primer problem

plumber01

Well-Known Member
I have a 6mmbr, its highly accurate , even at 900 yards .....but i am getting primers pierced by the firing pin,, I did swap out the firing pin , but same problem
I'm running 30-2 viht 140 with a 105 ( i think that's the weight) lapuna scennar , sometimes I'm getting tiny bits of primer back into the bolt.
Im using cci small rifle primers , there isn't any sign of over pressure, and the primers are well seated

Am i doing something obviously wrong, my feeling was to simply file down one of the firing pins
its a remington action by the way
 

reloader54

Well-Known Member
I have a 6mmbr, its highly accurate , even at 900 yards .....but i am getting primers pierced by the firing pin,, I did swap out the firing pin , but same problem
I'm running 30-2 viht 140 with a 105 ( i think that's the weight) lapuna scennar , sometimes I'm getting tiny bits of primer back into the bolt.
Im using cci small rifle primers , there isn't any sign of over pressure, and the primers are well seated

Am i doing something obviously wrong, my feeling was to simply file down one of the firing pins
its a remington action by the way


I would be inclined to reduce the powder,,, before "bubba"ing a perfectly good firing pin. just saying. pierced primers was a sign of excess pressure when I was taught reloading.
 

Muir

Well-Known Member
Peirced primers ARE a sign of over pressure, but, If that is the same LOT of primers it might be a bad LOT. This is pretty unlikely, however. Is this a custom chambered rifle?~Muir
 

1066

Well-Known Member
Laurie Holland is the chap to tell you about primers - They are certainly not all the same. A standard CCI 400 small rifle primer is made of metal .020" thick, the CCI 450 and BR4's are made from metal .025" thick.

Double check everything again, bullet weight, powder charge, seating depth etc. Have you shot these through the chrono?
 

Lateral

Well-Known Member
I used to have exactly the same issue on a rifle I have. Not with the firing pin piercing the primer, but with discs the size of the firing pin hole being punched out, and jamming the firing pin.

First time it happened, I had several discs inside the bolt.

On closer inspection, there was some corrosion in the throat, causing increased pressure. Throat was polished, which helped, but I still needed to reduce the load.

When I checked the new load, it had nigh on the same velocity as before.

It was also suggested that the firing pin hole could be bushed to tighten up the tolerance.
 

Laurie

Well-Known Member
I have a 6mmbr, its highly accurate , even at 900 yards .....but i am getting primers pierced by the firing pin,, I did swap out the firing pin , but same problem
I'm running 30-2 viht 140 with a 105 ( i think that's the weight) lapuna scennar , sometimes I'm getting tiny bits of primer back into the bolt.
Im using cci small rifle primers , there isn't any sign of over pressure, and the primers are well seated

Am i doing something obviously wrong, my feeling was to simply file down one of the firing pins
its a remington action by the way

'Blanked' SR primers are rarely a result of over-pressures, more usually incorrect primer choice and/or firing pin diameter / profile and/or fit in the bolt-face.

You say CCI SR primers. If that is the standard CCI-400, it is an incorrect choice for the 6mm BR. Some SR primers including the CCI-400 and Remington 6 1/2 date from early .22 Hornet rifles, a low pressure cartridge whose early rifles often had relatively underpowered ignition parts. So, these models are made with 0.020" brass cups, often of a relatively soft alloy.

Federal 205 and 205Ms use 0,0225" thick cups, Winchester WSR 0.021"; and most other models including SR magnum and BR models have the thickest and strongest cups, at 0.025". (For comparison, all LR primers irrespective of type have have a nominal 0.027" thickness.)

This makes some SR primers very prone to cup extrusion back around the pin tip and into any gap around it in the aperture in the bolt-face - 'cratering'. When it becomes too bad, you get 'blanking' where a disc, sometimes a surprisingly deep plug of brass is blown back into the bolt. This is a VERY undesirable occurrence as not only do these discs create the risk of mis and hangfires, but the escaping gas that comes back through the hole in the primer will quickly erode the firing pin tip and may also damage the trigger assembly as that's often its escape route.

The problem can be either caused, or aggravated by a fat firing pin and/or a poor fit in the bolt. Remington 700s are marginal for hot loads in the 6BR and similar and whether an out of the box model is OK or not depends entirely on how the firing pin / hole tolerances run on that example. When I ran a 700 6BR, I simply accepted that my maximum loads produced around 100 fps less than those quoted on Accurate Shooter (6mmBR.com as used to be - the mecca of 6BR aficionados). In the US, there is a small scale industry in turning pins down and bushing the bolt face - Gretan Engineering does it remarkably cheaply and quickly - but until recently few gunsmiths offered the service here. Some do now, but this is a £300 job if done properly, and I've heard some horror stories recently of badly done jobs that have ruined bolts.

So, if you are running with the CCI-400, step 1 is to change immediately to the CCI-450 SRM or BR4 match job, (Rem 7 1/2BR too or some others). If this is the case and that cures or ameliorates the problem enough, good and well. If not, it's a rifle problem and you need to rethink what you're doing as you either have to pay for a bolt bushing job or rebarrel / rechamber to something that uses LR primers. In your case assuming you want to stay with 6mm the latter option is 6mm Creedmoor or 243 Win. I found myself in this predicament with an FN SPR rebarrelled to 6.5X47 Lapua some years back that blanked primers with loads only 1-1.5gn above Viht's very mild starting loads. I had it rechambered to 260 Rem and that cured the problem as LR primers are much less susceptible to the problem.

https://www.gretanrifles.com/product-page/bush-firing-pin-hole-turn-pin

I have a three part series on small rifle primer performance and strength in http://www.targetshooter.co.uk - the site is currently down for some reason. (Been attacked by hackers recently, so maybe again!)

The final option is to simply reduce loads and pressures as I did with my Rem 700 BR benchrest rifle and you usually have to drop down to the accuracy node below, normally 100 or so FPS lower MVs.

In whatever event, don't carry on as you are now if it is happening at all frequently.
 

plumber01

Well-Known Member
HI all, thank you very much , particularly Laurie, very helpful, so its change primers and start with and a gentle load , I am going to try and work around this, the rifle shoots so well I don't really want to give up on it yet . I will try and post progress !
 

Cyres

Well-Known Member
Laurie as ever is a wealth of info on this subject. Common problem with heavy bullets in .223 which Laurie has also covered. I bet a change to BR primers will resolve this problem.

D
 
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