T/C 30 Herrett Short Chambered

[mtgrs737]

I have a new to me 10" Thompson Center heavy contender barrel in 30 Herrett that appears to be short chambered. Both my loading manuals have the rim thickness of the case listed at .062" - .063" but my measurements of the barrel rim counterbore is .058" deep. I have hand sorted thru some 30-30 brass and selected cases that are not more than .0575" rim thickness to make my 30 Herrett cases from. Now I find that my RCBS sizer die cannot be adjusted down far enough to set the shoulder down enough to get the action to close and lock enough for the internal hammer drop safety to allow the hammer to make firing pin contact. I suspect that the barrel is short chambered due to the rim counter bore being shallow and the die not being able to size the shoulder down enough.


I have called T/C (actually S&W) and they have agreed to take the barrel back and have their Gunsmiths look at it. This barrel is an old one, maybe 30 years old and the lad I talked to in customer service said that they would fix it free under warranty if they could. I think that it is about .005" short, T/C no longer chambers for this cartridge. Has anyone here dealt with this problem? If so whom was it that fixed it? Should I just ship it back and chance loss, mishandling or risk a chamber problem worse than what I have already? I have used a trim die to set the shoulder back enough to get the barrel to lock up, but I may not want to hand select the brass everytime and use a different sizing die. Of course I could just grind down the top of the shell holder or bottom of the die by .005".

This barrel is like new and has the old style brazed on front sight that I like.

So what do you guys think?

[725]

Would a chamber reamer from Mason fix the problem?

[Tom R]

A friend of mine's dad sold one that was the same way but his dies did fine. The first dies he used did not. It was sold in the lincoln Ne area. If that happens to be where you purchased it from and would like to sell it I know his son would love to have it back. He's not happy his father sold it as it had sentimental value. I guess it shot great

[mtgrs737]

Mine came from the east coast, but who knows maybe they got it from Ne. The barrel is like new with only very minimal frame marks and no other marks the bore looks brand new too. I figure that this barrel has a history of people moving it on due to the short chamber creating difficulties making cases for it. The more I think about it I may just grind .006" off the top of the shellholder and then it should be able to form/resize cases for it just fine. I will have to remember to keep an eye out for 30-30 cases that have thinner rim thickness to fit the .058" counterbore (the book lists .063" for rim thickness). But down deep I would like to see it fixed right. If I could get ahold of a reamer I think it could be hand turned enough to deepen the chamber .005".

[rockrat]

I would just take a bit off the die myself.

[Alan in Vermont]

Headspace dimension on a Contender is a combination of rim cut depth and clearance at the standing breech.

Before you go cutting the chamber deeper you need to determine how much space there is between the back of the barrel and the receiver. If your rim cut is .058 and the action will close on a .005" feeler gauge then there should be room for the .063" rim.

My own Contender with a .357 Herrett barrel will close with three plies of printer paper, around .010" between barrel and receiver.

Make sure the extractor is cut as deep as the chamber recess. Does a sized case fit in the chamber so that the rim is protruding less than the thickness of the feeler gauge that fits between bbl. and receiver?

[gsdelong]

What Alan said plus you might want to check out Mike Bellm's site www.bellmtcs.com/

[mtgrs737]

In order for my internal hammer block safety to disengage I need the barrel to touch the standing breach. I understand that I could just file down the top of the sliding barrel locking block to get it to disengage the hammer block safety but I would rather not. I have no gap between the breach end of my barrels and the breach face on any of my barrels.

[MostlyLeverGuns]

I would shorten a shellholder to accommodate the headspace. Easier to square up to the die and much cheaper than a 'custom' die. I have found many, many rimmed cartridges to have rims much thinner than maximum when carefully measured with a high quality dial caliper or a micrometer. I have seldom found rims of rimmed cases close to SAAMI maximum.

[FLHTC]

Your problem may not be with the chamber at all, but be with the locking lugs. I would say that your vintage barrel has a solid locking lug with a profile that prevents a solid lock-up. Installing a split locking lug or modifying the profile of your solid one will most likely answer your problem.

[mtgrs737]

Your problem may not be with the chamber at all, but be with the locking lugs. I would say that your vintage barrel has a solid locking lug with a profile that prevents a solid lock-up. Installing a split locking lug or modifying the profile of your solid one will most likely answer your problem.

It does have the solid locking lug, but the barrel locks up and releases the hammer drop safety so I feel that the lug is the proper size. I did have one years ago that the locking lug would not go deep enough into the frame to trip the hammer block device with an empty chamber and I had to slightly modifiy that one so it would. I have ground off the top of the shell holder about .010" and I can now size the case enough to get the barrel to close and lock up tight tripping the hammer block safety so the gun will fire. I have sorted thru many many cases and found a goodly number that have rim thicknesses of .0575" or less so I guess I am good to go on this one.


I do have one question though, what should the neck thickness be and how large should the I.D. of the sized neck be? (Two questions I guess) Mine is expanding the ID of the neck to .306" Leaving me a .329" O.D. neck. I suppose that throat of the chamber will accommodate a .331" O.D. loaded cartridge and still have a tad more room to expand to release the boolit.

[ubetcha]

+1 on contacting Mike Bellm. He seems to be quite knowledgeable on anything T/C as that's what he specializes in.

[mtgrs737]

I checked out Mike's websight and read up on headspacing a T/C. It seems that having to mod the die or shellholder is pretty commonplace. So I guess I have my answer. I took about .010" off the top of the shellholder and now I can get the action to close and lock properly with little effort like Mike suggests. Next will be fireforming those cases!

Thanks to all whom posted their thoughts and suggestions here I appreciate them all! What a great bunch of guys there are here!


mtgrs737