what size?

[charlie45]

I have aquired a .303 british and need a mold to cast with. Question which one. I sluged the barrel and found the grove dia. to be .3125, and the bore its self about .3045.
Another question is bore riding dia., i've read in other post that it should be as or slightly larger then the bore. please correct me if I'am wrong and any info would be helpful. :)

[NVcurmudgeon]

charlie, welcome to the board. Which model of .303 do you have, and how many grooves in the barrel? It is very difficult to measure a slug from a five-groove barrel (the most common) without a special mike. I have had good accuracy with a Lyman 314299 bore-riding mould, as have others on this board. My barrel slugs .3023 bore and .3138 groove. My mould casts .3025 and .3148, so I was lucky the mould fits my barrel so well. If you insert a bore rider boolit nose first into your rifle's muzzle it should be a perfect fit. A nose a little oversize has also been OK for me. If the nose wobbles in the muzzle, it won't ride and align as it should. The body of the boolit should be sized to .001 or .002 larger than groove diameter, or throat diameter, if you have a measurement of that. Once you have a boolit that fits, you are most of the way toward your rifle's accuracy potential.

[Buckshot]

...............Charlie45, that .3045" land my give you gas. The groove is sweet at .3125". Curmudgeon's recommendation of the Ly 314299 as the 'go to' slug for fat 30's is right on. As is his comment as to nose guidance. I like the bore riders to mildly engrave and not simply lay there on top of the lands.

Kinda like this:

http://www.fototime.com/EFE3BB919B282B7/standard.jpg

I have 2 M1909 Argentine cavalry carbine's. One is a dream and the other a nightmare because of fat lands. I couldn't match the bore with any boolit commonly available. I went to the next common size up which was the 8mm. I had the Ly 323470 which drops a 165gr Loverin.

Since it's all body and no nose it was a great candidate. I lube-sized it .323" and then ran it up through a Lee .314" nose first size die. Shot really well. Compared to how it USED to treat cast lead, it was match grade.

You really do NOT need the entire nose to guide. Another possibility is to bump the boolit while in the lube sizer. If you can bulge the slug there at the turn of the ogive enough to ride, you may be in like Flynn. I've done that.

Negatives to the above? Hard slugs can stress the lube-sizer press which isn't designed for it, and secondly the boolit may bend a bit. The nose is unsupported in the die and ram-die alignment issues will show up.

Our local chain sporting goods chain, Big 5 has SMLE Mk4 #1's on sale for $99. I have successfully resisted the urge.

.....................Buckshot

[charlie45]

Thanks guys! #1 NVCURMUDGEON , thanks for pointing out my improper measurement of my slug. My rifle is a 5 groove. But I do have the correct tools and gages at work to measure it . Some times I'am dummer then a rock!
#2 Buckshot, thats a bunch of good info after I get the correct measurements I will have to choose which mold to go with.
All this made me think about the notes that I keep on some of my older molds and I found that I have a Lee c309-170 gc that cast ww with a nose of .3025 x .3035 (out of round) worked well in my 30-30 M94. May try some of these for grins. :)
Well thanks again!