Cartridge to chamber fit

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  • Last Post 15 July 2015
SLUGGER posted this 14 July 2015

I am requesting input on the following situation: 1.  My .45-70 rolling block barrel slugs @ .459 2.  My Hoch mold makes a great .4602 bullet which sizes to .460 3.  The Starline brass has a case mouth wall of .0105 ( times 2 = .021 ) 4.  .460 + .021 =.481 5.  The block will not close the last 1/8" Obviously, the case mouth dia. is too large.  I have confirmed the problem by applying dykem to a dummy case and can see dykem removal at the case mouth. About .100 when the case is tapped in to seat. ( Note, Case length is 2.100 ) I see my options as follows: 1.  Find thinner walled cases ( I would rather use Starline. ) 2.  Find a .481 reamer  ( Where? ) 3.  Chamfer the case end. (I am doing this now - looking for a better solution.) 4. Shorten cases by .100 ( Not really a good idea. ) 5.  Sell gun ( Not a good idea, its a great shooter ) Well, There it is. Slugger  

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Tom Acheson posted this 14 July 2015

Do you think turning or thinning the necks would solve it?

Tom

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SLUGGER posted this 14 July 2015

Yes Tom, that's my third listed option. It works but very time consuming. My best option is to ream the one to two thousandths but I need to rent, borrow or have a reamer made.  I have not found an area gunsmith yet and am not interested in shipping this 12 1/2 pound chunk of steel around the country. Thanks, Slugger  

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muley posted this 14 July 2015

it seems from your indication with the dykem that your case is to long for your chamber.

u say it is .100. try to trim one case case by .100 and see if it fits. if it needs more

trimming, then do so.  do cases other than Starline work in your gun?

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rjmeyer314 posted this 14 July 2015

I have a similar problem with an old trapdoor carbine. I get some relief by changing to Hornady Leverevolution once-fired cases. These cases are 0.055” shorter than normal 45-70 cases. If you seat the bullet to the same place in relation tothe case mouth you may move the bullet back from the rifling enough to close the action. Using the shorter cases, plus seating the bullets a little deeper solved my problems.

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SLUGGER posted this 15 July 2015

Thanks for the input gents.  I'll work the problem with your thoughts and suggestions. 

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.22-10-45 posted this 15 July 2015

I am assuming you are loading black powder? If so, can you size your bullet smaller? The black will easily bump it to groove dia. Few weeks ago, I took an original Ballard .40-63 A-1 Mid-Range out for first time. I had loaded up some Lyman 406150 30-1 lead/tin alloy over 70grs. Swiss 1 1/2FG. Bullet drops from mould at .405". My Bore (land-land) slugs .404..groove is .4094". Shot a 1 1/8” group at 100yds.

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Tom Acheson posted this 15 July 2015

Slugger,

There are multiple approaches to “neck turning". The bench-rest crowd thins the neck uniformly a certain distance from the case mouth down towards the case head. This distance is often equal to or slightly longer than the length of the portion of the bullet that is seated in the case mouth. Then they need to be sure that the OD of the loaded round is slightly smaller than the ID of rifle's neck dimension in the chamber. Some people like to have about 0.001” clearance all the way around the loaded case mouth so that the brass can expand as it lets go of the bullet. If you look closely at an after market barrel that has been chambered for a specific round, you'll see that the gunsmith has stamped or engraved the barrel with the dimension of the inside dia. of the neck. This alerts the handloader as to be sure his loaded rounds are smaller than that stamped dimension.

Some people intentionally use brass they know is too thick, with the intention of eventually turning the necks to get a better “fitted” loaded round for their use.

I've not heard much discussion from the BPCR crowd on the merits or need to turn case necks.

Tom

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Larry Gibson posted this 15 July 2015

Have you removed the case mouth flair? If not then that sounds to me like that's the problem. A taper crimp die would be in order to solve the problem. You can see if that's the problem by removing the decap rod from the FL die and back it out of the press. Run the loaded cartridge up into it only enough to size the flair back to the bullet. The 45-70 is a tapered case so this works well.

Another possibility is if you are crimping the case mouth when seating the bullet. You could be slightly bulging the case if trying to crimp too much or the bullet is seating too deep with the case mouth bumping into the underside of the top edge of the crimp groove in the bullet.

LMG

Concealment is not cover.........

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SLUGGER posted this 15 July 2015

Great input, as time permits, I will work the problem and state results.

TNX, SLUGGER

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