Lyman M die vs. Dillon RL550B funnel

[El Bibliotecario]

I understand the purpose of the Lyman M die is to expand the resized case neck to accept a cast bullet without deforming it. It seems the funnel used with the Dillon RL550B to charge the case with powder when appropriately adjusted serves the same purpose, thus eliminating a need for the M die. I invite comment, pro or con.

[guywitha3006]

My experience (with a 650 but same funnels is my understanding) is they are for jacketed bullets and so the tend to be too tight for cast boolits. The Dillon funnels also do not have the wider step that the m dies do that make seating the bullet a bit easier.

[garandsrus]

The Dillon powder funnels work fine with cast bullets most of the time.

[Marcduper]

I have been making my own expander/funnels for a long while. The right amount expansion to the required size needed for my pistols has very much improved my groups. Improvments from 38 wad cutters to 44 mag 240gr. I never had any luck with the Dillon funnels with cast bullets.

[BrassMagnet]

Dillon pistol funnels work fine.
Dillon rifle funnels don’t because there is no expansion.

[Petrol & Powder]

I had Lathesmith make a couple of handgun cartridge powder funnels for a Dillon 550. The powder through expanders (Dillon powder funnel) that Dillon supplies are not optimal for cast bullets. The Dillon funnels work but they don't expand the case enough for cast bullets and the casing tends to swage soft lead bullets down a little bit.
The Dillon powder funnels also lack the Lyman "M" die type "step" that helps to align cast bullets before they are seated.

The powder funnels that Lathesmith made for me are absolute game changers. I highly recommend them.

The stem of the Dillon powder funnel is a bit small for cast bullets and the top of the funnel flares the mouth of the casing in a cone shape as opposed to the more parallel flare that the "M" die profile imparts to the casing.

[sigep1764]

Agree with Petrol. Lathesmith made me one for my SDB which works in the 550 as well. My OEM Dillon funnel plug expanded the brass .353 for 9mm allowing the brass to swage down my boolits. The one he made for me expands deeper and wider without overbelling the case mouth and cracking it. Its loaded prolly 50k 9mm in the last 3 or 4 years. His work is good and he's a helluva nice guy to talk to.