a fine example of taking that next step toward perfection

....not the answer I was looking for.

OK, then tell me this. What is the average slip fit clearance one gets with a bushing job?

I'm convinced a bushing job will not benefit my situation, or maybe even EasyShooter's as well. Time will tell when he gets to more testing.

Now Texas10's Savage was in dire need of fixing.

 

[bobm]

No range visit today here, cold and snowing. Got my loading all caught up. Wife is building a 1200 pc. puzzle. Messing with the Teslong sounded good. Pictures of the bolt and pin that lit up the primers in my pictures.

You can see the rough spot on the pin radius that's caused by thousands of drags across the lead in "funnel" inside the bolt body. That would be one benefit of bushing the bolt, full support in guiding the pin. The rough spot does reach into the primer dent but hard to see with the scope, very light imprint. That little nose nick visible at 8 o'clock in picture 007 is seen in the primer dent picture.