DIY Custom Seater Plug: 45-70, 459-500-3R Lee

Barnacle Brad · March 18, 2013, 07:05 PM

I made a seater plug to seat this 500gr bullet for my trapdoor. I had read about guys modifying their plugs using hot melt glue to form to the bullet profile, but the std seater die (RCBS) is designed for a FN bullet and therefore not deep enough to accommodate the long profile of this bullet.

When using a soft lead alloy (20:1) and even without factoring in the compression of BP, the nose of the bullet was being mashed out of shape when seated.

The solution was a 40 s&w case. When belled, the bullet fit far enough down the case to provide good support on the ogive for the seating process. Filling the case with hot melt provides enough surface area over the bullet to seat without any distortion or marks from the seater.

To make the seater plug:
(your RCBS die set may differ from mine. Check your stem diameter and thread pitch before starting!!)

Step 1: Prepare the cup for your plug.
Drill and tap the .40 case (decapped and neck sized with bell) with 1/4 - 28 threads

Step 2: Make the adjustment stem.
Cut 1/4 - 28 threads to 3" length on .25 round stock. (if you live in an area where you can easily obtain a 3 or 4 inch 1/4 - 28 screw, this step can be omitted)(duh)

Step 3: Mold bullet in hot glue.
With the stem screwed into the cup flush with inside of case head, squirt an amount of glue into the plug to cover the bottom of the 'cup' and let harden. Then fill the case to half with glue and press your lightly oiled bullet into the cup until it contacts the case neck. Let the glue harden and remove the bullet.

Notes:

I had to do step 1 two times. The first attempt yielded a plug that threaded a little cockeyed on the stem. Second effort was a little wonky but I ran with it.

Step 3 is not real easy to get the bullet centered. I tried to figure out a way to use the press for this operation, but failed to get good results. I did find that if you are not happy with your results - instead of digging the hard glue out of the case, stick your glue gun tip into the case and melt it out. In fact, my glue tip fit in about as far as the bullet did and with a narrower diameter. I lubed the glue gun tip before I inserted it to try and avoid drawing the glue back out of the cup, then pushed the bullet in to fill the cavity. Play with it you might figure something out that works better. Let me know!

No this is not a high tech solution or even something that I have high hopes for surviving very long, but it will work for me until one of you steps up and offers to machine one or two out for me.

Seriously though - if anyone has made a machined seater plug for this bullet I am interested in details. I can also provide detailed drawings if someone would like to play in their shop and build one or two. Hit me up! I don't mind paying if you don't mind playing!

Thanks for looking at my project. If anyone is interested I can provide some photos.

lll Otto lll · March 18, 2013, 07:14 PM

Send RCBS 3 sample bullets and they'll custom make a seater plug for a reasonable fee.

Barnacle Brad · March 19, 2013, 11:29 AM

Thanks Otto. I put in a request to RCBS!

March 18, 2013, 07:05 PM	#1
Barnacle Brad Senior Member Join Date: March 12, 2009 Location: Greybull, Wyoming Posts: 416	DIY Custom Seater Plug: 45-70, 459-500-3R Lee I made a seater plug to seat this 500gr bullet for my trapdoor. I had read about guys modifying their plugs using hot melt glue to form to the bullet profile, but the std seater die (RCBS) is designed for a FN bullet and therefore not deep enough to accommodate the long profile of this bullet. When using a soft lead alloy (20:1) and even without factoring in the compression of BP, the nose of the bullet was being mashed out of shape when seated. The solution was a 40 s&w case. When belled, the bullet fit far enough down the case to provide good support on the ogive for the seating process. Filling the case with hot melt provides enough surface area over the bullet to seat without any distortion or marks from the seater. To make the seater plug: (your RCBS die set may differ from mine. Check your stem diameter and thread pitch before starting!!) Step 1: Prepare the cup for your plug. Drill and tap the .40 case (decapped and neck sized with bell) with 1/4 - 28 threads Step 2: Make the adjustment stem. Cut 1/4 - 28 threads to 3" length on .25 round stock. (if you live in an area where you can easily obtain a 3 or 4 inch 1/4 - 28 screw, this step can be omitted)(duh) Step 3: Mold bullet in hot glue. With the stem screwed into the cup flush with inside of case head, squirt an amount of glue into the plug to cover the bottom of the 'cup' and let harden. Then fill the case to half with glue and press your lightly oiled bullet into the cup until it contacts the case neck. Let the glue harden and remove the bullet. Notes: I had to do step 1 two times. The first attempt yielded a plug that threaded a little cockeyed on the stem. Second effort was a little wonky but I ran with it. Step 3 is not real easy to get the bullet centered. I tried to figure out a way to use the press for this operation, but failed to get good results. I did find that if you are not happy with your results - instead of digging the hard glue out of the case, stick your glue gun tip into the case and melt it out. In fact, my glue tip fit in about as far as the bullet did and with a narrower diameter. I lubed the glue gun tip before I inserted it to try and avoid drawing the glue back out of the cup, then pushed the bullet in to fill the cavity. Play with it you might figure something out that works better. Let me know! No this is not a high tech solution or even something that I have high hopes for surviving very long, but it will work for me until one of you steps up and offers to machine one or two out for me. Seriously though - if anyone has made a machined seater plug for this bullet I am interested in details. I can also provide detailed drawings if someone would like to play in their shop and build one or two. Hit me up! I don't mind paying if you don't mind playing! Thanks for looking at my project. If anyone is interested I can provide some photos. __________________ Brad

March 19, 2013, 11:29 AM	#3
Barnacle Brad Senior Member Join Date: March 12, 2009 Location: Greybull, Wyoming Posts: 416	Thanks Otto. I put in a request to RCBS! __________________ Brad

March 18, 2013, 07:14 PM	#2
lll Otto lll Senior Member Join Date: June 1, 2008 Location: Lone Star State Posts: 295	Send RCBS 3 sample bullets and they'll custom make a seater plug for a reasonable fee.