.303 COL question

[mikeb]

Have been trying to ascertain a good COL for the Jungle carbine in .303

I was going to ascertain what it is and then pull back the bullet 30 thou in an attempt to reduce the jump of the bullet to the rifling. I have tried a couple of things (pushing in a loose bullet three times and measure the length but cannot seem to find out what it is.

I have been using 77.4mm COL to match the PPU factory stuff and was going to try something longer maybe start with 77.8mm and work from there. I tried something a little longer but this looked like it was coming very close to the magazine lip.

1. Can you recommend a simple, easy method to find the optimum COL.

2. What do you guys use in your Enfield's?

ps. Sierra .311 174g bullets, CCI primers, PPU cases, Varget powder.

MikeyB

[Alpha1]

There is no point in trying to set your rounds up to a certain jump 30 thou for instance as you quoted in your post the Lee enfield is not like a target rifle. Just set your cartridge overall length to what ever it recommends in the charge data you are using as long as it fits in the magazine it will be fine.
If you measure your rifle chamber with a stoney point overall length gauge you would probably find that the bullet would fall out of the case before it engaged with the rifling. Military rifles have to be able to chamber any old ammo you chuck at them the tolerances are no were near a remy 700 for instance.
I use any 174grain flat base bullet I can get my hands on with 41grains of Vitavouri N140 in all my 303 rifles including my P14. Just use one of your PPU rounds to set your seating die depth and go with that.

[Steve E]

+ 1 What Alpha1 has said.
Just seat you bullets to maximum magazine length. Unless your rifle has a very short chamber which is highly unlikely you will not get a seated bullet closer than .10" of the leade.

[saddler]

+2

Forget trying to get the bullet near the lands - the 303 chamber is for military use so has to be quite forgiving of less than pristine fodder

The only way you'll get even ball park close would be 220gr bullets or such, but then they'd be too long for magazine feeding!

Seat to max. length for the magazine & have fun... :)

[mikeb]

So straw poll then, what COL are you guys using to clear the mags in your Enfields???

MikeyB

[ovenpaa]

3.075" regardless of rifle is my default OAL however in the interest of science I will stick a case on an OAL gauge and see how close I can get to the lands with a Spitzer and SMK.

[mikeb]

Another slight issue I have been having with my Lee seating die and my RCBS rock chucker press is getting consistent seating length using Sierra Matchking (or PPU bullets) and the PPU cases.

If I set it up for a COL of 77.8mm then a number will be indeed 77.8mm but then quite a few will be either up and down from this figure, not 100% consistent.

Is this the die? cases? Operator? (me) or inconsistencies in the bullets themselves?

MikeyB

[ovenpaa]

How much of a variation are you seeing? Assuming everything is tight in the press the seating process is very straightforward, the head is the datum as it sits in the shell holder (Always make sure the shell holder is clean) the bullet is pushed down by the seating section of the die, this is a small round section with a cone machined into it. The cone of the seating insert should always press against the same section of bullet and accordingly push the bullet down into the case. If you see inconstancies on the length of bullet loaded it will invariably down to the following:

The seating insert is not compatible with the bullet and you are seating on the meplat - I very much doubt this is happening.

The ogive of the bullets is varying from bullet to bullet - SMK bullet are quite good and you are more likely to see variation in other parts of the bullet.

The measurement you are taking is from the cartridge head to the meplat - This will give differing measurements as the meplat is never uniform from bullet to bullet.

Best measurement is from the cartridge head to ogive and this should give you the most consistent measuring results.

[Dougan]

I've got pretty much the same set-up - Rockchucka and RCBS dies, and use PPU cases with either PPU or SMK 174 bullets - I just copy the PPU factory, which I measured averaging at 3.045".

When measuring from the meplat I aim for 3.050, but accept between 3.045 and 3.055 - I've found that you can get even more variation from the SMKs than the cheapies...if you look at the hole in the meplat on an SMK sometimes the little ridge isn't even, and I've found that if you look at rounds that measured long, the ridge is often elongated on one side.....though this doesn't necessarily mean that that extra length in the meplat is translated to the actual depth the bullet is in the case, as the die presses the bullet below the meplat.

As Ovenpaa says, measuring from the ogive gives a more accurate measurement of how the COL actually relates to the depth of seating - he kindly made me an insert for my comparetor (I think that's what it's called...) for measuring to .311 (the ogive), which I use if I'm being fussy...and then get a variation of 0.005" on PPUs and 0.003 on SMKs.

[Alpha1]

I just set my seating die up using a HXP bought round. I full length size the cases. Re prime them drop 41grains of N140 in each case using a RCBS powder measure. Seat the 174grain flat based bullet and go shoot them.
I use this recipe for my
No4
Smle
P14
So why complicate things this just works.