Bumping shoulders the right way

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Mike 3-4
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Bumping shoulders the right way

Post by Mike 3-4 »

Hi: I had a 6.5 x 55 Swede barrel built for my new G-2 frame and so far it shoots .472" at 100 yds. using 40.2 grn of H4350 & 140 grn SMKs, Rem 9/1/2 primers, Win.brass, OAL 3.050, 2500 Fps out of a 22" barrel with a 1 in 9 twist, SD 8.4. Knocked down 2 Ram the other day with the help of some nice guys at the range and the spotter said they went down real well with that load. My problem is several rounds wouldn't let the action close so I bumped the shoulder back 1/2 turn on the sizing die and now the cartridge is not firing although the firing pin is striking the primer. Please help me with a way to set my die to full length size my case properly. Thanks Phil
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malinois
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Re: Bumping shoulders the right way

Post by malinois »

Its a tuff one sometimes with the contender...I shoot a 7 TCU and it can be tricky...I only neck size...but in your case its going to be trial and error. You have to bump in smaller increments I fear that the half turn you applied bump you so much that the case drops far in to the chamber to where you are only getting a lite hit. you are looking for about .002 I think. usally you know your in the right range when you have to give it a slight smart rap to close.
Mike 3-4
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Re: Bumping shoulders the right way

Post by Mike 3-4 »

Hi Again: I set my die by raising the ram all the way up and screwed the die in to touch lightly, then lowered the ram and gave the die 1/2 turn. It seems the only way it will F/L size to the extractor groove with a piece of brass in the shell holder. Without brass the ram will cam over and stress the die. Am I sizing too deep into the die? Can I start all over by shooting a primed piece of brass in the chamber to create a long piece and reset the die? By the way I'm using Hornady new dimension dies with an RCBS shell holder. Phil
kevinbear
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Re: Bumping shoulders the right way

Post by kevinbear »

My brother had the same problem with a Encore in 6.5x55, I suggested trying a set of Lee dies and the problems went away. As far as inexpensive dies go I've had very good luck with the current production Lee dies, the RGB's are 14.49 at Midway. There currently out of stock but allowing backorders, usually in stock less than 10 days.
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Bob Mc Alice
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Re: Bumping shoulders the right way

Post by Bob Mc Alice »

Malinois...you are right on the money.

Mike 3-4... if only a few rounds gave you fit trouble, sounds like you were very close to proper die setting. Back off the die setting you have now and start over. With a standard 7/8-14 die thread, every full turn produces .071 of movement. At a half turn, .035 approx. That is alot of movement. You probably pushed the shoulder back too far. The case rim just being held by the extractor is not solid enough to provide support for ignition.

Dies are designed to size properly with out having to touch the shellholder, or to completely cover the extractor groove.

Try this: Take a fired case, degrease the shoulder. Take a grease pencil or roll up a tiny piece of parrifin wax about the size of a pinhead. Stick it to the middle of the case shoulder. Lube your case as normal and run it up the die. Turn the die down 1/8 to 1/4 turn at a time and watch for the wax start to flatten out as it comes in contact with the die shoulder. When the wax is flattened to about the thickness of paper, you are real close to correct sizing. Remember, for each 1/8 turn you are moving the die down about .009 (three thicknesses of common paper).
Wipe the wax off and try it in the gun. Keep turning very little till it will close without interference.
Mike 3-4
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Re: Bumping shoulders the right way

Post by Mike 3-4 »

Hi: Followed your instruction Bob & that appears to have done the job. Just for the heck of it I chambered the same brass and the smear looked great. Other than solvent and a chamber brush do I need anything to remove the greese? Will good old Zippo lighter fluid work. Thanks Phil
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