Mould for .303 British

  • Last Post 4 days ago
nworegonman posted this 02 March 2021

Hi All,

I have a .303 British and about 100 casings fired in this rifle.  I have neck sizer dies from Lee.

I slugged the bore and as best I could measured the max dia (one edge of the groove to the opposing other edge - if I said that right) as .313. 

What would folks recommend for dia and weight and actual mould numbers?

Thanks a lot,


Attached Files

Order By: Standard | Newest | Votes
Ed Harris posted this 02 March 2021

More important than barrel groove diameter is the diameter of the unrifled portion of the chamber ahead of the case mouth before the origin of rifling.  You want a bullet close to throat size to ensure a positive gas seal.  In most military .303 rifles you want .314-.315, whereas some wartime 2-groove barrels will need .316" or larger.

I would very highly recommend one of the NOE clones of the Ideal #311299, which they make available in various diameters so that you can buy one which will actually fit your gun, in either plainbase or gas checked.


NOE 316-213-RN-PB


73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

Attached Files

nworegonman posted this 03 March 2021

 Thanks Ed,

I slugged the chamber as best I could. I measured 0.315.  You can see where I worried the lead some with the calipers.

If I get you right, this .315 is the bullet dia I should be looking for vs. the .313 I measured in the bore.

Attached Files

  • Liked by
  • Bud Hyett
  • RicinYakima
JeffinNZ posted this 03 March 2021

I agree with Ed. Also, depending on what you want to achieve you may want a gas check capable mould. My .303's shoot best with a longer, heavier bullet. 200gr + would be a good idea. 14gr of 2400 under the bullet Ed suggested would put you around 1400fps.

Cheers from New Zealand

Attached Files

Larry Gibson posted this 03 March 2021

I agree with Ed and Jeff regarding the longer heavier bullets for use in the 303 Brit. I've two 303s; a Ross M10 with a .312 throat and a Long Branch 1950 No4 Mk2* with a .314 throat. Since I shoot them mostly at 300 yards on either an old Army "D" target or at ram or pig steel "dingers" I prefer a GC'd bullet at 11850 - 1900 fps out of them. I've found the Lee C312-185 and the NOE 314-299 (replicant of Lyman 314299) both to shoot very well in both rifles with the edge going to the 314299 at 00 yards.


Concealment is not cover.........

Attached Files

nworegonman posted this 04 March 2021

Thanks for your suggestions.  

I have another question.  I recently have seen discussions on powde rcoating to eliminate the need to lube cast bullets.  It has a side effect (apparently) I have not tried it yet.  It adds .001 to .002 to the diameter of the bullet.  

Any thoughts on using a cheaper .312 mold and using powder coating to increasing the dia. a couple of thousands? 

Is this a taboo subject?



Attached Files

nworegonman posted this 04 March 2021

Let me add - I am looking for plinking. I will not be shooting 300meters anytime soon.

Attached Files

pisco posted this 04 March 2021

You can still size a powder coated projectile down

Attached Files

nworegonman posted this 5 days ago

To follow up I got a NOE mold and will be trying it out soon!

Attached Files

Brodie posted this 4 days ago

nworegonman, powder coating and sizing down to fit the throat of your rifle is not a taboo subject by any means. In fact it is something that a number of members do regularly. I don';t know about everyone else, but my motto is :"What ever works!".


Attached Files