View Full Version : Improving the 303 British Cartridge and enhancing case life

02-06-2016, 06:32 AM
Shortly after arriving at Aberdeen Proving Ground I learned of the 30/303 round and I had not heard of that. Another Test Director ran a gun shop on the side and he had ordered a RCBS FL die for a guy (never picked up) and it is marked 30/303. He went on to explain that RCBS made them up so guys could load 308 bullets and shoot them in 303 barrels. Sounded rather unique and I did not load any ammo with it for years and one of the guys in my volunteer FD had a No 4 and asked me if I could reload some brass for him and I said sure.

I broke out the 30/303 and loaded him some pulled 173 bullets and to my surprise they shot quite well. It was also my first experience with Privi Partizan brass and that too was a pleasant experience. I adjusted the FL die so that that it just barely bumped the shoulder back and I had about six reloads on his brass when he and his wife moved to Kansas.

About three years ago I fell into a No 4 with a bad barrel and prior to that I found a 303 finish reamer on ebay and decided to rebarrel it.

I was introduced to the benefits of tight chambers about 30 years ago by the Chief Armorer from the US Secret Service who was a long time friend. He built the USSS Counter Sniper Rifles, their record setting match rifles and in a previous life had rebarreled all the ammunition test rifles at Frankford Arsenal. He had researched tight chambers for years and had custom reamers made with smaller and small dimensions and he taught me how to design custom reamers for better accuracy and much longer case life.

The steps in designing a custom reamer are simple so I pulled out 303 Brit ammo I had (both loaded military and new unprimed commercial cases) and measured the "base dimension". (Note: the base dimension is always measured .200" up from the case head which is where they tend to expand the most and 303 military chambers are huge to allow mud, dust covered rounds to be used. The rifles were never designed for reloading so there is no consideration to civilians picking them up years down the road or for reloaders to get them.

Since the rifle will never see combat again and there are no new surplus barrels to replace it with I decided to improve the 303 reamer.

The military brass was about .002" larger at the base than the commercial brass so I had the reamer reground to give a chamber .002" larger than the military but about .007" smaller than the military chamber. I also reduced the neck dimension to .002" larger than the military rounds and had the throat cut to shorten the throat to 30.06 length.

I call this the 222 Principle of Chamber design wherein my rifles when rebarreled will not allow a new case to expand over .002" in any dimension. They generally expand .002"on firing and spring back about .001" so the fired cases are only about .001" larger than a new case. When these are run into a FL die they are just barely moved and the case life goes up drastically. Cases wear out due to excessive expansion and when resized back down the brass gets longer and first thing you know you have incipient case separation at the base which can gas cut your chamber,or give you hot gas in your face. With a tight chamber you can reload the brass till the primer pocket gets loose.

I have my match rifles chambered in 30.06 so one day I decided to find out as I have a loading room right behind my test bench and I started firing one case,sizing it, in FL die, replaced the primer and loaded it over and over again. Every third loading I lit a candle to stress relieve the neck.

How long can they last? I don't know, I stopped the test at 157 reloads. I was using a LC Match 30.06 case which have tighter primer pockets and harder case heads (designed that way) than commercial. I have 308 rifles similarly chambered with 90 reloads on them using military match ammo.

I ordered a Douglas barrel blank and turned it down but left it larger under the wood than the military barrel as is done on the match barrels for the M14 (M1As) so it is stiffer.

Also while chambering it I used a new unfired case as a GO GAGE and I quit reaming when the bolt closed just as case shoulder contacted the shoulder in the chamber.

Now obviously there is a concern about .311 bullets fired in a .308 bore so I covered the action and shot ten rounds of my Brit Mil Surp as PROOF ammo and there was absolutely no signs of excess pressure when they went down the .308 barrel.

What is not widely known is the Canadian shooters and US shooters routinely get barrels made that are smaller than .308. I have one barrel in a 308 that is .298X.3055 and it shoots quite well. I use a reduced load on it and it still gives velocity in the range I want.

It is amazing to bore scope a large number of barrels and I see barrels all the time that the bullets just barely contact the bottom of the grooves in the middle which proves the bullets do not actually seal the barrel. I have one barrel with no signs of a bullet ever having contacted the grooves and they just ride on the rifling.

I remounted the military front sight and the rifle looks absolutely original but shoots much better.

02-08-2016, 01:24 PM
I just neck size and shoot .314" cast bullets. I like the Lyman 200 grain bore-ridding design with gas check and Lee Liquid Alox lube.