303 bullet fit

[brnomauser]

Just gearing up to start casting for my 303. I’ve got my mould dropping 0.315” bullets. These just fit in a fired case - as in runs a little bit fits easily by hand. I’ve got a 0.316 sizing die, bullets touch very slightly in one spot. I’ve used the die to seat a gas check, which measures 0.316” when installed. However this doesn’t comfortably fit in the fires case anymore - can sort of push it in by hand but it’s pretty firm, the press doesn’t notice it. Both a seated dummy round (from a fired case), and a case with a crimped-then-removed gas check sitting about 0.1” deep chamber with no resistance from the bolt, and drop in to the chamber easily with my finger. I did previously do a chamber pound but can’t remember the results (it was a few years ago) but pretty sure my conclusion was I should use a .315 or .316 bullet.

It’s a Sportco barrel in a no4 mk1*. Before I see how the shoot - does this sound safe to fire? I’ll start low obviously l, but I thought a Bullet should always fit in a fire case, but the fact they chamber with no resistance makes me think it’s probably ok?

[Stephen Cohen]

If its a safe load I see no problem as I have known a few who just hand seat and fire single shot. Regards Stephen

[brnomauser]

Thanks mate - only concern is that the neck might not have enough room to expand to release the bullet without over pressurising. I’ll resize before loading will just knock up an oversize expander

[303Guy]

When I load paper patched boolits, they are a press fit into an unsized neck. The paper compresses but the neck does not expand measurably so the clearance is only the springback which is not a lot. Not only that but the boolit seats up against the leade. I load a 194gr boolit like this over 44 grs of AR2209 which is a case full. Pressure is moderate.

What can cause pressure to rise unduly is too soft an alloy over too high of fast powder charge that will rivet the boolit into the chamber and leade then swage it down again as it enters the bore. Likewise if the boolit protrudes past the neck into the case, it can rivet before entering the neck, raising pressure. I have samples of all these boolits somewhere. Of course, paper patching is for higher velocities.

When I have loaded plain cast, I did not size the necks. Once I used a waxy stuff to fill the clearance in the neck and to hold the boolits in place. Shot pretty well. Since then I have gone bigger diameter.

I wouldn't load a jacketed bullet with too little clearance though.

[dale2242]

Not a .303 but, I am shooting .315 sized bullets in my Mosin Nagant 7.62X54 with a .314 bore with no issues.
I am using 16 gr. 2400 and a 1 gr. tuft of dacron.
Without measuring I assume the 303 and the 7.62X54 cases have fairly close to the same capacity so this load should be safe in your gun.

[Stephen Cohen]

When I load paper patched boolits, they are a press fit into an unsized neck. The paper compresses but the neck does not expand measurably so the clearance is only the springback which is not a lot. Not only that but the boolit seats up against the leade. I load a 194gr boolit like this over 44 grs of AR2209 which is a case full. Pressure is moderate.

What can cause pressure to rise unduly is too soft an alloy over too high of fast powder charge that will rivet the boolit into the chamber and leade then swage it down again as it enters the bore. Likewise if the boolit protrudes past the neck into the case, it can rivet before entering the neck, raising pressure. I have samples of all these boolits somewhere. Of course, paper patching is for higher velocities.

When I have loaded plain cast, I did not size the necks. Once I used a waxy stuff to fill the clearance in the neck and to hold the boolits in place. Shot pretty well. Since then I have gone bigger diameter.

I wouldn't load a jacketed bullet with too little clearance though.

I have never given consideration to what you refer to as the rivet effect on bullets seated below the neck, I have never been one to seat bullets that deep and I think you may well have made a very good case for not doing so. I for one can see the logic in your thinking and thank you for the heads up. Regard Stephen

[Larry Gibson]

Thanks mate - only concern is that the neck might not have enough room to expand to release the bullet without over pressurising. I’ll resize before loading will just knock up an oversize expander

That is not a concern with cast bullets. If the cast bullet is over .003" of the throat/groove diameter then a small increase in psi may be measured but it won't be much. With normal cast bullet loads accuracy will go south before you even come close to too much psi unless you are using the fast pistol powders(?).

[brnomauser]

That is not a concern with cast bullets. If the cast bullet is over .003" of the throat/groove diameter then a small increase in psi may be measured but it won't be much. With normal cast bullet loads accuracy will go south before you even come close to too much psi unless you are using the fast pistol powders(?).
Thanks Larry, that puts my mind at rest. I’ll start low and build up - I’ll be using ADI 2206H (sold as H4895 in the states) mainly but do like using AS30N (similar to Red Dot) for plinking loads. If accuracy is no good I’ll buy a 5/16 reamer and make another sizing die. I just bought the 8mm reamer that gives me the 0.316” so 5/16 should give me almost 0.314 then I can hone a bit if needed.

[Mike H]

It is good to see another Australian using cast bullets in the .303.28 grains of 2206H with a Dacron filler is good with bullets heavier than 200 grains in my rifles.

[Kraschenbirn]

+1 on what's already been posted. The barrel (original) of my Long Branch #4 Mk1 slugs at .312 and I shoot the Lee 312-185 (powder-coated and sized to .3145) over 29.5 gr. of H4895 with a tuft of dacron. Iron-sight accuracy approximates ball ammo out to 200 yds.

Bill

[brnomauser]

It is good to see another Australian using cast bullets in the .303.28 grains of 2206H with a Dacron filler is good with bullets heavier than 200 grains in my rifles.yeah it’s lost a bit of popularity over the last decade or so but I reckon it’s still cool as... that sounds like quite a moderate load - probably what I’ll go for don’t really need a full house - just a general purpose gun for when I’m out in the ute/bike at work


+1 on what's already been posted. The barrel (original) of my Long Branch #4 Mk1 slugs at .312 and I shoot the Lee 312-185 (powder-coated and sized to .3145) over 29.5 gr. of H4895 with a tuft of dacron. Iron-sight accuracy approximates ball ammo out to 200 yds.

Billsounds good - however my question was more about throat fit rather than bore

[303Guy]

My approach has always been to fill the throat and unsized case neck. I'm glad Larry has made a comment about pressure and neck clearance (with cast and paper patch). My findings have been exactly as he has mentioned but I did not have the means to measure and confirm. Reading primers is like reading tea leaves .... [smilie=1:

Be aware that while AS30N may be similar to Red Dot, there are differences such as the initial burn rate of AS30N being way faster than Red Dot. My suggestion with it is to keep the charge low - low enough that a double charge is still safe. It burns very clean when overloaded but dirty when underloaded. Not sure the dirtiness is an issue though. At too high a charge, it will distort the boolit quite badly but the primer doesn't show much pressure sign. I would use Trail Boss - much safer. In fact, that's exactly what I'm doing. 8-)

28gr of AR2206H is a nice load. I've shot that under 174gr FMJBT's and 150gr spire points. Mild pressure and mild recoil and s comfortable load to shoot. My load was actually 28.3gr, not because .3 gr has some significance but because that's what my measure was throwing. It is probably safe to go lower and according to the 60% rule, it is but I haven't tried going lower. I was using Dacron as a powder positioner. About 0.1 to 0.2gr of it.

[MOC031]

Having spent the last six months helping a friend get the carcass of what was once Montana Rifle Company up and running again manufacturing rifle barrel blanks (on 1930's Pratt & Whitney drills surplused from Springfield Armory), I jumped at the chance to borrow the shop's half thou pin sets used to QC/QA barrels prior to including them in shipments.

So my bought-new-in-the-grease 1950 Long Branch (95L, last of the best) pins at .3035" bore size. I have yet to get that five groove rifling properly measured off the cerrosafe casts I have done. But I spent a day in the company of my 40 year professional gunsmith/hunting/flyfishing/dual sport riding friend in his shop, hand lapping that barrel under his tutelage to the point where he pronounced it as good as it was ever going to get as far as uniformity end to end.

Like 303Guy and a lot of others, I size to best fit the throat/ball seat after casting (and powder coating).

And in the case of this rifle and this Accurate mould, that means putting the bullets through a .316" sizer after powder coating. As cast they measure .316" - but after powder coating, slightly too fat... the bullets have to be seated too deeply to avoid the fit to throat allowing the bullets to be loaded out anywhere remotely near magazine length.

The rifle shoots superbly well, both with Greek HXP 1985 surplus ball, and with these particular cast bullets? I haven't noticed any pressure signs even with full charges and those .316" 180 gr. cast bullets in a .3035" pinned bore.270880270883