Post by Richard on Jan 13, 2016 22:12:02 GMT -5
I started playing with putting a hollow cavity in the base of the 300 gr. SST last week. I only did five bullets and the cavity was not equal on all bullets…….close but not exactly the same. I did this by cutting a hole in the base with small counter-sink. The bullet was chucked in the lathe and r un in with the tail stock. As uneven as the depths were, the five bullets shot a one inch group at 100 yards……..so I felt I might be on to something??? Who knows with this stuff unless you try? My theory was that with the hole, it might allow the pressure to expand the base and give a better seal. Hollow bases have been used on other bullets both in shotgun, rifle and pistol so why not muzzle loaders.
So upon pondering the situation, I had to figure out (with the equipment I have) how to make the holes equal in depth? Running the countersink up to the shoulder would only be approximate. With that, I devised a collar that clamped onto the countersink to stop it from going only so far. The first problem I ran into was the swarf that came out of the bullet (copper and lead) had no where to go and stopped the countersink before it hit the stop. To remedy it, I had to mill two holes along side the countersink so the metal could flow out. Success! Mind you, this is done with a three jaw chuck. A collet chuck would be ideal. So now I get every bullet to right at 280 gr. give or take a half grain.
What I now wanted to test is the difference between shooting them with a .060” veggie wad, NO veggie wad and a bare bones bullet with no hole? Nothing I shot was conclusive but is giving me an indication that these bullets like to be shot with no wad so I plan to play some more. What also prompted me to try this route was due to the last 250 bullets I got from Weidners. They were marked Hornady SST – ML and their base had a very rounded edge. The base on a box I already had marked Hornady FTX, SST ML has a base almost as flat as the XTP. I prefer the flatter base. My thought is that some of the pressure buildup might be directed up alongside the bullet vs. on the entire base? So, in the event these did not shoot well, the hollow base might salvage them? BTW, they do not shoot that bad anyway but I think the hollow base shoots better………at least upon initial testing. I used the 10/60 duplex (Clays-H-4198) on all of these loads. I plan on trying a single of 78 gr. 4198.
My results showed five shot at 100 in at 1.0”………….Three at 300 in 2.0” and all five in 3.5”. When I shot at 300 with a wad I got 5.3” for five shots?
My final group of the day was shot with three 275 BE’s and the straight 78 gr. IMR-4198
load which measured 2..5” at 300. So, on this day, the Mickey Mouse altered 300 SST’s out shot the 275 BE’s. More shooting required!
