Boolit sizing question for 2 groove Enfield

[rayzer]

Hello, I want to shoot cast Boolits in my .Longbranch #4 MK.1*Enfield .303. This rifle has 2 groove rifling. Bore Dia. is .3016, groove Dia. is .3135. What Dia. should I size the boolits to? that bore dia. is awfully tight.

[nicholst55]

I would size them to .314, minimum, or else just lube them and seat a gas check without sizing.

[303Guy]

I have a two-groove Longbranch. Mine has a rust pitted bore but shoots j-words very well without any copper fouling (I use a wax-lube 'wad' under the boolit). Cast boolits (and paper patched too) has not been very successful. Two things happen; the boolit gests swaged down to bore size resulting in base deformation and the driving land wears into the boolit, opening a channel for gas cutting. Nevertheless, I have driven 220gr boolits to about 1800fps through it. My boolits were as cast and tapered making them a neat fit in the throat. I did not try them at lower velocities. I did do 'test tube' tests at lower velocity and found that the boolit would only pass through intact at very low velocity - way too low to be of interest to me. A boolit I tried and found to survive with un-distorted base was a g/c design without the g/c. A trick is to dip the boolit base into some sort of molten waxy-lube (in my case) to form a 'wad' on the boolit base and to fill the rebate. That's supposed to support the rebate until it's into the bore.

[JeffinNZ]

I would be very surprised if those measurements are true. 2 groovers are notorious for stout grooves. Shoot the fattest bullet you can chamber.

[Pirate69]

My Savage No. 4 Mk 1 gives a 0.315" groove.

[Bob S]

Mine was .316+ at the muzzle, 318+ at the throat. Never could get that DBR to shoot ....

Resp'y,
Bob S.

[wiljen]

I have 5 enfields of various marks and models in the safe and not one of them has a bore less than .304/.3145 and the worst of them is .3057/.3168. I've never heard of anyone getting one that was undersized so that .3015 # kinda surprises me.

[303Guy]

I do believe the bore diameter is not of much significance anyway. The groove diameter at the muzzle is easy to measure. That would be the minimum boolit size. The bore diameter at the throat matters only in so far as the bore ride section needs to make firm contact and since the bore is 80% of the 'hole' that means a rather accurately fitting nose so's it won't jam. Now if'n one were to use a tapered smooth sided boolit with a coating of firm lube (a lube patched boolit if you like) it becomes somewhat easier to get the boolit to fit properly - depending on the length and shape of the boolit.

A recovered j-word jacket showing the bore surface area. Note zero contact with groove surface.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-201F-1.jpg

This bullet shape is unaffected by the high degree of swaging that takes place.

As Jeff says - "Shoot the fattest bullet you can chamber."

[northof58]

I couldn't get my two groove Longbranch to shoot cast with or without a gas check. The bullets would tumble. Yet it would do well with jacketed bullets. So now I cast, run the bullets through a .311 die as I add the gas check. Then I paper patch and run it back through a .314 die. It now shoots well.

[JeffinNZ]

My 2 groove barrel is .303/.317 and with .3165 bullets (the fattest I have) it shoots like a freakin' house on fire.