case forming

[grhornet]

Does a bullet have to touch the rifling to properly fireform the case? I need to fireform some 7mm/tcu, and don't have any bullets long enough to touch the rifling.    Thanks

[Luckyducker]

No, the bullet doesn't have to be against the rifling in order to fire form the brass, in fact I think that could be a dangerous practice.  In order to form the brass to the chamber of your rifle you need a fairly stout load, and by that I mean a load that is not a reduced load.  There is no rocket science involved, it just takes enough chamber pressure to push the brass out to the physical limits of the rifle's chamber.  A side note here, you can use a cheap bullet if it is just a forming load as there is no need to throw the more expensive slugs for this.

[LaOtto222]

Luckyducker has it right for a 7mm TCU. Some cartridges need to have the bullet touching the lands because they need to blow the shoulder forward. A 7mm TCU does not, if properly formed it will still head space on the shoulder. It should just be able to close the action with out any excess head space in the case before seating a bullet. Keep adjusting your dies until you can just shut the action.You will just finish rounding out the shoulder.

[warf73]

No experience forming 7mm TCU, but when I fire form for my wildcat 22 cheetah.
I use 7grs. Of Red Dot fill the rest of the case with cream of wheat (uncooked) then top the case mouth with a bees wax plug.

But that’s for my wildcat not sure if this would work in your case? Maybe?

[Catfish]

A lot depends on what you are forming and what the parent case is. If your necking down a case you can always create a false shoulder to head space on. If your parent case is a rimmed case or a belted case you head space on the rim or the belt. Really the only time you have to set the bullets into the lands is when your blowing out the lenth of the case body and there is no other way to hold the case head against the bolt face.

[Buck O Bob]

grhornet; Im assuming your fire forming brass for TC barrel. Many TCs in 7 TCU have rather long throats for silhouette duty. The shoulder on the new case has to move forward from 1.438 to 1.455 when fire formed.[ shoulder also forms to 40 degrees and case diameter increases from .354 to .370] After you expand 223 brass to 7mm, trim all new cases to same length[ 1.739 min ] then sort cases by weight before fire forming. If your trying to determine distance to lands in barrel and bullets are too short try turning bullet backwards w/ base contacting lands. If your still not reaching the lands or experiencing missfires or frame unlocking when fired, PM me.