The new 33XC & 37XC cartridges designed by David Tubb

Jim Boatright

New Hide Member
Feb 21, 2018
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#51
I fear my earlier reply to this question from Skookum got lost when my internet service went down.

I cannot foresee any possible deleterious effects of shifting the tripping ring back about an inch behind the tip of any rifle bullet. For those bullets which can benefit from adding such a ring, it would not matter where it is relative to the ogive/body junction or any other break in the surface angles. The boundary layer L/T flow transition occurs after about 1.25 to 1.5 inches of laminar flow even for a flat plate in a wind tunnel. By shifting the transition point back about an inch, more of the bullet would experience the significantly lower-drag laminar flow.

One could ask David about this change, since he probably tried it.
 
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Skookum

Entropy Personified
May 6, 2017
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#52
I fear my earlier reply to this question from Skookum got lost when my internet service went down.

I cannot foresee any possible deleterious effects of shifting the tripping ring back about an inch behind the tip of any rifle bullet. For those bullets which can benefit from adding such a ring, it would not matter where it is relative to the ogive/body junction or any other break in the surface angles. The boundary layer L/T flow transition occurs after about 1.25 to 1.5 inches of laminar flow even for a flat plate in a wind tunnel. By shifting the transition point back about an inch, more of the bullet would experience the significantly lower-drag laminar flow.

One could ask David about this change, since he probably tried it.
Thank you for that answer, it makes sense.

In light of what you've said, it would make sense also that Tubb would want to put the ring farther forward to market his ringing tool more effectively. Because you can't know what bullet will be ringed, the further back you place it, the more likely it will not work for any single particular bullet. I'm not knocking or criticizing that, I'm just drawing logical conclusions. As long as it still has the advertised effect, more power to him.
 
Feb 12, 2017
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#55
Anyone else building or already built a 33 or 37xc? I just received my brass for the 33xc and made a modified case for checking seating depth. Here is a comparison pic of the 33xc vs 375 cheytac:
IMG_20181111_114743614.jpg
Here's the 33xc with a 277 single feed cutting edge mtac in a CIP length AI mag:
IMG_20181111_121145046_LL.jpg
Just wondering what action you guys chose to build on? It's definitely going to be a single feed cartridge unless you build on a cheytac length action.
 
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Bradu

Full Member
Aug 24, 2011
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#56
Anyone else building or already built a 33 or 37xc? I just received my brass for the 33xc and made a modified case for checking seating depth. Here is a comparison pic of the 33xc vs 375 cheytac:
View attachment 6969094
Here's the 33xc with a 277 single feed cutting edge mtac in a CIP length AI mag:
View attachment 6969099
Just wondering what action you guys chose to build on? It's definitely going to be a single feed cartridge unless you build on a cheytac length action.
Can you buy dies for the 33xc or are they going to have to be custom made?
 
Feb 12, 2017
827
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Michigan
#59
I'm waiting to see if the Ultra 338 suppressor can be used with it first before I order one.
I'm waiting for the same thing. Hopefully we will get an answer this week. It will determine weather I thread my barrel for the 338 ultra or my Desert Tech (elite iron) 375 can.
 
Jan 22, 2013
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#60
Anyone else building or already built a 33 or 37xc? I just received my brass for the 33xc and made a modified case for checking seating depth. Here is a comparison pic of the 33xc vs 375 cheytac:
View attachment 6969094
Here's the 33xc with a 277 single feed cutting edge mtac in a CIP length AI mag:
View attachment 6969099
Just wondering what action you guys chose to build on? It's definitely going to be a single feed cartridge unless you build on a cheytac length action.


What COAL is that.
 

Jim Boatright

New Hide Member
Feb 21, 2018
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#61
It looks like the 33XC chamber is 0.35-inch longer than that of a 338 LM, so COAL would run about 4.50 to 4.60 with long copper bullets seated out.