7-30 Waters and 7mm TCU early Contender handloads

[Bloodhound689]

Not sure if this should be in this area or case forming but I recently picked up two contenders (7-30 Waters and 7mm-TCU). This will be my first attempt at case/fire forming and have noticed both cases size just fine (using LC 5.56 and Win 30-30 cases). Both cases chamber and lock up fine prior to seating the bullet. Once I seat the bullet however the round does not chamber all the way and gets stuck. Doesn't matter how deep I seat the bullets. Almost like the bullet stretches the neck to much. I did not use any crimp on the bullets.

I read on here that you should start with the sizing die a couple turns out (which I did). After trying to chamber a round that would not chamber I ran the sizing die down to the shell holder then backed off a half turn or so. 2 of the 5 chambered. I am using RCBS dies. What are your thoughts?

I have been loading for a few years. Always learning though.

[daved63]

Are both calibers doing this? Did you measure the diameter of the neck once the bullet is seated? You should be able to measure and compare to the chamber specs to see if you are within tolerance.

[Bloodhound689]

Yes, both calibers. The necks measure .003-.005 bigger then the ones that do chamber. I didn't measure the bullets prior to seating though.

[Bloodhound689]

The bullets I am using are pulled 139g SP (brand unknown) from some reloaded rounds I received with the two contenders.

[725]

Different brass manufacturers may have different thickness of brass at the neck. I know my .38-55 needs Win brass for jacketed and Star brass for cast. If trying other headstamps doesn't fix the problem, you may have to neck turn your brass. Easy enough, but just one more step to do.

[Bloodhound689]

Good suggestion. I am usually picky about everything being the same headstamp but I am going to see what the others do

[Yooper003]

When I resized my 308 cases down to 7-08 ,I did neck turn to remove some stock. I got a simple hand turning rcbs mod. It works well.

[Bloodhound689]

I haven't loaded many bottleneck cartridges. Mainly handgun so neck turning is new to me as well. I'll order the tools.

[dk17hmr]

Are they factory TC barrels or aftermarket?

[Bloodhound689]

They are factory. 7mm-TCU 10" and 7-30 Waters is the Super 14

[daved63]

Yes, both calibers. The necks measure .003-.005 bigger then the ones that do chamber. I didn't measure the bullets prior to seating though.

What is the measurement on the ones that do not chamber? The SAAMI specs for the 7-30 Waters is 0.3062" at the end of the neck.

[BK7saum]

I am surprised that neither will chamber. Usually t/c chambers are generous. They should chamber reformed commercial brass. Not sure what the issue is. If you were applying a crimp, I would say that you had buckled the case necks.

[Bloodhound689]

They are measuring up at .3065.

[Bloodhound689]

If the case was buckled I would assume that they wouldn't chamber without the bullet as well. They don't appear to be buckled but then this is my first case forming. The double neck is different. Lol

[Bloodhound689]

Daved do you think a factory crimp die with no crimp would fix this .0003?


Corrected. Never mind. They are designed different for bottlenecks aren't they?

[dk17hmr]

Have you full length sized at all?

[daved63]

Looks like you will have to turn the necks or try a different brand of brass. I have formed quite a few 7-30 Waters and 7mm TCU cases and I don't recall ever having to turn the necks. Did you measure the bullets? I've shot cast bullets sized .285" in both of those cartridges and never had a problem. It seems strange that both would be doing it.

[daved63]

Daved do you think a factory crimp die with no crimp would fix this .0003?


Corrected. Never mind. They are designed different for bottlenecks aren't they?

One other thought since you are new to bottleneck reloading. How did you adjust the seater/crimper die? If it is over crimping it could bulge the case. Put an empty case in the shell holder and screw the die in until it touches the case mouth, then back the die out a half turn and lock it in place. Seat a bullet and see if you still see the same thing.

[Bloodhound689]

Have you full length sized at all?

Yes using RCBS dies

[Bloodhound689]

One other thought since you are new to bottleneck reloading. How did you adjust the seater/crimper die? If it is over crimping it could bulge the case. Put an empty case in the shell holder and screw the die in until it touches the case mouth, then back the die out a half turn and lock it in place. Seat a bullet and see if you still see the same thing.

I backed the die out a full turn