Bore size vs bullet size

[Minutemanqvs]

Hello all,

I'm quite new to using lead bullets (I don't cast at the moment, only buy them) and am wondering about an old rifle I inherited. It's a Swiss Vetterli with a .408 bore diameter and .421 groove diameter.

My question is quite simple...would you feel safe shooting a .430 lead bullet down a .421 barrel or is this too much of a shrink? I'm reloading since a couple of years but only jacketed bullets in modern rifles, and I usually stay at a groove diameter +0.001 in this case.

Thanks

[Ballistics in Scotland]

Here are a couple of useful articles, and the rest of the excellent www.swissrifles.com site is well worth exploring too.

Factory ammunition started out at .425in. and was reduced to .419in., but as is common from that era, I don't know if those figures included the paper patch. The author of one of the articles used .429in. bullets, but the only reason to go so large would be their availability. Such a reduction in the bore, while unlikely to be dangerous with a soft bullet, is very likely to produce irregular finning at the rear of the lands. There is a lot to be said for having a mould of a better diameter, and apart from various mouldmakers, you can design your own with the design utility on www.mountainmolds.com . A cheaper way would be a Lee lube and size kit, which is available in .410 (good for a bullet you will paper-patch) or .427.

http://www.swissrifles.com/ammo/



http://www.swissrifles.com/vetterli/article/

[aap2]

Minutemangvs: The articles mentioned above are great and the Swiss Vetterli is a great rifle. I bought a 1878 Swiss Vetterli that was in basically unfired condition which I converted to CF. The groove-groove is exactly .4355 which is larger than most owners report. The Vetterli is a little different than most rifles in that the factory ammo (ones that I have measured) have a boolit that is considerably undersize in relation to the groove-groove diameter of the barrel but still shoot accurately because the lands of the rifling are so tall that the undersized boolit is swaged larger when it engages the rifling. The Vetterli is an exception to the rule that the boolit must fit the throat (doesn't have one, just a taper) so our usual "use a boolit that is a few thousands over groove-groove won't apply (in most Vetterlis a boolit that large seated in a case won't chamber). In my .435 groove-groove rifle I shoot a .436 boolit of 300 grains cast in a custom Accurate mould and it shoots great and is long enough to work as a repeater (2.2" COAL to clear the elevator)...While I was waiting for my custom .436 mould I loaded a few Beartooth 320gr boolits that were only .432 with a GC expecting them to shoot poorly since they were way "undersize" but they shot fairly accurately (the tall lands swaged them to a larger diameter) and did not lead; not as good as the later .436 boolits but not bad. To finally answer your question of proper boolit diameter in a .421" groove-groove (check it again and measure with mics not calipers) and use a boolit close to .421 or smaller. Have fun. the Vetterli is a blast to shoot.

[seppos]

Vetterli rifles have also big meaning to the indipendence of Finland.
http://www.ditext.com/moorehead/4.html


There was almost 16 000 M-89 rifles and 2.5 million cartridges on board SS John Crafton and 2500 Webley revolvers that was suppose to come to Finland for the indipendence fighters.

S

[Minutemanqvs]

Hi all, thanks for your replies! I came across the swissrifles articles and they are indeed a good introduction. This weekend I'll do a chamber cast with Cerrosafe to get more useful measurements. I'm also willing to start bullet casting, an old rifle is a good excuse, isn't it?

I'm looking at shooting 100-150 rounds a year with this one, so not a huge amount. After some shopping around, my equipment choice would be:

Required for melting:
Lee Production Pot IV 220 V - http://leeprecision.com/production-pot-iv-220-v.html $86
Lee Liquid Alox - http://leeprecision.com/bullet-casting/bullet-lube/ - $7
Cast iron lathe: I already have that

Mold:
Lee Bullet Mold Handles - http://leeprecision.com/bullet-casti...-mold-handles/ $18
Accurate Molds 2 cavity 2.35" Mold Block 43-340A - http://www.accuratemolds.com/bullet_...=43-340A-D.png

Alloy:
It looks like Lyman #2 or Linotype would do the trick? A Vetterli bullet travels at around 1200-1400 fps and I don't want to use gas checks if avoidable

Optional, is this useful in my case?:
1x Lee Custom Lube and Sizing Kit in .423 - http://leeprecision.com/bullet-casti...nd-sizing-kit/ $38

The rationale behind the mold design choice is explained on a youtube video a guy does on reloading the Vetterli (https://www.youtube.com/watch?v=ofZdQ79NDdc):
- I'm using cases 42mm long (1.653")
- To feed from the tube, Vetterli cartridges need to have a COL of 2.2"
- So 2.2 - 1.653 = 0.547" protrusion of the bullet needed
- The 43-340A design measures 1.045" with the top of the crimp groove at 0.49", so 1.045 - 0.49 = 0.555 which is close enough to 0.547 as I can play a bit with case length

Also, as my lands are at .408 I would ask that for the top "riding band" diameter (or whatever this is called) so it just...rides on the lands. For the grooves I would go at groove diameter + 0.002", so 0.423. Does it seem logic to you expert casters?

Thanks



Any comments on this?

[Ballistics in Scotland]

Ah, I only looked at the off-the-peg Lee bullet sizing dies, and didn't know that they would make them to order. That is much better than .427, and the price isn't much more, although if you don't care for the waiting period you could enlarge the .410 with a wooden dowel and successive grades of abrasive paper, in an electric drill.

Your idea for the mould seems pretty good, although it will no doubt cost quite a bit. I am not sure I like the bore riding feature in this example, though. It can increase any effect of slight unevenness in the thickness of the case neck, if it presses the bullet to engrave itself slightly on one side of the rifling, and not touch on the other. I'd feel happier with a slight clearance all around. The sizing die would also leave lube on the surface around the grooves marked with R02 radius. I don't really see any need for two such grooves, although one would be useful. You probably do need to crimp the case necks to avoid telescoping of the cartridges in the magazine. Another possibility for this would be an annular groove behind the bullet, but blowing this out and replacing it might have a worse effect on brass life.

There is nothing much wrong with bullets shot as cast, if the diameter is right. But if you have the bullet the same nominal size as the sizing die, natural variation may result in some sized and some not. There is a lot to be said for having the mould a couple of thousandths over the die size, imposing the same size and texture on every one.

Reducing the heaviest available .427 bullet to .423 is quite a bit better practice than .430 to .421. If you could find a cheap ready-made mould in .427, probably for the .44-40, it would be a bit light for the Vetterli, but a cheap way into finding out if it likes you enough to shoot well.

[Minutemanqvs]

Thanks for the feedback, I'm not sure to understand your "I'd feel happier with a slight clearance all around"? The bore riding feature did exist on the original Vetterli bullet, I guess that's why it's there on this design too

And you are perfectly right about the sizing die potentially leaving lube in the R2 radius, this can probably be removed from the design. It's just a design that already exists but you can apparently create your own when ordering at Accuratemolds, I need to think about it...if I go with Liquid Alox as lubricant I might as well change the design to more but smaller grooves until I reach the .49 and eliminate the second crimping groove at .63

[Oklahoma Rebel]

I know this is old, but I would use soft lead in such an old rifle, maybe 1-30? would others agree?