Cast bullets and blowback

[Mustafa]

Hey all. I recently started casting for my 9mm and loading bullets. I took a load out to test the other day 3.5grains of TiteGroup 140 Grain bullets. The group was pretty big and ugly, but what really concerned me was that I seemed to be getting hit in the face with debris or blowback of some type when I shot. Any ideas on what is causing this and how I can fix it?
Thanks!

 

[FN in MT]

What firearm? Bullet? Lube? Sized to diameter?
Cast in many 9mm's can be problematic. Groove diameters run all over the place from small to large affecting bullet seal. Many get poor accuracy and leading as they are shooting a too small bullet down a large bore.

I learned to slug the bore with a pure lead slug. Read that with a good micrometer, then size your cast to .001" over bore diameter.

Bullet design, lube, alloy hardness even powder burn rate, fast or slow can ALL have an affect as well.

But...Once you have your sized diameter figured out the path to an accurate load gets a lot easier.

FN in MT