Barrel to Frame gap?????

[Jay, Tx]

Should there be a gap? Will not having one effect accuracy? What are y'alls thoughts on this subject?



Jay

[Hopalong7]

   There has to be a gap or the action wouldn't open or close.  Ask the Handi-Rifle guys.  The question seems to be how much gap is acceptable and how to deal with it when you got it.   In all the Contender barrels I've had I don't I don't recall aproblem with too little...or...too much gap.
Walt

[Jay, Tx]

Well I can close my Encore on a .001" feeler and not be able to pull it out. So either it's hitting the frame, or the clearance is less than .001". I have no .0005" blade, so it's kinda hard to check that. But mine will lock up. It even shoots decent, it just seems like there's some accuracy left to find. Was wondering what everyone else's experiences/thoughts were on this subject?

Within reason, I don't think too much gap would pose a problem. But if something like the ears on the forearm rubbing the frame is detrimental to accuracy, my thinking was that the barrel engaging the frame would be too.

Thoughts?

Jay

[quickdtoo]

Any gap would add headspace, if there's too much gap, you'll either get no fires or brass life will be shorter due to excess headspace. I had a 375H&H Prohunter barrel that wouldn't lock up tight on a .006" feeler gauge, never shot factory rounds in it, got around it by forming a false shoulder by necking up to .401" and full length sizing to push the false shoulder back just enough to allow the action to close and lock up, it shot under 1" at 100yds first trip to the range, once the brass is fire formed it's back to reloading normally. 

Tim

[Jay, Tx]

It's my understanding that the barrel to frame gap has no effect on head-space since the round head-spaces on the shoulder of the case (or the belt, the rim, or even the mouth). The head-space would then be dictated by the shoulder (in this case) in the chamber related to the breech-face on the frame. Is this not correct? If it is, then head-space could be altered by the set-up of a sizing die to set the shoulder of the case where it needs to be to provide the proper head-space (as you describe). Thus making the barrel to frame gap a moot point regarding actual head-space.

Now obviously there could be such a thing as too much barrel to frame gap that could cause problems. But I think we'd be talking about much larger clearances than what I anticipate seeing. I am looking at this from an accuracy standpoint. The barrel contacting the frame will put stresses on the barrel, right? This is the issue I'm concerned about, and asking about.

I did find I am at present using a round that has no head-space what so ever. But as I (and you) said above, this can, and will, be solved with a die adjustment. What concerns me is the barrel hitting the frame, and it's potential effect on accuracy. In my situation, if it even is one, some material could be removed from the breech end of the barrel. This would provide some barrel to frame gap but not effect head-space at all. That dimension would remain static since the shoulder in the chamber's distance would not be moved from it's present location, relative to the breechface.

I'm just wondering what peoples' experiences/thoughts are regarding the the barrel to frame gap, or lack there of, issue that I'm finding with this barrel?

Not trying to argue. I do not have enough experience with this design of rifle to argue with anyone. But the above description of things is how it was described to me, and it makes sense to my "alleged" brain.


Jay

[quickdtoo]

As Walt said, the barrel must clear the standing breech, since the barrel swings down in an arc, it has to have some clearance, ideally that would be just enough to clear which would provide minimum spec headspace, the SAAMI max is .006" excess....that would also assume that a charmbered round would be flush with the chamber face, if it's recessed any, that would increase the excess headspace.

Tim

[Hopalong7]

    Jay, From what I've seen, you've got one tight fit.  I think the general consesus is the less gap, the better at least as far as ignition goes and probably for accuracy too.  We've been taught from the get-go to use a crush fit sizing technique to ensure ignition, accuracy and good case life in break open actions.  Most cases run through a FL sizing die adjusted all the way down and most factory ammo will still have the rim protrude ever so slightly when chambered in a lot of TC barrels, at least in my experience.  Assuming the chambers are the same, the more gap you have the more head space you have. Walt

[Jay, Tx]

So what you're saying is I shouldn't concern myself too much that the barrel is hitting the firing pin bushing (I correct myself here, as I've been referring to it as hitting the frame)? I removed the bushing a minute ago and there is just under .002" from the frame to the barrel. It is the firing pin bushing that's engaging the barrel.

I also bottomed my die out against the shellholder, and it will not bump the shoulder at all. Only resizes the base of the body on the case and leaves the shoulder where it was after firing. Should I consider having a bit of material removed from the base of the die itself so I can bump these shoulder back? They are Redding dies BTW.

Thanks again fellas. I'm just trying to wrap my head around all this stuff. I appreciate the help.


Jay

[Hopalong7]

    I wouldn't be concerned about the barrel hitting the bushing as long as it closes and locks up OK.  If I remember I think I have some frames with the bushing protruding slightly.  Nor would I be concerned about the die bumping the shoulder as long as the barrel and action close with good lock-up.  If it becomes a problem then I would grind the bottom of the die ever so slightly until it cured the problem.  I think a factory chamber .219Zipper barrel was the only time I've had to shorten a FL size slightly to get the round to chamber properly.
Walt

[sk330lc]

You shoudln't have to Bump the shoulder as Long as it chambers..   Have you tried neck sizing only?  will they chamber?  Have you checked the clearances on your forearm (Floated it as much as possable)?   What Cal. are we talking about?

[Jay, Tx]

 Cal. is 280 ackley (40 degree shoulder) minimum spec'd. chamber. The round chambers. But it's a crush fit since there is no gap between the barrel and firing pin bushing, and the case head protrudes .005" from the barrel.

I talked with the manufacturer today. It looks like I'm gonna be sending the rifle back to them. The fella there said there should be about a .001" gap from the FP bushing to the barrel. He said then I should be bumping the shoulder back to where the case head sits flush with the end of the barrel.

He did have me size a case with the expander ball removed to see if the expander was too tight and pulling the shoulder back out. No dice there. It still didn't move the shoulder any with the die bottomed out + 1/4 turn. This, I can get past though. While the rifle is in transit, I'll be ordering a set of Redding Competition shell holders which are ground incrementally up to .010". With these I should be able to take care of the shoulder issue. But I always knew this would be a relatively easy fix anyway. It's been the barrel to FP Bushing contact that I questioned all along.

Forearm is on a hanger bar, no contact anywhere but to the bar itself.


Jay

[Jay, Tx]

Correction, the Redding comp shell holders are NOT gonna fix my problem. They are ground to the positive side, not the negative. So that would be going the wrong way (not doing anything to help me).

Looks like my only answer to this is to send the dies to my machinist, or to Redding, and have the the sizer cut down a bit.

Or have the smith cut the chamber a bit deeper. But even then, I still don't know if my die will need to be cut or not, since I don't know if it would bump the shoulder then or not. Sooner or later though, I'll get all this worked out. Man, all this from a few flyers! It's fun though, and I'm learning.

Jay

[Hopalong7]

     A little emory cloth and a good flat surface will fix the die in short order.
Walt

[Jay, Tx]

     A little emory cloth and a good flat surface will fix the die in short order.
Walt

I was thinking the same thing. But I might actually experiment with cutting a shell holder down first. the effect should be the same, and not have to alter the die itself. It would just have a dedicated shell holder from the on.