Fire forming the .303 British case

  • Last Post 11 December 2016
loco posted this 28 February 2016

Is there a cast bullet load that works for fire forming the .303 British case, or is it best to just go with full house jacketed loads?  I have 100 new cases that need formed for cast bullet shooting, neck sized after forming etc. Cases are Prvi Partizan. Thanks,Loco. 

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onondaga posted this 28 February 2016

Hodgdon Data has H4895 loads with bullets 125-180 gr, so the Hodgdon 60% Rule can be used for the 303 Brit to make reduced loads very safely without ignition problems with as low as 1/2 available case volume. I wouldn't go that low, but I would be happy using a 60% full case of H4895 fire-forming. Staying within the Hodgdon recommendation like that offers both confidence and safety for fire-forming. The rule is valid for shooting jacketed or cast bullets. If unfamiliar with that rule a google search on “Hodgdon 60% Rule brings up a couple of PDFs from Hodgdon on their rule for reduced loads. Gary

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Ken Campbell Iowa posted this 28 February 2016

couple things::

there is a good method to fireform using bullseye and a caseful of creme-of-wheat ... saves lead .

i prefer to shoot mild loads .... and plink .... the funny thing is that fireforming loads usually shoot pretty good .... kind of an argument that perfect attention to minutiae may not be the key to reasonable accuracy ...

i had a varmint rifle that never again matched the fireforming groups ....

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gnoahhh posted this 28 February 2016

I gotta ask, why be concerned with “fire forming” new brass if it'll be used in the chamber it's intended for, cast shooting or not? I never bothered- just uniform them in a die, and proceed with standard cast bullet loading protocols.

The only thing I would do if it were a .303 Enfield of some sort would be to expand the necks a size or two and go back into the .303 die slowly adjusting the die down until I had a secondary shoulder that just barely allows the bolt to close on an empty case- effectively causing it to headspace on the shoulder not the rim. That is, of course, unless your rifle is one of the 10% or so that actually has nice tight headspace. That will save a lot of brass stretching that is the bugabear with .303's in general- at least in my experience with them.

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Larry Gibson posted this 28 February 2016

I use 28 gr 4895 with a 1/2 - 3/4 gr Dacron filler under a 185 - 200 gr cast bullet. If shooting from a bench or workable clean place (minus dust and dirt) I put a very light coat of case lube (pure lanolin works fine also) on the cases so they don't grip the chamber walls. Not enough psi with that load to cause a hard thrust against the bolt. Works perfectly.

BTW; this fire forming load does shoot quite well so you can get some decent practice in also.


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

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tturner53 posted this 28 February 2016

This is a well covered topic. I've read about using lightly oiled cases and LIGHT loads to gently fireform your brass. After that, use the Lee collet die. Works like a charm.

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loco posted this 29 February 2016

Thanks for all the info guys. I guess I should have first ask, do I need to fire form. I was not sure if a normal cast bullet load would even expand the .303 case fully into the chamber. On cowboy loads for the 45lc, you get some blow back past the case because the case doesn't expand against the cylinder, causing a black smokey case. I knew the 303 chamber is a bit over size , so took a chamber cast and have bought the correct mold and size dies etc. I also have 100 jacketed bullets but, am I right to assume that a cast gas checked load at 1600-1800 fps will form the brass to the chamber as well? I just wanted a load that I knew would stretch the new brass , to chamber dimensions , the first time out. Hope I'm making more sense. Loco

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gnoahhh posted this 29 February 2016

No need to “fireform", IMO. You'll be generating enough pressure to snap the case into conformity with your chamber with about any load you choose- from cat sneeze to full tilt. But still. you can extend case life by at least one shot by starting out the way I suggested.

A cast load at 16-1800fps will do all the “case forming” that you wish.

.303 Enfields have generated more headaches/challenges than any other breed of rifle, to me!

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mckg posted this 29 February 2016

As an alternative to gnoahhh and LMG's methods, I seem to remember some shooters placing an O-Ring over the cases rims, in order to prevent them to move in oversized chambers. This of course is if you can close the bolt on them.

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loco posted this 29 February 2016

Ok, I think you guys have me on the right track, thanks. Many good ideas on helping case life as well. Gnoahhh.....think you're right about the 303 and headaches!!! I bought this Enfield from a friend , years ago, at a great price. Never shot it !! I'll see if I can make it work. Two other calibers over the years that caused me grief , were the 6.5x55 and the 38-55 as well. Wish me luck. 

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JeffinNZ posted this 09 December 2016

I am a fan of the secondary shoulder and a mid range load. Then neck size only with a Lee collet die henceforth annealing as required.

Cheers from New Zealand

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Dirtybore posted this 10 December 2016

I like to use 10 gr of Unique under a cartridge full of corn meal.  Top that with a small plug of candle wax.   That way you don't waste any cast bullets.  

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beemer posted this 10 December 2016

I noticed this thread is almost a year old but  here goes anyway. I have several hundred PPU cases that I have used for years, they were fired factory loads. My rifle has proper headspace so cases were sized with a Lee collet die with an occasional annealing , they are still good to go so getting them right to begin with is a big help.

Loco, could you elaborate on the problems you has with the 6.5 X 55. This is maybe another issue and OT but I was given a Swede that someone ruined the receiver trying to remove the barrel to correct the headspace. Someone checked it and said it was excessive but it was still tighter than two that I have shot for years with no problems. All three rifles had matching numbers on the bolts. I did some snooping around and found that the Swedish military had looser standards than the US. The rifle is a sporterized Kimber with a nice barrel so I am putting it on a Oviedo 93 receiver I have.


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loco posted this 11 December 2016

Hi guys. As for the head aches I've had in the past with 6.5x55 and also the 38-55 came from lack of knowledge mostly! 38-55 can be a .375 bullet to a .378+ on older guns, oversized chamber etc. Even the brass and dies are set up for one size but not another. Had a Uberti High Wall in 38-55.....needed a .380 bullet if I remember correctly. Uberti told me on the phone,they copied an original, and that's what it was? The twist wasn't what I needed for the range I wanted to shoot, so I had a fast twist liner installed,1in 14, but this time the bore was a .375. You get the picture. 6.5 Swed ....same thing. I was trying to shoot a .266 bullet. Did some reading and ask around here on the forum and found out I needed a larger bullet, mostly due to oversized throats on the Sweds. Did a chamber cast and started over. All good now!!!!  This is an awesome place to learn if you don't mind asking for help. I've learned a lot here,so thanks to all. 


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David Reiss posted this 11 December 2016

Just moving the thread back to the latest.

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
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