Reloading .303 British with cast bullets

[TD1886]

I am lazy and cheap so normally shoot PB Boolits in all guns unless I have to use gas checks or paper patch. I found that in large bore .44 magnum and .45-70 I didn't need gas checks even with hefty loads but with my .308 I did. I tried the Lyman 31141 170 gr. GC boolit barefoot and gas cutting was impressive! I shot boolits in heavy snow so recovered some. Accuracy was non-existant! Gas checks solved that and I got very good accuracy using IMR4227 and cast boolit load data. I didn't push those terribly hard. Rifling twist is 1:12"

When I got the .303's I made a couple of smooth moulds for 200 and 215 gr. boolits which were shot PB over mild powder charges and that worked fine but if I pushed the velocity I got bad gas cutting. So, I bought an NOE 316299 GC mould and made a gas check maker. That helped but if I pushed loads to upper end cast boolit loads I found that I got "skidding" where the grooves in the boolits were wider than the rifling lands in the gun so wide grooves and narrow lands on the boolits and gas cutting. I decided a harder boolit was the next step so oven heat treated and that solved the problem for me.

The rifling twist is 1:10" in the .303's so I figured the faster twist and heavier boolit than .308 was resulting in rotational interia causing the skidding with softer lead. The gas check did not stop that but the gas check and harder boolit did. WQith low to mid range cast boolit loads there is no problem, only when pushing velocity a bit. For me anyway.

Longbow

I had a Lithglow Mark III*. I used the Lyman 314299 in it without any problems at all and very good accuracy.

If I were to use a filler I would use the shotshell fillers from BPI and like Longbow said work your loads up using the filler. One of the many things filler does is fools the case into thinking it has a smaller capacity.......see what I mean?

[Vonllamawitz]

Great info! I've just recently started to cast my own. I grew up watching Dad do it and finally started myself. He actually sent me all of his old moulds so they are seeing hot lead again! I know that 303 is a bear to reload for because of all the bore and chamber variations but I've stuck with my Long Branch 44 for 40 years and have figured out a lot about her. Casting is new field for me but I'm excited as finding FMJs can be a challenge sometimes.

[longbow]

I use COW with powdered graphite added for filler in the .303's under PB boolits and find it works well for me though granular fillers is a controversial topic for many. I read about it on .303british.com in an article by David Southall and contacted him for more info. I use COW and like it. Ad TD1886 says, it fools the cartridge (or is it the powder?) into thinking it is smaller capacity. The benefits I see are:

- filler helps protect the base of the boolit (not to the point of replacing gas checks but yes it helps)
- filler "fills" the empty space so loading density is always 100%... there is no chance of a double charge of small quantities of fast powder and it allows use of smaller than normal charges of slow powder because there is no empty space!
- it is quick and easy to "install" using a dipper

Also as TD1886 says, shotgun buffer is a good filler though I have not used it yet, I do have an article from surplusrifle.com on using shotgun buffer under cast boolits.

My opinion is that granular fillers properly used have their place. If you don't like them then don't use them. If you don't want to use them properly then don't use them! You can't just dump filler into an already established load and not expect things to change! I like them and use them.

Yes, fillers raise pressure but as long as it is in an acceptable range who cares? Smokeless powders need a certain amount of pressure to burn properly. Work up your load with filler just like working up a regular load. When you see excess pressure signs like flattened primers stop there and maybe drop powder charge a bit and top up filler.

Back to plain old cast boolits... I find that I get best accuracy when the boolits are just able to fit the throat and all of my .303's seem to like boolits of 0.315" or larger. I have 4 that all seem to have the same chambers and bores and brass interchanges. I have one tight one but it also likes the 0.315" boolits.

I have mostly loaded using Unique for mild loads. IMR4227 for moderate loads and IMR4064 with COW filler for somewhat heftier loads but haven't really pushed the velocity envelope hard. I have also had decent success using paper patched boolits.

Longbow

[Alferd Packer]

Google Lyman 3rd ed.cast bullet manual.
FREE TO DOWNLOAD, GOOD 303 LOADS

[Vonllamawitz]

Any tips on measuring a slug for groove diameter. My rifle has 5 lands which makes it challenging.

[TD1886]

Any tips on measuring a slug for groove diameter. My rifle has 5 lands which makes it challenging.

Make yourself a little V tool out of a strip of metal at least 1/8 inch thick and about 3/8 inch wide and say 1 inch long and bent it into a pefect 90 degree angle. Then file that outside sharp tip flat so that the V will sit perfect upright on a table. Don't file so far through that it weakens it. Now take your regular 0 to 1 inch mic and measure something of a known value such as a new 308 bullet. Mic the bullet first to see exactly it's measurement. Then put that V block on one of your mic's anvils and measure that 3/8 bullet again. You'll get a larger reading. Subtract the 308 bullet's measurement from that larger reading and that number will be your constant. Now measure a lead slug you forced through the bore of your 303 barrel. You will see how the V block only contacts the groove bands. So you don't get mixed up on a bullet thos larger outer grooves are grooves in the barrel, and the deep inset grooves on the bullet are your lands in the barrel. Substract that constant number from your reading and that is the diamter of the bullet your forced through the barrel or in other words your groove diameter. Here's a pic of the V block I drew.

[WinchesterM1]

My go too load for the 303 is a NOE 316299 Powdercoated GC sized to .316, over 25 grn of IMR 4198 and it shoots at point of aim, i have no idea what the velocity is, but it hits hard. I will probably hunt with this load this season.

[ukrifleman]

Any tips on measuring a slug for groove diameter. My rifle has 5 lands which makes it challenging.

Wrap a piece of copy paper once around the slug and take a measurement, then measure the thickness of the paper and subtract twice the thickness.
This will give you the groove diameter.
ukrifleman

[groovy mike]

16 grains of Alliant 2400 or 13 grains of Red Dot without any fillers should make mild target loads that would also be suitable for hunting under 100 yards or so.