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Opinions; 6.5 or 7 TCU in an AR15

FreezerFreezer Senior MemberPosts: 1,756 Senior Member
Why hasn't the 6.5 or 7 TCU been popular in the AR15. The 6.5 TCU performs well compared to the 6.5 Grendel without being a barrel burner. Both can be adapted to an AR without major modifications. Both are very efficient and can be used for hunting deer and pig. 
Why haven't they caught on?
I like Elmer Keith; I married his daughter :wink:

Replies

  • Diver43Diver43 Senior Member Posts: 10,905 Senior Member
    First guess would be commercial availability
    Logistics cannot win a war, but its absence or inadequacy can cause defeat. FM100-5
  • mitdr774mitdr774 Member Posts: 1,445 Senior Member
    It seems to run a little slower than 6.5 Grendel, which can be run in an AR.  Even 6.5 Grendel seems to be dropping off in popularity.  I really like my Grendel so far though.
  • knitepoetknitepoet Senior Member Posts: 21,089 Senior Member
    I have 2 Grendels, and a 7TCU Contender
    1) COAL too long for the 2.26" AR mag (2.4" "standard with 6.5TCU) Not sure the ogive will be outside the case mouth if loaded to mag length.
    2) Lack of powder capacity. Using the Quickload defaults, the Grendel has a water capacity of 37.5gr. The 6.5 TCU has 32.3gr

    Running the 2 rounds through QL using a 120 Ballistic Tip w/20" barrels fastest load is ~2350 in the TCU, and ~2550 for the Grendel.

    200fps doesn't sound like much, but that's roughly the gain you get going from a 30-06 to a 300win mag

    I just used the 6.5s so I could compare using the same bullet.

    I KNOW, to get to 2.26" it's going to seriously cut into the powder capacity on the 7TCU and it doesn't have any to spare
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


  • FreezerFreezer Senior Member Posts: 1,756 Senior Member
    Knitepoet , thank you, you hit the nail on the head. I had a Model 7 in 7 TCU and it was a great quiet 200 yard deer rifle. Very accurate and efficient. The Grendel may be a bit faster but it's a barrel burner. It's not as efficient and will cost you in the log run for  small return. At best it's a 250 yards deer cartridge. 
    I like Elmer Keith; I married his daughter :wink:
  • knitepoetknitepoet Senior Member Posts: 21,089 Senior Member
    edited January 2019 #6
    I disagree with you on a couple of points
    1) In my experience, the Grendel is NOT a barrel burner. 25-30gr of rifle powder is not a huge amount to put down the bore every shot. Much less than a 308. or, staying with the .264 bore, 260 Rem, neither of which are known as "barrel burners" (Actually, close to the same amount of a different powder [seriously compressed] I use in my TCU loads)

    2) With a 123 SST or Amax at 2500fps (easily doable with my 24" barrel) I am comfortably above the 1800fps expansion "floor" well past 400 yards. Which is further than I can see game anywhere I hunt. However, I'd have no qualms taking a shot at 400yds with it, if my hunting situation changed. (Yes, I have my confirmed DOPE, in 100yd increments IIRC,  out to 500 with it, on a laminated card I carry with me)

    edited because I looked at the xcel file on my computer and I had the distance increments for my DOPE card incorrect
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


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