Thread: Fire forming AI brass

it could be done PM if ya want but how long till ull need the brass?

James,
An easy way to fireform brass is to use a powder with a fast burn rate (shotgun powder), in your case AP70N, to provide the pressure.

Put in your normal primer, 10 to 15g of powder (for the 243ai) and then using a small screwdriver or rod push a 3/4 inch square cleaning patch (cotton) into the case above the powder to keep the powder against the primer, push it down well.
It is possible to use too much powder and ruin your brass on the first shot so start at 10 grains and check how sharp the formed shoulder is, only you will know if more powder is needed.
Dont forget to lube the outside of the case with redding sizing lube so that it moves/conforms to the chamber wall with a nice sharp shoulder.

load the case into your rifle and fire it in a safe direction. The cleaning patch flying out the barrel is not harmless and make sure you fire it into a backstop or safe area.

So easy to do, just keep an eye on barrel heat while you are doing it, give the barrel time to cool down if you have to. I have done countless brass this way and its great.

Then give your barrel a good clean, and fire your last fireforming load down it, this puts a film of carbon on the barrels internals so your first ever projectile fired in your new barrel has some carbon "lube" to help reduce fouling and speed up the bedding in period.

All this info and much more can be found in the "precision shooter magazine" a fantastic read and well worth the cost.

http://www.precisionshooting.com/

Originally Posted by 7mmsaum

James,
An easy way to fireform brass is to use a powder with a fast burn rate (shotgun powder), in your case AP70N, to provide the pressure.

Put in your normal primer, 10 to 15g of powder (for the 243ai) and then using a small screwdriver or rod push a 3/4 inch square cleaning patch (cotton) into the case above the powder to keep the powder against the primer, push it down well.
It is possible to use too much powder and ruin your brass on the first shot so start at 10 grains and check how sharp the formed shoulder is, only you will know if more powder is needed.
Dont forget to lube the outside of the case with redding sizing lube so that it moves/conforms to the chamber wall with a nice sharp shoulder.

load the case into your rifle and fire it in a safe direction. The cleaning patch flying out the barrel is not harmless and make sure you fire it into a backstop or safe area.

So easy to do, just keep an eye on barrel heat while you are doing it, give the barrel time to cool down if you have to. I have done countless brass this way and its great.

Then give your barrel a good clean, and fire your last fireforming load down it, this puts a film of carbon on the barrels internals so your first ever projectile fired in your new barrel has some carbon "lube" to help reduce fouling and speed up the bedding in period.

All this info and much more can be found in the "precision shooter magazine" a fantastic read and well worth the cost.

Precision Shooting Magazine - Welcome

Andrew, do you not use any filler? Some articles suggest this is needed to drive the case out into the correct shape. Typically it is Yankee data using Cream of Wheat. My reading suggests this is something like Cremota or Semolina?

No filler, the fast burning powder makes all the pressure you need forcing that cleaning patch out the neck of the brass, and as previously mentioned dont put in too much powder, as you can over pressure the brass first shot and loosen the primer pocket, without it ever having held one !!!

Id say Shotgun powder is a formidable beast in the wrong quantities.

Using fill in the case when fire forming dose give a slightly better fire formed case than the patch and shotgun powder but when using fill it dose leave you with allot of mess to clean up, either way works well enough if done properly.

Originally Posted by Terminator

Using fill in the case when fire forming dose give a slightly better fire formed case than the patch and shotgun powder but when using fill it dose leave you with allot of mess to clean up, either way works well enough if done properly.

Donald, would you recommend any locally available product for fill rather than Cream of Wheat? i can do this outside so mess is not a problem.

Hi kiwijames, I've fireformed quite a few cases for my 300Lapua improved. I use N320 from my pistol shooting days and oat bran from supermarket with a patch to plug the end. Work up from a lite load something like 10gn in .243 till you get the case forming out fully. Just finished 50 cases for my 338-416 but it took 27gn to fully form the brass and had less than a .001 run out in the necks.

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Originally Posted by 7mmsaum

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Made that step many weeks ago