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    • #34659
      Whiteoak
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      Well after slugging the bore of my Marlin 336ER multiple it is obvious that there is a tight spot in the bore at the rear sight dovetail.
      This spot swages the slug down to .357 which is .002 under the rest of the bore.
      Do any of y’all have any experience eliminating this type of restriction?
      Maybe firelapping?
      This rifle shoots Jacketed Sierras very well, but I haven’t found a good cast load yet.

    • #34666
      GhostHawk
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      I have a win 94 in .30-30 with exactly that issue.

      I went to slug the barrel, took a soft .314 185 gr gc mosin bullet and drive it into the muzzle. Went smoothly but I could tell it was getting progressively tighter until it hit the rear sight dovetail and at that point I was stuck.

      I ended up disembling the rifle so I could drive the slug out forward. Which being brand new to lever guns was a hair raising experience. But I put some oil down there and figured the action out. 3 good taps and the slug came loose and a 4th sent it down the barrel to the floor.

      In my case I have been waiting for funds to send it to JES. Turn it into a .35-30-30. Fire form brass when the rifle comes back. I can probably figure out a way to seat cast boolits with a .357 mag die run well up. One way or another I’ll figure it out. Check arrived Friday, just need to get to the bank and I can start the ball rolling.

      How tight the breech end is I have no idea. But it kind of explained how I could shoot 9 shots at a 9×11 target at 25 yards and have only one touch the paper.

      I’d rather invest a bit more in the old girl and get a shooter than just hang it on the wall worthless.

    • #34675
      Harter
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      I had a Savage in 06′ that displayed a tight first 3″ at the chamber and a tight last 3″ at the muzzle . A few fire laps of medium grit and it was mostly cleaned up . It remained .312 to seal the breach end with the muzzle at 300x 307 . Most of the constriction was under the roll marks but remained round . I have no explanation for the choked muzzle .

    • #34681
      Wright Arms
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      Whiteoak;n15745 wrote: Well after slugging the bore of my Marlin 336ER multiple it is obvious that there is a tight spot in the bore at the rear sight dovetail.
      This spot swages the slug down to .357 which is .002 under the rest of the bore.
      Do any of y’all have any experience eliminating this type of restriction?
      Maybe firelapping?
      This rifle shoots Jacketed Sierras very well, but I haven’t found a good cast load yet.

      I have a Henry Big Boy in .357 Mag that had 4 tight spots in the bore. It would shoot nearly anything within 2″ @ 50 yds, but many of the same loads would not stay on an 8 1/2″ x 11″ piece of paper @ 100 yds. I poured lead laps and removed the constrictions using 400 grit lapping compound and lots of elbow grease. The process took around 8 hrs to complete. The rifle will now hold an honest 4″ @ 100 yds. I’m still not real happy with it. But it is a significant improvement over what it was before.

    • #34683
      Whiteoak
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      This spot is only .002 .357 vs .359.
      I have been able to get very good groups with Jacketed and around 2″ with cast
      Lee clone of the RCBS 200 gr FP.
      Have not been able to get the RanchDog 190 to group well though.
      Hopefully firelapping can help take some or all of it out.

    • #34735
      Larry Gibson
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      Whiteoak;n15773 wrote: This spot is only .002 .357 vs .359.
      I have been able to get very good groups with Jacketed and around 2″ with cast
      Lee clone of the RCBS 200 gr FP.
      Have not been able to get the RanchDog 190 to group well though.
      Hopefully firelapping can help take some or all of it out.

      If you get good groups with the RCBS 35-200-FN and not the RD 190 then the “tight spot” is not the problem. Otherwise you would not get good accuracy with the RCBS. The problem is with the RD 190 bullet. I doubt fire lapping will solve that problem.

      To be frank, I have not got the stellar success with RD bullets that others claim. It is my opinion based on testing several in .30, 31 and 35 calibers that the very large meplat is just too much of a good thing. Some of the RDs are too much like a WC which aren’t exactly known for great accuracy much past 50 yards.

      Larry Gibson

    • #34736
      popper
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      I have a 336 MG with the same problem. Just about gave up on cast with the RD style. If you jam the lands it works, any jump and lousy results. I now use a washer to ‘nose size’ just enough to get the nose into the lands that I don’t have to jam the lands and accuracy is great, with a soft alloy. yes, the BC of that style isn’t great for long distance shooting.

    • #34846
      Whiteoak
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      I am starting to agree with this. I have not gotten good acurracy from the RD in any
      of my three rifles that take 35cal.
      Which is disappointing because the NOE mold cast then beautifully.

    • #46162
      Whiteoak
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      So here is an update on my Marlin 336ER.

      First of all I started over with slugs made from a mold using two blocks of wood. This gave me a better surface to measure than the egg shaped fishing weights I was using.

      Turns out my barrel slugged at dead on .358 until the rear sight dovetail, which swagged the slug down to .3577. That is not a lot, just enough to feel it

      I firelapped the bore using 320 grit compound on Lee 35-200 bullets and 4gr of titegroup. Fired  5 bullets cleaning with bore cleaner and a bore snake after each one. Then ran another slug thru and I could still feel a little resistance at the dovetail. I then changed to 600 grit and fired a total of 10 bullets, again cleaning between each shot.

      The next slug pushed through with almost indistinguishable resistance at the dovetail and measured to my relief .358.  Because this was my first attempt at firelapping I was very nervous to do it.

      My next and probably more effective thing to do was to aquire a RCBS 35-200-FN mold. Sized to .360 with ACCOWW and 2% tin (had to beagle the mold) 219grains with Hornady GC and Glenn’s Carnunaba Blue.

      Next I decided to make a change from H4895 to IMR3031 which as been the most accurate powder in my .358Win.

      Starting at 38.5 gr and working up I was smiling right away. I only have 70yrds to work with at my house but the worst group it shot was 1.25″ with 41.5 gr and 2,180fps.

      The most accurate load has been my starting load of 38.5. That has given me .8  groups at 1,998fps average ES of 6 and SD of 3!

       

    • #46165
      Glenn
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      Excellent work.  Sounds like you’ve got a winner for sure now. 🙂

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