Gunsmithing Rem700 bolt question for you who KNOW. *UPDATES*

[Keith Johns]

I have been breaking cross pins. Think I know why



Heres 2 Remy assemblies:

Notice no gap. The holes line up perfectly.

Heres a aluminum firing pin assembly from company "Z"

Again, no gap.


Now, with my aluminum firing pin assembly from company "X", the holes do not line up because the firing pin can go deeper into the cocking piece. This means that 100% of the pressure is on the cross pin when assembled.

I've checked several Remy factory assemblies, all had no gap.

As shown above, the two Remys and one after market one have no gap.


So, should there be a gap between the cocking piece pocket and the end of the rear of the firing pin shaft, causing the holes to go "past" lining up?


Thanks for any input.

Pics of assemblies you took apart would speak 1000 words.


Thank you

Keith

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

I should mention I fixed the cross pins breaking in my assembly, by shimming the gap between the firing pin and the cocking piece pocket with a shim about .009" thick.

So no gap, no break. Gap, break.


Just my findings

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

BTW I'm talking about a gap behind the shaft, in the pocket of the cocking piece.

Not the sides of the shaft.

Should the rear of the shaft, and the pocket of the cocking piece touch? or should there be a .010" or so gap

 

[zenbiker]

Re: Breaking cross pins... Should be a gap here......?

Just thinking out loud here. OK, brand "Z" has extra space between the rear of the firing pin and the inner face of the cocking piece. When cocked, the cross pin is under tension created by cocking the bolt, storing energy in the spring in a slow gradual fashion. Upon firing, the cocking piece snaps forward, and any inertia not transferred to the primer, firing pin contact with the inner front of the bolt, and friction is transferred to the cross piece in a sudden, intense manner IF the firing pin does not rest against the inner face of the cocking piece. This shock could very well cause microfractures to form and propagate along grain boundaries of the crosspin, if not in the cocking piece itself.

Somebody with better knowledge of metallurgy and the hardness and composition of the pins would probably be able to make better sense of this rambling.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Right.... if there's a gap, every time the rifle is fired, the only thing stopping the cocking pieces momentum is the cross pin.

Plus I think the fact that the factory assemblies have no gap says something.....

 

[Grand]

Re: Breaking cross pins... Should be a gap here......?

Keith: I have swapped out several firing shrouds, and would concur with your observation. I do not recall, however, seeing cross-pins as short as the one shown in your pic, and with a concave end.

 

[zenbiker]

Re: Breaking cross pins... Should be a gap here......?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body">I should mention I fixed the cross pins breaking in my assembly, by shimming the gap between the firing pin and the cocking piece pocket with a shim about .009" thick.

So no gap, no break. Gap, break.


Just my findings </div></div>

Goes right along with my ramblings.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Grand,

You mean cocking piece? I dont show any cross pins in my pics

 

[zenbiker]

Re: Breaking cross pins... Should be a gap here......?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grand</div><div class="ubbcode-body">Keith: I have swapped out several firing shrouds, and would concur with your observation. I do not recall, however, seeing cross-pins as short as the one shown in your pic, and with a concave end. </div></div>

Grand: I think you're seeing an optical illusion, fooled me too. There are no pins in any of the assemblies; you're seeing through the perfectly aligned holes to the lighted background. You can even see the edge of the carpet in the second pic.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

When the Cerakote is cured, I'll post pics of an assembly from company "X", that shows the gap, and the cross pin misalignment.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Here is what I believe is breaking the pins


Heres a pic from an assembly from company "X"

See how the holes do not line up like the factory two and the other aftermarket one does.

I fixed it by putting a shim in the pocket of the cocking piece. My guess on shim size was .005" to .007".

A small change in design to the firing pin shaft could fix this. I spoke with manufacturer "x", and he and I couldn't find any reason NOT to lengthen the shaft a few thou. He didn't agree to do it though, understandably for many reasons.

Can anyone else chime in and say why it could be bad to lengthen the shaft a few thou so it contacts the cocking piece?
If factory ones touch, which they appear to do, why not set up all aftermarket assemblies the same?





I would also like to add, I WILL continue to buy from this manufacturer. They took the time to speak with me and have been very helpful and caring. That is why I have left names out. I simply want to understand what is going on.

 

[apache308]

Re: Breaking cross pins... Should be a gap here......?

Keith: One thing I have found occasionally on M700's and various clones regarding the pin misalignment is that when a slight alignment issue exists you can rotate the firing pin itself 180 degrees and in some cases it will better align. I know it sounds crazy but sometimes the pin hole will be drilled from the manufacturer with a slight cant. It happens more than one thinks and in fact I had it happen today on a M700LA (factory firing pin assembly) I was reassembling. SR

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: apache308</div><div class="ubbcode-body">Keith: One thing I have found occasionally on M700's and various clones regarding the pin misalignment is that when a slight alignment issue exists you can rotate the firing pin itself 180 degrees and in some cases it will better align. I know it sounds crazy but sometimes the pin hole will be drilled from the manufacturer with a slight cant. It happens more than one thinks and in fact I had it happen today on a M700LA (factory firing pin assembly) I was reassembling. SR </div></div>


Thats not whats being discussed.

 

[DAVETOOLEY]

Re: Breaking cross pins... Should be a gap here......?

Your diagnosis of the problem makes perfect sense but in all the years I've been doing this I've never had to replace a broken cross pin. Strange, why now? I'm going to assume a lighter pin with a heavier spring meaning higher velocity for the firing pin which would increase the shear load on the cross pin when striking the primer? Another victum of unintended consequences?

Thanks for sharing.

 

[apache308]

Re: Breaking cross pins... Should be a gap here......?

Keith: I understand perfectly what is being discussed and have ran into that myself with aftermarket components - but I have never broken a pin - yet. I just thought I would add the misalignment comment to the post as it does crop up time to time. No deed goes unpunished I guess. Sorry to post on your thread.....I think you have it figured out. SR.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

No sir I dont have it figured out.

The question is, should there be a gap between the rear of the shaft, and the pocket of the cocking piece?

And by gap I dont mean .001". Its a enough thats you can visualy see it in the pics above. Probably .007"-.009"


The misalignment is caused by the f-pin shaft hole passing the cocking piece hole(going in too deep)

Dont appologize for posting on the thread... I'm just asking a question other than what you answered.

Should there be a void between the rear of the f-pin shaft and the pocket of the cocking piece?

 

[427Cobra]

Re: Breaking cross pins... Should be a gap here......?

For the record I think Gre Tan FPA suck too!

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

...I have nothing against Gre-Tan or any company.



I spoke with my head instructor at my gunsmithing school and here's why he thinks I'm breaking the cross pins....

He said a slight gap behind the shaft is normal. He said however that any wiggle room in the holes could cause breakage. The holes do seem a bit oversized. The cross pins fall right in very easily. Too easily maybe.




I'm still at a loss as to why theyre breaking, and the answer I get from people is: aluminum pins cause problems like this. Well I think thats bullshit. A Product should work and be strong enough to last 10000 dry fires/firings, whatever.


My solution to this is, I shim the gap between the shaft and the cocking piece pocket. It has fixed the problem so far and I will continue to do this until an answer unvails itself.

 

[DAVETOOLEY]

Re: Breaking cross pins... Should be a gap here......?

I've never seen aluminum cross pins on the cocking piece before. If they are then that's your main problem. Get a steel dowel pin.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Thats aluminum firing pin shaft. Not cross pin.

Cross pins are steel.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

I may have an idea as to why they're breaking. I will try to study it tonight and see if I can figure anything out.



The question on whether a gap should exhist between the shaft and the cocking piece pocket seems to still be up in the air. I have heard from sources I trust that a gap is common, but I have yet to find one in any factory assembly... And I check quite a few of them as you can imagin with my business.

However the question on why the steel cross pins are breaking in the middle is yet to be answered.


My instructor said there's a good deal of bounce back after the firing pin has struck the primer. He said this bounce back could be doing it COMBINED, with sloppy cross pin holes. AND, if thats the case, I blame that gap behind the shaft even more!




Randy....? I'd like your input

 

[Dans40X]

Re: Breaking cross pins... Should be a gap here......?

p.m. inbound

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

PM back Dan. I appreicate the help.


I didnt get around to checking into what I mentioned above. I'm really busy with school and the bolt work.

I will post results this weekend. Cocking piece, shroud, firing pin protrusion, any guesses as to my assumption? Like I said I'll check this weekend.

 

[Hateca]

Re: Breaking cross pins... Should be a gap here......?

Having a gap behind the pin and the cocking piece is common as long as it's not overly excessive. Aftermarket pins and cocking pieces I have seen .002 to .003 which appears to be pretty common and haven't seen a problem. I've seen a few with more but no problems there either. In 20+ years I’ve only seen a handful of broken cross pins, all on factory rifles and they could have been broken when Remington pressed them in during assembly and I only found it when I took it apart.

Remington pins are assembled and then drilled for the cross pin. I suspect this is why there is no gap but this is also why factory assemblies will sometimes only go back together one way, or why if you mix up firing pin parts with more then one rifle they won't always go back together very easily.

I wouldn't suspect that just the gap between the cocking piece and firing pin is the only problem since there are thousands of aftermarket assemblies out there that are doing just fine.

That being said if there is another problem this could be compounding the issue causing the cross pin to break.

Problem such as long firing pin protrusion, I don't like anything longer then .050 to .055. Bad heat treat on the cross pins. Heavier firing pin springs. Sloppy fit between the cocking piece and firing pin. Any combo of these things could be adding up to cause the problem.

Some manufactures of aluminum firing pins will recommend not to dry fire with their aluminum pins installed due to the danger of breaking the firing pin. I don't use aluminum pins in my builds so I can't attest to the cross pin being broken by dry firing with an aluminum firing pin but I have seen aluminum pins break in other ways, both with and without dry firing, so there may be some validity to it.

The stainless steel firing pins for me are bullet proof and I never really saw any benefit of going to a lighter pin and heavier spring in a field or tactical rifle for “faster lock time”, In fact I saw more problems then it was worth.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Hi Randy, glad for your input.


The gap I'm speaking of is alittle more than a few thou. Notice the pics above where the holes are misaligned. Thats the aftermarket assembly I'm talking about. Looks to be off more than any other I've ever seen.


I'm familiar with how Remy drill theirs. Thats why I challenge the "fact" that there's gaps that big in Remy assemblies. Maybe a thou, but not as much as shown above. I dont care what Remys blueprints say... they slap 'em together to get them out the door. And the cross pin hole to firing pin, shoulder?, has to be the same measurement. Thats what theyre focusing on I'd assume, because thats what matters.


I will check what I mentioned yesterday, today. And I will take the new assembly coming in from my supplier, and shorten protrusion to .050 to see if that fixes it. I doubt it will.




As for not being able to dry fire aluminum assmblies or them being less tough as steel... I wont accept that. I found one problem with them after 1000s of dry fires and 100s of firings... the broken cross pins. I've already figured out how to fix this little problem with a shim or shim bed, and will do this to every aluminum assembly that comes through.


I like the light feeling strike of the aluminum pins and will use them no matter what it takes to "fix" them.




***An important note: assemblies with broken pins do not fall apart, or stop striking. They still function and you would never know it was broken in half unless you took the assembly apart.
I shot mine for an estimated 3 months with a broken cross pin. NO missfires, NO problems.




And for all you people who jump ahead to the last post and dont read the thread, we're talking cross pins, not firing pins breaking.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Just did a little test. I dont know if it matters or not but heres the results.

The shoulder of the firing pin is hitting the shoulder in the bolt body, long before the cocking piece is contacting the shroud shoulder on the inside of the shroud.
So again, the cross pin is the only thing controling the forward momentum of the cocking piece, along with the bounce back of the f-pin while the cocking piece is STILL trying to go forward. This has to equate to massive forces on the cross pin.

I dont know if this is supposed to be, or not. But can you imagin the forward momentum of the cocking piece slamming forward at that speed then abruptly being stopped, AND then the firing pin bouncing back while the cocking piece continues forward?

 

[Hateca]

Re: Breaking cross pins... Should be a gap here......?

If the cross pins are breaking during dry fire the firing pin protrusion isn't going to be a problem.

I know you might not agree with or buy into not to dry fire aluminum firing pins but if the manufactures says not to there must be a reason for it.

The cocking piece shouldn't bottom out on the shroud, the front shoulder of the firing pin against the inside of the bolt shoulder is what stops forward movement of the firing pin.

If shimming the rear of the firing pin to take up the space is fixing the problem that you're experiencing that may be your only hope, but there are other builders and users using aluminum firing pins with no problem so I would still believe there is a combination of issues casing this problem.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Okay so it's not what I investigated above.

I'm running out of things to check except for, like you said, a combo of very small things that could be adding up to them breaking.

I will punish mine to hell and back.
If it holds up fine I guess I solved my problem. And I'll put the rumor of not being able to dry fire aluminum pins to the test.
I think if the shafts were bedded into the cocking piece(with release on the shaft), so there was NO movement, and the cross pin went in stright and tight, there'd be no problems.
Would do the same thing my shim does right now, but better.
Sounds like a pain though.

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Kool logo by the way Randy

 

[Hateca]

Re: Breaking cross pins... Should be a gap here......?

You might try using some drill rod of the appropriate size as a cross pin and see if that stops your problem. If it does then I would suspect a problem with the manufacture or heat treat of those cross pins.

 

[Dans40X]

Re: Breaking cross pins... Should be a gap here......?

3/32" drill rod was suggested a couple days ago by myself to cure the brittle dowel pin problem.

Schools still in cession!

 

[Keith Johns]

Re: Breaking cross pins... Should be a gap here......?

Yes school is still in session, but you claim you already "know more than every one else I listen to combined". Everyone else meaning smiths on this board and my school instructors I assume?

I appreciated your help until you acted like your normal self.

You need people skills

Thanks

 

[Dans40X]

Re: Breaking cross pins... Should be a gap here......?

A simple assembly with a total of 5 parts w/1 part that fractures is not Rocket Science 101.

One should test inferior aftermarket pieces/parts on their own weapon systems prior to painting said parts & sending them out the door.

 

[Keith Johns]

Re: Breaking cross pins...

I've been using one for about 5 years.

Been installing them for 6 months.

Didnt experience this problem until about 3/4 months ago when I switch supplier.
I test everything on my own rifles first, and I only offer parts I have on my rifles.

And those 5 parts can have a lot of things happen and can be manufactured in many different ways. You know this Dan the man

 

[msiebert]

Re: Breaking cross pins...

FWIW....the gap does not belong, period end of story. When I install speed lock kits{or any other name you want to hang on any brand of "performance" aftermarket striker assemblies} if there appears to be anything less than zero gap I chuck it in my vertical mill vise jammed up tight together and redrill the assembly slightly oversize. Drive in the new pin and chalk it up as one of those "extras" we all have to occassionally do. Will it work with the gap??? Yeah, maybe for a while. Is it worth trusting it to hold up any length of time?? Nope, not me. Should you dry fire it?? A dozen times or so shouldn't hurt, but why any more??? I think expecting it to last 10,000 dry fire cycles is unrealistic. The factory one is probably not expected to be fired that many...come on. As far as "is it really needed??" Who cares?? You will be alot richer if you shut up, smile and take the money and run!!! Half the shit I put on these guns is not needed but I aint about to tell my customer he's wrong if: A. He thinks he is right,and: B. His thinking places more money in my pocket!! Good luck.

 

[Keith Johns]

Re: Breaking cross pins...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: msinc</div><div class="ubbcode-body">FWIW....the gap does not belong, period end of story. When I install speed lock kits{or any other name you want to hang on any brand of "performance" aftermarket striker assemblies} if there appears to be anything less than zero gap I chuck it in my vertical mill vise jammed up tight together and redrill the assembly slightly oversize. Drive in the new pin and chalk it up as one of those "extras" we all have to occassionally do. Will it work with the gap??? Yeah, maybe for a while. Is it worth trusting it to hold up any length of time?? Nope, not me. Should you dry fire it?? A dozen times or so shouldn't hurt, but why any more??? I think expecting it to last 10,000 dry fire cycles is unrealistic. The factory one is probably not expected to be fired that many...come on. As far as "is it really needed??" Who cares?? You will be alot richer if you shut up, smile and take the money and run!!! Half the shit I put on these guns is not needed but I aint about to tell my customer he's wrong if: A. He thinks he is right,and: B. His thinking places more money in my pocket!! Good luck. </div></div>
Glad to hear you agree on the gap.
But about half way down your paragraph I disagree.
They should out last the number of times you can do it in the time you own the rifle, or the next guy owns the rifle.
And the last part of your paragraph I absolutely disagree with. I wouldnt sell/offer anything I wouldnt put/own on my own rifles. In fact, I dont offer anything that isnt on my one and only rifle I use for everything, and fire/dry fire, a LOT.



I not only test things on my rifle first, but I make my close friends let me test on theirs too

To their liking I might add

 

[Grand]

Re: Breaking cross pins...

Keith: I'm thinking through the forces acting upon the pin. Can you post up a pic of the failed pin? Are the pins failing in the middle, or the end? If on the end, which end? Is the diameter of the pin identical to the diameter of the hole in both the cocking piece and firing pin?

As Randy points out, the factory assemblies are drilled together during assembly. Most factory assemblies that I have played with require a fair amount of force to reset the cross-pin, indicating close tolerances. Therefore, when force is applied, the load is distributed equally along the pin. It seems to me that if the pin diameter is smaller than either the hole in the cocking piece, or the firing pin, the load is no longer equally distributed, and may be the cause of your problem.

 

[Keith Johns]

Re: Breaking cross pins...

The ones I've pulled out broke in the middle.

Tolerance around the cross pin in the hole is loose compared to factory Remys.

The company that makes them has helped me out and has gone to great lengths to make me happy. I am very happy and will continue to use their products. They said they will change some things slightly to try and help/solve my problem. They've been GREAT to deal with.