One for the Gun Designers...

[ovenpaa]

I know one old gunsmith that still re-crowns by eye with a file and an emery board.

[TobyH]

How do you know that you're cutting the crown trully square with the bore on a lathe as your clamping on the outside of the barrel. (just out of interest, not having a go at anyone!) With the brownells kit at least you're using the bore to cut against.

[Robin128]

It has to be the bore that is referenced.

[TobyH]

Thats what I mean, how do you reference the bore when using the lathe? I've done a bit of machining, but I'm not experienced enough, there must be a way of referencing the bore before cutting....?

[Robin128]

No expert on this I can tell you... but I've heard cheapo solutions put a rod in the barrel...which can damage the rifling...where are the experts when you need them?

:)

[ovenpaa]

I would not have thought the alignment of the outside of the barrel to the bore would be out by much as to impact on the crowning, however if this is in doubt you could always use a four jaw chuck and clock off an interference fit mandrel in the end of the barrel. Ensure everything is lined up and then part off the end section and crown from there.

There are probably a number of ways to do it.

[TobyH]

Just found out how its done!

2nd Barrel in this video he shortens it, but uses a dial gauge to check its centred on the bore.

http://www.wonderhowto.com/how-to-repai ... el-390777/

[littlefraggle]

That's right. Cross-slides on lathes run perpendicular so no need to clock it in if the muzzle has already been dialled in.

I always cut an 11 degree crown as it has never been shown to be worse than a recessed crown.

Easier to clean too....

[TobyH]

I'd love to see the testing on why an 11deg crown is the one to go for. I personally would like the 11 deg crown as it just seems a smoother way of crowning.

There must be something out there on someone doing this kind of testing, maybe even done what I asked in my original question. I can't believe its just because of protection...

[The Gun Pimp]

The eleven degree crown was all the fashion a few years ago but, if you want to know the most accurate crown, look at what American short-range benchrest shooters are using - almost all use a 90 degree - now!

I don't think it's any more - or less - accurate but the 90 degree crown is much easier to inspect for sharpness - just run the tip of your finger across it. But, go with what you like - if it's done right it will shoot just as well.

We usually recess the 90 degree crown so it offers the same protection as the eleven - but, as someone commented, we hardly mistreat our rifles.

Incidentally, the last damaged crown I had was courtesy of the Proof House - how they managed to damage a recessed crown accidentally, I can't imagine.

Cheers
Vince