7mm TCU question

[Wolfdog91]

So been having fun with my first old...er , school wildcat. Don't think my 17-5.56 counts too much as a legit wild cat ..anyhow in making my brass with once fired ( got a bucket of stuff from the local range along wit a bag of LC saw head stamp and a bag of wolf) .223/5.56 found out the easy way to avotalot of head aches is to just test every case in the gun.
If they don't go in and let the gun close nice and easy there just not going to even after going in the 7 TCU die


Played with all kinds of shoulder bumps and stuff and really seems like the problem is the last 1/5th of the case.

Only thing I can figure is some of the guns have bigger chambers and the that part blows out a bit more and regular does don't really touch it.

So all that leads me to this. Would getting and using a small base die help alleviate this ? I've never used one but see people dealing with once fired 5.56 reccomended them alot... but never seen anyone messing with .7mm TCU mention using one.
I mean I just got 100 PCs of brand new starline brass just to convert and they all fit perfectly so I'm not stressing for brass but now I'm just curious on the matter.

 

[JEFFPPC]

Don't invent a problem. I shot 1000s of rounds out of a pair of Contender 7hTCUs using basic RCBS dies. Great cartridge. 3031 with Hornady 139 and 154 bullets. Have fun.

 

[snert]

^^^^^^

 

[fkimble@charter.net]

Well the last/lower part of the case is where a Small Base die does it's thing!. Range pickup brass gets a trip thru a SB die first go a round, then just a regular die for the rest of it's useful life

Frank

 

[JSH]

Anything you think you know about reloading, can pretty much be thrown out when dealing with the TC’s. Yes some get by with once fired brass. Various dies can size all over the place.
For the thousands of 7TCU I loaded, 90% were once fired LC. I annealed and sized in 223 dies.
Why? Because nothing like getting to a match and finding chambering issues.

 

[Krogen]

JSH mentioned annealing. I know you didn't ask Wolfdog91, but I found that annealing is mandatory. Many moons ago, I shot a 7mm TCU. A direct route to cracked necks is failing to anneal. It's a really big stretch from 22 to 7mm. Cases sized ok, but cracked on the first firing if I didn't anneal. You might try annealing >before< you run your cases into the die so you don't get so much spring back. That may cure your fit issues. And definitely anneal after you stretch the mouth up to 7mm.

 

[Wolfdog91]

Anything you think you know about reloading, can pretty much be thrown out when dealing with the TC’s. Yes some get by with once fired brass. Various dies can size all over the place.
For the thousands of 7TCU I loaded, 90% were once fired LC. I annealed and sized in 223 dies.
Why? Because nothing like getting to a match and finding chambering issues.

Well actually annealed everything right off the bat to begin with along with all the cases after. Didn't seem to help with my current problem I discussed.




Also tried both annealed and non annealed though a .223 due first and no dice if they don't don't in before all this to begin with

 

[Wolfdog91]

Don't invent a problem. I shot 1000s of rounds out of a pair of Contender 7hTCUs using basic RCBS dies. Great cartridge. 3031 with Hornady 139 and 154 bullets. Have fun.

Don't see how it's " inventing" anything if I noticed a problem and try and figure out a solution...so

 

[10XSHOOTER]

99% of range pick up brass has been shot in a AR. They have oversized chambers.
Get a small base .223 die. Anneal, size, anneal and resize again.
Are you trying to neck up in one step? get a 6mm mandrel then 6.5 and then finally 7mm mandrel.
anneal between each neck up.

 

[PhilKeil]

A thought here,
Are you sure you're getting the necks up to about 750 deg? I don't see how you could hold on to one of the cases with bare fingers when they get to that temp in the neck/shoulder region. +1 on what 10x mentions on the oversize chambers. Especially if it is coming from the military.

 

[Wolfdog91]

So here's the deal, I'm having zero problems when it comes to necking them up ,like none at all. I anneal till I get a flame change ( I played around. With flame change, templiq , and visual and they call are about the same from what I can tell, sometimes I'll use my fingers most of the time I use a drill with a socket)then just run them up in the die haven't had any crushed or split necks . Not quite sure what the point of a 6mm then 7mm mandrel would be unless I was no annealing.This things is a cake walk compared to necking down for my .17-5.56.

Also I tried taking brass that wouldn't fit bumping shoulders back stupid far , full length in a regular.223 die then in the TCU , long story short if the bass doesn't fit in to begin with its not gonna and it always seems to be down there by the base, hence why I'm asking about small base dies.

 

[Wolfdog91]

99% of range pick up brass has been shot in a AR. They have oversized chambers.
Get a small base .223 die. Anneal, size, anneal and resize again.
Are you trying to neck up in one step? get a 6mm mandrel then 6.5 and then finally 7mm mandrel.
anneal between each neck up.

Alrighty that's what I kinda figured, that's for the confirmation