Piercing Primers, again !
- Thread starter Ronnie3
- Start date
Check the shape if the firing pin tip. Make sure it doesn't look like a hole punch. It needs to be nicely rounded, no sharp or squared off edges.
If you have put in a light spring, go back to the heavy spring.
If it is an lightweight firing pin go back to the std weight firing pin.
Make sure you didn't get a thin firing pin tip in the std rem opening. Can't remember the dimension off the top of my head but there is about an .010 difference.
If you have put in a light spring, go back to the heavy spring.
If it is an lightweight firing pin go back to the std weight firing pin.
Make sure you didn't get a thin firing pin tip in the std rem opening. Can't remember the dimension off the top of my head but there is about an .010 difference.
If its punching out a disc of primer metal that ends up in the bolt. It is because the firing pin hole is to big for the pin. As you go up in pressure you need a tight fit on this. If the tolerances on the rifle are right all you should get is flattened primer and bolt that is hard to lift. Two ways to fix it, Get a over sized firing pin like the ones from Hollands and have cut and fit, done many of these. Or bush the pin hole in the bolt done this as well. You can put in a heavier spring, but in my experence it doesn't work the best. Remember that there is some 40000 plus psi in the case at ignition. Even the flash hole in the brass is small. It works out to some 250 in the primer more pressure than any spring.
Richard, Yes the newer Thick Target 108's. When we bought the gun Steve gave us the brand new rem. bolt that came with the gun, so I took the firing pin assy. with the spring and all out of the PT&G bolt and replaced it with the brand new firing pin & spring assy from the rem. bolt, at the same time I found a drill bit that just fit snug, just a little drag and compared both the firing pin holes on the new rem bolt and on the PT&G bolt and they were exactly the same. Yes it does punch out little round discs pieces of metal primer. I tryed that same drill bit on our old Rem 722 6 br and it was very sloppy , even ovalled out, and I shoot the same and even a bit hotter loads in it ( 30.3 grs of varget, same primers, bullets, etc ) without any problems. So, I'm kinda stumped, the hole in the bolt is the same size as brand new, I tryed a brand new firing pin with spring, and I lowered the load down from 30.6 grs of varget ( which is what I used to shoot in it ) to 30.1 grains, we even had a brand new barrel installed ( same krieger barrel, just 1 " shorter than the origonal ) and its still piercing primers, hummmmmm !! I think I'll just try and jump the bullets, rather than jam them and with the weather a little cooler now, just take a chance and shoot it like that at the running of the V bulls, ( I will still keep the bolt tool right beside me ) pretty sure I can pull the bolt apart and tap out the disc in less than 30 seconds by now ( if I have to ) I've done it so many times 
.
Thanks, Ron
.Thanks, Ron
Just thought of something else, is it possible the spring in the brand new rem bolt ( was for a 223 ) that steve gave me with the gun could be a lighter tension spring than a 22-250 bolt spring ? When I close the bolt on our new rem xr100 ( that started out as a 22-250 ) the tension does feel greater than the one in the xr100 that I'm having the problems with.
Just a thought .
Ron
Just a thought .
Ron
I had primer problems years ago. I had a single primer pop because of a bad choice of powder charge. Just enough to pop it. In the following weeks, I had some problems with a slower lock time. I could hear the delayed firing of the cartrige. I popped two more primers with a proven load. I took the bolt apart and found the culprit. The first primer rupture had sprayed a small amount of primer cup into the bolt body between the pin taper and bolt body. This was hanging up the pin movement. My guess was that the firing pin protrusion and speed was just enough to ignite the cartrige, but left a gap between the pin and bolt body. This would leave a gap of unsupported primer cup. Thus the pressured up primer cup was bursting through the gap.
This is my theory of the problem I had.
What do you guys on gun nutz think?
Could this be a contributing problem for you?
Hope this was helpful.
Good luck and have fun shooting!
This is my theory of the problem I had.
What do you guys on gun nutz think?
Could this be a contributing problem for you?
Hope this was helpful.
Good luck and have fun shooting!
It is not uncommon for rifles which are chambered for cartridges which are loaded to high pressures to pierce primers. The condition is worse when small rifle primers are used with some brands being more suceptible than others. Now, I'm going to bore you all with a bit of an explanation of this phenomenon and the causes and ramifications thereof.
There is a difference between "piercing" and "blanking". In most cases, piercing may be described as being caused by the firing pin while blanking is caused by a combination of firing pin damage to the primer cup and the pressure of the load. There is some overlap.
Piercing is usually the result of a poorly shaped firing pin which tends to cut the primer cup or "pierce" it. Blanking is caused by a combination of high pressures and a pin which is too large in diameter. The firing pin weakens the cup and the pressure forces the pin and the cup back into the firing pin hole. Ultimately, the entire depression created by the pin is blown out or "blanked". The major culprits in blanking are the diameter of the firing pin, along with the firing pin hole in the bolt face, and high pressures. Firing pin shape can also play a part, as can the amount of penetration by the pin. This, the amount of penetration, is determined by the amount of firing pin protrusion.
Among factory actions, the worst offenders are the Winchester Model 70's (post-64). These have a very large diameter firing pin. Remingtons also have some problems. Although their pins are of a smaller diameter, the striker is lighter (less supporting mass) and the firing pin hole is sometimes a bit large. By the way, it isn't the difference between the diameter of the pin and the hole which leads to cratering but simply the diameter of the hole. Put a bigger pin in it and the rifle will probably still crater. Ctratering may be considered to be incipient blanking. Those who have used them will know that cratering is a seldom-encountered problem with a Mauser. This is simply because the firing pin, or striker, is quite heavy and it's mass supports the primer cup very effectively. Of course, heavy strikers also mean slower lock times and more rifle disturbance; neither of which is acceptable to today's precision shooter.
So, how to deal with it? Some possible cures have already been mentioned and I may repeat them simply due to their validity.
My first move would be to check the shape and finish of the firing pin tip. It should be hemispherical and polished smooth.
Next, I would check firing pin protrusion. In a precision rifle which is firing brass which fits the rifle well (little, if any, head clearance) there is no need for any more than .045" of protrusion.
The next item is spring pre-load. This determines the amount of resistance the firing pin offers to the pressure produced by firing. I like to see 18 to twenty pounds of preload. This is the amount of weight which is required to deflect the striker when it is in the fired position. Eighteen pounds is roughly, what you will find on a new Remington 700. In this case, pre-load is of more importance than spring rate. Spring rate will decrease lock time and increase striker energy but may or may not increase pre-load. Pre-load has no effect on spring rate and very little effect on lock time or striker energy. Ideally, a heavier spring should be designed so that the pre-load remains in the 18 to 20 pound range. If the preload ends up being significantly greater, the heavier spring can actually exacerbate blanking. Why? Because the stronger spring rate at the end of the striker's travel actually powers right through the primer cup and the firing pin bottoms on the shoulder inside the bolt. From this point, it may actually bounce back a bit and will no longer support the weakened cup. In an ideal situation, the firing pin will JUST bottom at the point that the tip has deformed the cup to full depth.
Going to a 1/16" diameter pin, with the accompanying smaller hole, is an almost certain cure (providing that tip shape is correct) but shouldn't really be necessary in this case. Good Luck. Regards, Bill.
There is a difference between "piercing" and "blanking". In most cases, piercing may be described as being caused by the firing pin while blanking is caused by a combination of firing pin damage to the primer cup and the pressure of the load. There is some overlap.
Piercing is usually the result of a poorly shaped firing pin which tends to cut the primer cup or "pierce" it. Blanking is caused by a combination of high pressures and a pin which is too large in diameter. The firing pin weakens the cup and the pressure forces the pin and the cup back into the firing pin hole. Ultimately, the entire depression created by the pin is blown out or "blanked". The major culprits in blanking are the diameter of the firing pin, along with the firing pin hole in the bolt face, and high pressures. Firing pin shape can also play a part, as can the amount of penetration by the pin. This, the amount of penetration, is determined by the amount of firing pin protrusion.
Among factory actions, the worst offenders are the Winchester Model 70's (post-64). These have a very large diameter firing pin. Remingtons also have some problems. Although their pins are of a smaller diameter, the striker is lighter (less supporting mass) and the firing pin hole is sometimes a bit large. By the way, it isn't the difference between the diameter of the pin and the hole which leads to cratering but simply the diameter of the hole. Put a bigger pin in it and the rifle will probably still crater. Ctratering may be considered to be incipient blanking. Those who have used them will know that cratering is a seldom-encountered problem with a Mauser. This is simply because the firing pin, or striker, is quite heavy and it's mass supports the primer cup very effectively. Of course, heavy strikers also mean slower lock times and more rifle disturbance; neither of which is acceptable to today's precision shooter.
So, how to deal with it? Some possible cures have already been mentioned and I may repeat them simply due to their validity.
My first move would be to check the shape and finish of the firing pin tip. It should be hemispherical and polished smooth.
Next, I would check firing pin protrusion. In a precision rifle which is firing brass which fits the rifle well (little, if any, head clearance) there is no need for any more than .045" of protrusion.
The next item is spring pre-load. This determines the amount of resistance the firing pin offers to the pressure produced by firing. I like to see 18 to twenty pounds of preload. This is the amount of weight which is required to deflect the striker when it is in the fired position. Eighteen pounds is roughly, what you will find on a new Remington 700. In this case, pre-load is of more importance than spring rate. Spring rate will decrease lock time and increase striker energy but may or may not increase pre-load. Pre-load has no effect on spring rate and very little effect on lock time or striker energy. Ideally, a heavier spring should be designed so that the pre-load remains in the 18 to 20 pound range. If the preload ends up being significantly greater, the heavier spring can actually exacerbate blanking. Why? Because the stronger spring rate at the end of the striker's travel actually powers right through the primer cup and the firing pin bottoms on the shoulder inside the bolt. From this point, it may actually bounce back a bit and will no longer support the weakened cup. In an ideal situation, the firing pin will JUST bottom at the point that the tip has deformed the cup to full depth.
Going to a 1/16" diameter pin, with the accompanying smaller hole, is an almost certain cure (providing that tip shape is correct) but shouldn't really be necessary in this case. Good Luck. Regards, Bill.
I'm having similar problems both in an 700 SA and an XP 100. All I'm using is 30.5 of Varget and Berger 105s, CCI br and about 30 thou of jam. Ive just decided to back off powder charges and see what happens. That powder charge is my old load and had never failed me before but I'm willing to play. PITA! Piper.
