303 Epps – Notes on Improved Cases

Copyright 1999 – Stephen Redgwell

The 303 British vs the 303 Epps

The 303 British suffers from “droopy shoulders”. Good in its day, the shallow 16 degree angle was designed to help in loading and placement of the long stranded propellant “cordite” in the case. While it was good for factory production then, it’s a real problem for the reloader today.

Any cartridge with shallow shoulders is more prone to case stretching, case wall thinning and thickening around the neck. Maximum loads fired from these cases accelerate the process.

Canadian gunsmith Ellwood Epps saw the problem and corrected it. He knew that steeply angled shoulders helped modern spherical and extruded powders burn more within the case and less up the barrel. His solution was to increase the shoulder angle to 35 degrees from 16. At the same time, he decreased the body taper by over 50 thou. The resulting improved cartridge showed a 15 % velocity enhancement over the standard 303 British when fired from the P-14.

After consulting with PO Ackley, Mr Epps reformed the cases with minimal body taper and sharply angled shoulders. Reduced body taper lessens the rearward pressure effects on the bolt and lugs (bolt thrust). Sharp shoulder angles inhibit forward brass flow, which reduces the need to trim cases as often.

Originally, the improvements were made to increase brass life, not to produce a higher velocity round. Mr Epps knew that reshaping the case into a more efficient design would yield this secondary benefit, but considered improved case life to be the most important factor.

A short review before we carry on.

With older case designs, lots of taper and shallow shoulders present problems for reloaders. They allow more case stretching and shorten case life.

The primary advantage to improved cases is increased case life. The secondary benefit is additional velocity. Normally, older designs benefit more from these enhancements.

When Mr Epps created his improved cartridge, he wanted it to be a simple chamber reaming with no other required alterations. He wanted to be able to fireform new cases using existing 303 British ammunition. He accomplished this handily, and began modifying rifles at his gun shop in Ontario, Canada.

At first, he “Eppsized” No 1s, No 4s and P-14s. He found however, that because the action strengths were different, loads developed in P-14s were dangerous to use in modified Lee Enfields. He preferred the P-14 action, and told anyone wanting their Lee Enfield reamed to 303 Epps not to expect the same velocities. Case life would still be vastly improved though.

He also warned customers not to use 303 Epps reloading recipes unless they could absolutely confirm that they were safe. He regularly gave owners of Lee Enfield conversions handouts for the proper load levels in their rifles. Since he talked with anyone getting this job done, Mr Epps was sure that the right reloading information was being distributed.

Author’s Note – This was before the “sue for anything” days when people took responsibility for their own actions, unlike today, where if you can blame it on someone else, go ahead.

In the 50s and 60s, as this new cartridge was becoming more widely known, reloading equipment manufacturers began producing dies and reamers for it. Gunsmiths all over the world started offering this conversion. Heck, it was an inexpensive job, and very attractive to hunters that owned some sort of 303.

Is this a viable idea today? Is there any recent load data? Is it still viable?

Why not? But I’d like you to consider the following.


When you get the chamber reamed, you’re altering the rifle. If it’s a collector piece, then it’s probably not a good idea. Try and find a rifle that has already been chopped.

The alteration should be considered as part of an overall plan. Many people forget that just because you improve a cartridge, you do not have to load it hotter than the original. I know that this will never be a popular position, but think, how many shooters complain about lousy case life, oversize chambers etc.? A 303 Epps conversion gives you a normal chamber with the case enhancements discussed earlier.


Okay velocity chasers, you’ve been impatiently waiting to hear what this translates to in fps. These figures are for a 150 and 180 grain bullet respectively. These are shot from a No 4 Epps conversion. You should be able to squeeze a bit more velocity from a P14.

A standard 303 British versus the 303 Epps Improved

2700 fps versus 2865 fps (approx 5% improvement)
2440 fps versus 2650 fps (approx 8% improvement)

This makes it perform like a 308 Winchester doesn’t it? Not bad for a beater.

Is there any load data?

Here’s where I’ll get the pouty faces. Not a lot of work has been done on this cartridge for about 40 years. Load data using IMR powders is available, but almost always for the P-14 action. You must not use this for a No 1 or No 4! Many new powders have been developed since the last serious work was done with the 303 Epps. Where does this lead us? To a disappointing ending? Certainly not!

I have some loads listed in my big book of loads – SHOOTING AND RELOADING THE 303 BRITISH AND THE 303 EPPS. Just click on the link on the main page.

Here’s what I get from the No 4 Epps – SAFELY!

180 grain bullet – 2646 fps (std best is 2450 fps)
215 grain bullet – 2381 fps (std best is 2225 fps)