Cast bullets tumbling in 303 Britsh

[aspangler]

I have a NO.4 MK 1 that I can't seem to get the thing to shoot cast boolits. I have tries the old Ideal 165 gr sp and the Lee 185 gr rn. both were gas checked and sized to .313 which is just over groove dia. I have tried hard alloy and soft alloy with various powders (h4895,2400,red dot,trailboss,and others) and they all tumble and hit the target sidewise at 50 yrds. I have no trouble with my 8mm mauser or any other rifle or pistol that I have with cast boolits. Any help would be appreciated. BTW it shoots j-words fine. HELP PLEASE!! I want to keep this old two groove buit if I can't get it to shoot cast I will get rid of it. Thanks.

[Larry Gibson]

I recently had to take 1/2" off the end of the barrel to clean up the crown with a SMLE just like yours. Might check the crown to see if the 2 grooves come cleanly to the crown.

Also, what loads of 4895?

Larry Gibson

[JeffinNZ]

It's very possilbe .313 just is not big enough. If it's a No4 it's like a 2 groove and they are very fat in the groove.

[SpotHound]

.315 is common here for No4s.

[MT Chambers]

Yes and that is why CBE made me a mold at .317"

[runfiverun]

they also seem to favor longer more parallel sided boolits.
those 2 skinny grooves don't give you a lot of purchase on the boolit, you have to make the most of them.

[aspangler]

My barrel slugs at .312. The Load of 4895 I don't remember offhand.

[Gunnut 45/454]

What was your velocity? You could be throwing them to fast IE the bullet is stripping the rifling?

[aspangler]

I even went down to 11 grains of trail boss and they Still tumbled.

[swheeler]

Drive a slug into the muzzle an inch or so , drive it back out, then measure it. Sounds like a blunderbuss muzzle on your smelly, I still have a 91/41 Carcano that now has a 25 inch barrel( instead of the org 27") no more sideways impacts.

[madsenshooter]

Make sure you're expanding the slug all the way out into the grooves. I see a lot of people here telling how they slugged their bore by pushing a slug through the bore. You have to put the slug against something solid and expand it to get a true measurement. Veral Smith calls them impact slugs.

[docone31]

I paper patch to .314, I cast them to .317. Less than that and they hum when they fly. 20' groups at 100yds.
I only paper patch them today.

[303Guy]

The two groove has a tapered throat starting out at something like .318 and tapering down to bore diameter with a 3 degree included angle (1.5 degree per side). The boolit would do well with a matching taper profile with parallel base section. However, all it takes for a cast boolit to strip the rifling is a rough groove.

On boolit diameter, with a large diameter and only two narrow grooves, the metal has to go somewhere when the boolit gets swaged into the bore and therein lies a problem - the base edges get distorted by the displacement. A smaller boolit might leave a gap in the grooves which can get flame eroded to the point where the boolit has no rifling grip. But there is a solution. Wheat germ filler. It forms a sealing wad behind the boolit. It does need a little compression to prevent it tamping loose.

[aspangler]

Tried seating boolits out to engage the rifling and then the tumbling stopped. 16 gr 2400 Lee c312-185 r . Will try a stiffer load and see if I can get it to shoot a good group. Haven't tried the COW filler yet but plan on trying it soon. Thanks for the PM 303guy. Very interesting reading and lots of info. Thanks to all for the help. I'll update with results of further test as they come along.

[longbow]

While fillers are a controversial subject, I have gotten very good results to date using COW.

After reading the David Southall article on .303british.com I managed to get hold of David through e-mail and he passed on some good info.

His article here:

http://www.303british.com/id37.html

I don't own a two groove and so far have not had a lot of trouble getting decent accuracy from my .303's but when I started out they grouped quite large until I started sizing to suit the throat. Also, I found that since my guns have typically oversize military chambers and bores, I needed a 0.315" boolit to fit the throat well. Regular dies size the brass to suit 0.311"/0.312" bullets so the brass can actually size down your boolits some when seating with that much difference in diameter ~ and it is hard on brass! I now use a Lee collet sizer with 0.313" mandrel and that made a noticeable improvement in accuracy too.

Lots of little tricks to learn.

If you use a filler, back your load down and work up again with filler. The filler will raise pressures.

Longbow

[quasi]

grooves dia. is not the determining factor, it is throat dia. Take a fired case and determine the maximum dia. boolit that will easily slide in the unresized case neck. ( use boolits or pin gauges)