Enfield-Rifles.com Homepage
Forum Home Forum Home > Reloading > Reloading .303 British
  New Posts New Posts RSS Feed - Mexican Match
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Mexican Match

 Post Reply Post Reply
Author
Message
britrifles View Drop Down
Senior Member
Senior Member
Avatar

Joined: February 03 2018
Location: USA
Status: Offline
Points: 972
Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Topic: Mexican Match
    Posted: July 11 2019 at 4:06pm
Ive got a fair bit of Canadian Mk VIIZ service ammo.  Accuracy is quite good for some of the ammo, others more typical of issue service ammunition.  

So, I had an idea to make up some “Mexican Match”, a term used to describe pulling bullets on factory rounds and substituting a Match grade bullet.  

To start this test, I first selected DAC 1951 Mk VIIz,  Large Berdan primer, loaded with 38.5 gr of a stick powder that resembles IMR 3031.  

I first broke the sealant used on the bullet by pushing it into the case slightly using the seating die.  Then pulled the bullet with a collet type puller.  Cases had been taper crimped into the cannelure so had to take a firm grip on the bullet.  Dumped powder into the weight scale pan, chamfer inside of neck, ran empty case into a Lee Collet neck sizer (cut off the decamping pin integral with the mandrel on my spare), refilled case and seated 174 gr SMK.  The neck sizing was necessary as the 174 gr SMK was loose in the case neck.  

I don’t know if the collet puller damaged the bullets, but I took 20 of the pulled bullets and loaded these with my standard match load:  40.0 gr Varget under 174 gr SMK, RP case, CCI #200 primer.  

I also had a bucket of pulled Mk VII bullets my day had acquired back in the 1960s, so I loaded 20 of these with 40.0 gr Varget.  I don’t expect great accuracy with these bullets.  

I’ll chrono and shoot for accuracy off the bench from No. 4 Mk I(T), it will give a good comparison of the two Mk VII bullets and the SMK. I will include the service DAC 51 Mk VIIz ammo as loaded. I’m curious how the different bullets will perform in terms of velocity and accuracy with the same powder charge.  The SMK has significantly less bearing surface area so I suspect it will produce a higher MV, and obviously, better accuracy.

Bullets left to right:

Mk VII from Defence Industries DI 1943
Mk VII from Dominion Arsenal DAC 1951
174 gr Sierra MatchKing

The Mk VII bullets measured 0.312 and the SMK are 0.311 diameter.






Back to Top
Sponsored Links


Back to Top
Shamu View Drop Down
Admin Group
Admin Group
Avatar
Logo Designer / Donating Member

Joined: April 25 2007
Location: MD, USA.
Status: Offline
Points: 11047
Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: July 12 2019 at 6:23am
That's a whopping difference in the 2 MkVII crimp grooves!
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
Back to Top
britrifles View Drop Down
Senior Member
Senior Member
Avatar

Joined: February 03 2018
Location: USA
Status: Offline
Points: 972
Post Options Post Options   Thanks (1) Thanks(1)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: July 12 2019 at 6:54am
Sham, the case necks are choked to the bullets at different locations.  

DI ‘43 on left, with three horizontal crimps midway down the neck into bullet cannelure. 

DAC ‘51 on right, taper crimped at case mouth into bullet cannelure. 


Back to Top
Shamu View Drop Down
Admin Group
Admin Group
Avatar
Logo Designer / Donating Member

Joined: April 25 2007
Location: MD, USA.
Status: Offline
Points: 11047
Post Options Post Options   Thanks (1) Thanks(1)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: July 12 2019 at 8:06am
Ahh! that explains it, thanks.
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.