Author Topic: 7-TCU Deep Throat (Read 553 times)

Tad Houston · « **on:** March 22, 2005, 11:59:52 AM »

Were are the lands!! I loaded up some Nosler 150gr. Ballistic tips, and could not find the rifling on this barrel. They drop right in with the bullet just stuck in the case neck. I guess this thing was made to shoot 165 grainers or something? Oh well, just have to see if it shoots these 150's. I know they say one caliber deep for seating, but whats the least amount of bullet in the case neck that can work?

Thanks-too much fun playing around with these things!

22popnsplat · « **Reply #1 on:** March 22, 2005, 12:17:15 PM »

I have several contender barrels that you cannot reach the lands and have the bullet in the case , My 7 tcu and .223 are both like that . It does not mean it isnt going to be resonably accurate , I have barrels that will shoot 5 shot sub MOA groups and thats 2 of them.

Racepres · « **Reply #2 on:** March 22, 2005, 01:38:11 PM »

I have to load "1 cal. deep" in my 7 tcu but it does not seem to cause any problems whatsoever. it shoots MOA w/ me behind it so I know it can do sub-MOA. Don't worry abt it. Marty

Justin Smitty Smith · « **Reply #3 on:** March 22, 2005, 02:18:07 PM »

Hi tad MY 7mm TCU is the same way, but I still have not shot it enough to tell you how it will group.

Robert · « **Reply #4 on:** March 22, 2005, 02:27:50 PM »

It is like that for large bullets for siloquette (however you spell it) I bought a 7-30 Waters expecting to be able to load big cast bullets in it also....but it didn't work. The little 7tcu has a lot more throat.

braud357 · « **Reply #5 on:** March 22, 2005, 03:39:31 PM »

Well, I have been loading and using the 7 TCU for over 20 years, and I never had a TC barrel in which the bullets could be seated to touch the lands. what I arrived at, and what I still use today, is this. I am using Sierra 150 Matchkings, with 23 gr. XMR-2015. I seat the bullet so that the base of the bullet is touching the powder level in the case. I do not compress the powder - just barely touch. This worked very well in my last 10" barrel, and also works well in my 7 TCU XP. Both of them out-perform the operator !

Jay HHI6818 · « **Reply #6 on:** March 23, 2005, 04:12:15 PM »

All of the factory barrels have Loooooooooong throats.
I was loading some 6TCU for a 21 inch carbine barrel and the Nosler 70 gr BT is .075 inches out of the case mouth before it touches the rifling.

Steve P · « **Reply #7 on:** March 23, 2005, 04:17:01 PM »

You are typical and normal. Load that 150 bt so the base of the bullet is even with the base of the neck. Pack it full of H335 and you should have about a 1/2" group at 100 yards.

Steve

Nate C · « **Reply #8 on:** March 23, 2005, 05:32:32 PM »

I'll echo the comments the other above posters have all made - the factory throats are quite long. I've owned 4 7tcu bbls, 3 were 10" and one was a sup 14. All of them were long-throated, and all of them shot very very well - MOA when scoped.

The comment about silhouetting is correct as well - when these were first developed the primary need was for 160~ gr bullets at 'jacked up' velocities. The throat worked great for the longer bullets, and was a safeguard to (slightly) lower the chamber pressures.

Another little known fact about heavy 7tcu bbls - each of mine had a 1:9 twist. I think that if you wanted to make a "7 Whisper" you could have fun with the Sierra Matchkings...

My silh load was somewhat lighter than most - 139gr Hornady spt with 27g H335. My OAL was 2.700". Hope this helps.