Bushing a firing pin

[DANNY-L]

Glad I spotted this, going through the same problem with a model 7 7mm08

 

[AlNyhus]

I am experiencing primer flow and pierced primers on a Rem700 footprint custom action with a .068 pin diameter. The manufacturer checked the bolt this week and everything is in spec. Firing pin diameter, firing pin hole diameter, firing pin protrusion, firing pin shape, etc.


I am think would be nice to have the pin diameter reduced for peace of mind. I called Gretan And they are not interested in taking this work.


1. Is there any reason why I should not reduce the firing pin diameter? Any disadvantages to doing this?

2. Any recommendations for a machinist that is qualified to do this?

-Trevor

Trevor, I would verify the pin hole diameter. A .068 pin tip shouldn't be a problem, provided the pin hole is correct and isn't jagged. -Al

 

[Jeff Porter]

Try some harder thick cup primers.

 

[AlNyhus]

Try some harder thick cup primers.

You're right...the OP didn't say what primers he was using. It could be as simple as that.

 

[J.d. Popkes]

Sent it to Longrifles Inc. Fast turn-around and great quality. I had mine done because my 223AI kept piercing primers when it shouldn't. They did a great job on it and no more pierced primers.

Chad and the gang are the best

 

[ELR LVR]

I never had a problem with any of my Remmy's
I just don't understand all these Rem 700 horror stories
I mean statistically speaking sure
When we have 2.2 Millions members on here
and maybe 1/10,000 remmys got a little wack
We're going to hear over 200 horror stories instantly come out of the woodwork once 1 of them pops up
I've read even custom actions can have a bad day, new out of the box occasionally.
---
If I drive pressures up to where we see presure signs sure, I can get some cratering goin on
Thats just basic physics - there has got to be SOME clearance in the bolt for the pin to go through
And once pressures go high enough, the brass flow will take path of least resistance.
Into that clearance...
But - ??? I don't see why some people think every single bolt in existence needs to be bushed
Wondering if some people are not understanding why cratering happens
(IE: tune the load down a notch, its a pressure sign)

 

[AlNyhus]

Having had several 700's with this issue, I can vouch for it being a real deal on some actions.

The stock 700 bolts don't provide any guidance for the pin tip when it's in the cocked position. Because of this, there has to be enough pin hole clearance to let the pin tip find it way through the hole. That clearance lets the primer flow into it...thus, the 'crater' or ridge around the pin indent in the primer. If the pin hole is jagged and sharp, this gives a punch effect that can shear little bits off the primer cup.

 

[DaveTooley]

I've seen an intentional chamfer on the firing pin hole on Remington 223 bolts by a parts supplier . A Remington engineer said QC missed seeing it.

 

[JPB3]

I've seen pin holes chamfered too, Dave..

 

[Coyotefurharvester]

I had one M700(22-250) that really had a raised ring spent primer at mid range book loads. I tried sizing too close with tension but it is a hunting rifle. I sent to Carlsbad, now primers are all normal up to book max with Varget. I wish I had saved more chrono/group data before bushing, it seems to shoot better now with a wider powder charge weight range(??).

 

[Tommie]

But - ??? I don't see why some people think every single bolt in existence needs to be bushed

I’ve never heard anyone say that. But I will say that bushing the pin did solve primer flow issues on one of my rifles with loads well below max using CCI 450’s. Stacking tolerances can and does happen. Throw in human error and worn tooling for icing on the cake.

 

[pavementends]

This seems to be mostly an issue with 223 bolt face. The CCI 400 primer cups are thinner than the 450's and many times changing primers cures the issue. I have not seen the same issue with large rifle primers

 

[Hengehold]

You're right...the OP didn't say what primers he was using. It could be as simple as that.

I am using Fed 205M primers.

 

[ELR LVR]

I’ve never heard anyone say that. But I will say that bushing the pin did solve primer flow issues on one of my rifles with loads well below max using CCI 450’s. Stacking tolerances can and does happen. Throw in human error and worn tooling for icing on the cake.

I've read enough posts when someone has primer cratering at all, or pierced primers
Several will jump in and insist it needs to be bushed, without asking for measurements, clearance etc.
And that all their 700's are bushed
etc.
---
Not that it hurts to have it bushed even if it may not need it
Just that, there are also, other, reasons for primer cratering/ piercing before jumping to the conclusion it must be bushed because it's a Remington.
---
I'm not against it, I just have not personally needed it on any of my own remingtons
So it surprises me is all when I see so many insist on it
---
So if someone has experienced it more than once, I get it, decent insurance to weed out future troubleshooting
---
I am more the type of person that troubleshoots until the root cause is found
as opposed to throwing money at it in every way until its fixed
---
Kind of like, there's some mechanics who troubleshoot by arbitrarily replacing parts until it finally runs
instead of troubelshooting to find the one part that actually "NEEDS" replacing
I don't know how many times I have heard someone say they replaced "the coil" on their engine cuz they couldnt get it to start
When the problem was the carb
---
Typical convo'
---I couldnt get it to start, so, I replaced the coil, it still wont run
Why did you replace the coil? Coils hardly ever go bad
---I figured that was the first place to start
Did you test the coil first?
---??? How do you do that?
(Heeeeere's yer sign)

 

[AlNyhus]

I am using Fed 205M primers.

Trevor, despite what many say, the 205M's are a fairly tough primer. I've used literally tens of thousands of them (and standard 205's) in high and very high pressure loads w/o any cratering issues. Pin tips are from .062 to .068 with .001 pin hole clearances.

Long way around saying that while my suspicion is still the pin tip clearance, it would be a good idea to plop some CCI 450 or BR4's in a few cases just to see if there's any change.

Another thing that can contribute to the cratered appearance is a weak or low pressure firing spring. Last month, I worked with a friend whose action came with a 17 lb spring. After making a spacer to pick the pressure up to 22 lbs, the groups came around (less vertical) and the primers looked more 'normal'.

There's certainly a dynamic that happens here that may or may not show up exactly the same in all cases.

I'll include having the primer pockets well uniformed with no rounded edge at the bottom of the pocket in this dynamic. That'll get some bricks headed my way but there it is.

As always, start with the easy stuff but keep the whole picture in mind. Find someone with pin gauges to check the pin hole, as a start...hint.

Let us know what you find. -Al

 

[338 Mollett]

.068 with .001 pin hole clearances.

This !

 

[LCazador]

I am using Fed 205M primers.

Federal 205M are .022" thick. While CCI 450, BR4, and Remington 7 1/2 cups are .025" thick.

 

[Hengehold]

Trevor, despite what many say, the 205M's are a fairly tough primer. I've used literally tens of thousands of them (and standard 205's) in high and very high pressure loads w/o any cratering issues. Pin tips are from .062 to .068 with .001 pin hole clearances.

Long way around saying that while my suspicion is still the pin tip clearance, it would be a good idea to plop some CCI 450 or BR4's in a few cases just to see if there's any change.

Another thing that can contribute to the cratered appearance is a weak or low pressure firing spring. Last month, I worked with a friend whose action came with a 17 lb spring. After making a spacer to pick the pressure up to 22 lbs, the groups came around (less vertical) and the primers looked more 'normal'.

There's certainly a dynamic that happens here that may or may not show up exactly the same in all cases.

I'll include having the primer pockets well uniformed with no rounded edge at the bottom of the pocket in this dynamic. That'll get some bricks headed my way but there it is.

As always, start with the easy stuff but keep the whole picture in mind. Find someone with pin gauges to check the pin hole, as a start...hint.

Let us know what you find. -Al

Manufacturer re-checked pin hole and it gauges at .070 and the pin is .068.

I’ll try some thicker primers

 

[Hengehold]

Federal 205M are .022" thick. While CCI 450, BR4, and Remington 7 1/2 cups are .025" thick.

Ok, that sounds like it might make a difference.

I have Rem 7 1/2 and PMC Small Rifle Mag primers that I will try.

I am curious to see how substituting with the small “magnum” primer will influence the pressure and velocities of the load.

I will make a point to start with a new pressure ladder, and start low.

 

[LCazador]

Ok, that sounds like it might make a difference.

I have Rem 7 1/2 and PMC Small Rifle Mag primers that I will try.

I am curious to see how substituting with the small “magnum” primer will influence the pressure and velocities of the load.

I will make a point to start with a new pressure ladder, and start low.

I've seen little to no difference between magnum and standard primers as far as pressure and velocity. Better ignition and load consistency, yes. Especially in small rifle pocket large cases like 6 Creed and 6X47 Lapua which I shoot. Wives tale or just my experience?