Forming 7 TCU Brass

[jbolt]

One of the barrels that came with my Contender is a 7 TCU so I'm going to use it as my production gun. While I have been hand loading for over 40 years I have no previous experience with the 7 TCU

I have some new Lapua 223 brass to make the 7 TCU brass. The Contender I purchased from a fellow club member gave me a Pacific Durachrome 2 dies set and a Redding sizer dies. I am not familiar with the Pacific dies. Another fellow shooter also gave me a new RCBS 2 dies set. Both the Pacific and RCBS sizing dies have tapered expanders that will fit into the 223 neck. The tapers seem short to me but I tried both dies on some cheap federal 223 brass and they both seem to work with the RCBC being smoother.

Questions:

Is it okay to expand the necks in one go or should they be sized in steps?

When sizing in one step or at the final if sizing in more than one step should I full size or back off the sizing die and just expand the neck?

After the first firing does this cartridge prefer neck sizing only or full length sizing? In general I full length size most bottle neck calibers I shoot just enough to bump the shoulder back a few thousands.

[JACKIE40X40]

One of the barrels that came with my Contender is a 7 TCU so I'm going to use it as my production gun. While I have been hand loading for over 40 years I have no previous experience with the 7 TCU

I have some new Lapua 223 brass to make the 7 TCU brass. The Contender I purchased from a fellow club member gave me a Pacific Durachrome 2 dies set and a Redding sizer dies. I am not familiar with the Pacific dies. Another fellow shooter also gave me a new RCBS 2 dies set. Both the Pacific and RCBS sizing dies have tapered expanders that will fit into the 223 neck. The tapers seem short to me but I tried both dies on some cheap federal 223 brass and they both seem to work with the RCBC being smoother.

Questions:

Is it okay to expand the necks in one go or should they be sized in steps?

When sizing in one step or at the final if sizing in more than one step should I full size or back off the sizing die and just expand the neck?

After the first firing does this cartridge prefer neck sizing only or full length sizing? In general I full length size most bottle neck calibers I shoot just enough to bump the shoulder back a few thousands.

Utube has several videos of how to form 7 TCU brass.

[260 Striker]

It is OK to expand necks in one operation. I had some necks split if trying to just jamb the case into the FL die so go easy and use plenty of lube inside the neck. Also helps to inside chamfer the neck before expanding in case there is a small burr. FL sizing fired cases is fine as long as you don't set the shoulders back. You will also find the 7TCU is very easy to find accurate loads. I have fired many matches while fire forming cases and did not notice much difference in accuracy than using already formed cases. I used 139 Hornady bullets for first three animals and then loaded the 154 Hornady bullets for hard set rams. The ogive on both those bullets are very similar so you don't have to change the seater stem to load either bullet. You will find the 7TCU to be a mild recoiling but very accurate cartridge.

[nutcase]

to tell the truth, Lapua brass will probably be the worst brass to make 7TCU brass. The Lapua brass has a tendency to develop a Donut in the neck which requires neck turning the brass to get rid of. I made 200 cases from Starline and not one lost case and just had to fireform them. The 7TCU though is just as accurate with a case being fireformed.

Just use the Tapered expander die and you will be fine. just keep the neck lubed.

a trick a lot of us on the left coast do is to take a full length sizing die and back it off 1/2-3/4 of a turn after the case is fireformed. this allows a slight resizing of the case but does not push the shoulder back.

also, Accuracy has been found best when you seat the bottom of the bullet even with the neck. most 7TCU barrels have too long of a throat to ever get close to touching the rifling.

[LOCKHART]

I've found that if I anneal the necks on the .223 brass first, I have far fewer rejects. I have up to 10% loss without annealing. It's a pain in the rear, but my brass seems to last longer. Since I'm shooting them in an XP-100 I only neck size after the first firing. You might have to full length size if you are shooting them in a Contender or BF pistol.

[jbolt]

Thanks for all the info.

I ran 100 pieces of the Lapua through the die last night and they all formed fine. I see the issue with the Lapua brass. I made up a dummy round and they chamber fine so I will deal with any neck issues after the first firing if needed.

[wheelgun7360]

The 7 tcu is an amazing round for ihmsa. I use starline brass & anneal before necking up. I use the Hornady 139 powered by H-322. Very accurate. You will be pleased with the round.

[dan in mi]

most 7TCU barrels have too long of a throat to ever get close to touching the rifling.

THAT is why I use 222 mag brass for my 7TCU. (and don't trim to spec, trim to consistent max length possible)

I also took a different expander - not sure of the brand -- that is longer than the std Pacific and swapped it out for a longer slower expander. I never lose a piece when forming.

[260 Striker]

204 Ruger brass is easier to find than 222 Mag brass but you do need an expander that will enter the 20 cal necks. You will end up with longer brass and need to trim to length. When I used 223 parent brass, it was always too short and you never had to worry about it getting too long as 7 TCU.

[LOCKHART]

I have been buying Lake City military brass from Cabelas. It says on the package of 100 pieces that is has been deprimed and the primer pockets swaged to remove the military crimp. Well, whomever did the "swaging" wasn't too good at it because I had to do almost all of them over with an RCBS prime pocket swager. But after doing all that, I have found that it is very good brass, and I lose almost none to split necks upon forming them. And this is without my usual neck annealing. If you have a Cabelas or Bass Pro shop near you, you might try this brass. It is priced very well too, and has already been tumbled and shined.