Customizing an RCBS seater stem to fit the 200 grain XTP...

[Ridgerunner665]

Last night I discovered the RCBS seater stems don't fit the 200 grain XTP very good at all, they crush the nose upon seating ...what was even more disappointing was finding out you can't just buy a seating stem that will work either. RCBS makes stems for Gold Dots, but not XTP's.

So...I made my own, or rather, modified theirs.

I took the stem for truncated cone bullets and lit into it with the Dremel. I used a chain saw sharpening stone (#453) to do the work...took about an hour of careful work but it turned out great.

No crushed nose, no bullet scarring, and no excessive run-out.

Before on the left, after on the right.

[The_Shadow]

Yep, good job!  The only time I crushed the nose of the XTP was loading full compressed charges of AA#9.  They even pushed the bullet back out some...

[Ridgerunner665]

What dies do you use?

[The_Shadow]

I have a old set of RCBS 10mm (ONLY) dies (1990)  has two seater stems, one is TC the other is Gold Dot.  I do seat and crimp separately.  I have to place a 1/8 " spacer under the lock ring to raise the die high enough to prevent the taper from closing the casing back against the bullet while seating.  That is why I don't get the ring or closure of the HP on the Hornady XTP's.  The bullet is free to move inside unimpeded.  The taper starts closing the casing too fast if trying to seat and crimp in the same step.

After I seat all of my bullets of a run, I remove the spacer because the lock ring is set for crimping operation, and back the seater stem out as not to contact the bullet.

[Benchrst]

Nice job!

Like Shadow, the only time I've collapsed the nose of an XTP was compressing (125%, according to QuickLOAD) #9.

#s were worth it

[Ridgerunner665]

I don't crimp at all for pistol rounds, just remove the bell.... Been doing that for 45acp for many years now.

With the 10, I just barely bell the mouth, no crimp, and when I seat the bullet the mouth comes out to .422"-.423", as is.

The seater plug was crushing the nose with no crimp at all.

[The_Shadow]

BTW Ridgerunner your stem is the newer type like the one in my 40S&W crimp die. 
My old 10mm only dies have a 1/4" thread stem that loads in from the bottom side of the die is slightly different inside.

Here are both


Another view of the older 1989 stem

[Ridgerunner665]

Yep.... I have some of both types too.

One set of 45 dies (I have 2) and my 38/357 dies have the 1/4" shaft.

[triggerman10]

I use Lee dies and never noticed a problem.

[Ridgerunner665]

I finally got a set of Hornady 10mm dies, these are just all around better dies I think...better seating stems, better function, better design, better everything.

The modified RCBS dies worked but were limited to that one bullet type unless I got other seating stems...the Hornady dies work just fine with Nosler and Hornady hollowpoints, seating the bullets off the ogive by design, without modification.

[Benchrst]

I finally got a set of Hornady 10mm dies, these are just all around better dies I think...better seating stems, better function, better design, better everything.

I'm glad they're working out for you Rudgerunner.

Not something you normally hear about Hornady dies.

[Ridgerunner665]

Just don't crimp and seat with them, but I've never done that anyway... Always did what little crimping I do in a separate operation.

[Ridgerunner665]

Took this modification to the RCBS seater plug a step further yesterday...

Used Gorilla brand epoxy to custom fit the seater plug to the 200 grain XTP, just tested it out... It appears to be a success, the bullets look like they were seated at the factory.

Pretty simple to do.

Fill the nose cavity of the bullet with modeling clay.

Rough up and enlarge the inside of the seating plug... I used a Dremel.

Pick a bullet that doesn't have any imperfections on the important parts... Below the skives, above the case mouth.

Coat that bullet and the outside of the seater with Kiwi neutral shoe polish.

Put the epoxy in the seater, place the bullet in the seater plug, put them in a vice under light pressure (just enough to hold them in place and straight), wipe the excess epoxy from the outside of the seater plug... Let that sit for at least 6 hours, and don't use it for 24 hours.

Presto! A custom seater plug.

[Spudmeister]

Took this modification to the RCBS seater plug a step further yesterday...

Used Gorilla brand epoxy to custom fit the seater plug to the 200 grain XTP, just tested it out... It appears to be a success, the bullets look like they were seated at the factory.

Pretty simple to do.

Fill the nose cavity of the bullet with modeling clay.

Rough up and enlarge the inside of the seating plug... I used a Dremel.

Pick a bullet that doesn't have any imperfections on the important parts... Below the skives, above the case mouth.

Coat that bullet and the outside of the seater with Kiwi neutral shoe polish.

Put the epoxy in the seater, place the bullet in the seater plug, put them in a vice under light pressure (just enough to hold them in place and straight), wipe the excess epoxy from the outside of the seater plug... Let that sit for at least 6 hours, and don't use it for 24 hours.

Presto! A custom seater plug.

Very nice Ridgerunner!  It's a creative solution to an aggravating problem.

I run Lee dies and have the problem with XTP bullets.  Always a little and a lot when pushing the bullet against a full charge of AA9.  Lee says I can send a specific bullet into them and they will design a seating punch for it.  Keep meaning to do it but mostly shoot lead bullets. 

In any case, thank you for sharing your success and ingenuity.