7mm wildcat help

[new wildcatter]

I recently 'borrowed' my late uncle's 14" t/c from my aunt. here lies my problem, he had a 7tcu rechambered to his own? creation. It is a shortened 7mmSTE, i think. using 307 cases, he cut them off to 1.905, reset the shoulder and neck to be the same as a 7-08. the dies are rcbs 7-08 with the correct amt cut off the bottom. Wildcats are new to me, and i'm not getting the fps expected. My uncle died before he could do any serious load developement. His notes say that the cases hold 4-6% more powder than a 7-30, maybe a 7-30AI equivelant, with shorter, fatter, more PPC like case.
  My best loads w 120gr horn sp are 42 gr H380, and 37 gr of AA2460, both reaching 2400 fps, at 10' from the muzzle. That barely duplacates 7-30, and it uses more powder to boot. any suggestions?

[poule d'eau]

I would say to maybe look at some of the JDJ calibers, seems there is one fairly close to what you are talking about. Other wise maybe try the 7-30 AI data.
Jeff

[New Hampshire]

There is a Wildcatting forum here on GBO.  You might find some better answers there, but no promises  :grin: .  I sure do like the idea of wildcatting.  Maybe someday Ill get into it myself.  
Anyways, good luck in your venture.
Brian M.

[Graybeard]

Rule of thumb is a 4% increase in powder capacity should equate to a 1% increase in velocity. Some times it works just the opposite tho. In the real world 2400 fps is not always reached in the 7-30 with safe pressures. You have to have a really fast barrel to reach 2450 fps at safe pressures. That is from 14" barrels.

If the load is accurate just be happy with what you have. Another 100 or even 200 fps will not kill game any deader or any further.

GB

[Steve P]

I think you need to look toward different powder combinations.  The case and sizing etc is similar to some of the Bower Wildcats.  Don Bower always recommends loads where powder nearly fills the case.  Use slower powders like H414, H4350, etc.  Try some of the 7-30 water loads and slowly work up.  See if this helps.

Steve  

[new wildcatter]

here are my test results so far:
37.5 4064=2266 fps
38.0 bl-c2=2375, EXCESSIVE MUZZLE BLAST it blew the chrony sideways at 10 ft
37.0 AA2460=2410fps
38.0    ''       =2500fps- HOT flat primers
44.0 H414    =2215  powder compressed
42.0 H380  = 2412  max

 I have loaded 35,36,37 gr IMR 4895, and 38, 39, 40 gr WW760, but haven't got a chance to shoot them yet. also am going to try approx 37 gr ww748.
 all results are at 10 ft from muzzle