Longest practical length for a 7mm TCU?

[jason280]

I have given up on finding a carbine length 7mm TCU barrel, so I will be ordering one through the T/C custom shop.  Question is, at what point will a longer barrel really not help the velocity of the TCU?  I would like to keep the barrel as short as possible, but I still want to achieve around 2400-2500fps with a 120-130gr bullet.  Will a 22" barrel give that much of a velocity increase over an 18" barrel?  Thanks!

[Robert]

If you are going Carbine...have you considered the 7-30 waters?  The TCU is a great little cartridge.  I have both.  In a short barrel the 7-30 dosent have much velocity gain over the TCU, but it starts to 'shine' with the longer barrels.  Plus...the case has superior advantages over the TCU. First off..it is rimmed and head-space and misfires arent a factor.  Proper headspace with the 7-30 will probably improve accuracy, but will not cause misfires.  The 7TCU can be a little finicky sometimes.  The other drawback with the TCU is the extremely sharp shoulder.  I have when shooting the TCU to take a cleaning rod and an oversize bore brush with me to push out the occasional separated neck.  The shoulder on these is so sharp that it is very easy to 'cave it in' when seating the bullet.  When you fire it...it bends back the other way and snaps off leaving the neck in the throat.  I am sure that some folks will argue that if you are re-loading properly and paying attention...this will not happen.  But,,,It DOES happen...and can be a real pain in the arse if it happens to be the only firearm you brought along and the nearest cleaning rod is 20 miles away after your first shot.  
   The 7-30 however..NEVER has a neck separation...Never misfires  (excepting faulty primers) and is just plain Easier to handle loading.....especially in the winter when you might have gloves on or frozen hands.
  Also..Look at the Sierra data for the two with max loads....(14" Barrel)
7TCU  120 gr 2200 fps  Energy 1289    140 gr 2000 fps  Energy 1243
7-30   120 gr 2450 fps  Energy 1599    140 gr 2250 fps  Energy 1573
  This makes the 7-30 an effective deer rifle out past 200 yds....I would not consider the TCU past 100.  That is not saying the TCU is not accurate to 300..it is.  But the 7-30 gets there with some poop left.  You can expect a little more with a longer barrel.

[jcunclejoe]

How much velocity gain will depend on the powder that you are using. A fast burning powder like H322 will not gain as much as a slow burning powder like W748.  You will not know which powder shoots the best until you get into your load testing and by then the barrel length is already set.

If you were really concerned with maximum velocity then you would not be looking at the 7mm TCU in the first place.
You should have the barrel made to the length that you like, that will handle the way you want, that will best fit your hunting style (brush or wide open) then just let the velocity be what it is.

I have always preferred accuracy over velocity any day. If it shoots little tiny groups, who really cares how fast it is going (within reason of course). And the bullet must be within it's intended velocity/performance window.

Get what you really want and don't worry about the velocity.
Good luck and have fun with that new barrel.
Joe

[fyrepowrx]

Joe was absolutely correct...get what you want, and dont worry about velocity...You will gain about 40 , maybe 50 fps velocity with each inch of barrel, not a huge amount of difference. I have Carbine barrels in all sorts of calibers in about every length from 16" to 24", and to me they seem to balance better with about 21 to 22" of barrel, but that is just what feels good to me with tapered barrels, which i prefer. With bull barrels, they feel OK a bit shorter. I doubt the deer would know the difference between a 2400 fps bullet & one going a hundred feet faster.
Either way, it aint gonna make your TCU into an Elephant gun.. My 7TCU carbine barrel is one of my favorites, i think you'll like it. In fact, i liked it so much i sold my 7x30 carbine barrel, since i never used either one at much over 100 yards. At that range, the TCU was quite adequate.

Ed had a 24" Bull 7TCU carbine barrel in stock a little while back, you might check with him if that is of interest.