Reloading .303 British : Mexican Match

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.