Seating Sierra flat based 6mm 75gr. hollow points with a Lyman M die.

[Xerothermic]

I confess that I've never reloaded flat-based bullets. I've never had a problem reloading boat-tails but this "M" die and flat-base is new to me.

Putting old school aside, I'm into older rifles with wood, I would like to know of any tips or knowledge regarding the seating of these bullets. Guidance on using the neck flaring part of the "M" die mandrel, should I run into problems seating the bullets, would be appreciated.

Kinda vague, I know, but if I can learn from those that use the "M" die for rifles it might save some grief on my end. I will be using Hornady 6mm Remington brass sized/trimmed/deburred/graphited necks but the expander ball, even with using graphite, seems to require quite a bit of effort to extract. So, I'm going to give this "M" die a whirl.

That's my story. I've read a lot on this subject (secondscount's thread) amongst others but the use of the flaring feature is mentioned little if at all. (my bullets are still crawling across country by the way)

 

[RegionRat]

You obviously see the issue ahead of you, so when you get those FB bullets you will be able to experiment with how they seat and the brass prep options.

BTW, there are also very simple universal rifle sized flare dies that can also be an option.

You will want to play around with all of these, plus your chamfer process, trim, lube, cleaning, etc.,, and decide on your best prep process.

 

[kenhwind]

I've been using the Lyman "M" dies for years as I shoot the Winchester Model 94's and those bullets are flat based. The "M" die doesn't actually flare the case as much as just expands the case mouth. So what you need to do is set the die up so that you can set you bullet in the case mouth. If you're using the "M" die the expander plug in the sizing die may not be necessary, although I use them.

If it seems hard to do try some dry lube.

I generally size my brass then run them into the "M" die, then trim if needed, etc.

 

[Webster]

I confess that I've never reloaded flat-based bullets. I've never had a problem reloading boat-tails but this "M" die and flat-base is new to me.

Putting old school aside, I'm into older rifles with wood, I would like to know of any tips or knowledge regarding the seating of these bullets. Guidance on using the neck flaring part of the "M" die mandrel, should I run into problems seating the bullets, would be appreciated.

Kinda vague, I know, but if I can learn from those that use the "M" die for rifles it might save some grief on my end. I will be using Hornady 6mm Remington brass sized/trimmed/deburred/graphited necks but the expander ball, even with using graphite, seems to require quite a bit of effort to extract. So, I'm going to give this "M" die a whirl.

That's my story. I've read a lot on this subject (secondscount's thread) amongst others but the use of the flaring feature is mentioned little if at all. (my bullets are still crawling across country by the way)

Don't understand the need for M dies. I have been reloading 6mm flat base bullets for 50 years with standard dies. Flat base bullets are not squared off at the back, there is a radius. All my bullets seat with very little force. If your die sizes the mouth to small I could see a problem. For the last ten years I have been using bushing dies to control neck sizing. Make sure the bullet looks straight on the case mouth before you pull the lever.

 

[AWS]

with an inside chamfer you shouldn't need a "M" die. The only time I use one is for cast bullets and even there seldom.

I will say that the Hornady seater with the sliding sleeve keeps them aligned better.

 

[Doom]

I load flat based bullets in 223 all the time and I don't do anything special other than chamfer the neck. Never had a problem. Pulled bullets show no issues. The only issues I can see come from too much neck sizing or if the neck is too hard.

 

[Xerothermic]

Don't understand the need for M dies. I have been reloading 6mm flat base bullets for 50 years with standard dies. Flat base bullets are not squared off at the back, there is a radius. All my bullets seat with very little force. If your die sizes the mouth to small I could see a problem. For the last ten years I have been using bushing dies to control neck sizing. Make sure the bullet looks straight on the case mouth before you pull the lever.

I bought the 6mm "M" die mostly for the mandrel with the flaring option as needed. My Lyman sizing die expander plug really works the brass on extraction even while using graphite.

I put my readers on and used a magnifying glass to see that there is indeed an ever so slight bevel. (Sierra 75 gr/HP) I probably jumped the gun on the "M" die, but I have had excellent results loading 9MM pistol with one and the flat based bullets.

Thank you, for posting your experiences with the flat base 6mm bullets in that I really don't want to add a de-flaring step to the process.