OP, have you measured your bore diameter???
All marks of Lee Enfield rifles, other than the later, post war built No4 MkI, MkI* and MKII models, bores could be either on the small side or large side of specified mean diameter of .314 inches
Lee Enfield Barrels
Copyright 1998 - Stephen Redgwell
This is a re-print of an article I wrote for a collector’s magazine. It explains why most military surplus Lee Enfield rifles don’t shoot too well with modern bullets.
With military surplus rifles, always slug your barrel to determine what diameter bullet you need!!
303Bore.JPG
Why doesn’t my Lee Enfield shoot well? I use good bullets and follow the reloading manual instructions to the letter.
Your rifle will only shoot well if it is fed quality ammunition. For reasons long forgotten, bullets made by modern manufacturers are all undersized. They are either .311 or .312 inches in diameter. In short, today's bullets are too small! What?!? It's true. The original plans for the P14 and Lee Enfields called for a .313 to .316 inch diameter barrel. They were rejected if found bigger than .317 when inspected. That means if you want your rifle to perform, your reloads need the right size bullets!
A number of armourer’s instructions have been published since the beginning of the 20th century. Regardless of which addition you read or its country of origin, barrel diameter was designed to be between .313 and .314. The original drawings stated 0.3143. That’s why Sierra’s .311 and Hornady’s .312 diameter bullets may not group too well in your rifle.
Machining practices in the early part of the 20th century were crude by today’s standards. Nevertheless, you should slug your rifle’s bore to determine its actual size. You’ll be shocked to learn that your rifle barrel isn’t .311! That’s why cast bullet shooters get better results. They make bullets of the right size and ease back on velocities. The bottom line? 303 British barrels will vary by several thousandths of an inch.
The diameter difference was NOT usually caused by wear, but rather, less precise machining tolerances. That was why armourers and factory inspectors employed special bore gauges to determine barrel serviceability. What does that mean for you? For precision shooting, consider using cast bullets.
Here is the math behind barrel size:
The 303 British is called a 303 because of the measurement between the lands, which was 0.303 of an inch.
The depth of the grooves was 0.005 to 0.0055 inches. Some publications list it as great as 0.008 inches. In any case, you double the groove depth and add the result to the bore diameter to determine the correct bullet diameter.
Example: 0.303 + (2 x 0.005) = 0.313 inches
Shooting bullets that are closer to the actual diameter of your rifle’s barrel will increase its accuracy. It will make you happier too!!
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2010 Update: Ruger’s technical department says that their newly manufactured No 1 single shot barrels are made according to original specs – .314 to .316 inches. Yes, you read that right! This has been verified by a number of shooters that have slugged their bores.
steve@303british.com
The bullets you have are likely excellent and well made. However, before the boat tail bullets came along with sealed bases, bullets for the 303 Brit used to have sealed noses with exposed lead, flat bases. The exposed lead was pushed forward by the pressures of the expanding gasses along with heat up into the jacket, which helped the jacket to obturate into the shape of the bore, which lead to better accuracy.
Your rifle may shoot very well with these bullets and the first boat tail, 174 grain design started being issued while SMLE rifles were still in service.
The load you suggest is a very decent place to start, if your rifle is in good shootable condition.
Mbogo3 is right on the money. The loaded length of your cartridges should be at least .050 in less than the inside length of your magazine, for proper function.
These rifles, all have generous chamber dimensions, with long throats, to accommodate dented and dirty rounds when used under stressful conditions.
One other thing, BLC-2 is a good powder, used for a lot of different cartridges during WWII. 303 Brit being one of them, from the US manufacturers.
Some people don't like ball powders because they can be difficult to ignite when it gets cold. The military used hotter primers than most civilian loads got because of this, or that's the rumor anyway.
I would suggest magnum primers for your loads.
