Question Regarding Primer Blanking….

[adammiddagh]

You may need to replace or bushing the bolt head and pin at this point. With the number of pierced primmers you have had could have erroded the parts a signifigant amount. You will be able to tell when you measure it. I don't know the clearance off the top of my head, but you should be able to find that with a quick search.

[BillPa]

I'm getting a sizable lip on the crater formed during firing.


..and here is one reason why. Two pins.
http://oi47.tinypic.com/3096838.jpg

The tip of the left pin is ground more or less on a taper from the factory which extends ~.030-035" back from it's tip to the shank. On the right a pin I reground to a radius. From it's tip to the shank is about .015".
The same two pins (L-R) set to .020" protrusion in the same junk bolthead or about the maximum a pin will ever indent a primer., most times its in the .016"-.018" range.

http://oi50.tinypic.com/2ur0aaw.jpg http://oi48.tinypic.com/2e3oq5s.jpg
Notice the gap between the pin-pin hole on the left and the lack of it with the radiused pin on the right. As I said prior, a pin will never indent a primer cup more then .020" so the pin on the left allows roughly .007" clearance around it and the hole for a primer cup to flow into. Add any chamfering on the edge of the pin hole in the mix the amount of that gap increases.

BTW, Sharpshooter mentioned this issue ten or so years ago. I ain't that there schmart 'nuf to figure this hear stuff out meself!:p

Bill

[Texas10]

Bill, your post is exactly what i've been thinking of, just couldn't remember where I'd read about re-profiling the pin. Thanks for that tip…pun intended..LOL

[Texas10]

Adam, I tore the bolt down and cleaned everything checking for damage. Launched my extractor ball bearing across the garage, but luckily found it. I think that's the third time now. It found a gap in the baggie I was using to catch all the parts during disasembly, so I ran right out an bought a power ball ticket…he-he.

[LongRange]

Bill, your post is exactly what i've been thinking of, just couldn't remember where I'd read about re-profiling the pin. Thanks for that tip…pun intended..LOL

i did this to my long action pin last night..ill shoot a couple of rounds this weekend and post up how it works out.

[Texas10]

Cool beans, LongRange. Can't wait for your report.

Here's the latest on the firing pin saga. Took the bolts down to the machine shop and pin guaged the bolt head holes in both my BVSS and the subject FV.
Then measured firing pin diameters. BVSS has a .0705 dia pin and .072 hole in bolt head. FV has a .0675 pin and .073 hole. I measured protrusion and found the BVSS at .045 so I decreased the protrusion on the FV to .035. per your suggestion, LR.

I also sent a service request to Savage asking for a firing pin that measures .070-.071.

Any thoughts?

Anyone?
Anyone?
Bueller?

[BillPa]

FV has a .0675 pin and .073 hole. I measured protrusion and found the BVSS at .045 so I decreased the protrusion on the FV to .035. per your suggestion, LR

Any thoughts?
Bueller?


If the FV's measurements are correct it has .00275" around the pin in pin hole which is a bunch. Couple that with the tapered pin tip stopping at .020" or less when it whacks a primer I'll venture to say the clearance is in the .004" or more range around it. Little wonder you're having problems!

Radiusing the pin tip may help but if it were mine I'd be bushing a bolthead.

Bill

[LongRange]

Cool beans, LongRange. Can't wait for your report.

Here's the latest on the firing pin saga. Took the bolts down to the machine shop and pin guaged the bolt head holes in both my BVSS and the subject FV.
Then measured firing pin diameters. BVSS has a .0705 dia pin and .072 hole in bolt head. FV has a .0675 pin and .073 hole. I measured protrusion and found the BVSS at .045 so I decreased the protrusion on the FV to .035. per your suggestion, LR.

I also sent a service request to Savage asking for a firing pin that measures .070-.071.

Any thoughts?

Anyone?
Anyone?
Bueller?

like Bill said i dont think anything you do is going to help the BVSS with the .0675 pin and .073 hole thats a pretty big gap around the pin even if you radius the pin...both my rifles have PT&G bolt heads and the long action pin measures .067 and the hole measures .069...i just measured the factory bolt head hole from my short action and it measures .072...im measuring both with calipers so the holes may be + or - a little...im going to shoot a couple of rounds through the long action today before i mess with my short action because it shoots so well but it does blank just a little.

[LongRange]

so i fired 6 rounds about an hour ago after radius-ing the pin and as you can see its 99% better...

2 cases on the left were fired last weekend before doing the work to the pin....48.5g H4831sc with a 142g smk and the pin set at .032
the 2 cases on the right were fired today with 49g H4831sc and a 142g smk with the pin set at .023 protrusion
the case in the center was fired today same load as above but i decreased the pin protrusion by a 1/4 of a turn..not sure what the protrusion measurement was as i made the adjustment in the field today after shooting the first 2 rounds then set it back to were it was after firing this round.....

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1454184261.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1454184261.jpg.html)

i didnt take a before pic but will when i do my short action...heres the bolt after shooting today...and thanks for the info BillPa you saved me a $160 bucks and a long wait!!

http://i1239.photobucket.com/albums/ff515/LTT-/Mobile%20Uploads/1454184558.jpg (http://s1239.photobucket.com/user/LTT-/media/Mobile%20Uploads/1454184558.jpg.html)

[Texas10]

Quite clearly firing pin dia vs hole dia is a factor here, as is firing pin tip radius. The radius of the factory pin tip must be in the area of .034 but if the pin is only protruding .020, that leaves .014 still in the head when the primer cup is trying to crawl up the pin and into the head. I don't know the math to figure out the radius gap that is on top of the clearance caused by tolerance stack between the pin and the head, but it must be playing into the scheme.

BTW: why replace the head if replacing a cheap firing pin accomplishes the same thing?

The pin on my BVSS and the FV appear the same, and part finder lists the pin as costing $2.00.

The interesting thing is that the serial number for the FV does not exist in Part Finder, which makes it hard to order a part. In fact, the latest serial number in the system is J662160 which leaves several thousand numbers not accounted for.

[LongRange]

If your referring to my bolt head this rifle was a 300wm its a 260AI at the moment...I replaced the bolt head in my short action because I replaced the bolt body as well and figured might as well...at this point I'm glad I did because the hole in the factory short action measures .072 and the PT&G is .068.

if you can get a larger diameter pin that's the way to go if not bushing the bolt head you have would be better than buying a bolt head from PT&G as they reaised the price of them.

[BillPa]

...and thanks for the info BillPa you saved me a $160 bucks and a long wait!!

IIRC when you reworked the tip you checked it @.025" protrusion, the reason I think I'm still seeing some cratering and some clearance on the pin fit. The tip should almost completely fill the hole or close to it @ .020" and set the bench protrusion @ 30-30. like this.
http://oi48.tinypic.com/2e3oq5s.jpg

So, round off the tip a bit more and recheck it at .020".

Oh, and a thanks is unnecessary, gratuity on the other hand!:p

Lemmie know how ya make out.

Bill

[LongRange]

IIRC when you reworked the tip you checked it @.025" protrusion, the reason I think I'm still seeing some cratering and some clearance on the pin fit. The tip should almost completely fill the hole or close to it @ .020" and set the bench protrusion @ 30-30. like this.http://oi48.tinypic.com/2e3oq5s.jpg So, round off the tip a bit more and recheck it at .020". Oh, and a thanks is unnecessary, gratuity on the other hand!:pLemmie know how ya make out.BillSo your saying round the tip more at the peak and check as I'm going and at .020 stop and then set the protrusion to .030? I radiused the pin in my short action this weekend and have it set at .019 and the hole is pretty full should I adjust it out 1/4 turn?which will make it right about .025-.028

[BillPa]

So your saying round the tip more at the peak and check as I'm going and at .020 stop and then set the protrusion to .030? I radiused the pin in my short action this weekend and have it set at .019 and the hole is pretty should I adjust it out 1/4 turn?which will make it right about .025-.028

I think maybe I'm confusing you. Forgive for the crappy pic but....
http://oi59.tinypic.com/nqcnc5.jpg

There I have the pin assembly clamped in a vise and the bolthead just set on top of it with protrusion set to .03455" (.035") from the boltface to the tip of the pin or what I call the "bench" protrusion setting. When checking an as-is or a re-profiled pin tip I use the same setup but set the protrusion to .020". That way I can see how much or little clearance there is between the tip and pin hole.
If you look back at the pics of the pins-bothhead I posted earlier its what I'm looking for, the amount of clearance between the two pins. I haven't found a way to accurately check the amount clearance so I just get a close length measurement from the tip of the pin to it's shank. If that length is .020" or less I assume the full diameter of shank is in the pin hole when the pin strikes a primer.

Clear as mud?:p

Bill

[Texas10]

I called Savage Customer Service. They would not "hand pick" a firing pin for me, and I could not buy a quantity of them to sort through myself. I could buy just one, but i'd have to sign a waiver.

They were also concerned that the problems I was seeing where while shooting hand loads, so I said "fine, I'll shoot some factory loads and include the spent casings when I send it back for warrenty repairs. Just trying to save you a buck".

I set the firing pin protrusion back as LongRange suggested and shot several rounds each of 4 different factory ammo. Got the same results, cratering and piercing.

Big brown truck should arrive today to take it back for another "shot" at making it right…he-he.

[LongRange]

I called Savage Customer Service. They would not "hand pick" a firing pin for me, and I could not buy a quantity of them to sort through myself. I could buy just one, but i'd have to sign a waiver.

They were also concerned that the problems I was seeing where while shooting hand loads, so I said "fine, I'll shoot some factory loads and include the spent casings when I send it back for warrenty repairs. Just trying to save you a buck".

I set the firing pin protrusion back as LongRange suggested and shot several rounds each of 4 different factory ammo. Got the same results, cratering and piercing.

Big brown truck should arrive today to take it back for another "shot" at making it right…he-he.

Texas10 im interested to hear what they do and if it resolves the issue.




I think maybe I'm confusing you. Forgive for the crappy pic but....
http://oi59.tinypic.com/nqcnc5.jpg

There I have the pin assembly clamped in a vise and the bolthead just set on top of it with protrusion set to .03455" (.035") from the boltface to the tip of the pin or what I call the "bench" protrusion setting. When checking an as-is or a re-profiled pin tip I use the same setup but set the protrusion to .020". That way I can see how much or little clearance there is between the tip and pin hole.
If you look back at the pics of the pins-bothhead I posted earlier its what I'm looking for, the amount of clearance between the two pins. I haven't found a way to accurately check the amount clearance so I just get a close length measurement from the tip of the pin to it's shank. If that length is .020" or less I assume the full diameter of shank is in the pin hole when the pin strikes a primer.

Clear as mud?:p

Bill

i get what your saying now.

[Don-T]

FWIW, CCI 400 primers are kinda soft. I had to go to WW and Wolf primers to better contain my 223AI pressures.

[Texas10]

I agree, primers do come in various flavors. FWIW I find Winchester primers to be a little softer than CCI 400, and that is one reason I switched from WW to CCI. I do shoot identical loads in both my model 12's, and in my BVSS I only see cratering at very high velocitiy loads. I've never experienced a pierced or blanked primer in my BVSS, even at half a grain over max book load when working up a new load.

I also have magnum primers and benchrest primers to try out. I believe that both of those have slightly thicker cup materials and will be less likely to blank or partial blank. Interestingly, none of my blanked primers exhibit any flattening, which leads me to believe that this is definitely a firing pin fit/clearance issue.

[BillPa]

Tex, here Greg Tannel (Gre-Tan) explains the causes of cratering-blanking and how to fix it.
https://www.youtube.com/watch?v=-CDJKLp7BsI

Bill

[Texas10]

Great video, Bill. Thanks for sharing that. I get what he is saying about support behind the primer, and with higher than normal operating pressures, his fix is probably the best one. Personally I like the idea of a tighter fitting firing pin vs one that is rambling around inside the head as it is slammed forward.

However the bolt head hole in the subject model FV is only .001 larger than my BVSS which has no issues with cratering at normal pressures (Holes were measured with precision pin gages) so I'm unconvinced that a larger hole is the issue in this instance. But with .0055 pin to head clearance in the FV as compared with .0015 in the BVSS that is shooting well, my first avenue of pursuit is trying to get a larger firing pin for $2.00 (or free under warranty). Second would be a new bolt head for $29.00 (maybe free too?) but I'd likely have to re-set the head space, and I don't have the wrenches or vice. So hopefully with the gun back at Savage, they'll fix this issue and my son can go back to shooting really tiny groups with it.:cool: