An alloy with decent tin and antimony content is needed to get good fill out and hardness on 223 bullets which are so small it is a struggle to get the mould up to temp. I preheat the mould on a hot plate to help with this.

A good gascheck design of approximate 55-60 grain weight and a modest 17-19 grain charge of powder similar to 4895 used with Dacron to position the charge will cycle the gun, lock it open when empty and shoot as well as most inexpensive factory FMJ. The key to easy effective results is to run the gun as slow as can be and still operate. Forget high velocity. Speed will be in the 1900 odd fps range. This is as slow as one can go and operate the gun.

When the rifle has a 200 yard zero with full power 55 FMJ these reduced loads will hit on at 100 yards, which is handy.

The Dacron is helpful to avoid velocity variations which give function problems at the necessary low speeds. These loads only partially fill the case which cannot be avoided.