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Re: Regarding crowning with a mouse ball and V.C.

6K views 8 replies 6 participants last post by  swany 
#1 ·
#2 ·
Re: Regarding crowning with a mouse ball and V.C.

Kerr,

It looks nice done with a mouse ball and valve lapping compound. BUT your bore on that .35 would most likely be too small for the mouse ball to work because of the curvature of the ball. I know the mouseball works on a .444 and 45-70. Look for a smaller ball that is hard to try that on would be my suggestion.
 
#3 ·
Re: Regarding crowning with a mouse ball and V.C.

I just took a couple extra minutes on my 30-30 and stuck with the bolt and drill method, which left a cleaner looking crown. DRAMATICALLY improved my accuracy!!!!
 
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#4 ·
Re: Regarding crowning with a mouse ball and V.C.

458okie said:
I just took a couple extra minutes on my 30-30 and stuck with the bolt and drill method, which left a cleaner looking crown. DRAMATICALLY improved my accuracy!!!!
Jeff,
Would you mind sharing step-by-step instructions including tools/materials used? Especially helpful would be the size of the head on the bolt and the type of steel it's made of. I bought a used 336 a few weeks ago and it has a nick in the crown that I would like to remove so any advice you can share would be appreciated.....Thanks,B.
 
#6 ·
Re: Regarding crowning with a mouse ball and V.C.

BDavis said:
458okie said:
I just took a couple extra minutes on my 30-30 and stuck with the bolt and drill method, which left a cleaner looking crown. DRAMATICALLY improved my accuracy!!!!
Jeff,
Would you mind sharing step-by-step instructions including tools/materials used? Especially helpful would be the size of the head on the bolt and the type of steel it's made of. I bought a used 336 a few weeks ago and it has a nick in the crown that I would like to remove so any advice you can share would be appreciated.....Thanks,B.
Okay, here goes:

1. Removed lever and shoved a thoroughly greased up patch from the breech end to within 1/8th inch of the muzzle to "plug" the bore to prevent grit from the valve paste from getting into bore.
2. Chucked carriage bolt (high grade steel) into hand drill and lightly coated with valve grinding/lapping compound (about $4 bucks at Auto Zone). The carriage bolt head was smooth and slightly larger than the bore (about 1/8" to 3/16" larger in diameter, I guess. Just grabbed a bolt off the shelf in my garage without considering the exact size except the head was slightly bigger than the bore.
3. With very light pressure against crown, operated drill for about 20 seconds at a time, pulling drill away and dapping compound evenly around panhead of bolt between each 20 second procedure so it was lightly but evenly distributed on bolthead (bore helped self align the panhead of bolt to keep things centered, but I MADE SURE I was perfectly lined up with bore as I performed the procedure.)
4. When I had acheived a nice, uniform, lightly recessed crown, I wiped off excess compound at muzzle end of bore, pushed greased patch out muzzle end of barrell, and then thoroughly cleaned bore to assure all grit was gone, always cleaning from breech end toward muzzle end, of course. Lightly oiled everything.

The bolt head was ground down a bit, too, when I was finished, but left a nice, smooth new crown with faint circular grind marks wich added flare and classy looks to the crown in my opinion, without looking rough in the least!

Hope that helps!
 
#7 ·
Re: Regarding crowning with a mouse ball and V.C.

Thanks Jeff,
Now for my next problem. I looked around in my shop this afternoon and found a few bolts that fit the sizes you mention. But when I chucked them in my drill they all had a noticible wobble when spinning. I tried six different bolts and two different drills........same thing........ Some wobbled more than others but they all do it. Now I'm no genious but it seems to me that to get an even crown, the tool would have to be spinning almost dead-level with the bore. Did you check your lapping bolt for straightness before using it and, if so, do you think it makes any difference? Or, am I just making this more difficult than it has to be?......Thanks,B.
 
#8 ·
Re: Regarding crowning with a mouse ball and V.C.

Heck, you sound about as anal retentive as I was before operating on my beloved Marlin! Man I was NERVOUS!!!!

There should be no wobble. I noticed "apparrent wobble" in my bolt (ever so slight), but it was just the reflection of light off the uneven underside of the bolt head, not actual wobble...just "visual wobble", if that makes any sense. With the threaded end chucked in the drill squarely and firmly, operate the drill and feel the rounded panhead portion of the bolt that will make contact with the crown to see if you feel the wobble, if not, proceed, if so, get another bolt.

Perhaps you are making it just a bit more difficult than it actually is! I did, too! Until I got to the range to assure my crowning job was okay, I was second guessing myself the entire time. I did mine with a hand drill by "eye" to true and square it, but the bore guided it, and I kept everything minimal until the desired result was obtained.

If your rifle shoots fine now, I would leave it alone. If it shoots poorly, I would check the proper tightness of screws, rule out the scope and perform other less intrusive assessments first...THEN consider recrowning....just my humble opinion.

Hope this helps.

PS: Of course the threaded end of the bolt gets chucked into the drill and NEVER in the bore. The rounded head (top) of the bolt (plus valve compound) does the grinding as it lightly rides on top of the crown with its bearing surface on the bore of the crown. Grinding away material where the rifling meets the crown as it currently exists.
 
#9 ·
Re: Regarding crowning with a mouse ball and V.C.

Buy a longer bolt and cut the threads off. Chuck it up by the unthreaded shank.
 
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