Barrel Gap/ Headspace

[Spokerider]

Who measures the barrel to breech face gap on their contenders? Do you shim for headspace correction?
I measured two of my barrels.........one was .005" the other barrel was .003" Now, when you get a cartridge that sits .003 or .004" below the face of the barrel / chamber [ measured with feeler gauge ] you have a head space of up to .009"
Wondering what the acceptable standard is for contenders in relation to consistent performance and no misfires?
 

[Hopalong7]

    Assuming you're reloading and talking about a bottle neck round, fireform your brass to where it rests flush with, or slightly above the face of your breech....end of problem... if there was one.
Walt

[Spokerider]

45 70

[Keith L]

What problem has you asking this?

[Hopalong7]

    A 45-70 should not be chambering 3-4 thousandths below the breech face .  Sorry, I assumed that we were discussing a rimless bottleneck round.
Walt

[Spokerider]

It's a brand new TC 45 70 12" barrel, and the Starline case sits .003 deep into the chamber. This barrel / frame combo has a gap of .005" between the breech face and the barrel-chamber face. When you add these two numbers together, you get a *headspace* of .008"   Further, when I seat the rifle primers into the cases, they sit down deeper than flush with the case, so the headspace is actually more than .008". Exactly how much more I dunno, I can't measure how deep the primers sit. These are rifle primers......not the shorter pistol primers either.
 
Keith, I've been getting lots of misfires, as in 50%. I loaded up some 45 70 and took the Contender to the range for the very first time......first time ever shooting the frame and with the brand new 45 70 barrel. About every other round was "click" "click".
 
I do have another contender frame that has some missing hammer pieces, so I could not swap the barrel onto it to try, but I did note that the hammer spring felt weaker in the frame I was shooting with. I also spent 2 hrs swapping and trying my different barrels on the two frames back at home, and I am confident it is not a lug bolt to frame clearance issue with the sliding locking bar or whatever that internal mechanism is called.
 
I have some new hammer springs on order, and a headspace shim kit coming from Bellm. I do hope this misfire problem gets corrected with these two changes. I read a few threads on stretched contender frames, and neither frame shows any evidence of being stretched.
I know there has to be *some* barrel to frame gap on these things, or else the lock-up is compromised if there is no gap, but .005" gap does seem pretty big, as does .003" for the case face to chamber edge gap.
 
Wondering what sort of gaps you guys have on your contenders and barrels? I sure didn't anticipate this trouble when I decided to switch from encores to contenders........grrrrrrr.
 
 

[Richard P]

If you are using a lead bullet; have you thought of seating it long enough that the bullet is on the rifling and the case head now rests flush with the breech of the barrel ?  You'd effectively headspace on the bullet and may have to adjust your loads a bit.
Have you checked for a broken firing pin ? They do break but my last one took eleven years to do so. Also the spring could be worn. Hammer springs can get weak but they usually just break.  A tip: Make a slave pin the width of the hammer and let it hold the spring while you insert the assembly, then drive out the pin (which you retain.)  I hope that helps.  Richard 

[Hopalong7]

     I wouldn't consider a barrel to frame gap of .005" very ecsessive....typical might be a thousandth or two less.  Now .003 below flush with the breech does not sound good.  I've not used any Starline 45-70 brass that I recall. so I'm not familiar with their rim thickness.  If you have a caliper handy, measure your rim thickness and we can compare to other brands.  Could be that you rim channel is cut too deep.  If so, since it's new (and even if it wasn't), a quick can to TC (I know...,S&W) would be in order, and they should send you a new barrel.  This exact problem is one of the main reasons that I MUCH prefer rimmed cases.....shouldn't have this happening with rimmed cases, occasionally it does, but not often.  I shoot a lot of 45-70, and have never encountered this with at least 4 different TC barrels.  Good Luck and keep us informed.....don't give up on the 45-70....It's more fun than a barrel of monkeys .
Walt

[Spokerider]

I thought about seating the bullet into the lands a bit, for paper it would be OK but for hunting I don't like tolerances that close and sticky bullet extraction.
Firing pins on both frames look identical.....can't see any broken / damage to either, but JIC, I have a new one coming.
 
The starline 45 70 case rim is .064-.0645" thick on my micrometer. Walt, have you measured how deep, or not, the cases sit in your 45 70 barrel?
 
I have a .357 max barrel and the cases sit .002" down into it. On my other frame, this barrel to frame gap is .007". I have not yet shot this. I can see similar problems however.
I have a TC 30/30 barrel rechambered to 30/40 Krag by SSK. The case sits proud of the chamber by .002-.003" [ I didn't measure, just a guess ] The barrel to frame gap on the same frame as with the .357 max barrel is .003". I can tell with closing it with a round chambered that it is a tight fit against the breech, but there is no problem with the hammer block not falling as designed. This combo will have .001" headspace or less. Will be no problems with this combo. Have not shot it yet.
 
Such variation between frames and barrels and just between barrels on the same frames! Yes, I could be shooting the other barrels, but I am wanting to get this 45 70 dialed in right now.
I am reluctant to send anything to S&W USA for repair [ they don't want to receive it anyway, I tried ] as being in Canada, shipping stuff to the USA and receiving back would be a paperwork nightmare, and the S&W repair / warranty guys here in Canada have bugger all for parts, and don't seem to want anything to do with it. I know, because I'm trying to get a contender hammer nose, detent balls and spring right now, so I can get the second frame back in action, and none of them seem interested in getting the parts or even a new hammer.
 
 
 

[sr sawyer]

Rim thickness on my current supply of new Starline nickle brass is on average .066.  The once fired Hornady brass is on average.067 or smidge over but would not average .068. 
IMO you have a barrel with a chamber rim cut too deep because this round headspaceses on the rim.  Your barrel to breech face is not excessive.
You cannot relate primer depth to headspace.  All primers should seat flush or slightly below flush (preferrably) with the case head and they should fire reliably that way.  I really think you have a chamber/barrel problem.
 
Ken

[Spokerider]

Thanks for measuring the brass rim thickness. Maybe mine is a tad thinner than normal, adding to the hedspace thing?
 
I know primer seating does not factor into headspace, but I was thinking more along the lines of the reason/s for the misfires and light primer strikes. A deeply seated primer is just that much further away from the tip of the firing pin.
 
I asked my bud to measure how deeply the case goes into his Contender 45 70...........002".
 
Waiting on the stuff coming from Bellm.
Dunno how I got italics going here, but I did.

[SHOOTALL]

I think if I were you I would see where a factory loaded round sits in the chamber .
I would check the bolts by coloring the wedge surface with a felt tip marker closing and seeing if infact you have engagement at least half ways up the wedge.  I would also check the hinge pin for any play. It could be a combo of things.
 If the factory round fits and works then I would size the cases to work. Over the years in Contenders and other guns I have found that just because the case has a rim doesn't mean  it can't be sized to chamber on the shoulder and benefit case life. 

[Richard P]

I'm just throwing out an idea------but have you tried sizing your cases only as much as holds the bullet?  If fired cases chamber and extract easily that may allow the case to sit flush with the breech. Cases with shoulders do benefit from headspacing there but I don't believe that is going to apply in your 45-70. rp

[SHOOTALL]

I'm just throwing out an idea------but have you tried sizing your cases only as much as holds the bullet?  If fired cases chamber and extract easily that may allow the case to sit flush with the breech. Cases with shoulders do benefit from headspacing there but I don't believe that is going to apply in your 45-70. rp

Isn't what you suggested just that head spacing on the shoulder ?

[Spokerider]

I measured a factory Hornady Lever Revolution round at .002" below chamber mouth.
 
I'm not sure what is entailed in sizing a 45 70 case "on the shoulder" since it doesn't have a shoulder? What's to keep it from falling all of the way into the chamber right to the rim?
 
In any case, that seems much to fiddly for my liking. I'm going to start with a new hammer spring and shim the firing pin bushing first.

[Hopalong7]

     Last night I checked my brass and it all measured .062"....many different lots, but all R - P.  I then checked all my barrels...one older S-16 Contender barrel...one newer 23" (cut to 18") Contender barrel....one Encore 18" barrel...and one NEF Handy.  Both of the Contender barrels and the Encore barrel chambered loaded rounds, sized but not loaded brass, and fired, unsized brass almost perfectly flush with the breech.  All of the brass protruded slightly (maybe .002") in the Handy barrel.  I would conclude that your chamber or at least the rim channel is cut too deep.  Sorry .
Walt

[Spokerider]

Thanks for all of the measuring and providing the info Walt.
Seems I may have a dud barrel...........

[SHOOTALL]

I measured a factory Hornady Lever Revolution round at .002" below chamber mouth.
 
I'm not sure what is entailed in sizing a 45 70 case "on the shoulder" since it doesn't have a shoulder? What's to keep it from falling all of the way into the chamber right to the rim? Sorry "mouth of the case . I would trim until the action just closes .
 
In any case, that seems much to fiddly for my liking. I'm going to start with a new hammer spring and shim the firing pin bushing first.