Pet loads - JHP deformation when seating

JHP deformation when seating

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Category: Auto Mag Pistol
Forum Name: Pet loads
Forum Description: Shooters loads and results.
URL: http://www.amtguns.info/forum_posts.asp?TID=2862
Printed Date: 26 Mar 2026 at 11:29pm
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Topic: JHP deformation when seating

Posted By: firingpn
Subject: JHP deformation when seating
Date Posted: 26 Sep 2023 at 1:52am

Greetings,

Log time reloader here and Forum member. I'm having a problem seating my Nosler 240 gr JHP bullets without them being deformed to the point of them looking like Roundnose bullets. I'm using new RCBS .44 AMP tapper crimp dies and the Roundnose seating stem. Even without a taper crimp I still get significant deformation. Cases are new Starline brass, sized and slightly expanded for bullet seating.

Anyone else experiencing this problem? I've never had a problem doing any of my other handgun bullets; .44 mag, .357.....

Any comments would be appreciated.

Thanks

Replies:

Posted By: firingpn
Date Posted: 26 Sep 2023 at 1:55am

Also, I've the SWC seating stem and end up with Flat nosed bullets (no surprise.)

Posted By: omie01
Date Posted: 26 Sep 2023 at 2:21pm

I would measure the bullet diameter and make sure they are the .429 bullets, then I would check case diameter vs a known good bullet if you have one and see if there are any big differences. For some reason you have a lot of case neck tension, it is possible they have been resized too much, maybe check your resizing die. I love Nosler bullets and have loaded MANY of them and have never had any issues. Also maybe your bullet lot has thin jackets, or some other problem causing them to deform easily. Good Luck!!

Posted By: firingpn
Date Posted: 30 Sep 2023 at 1:17am

Thanks OMIE01

All measurements in spec. I ended up starting from scratch. Only had 7 deformations. I did find some of the Starline brass had rims a few thousands over which wouldn't slide into my Lee hand priming tool. But that wasn't related to the deformation issue.

Jaay

Posted By: Luc V.
Date Posted: 30 Sep 2023 at 5:27pm

First make sure your resizing die is not "oversize" the cases. Making them to small in diameter. (I had that issue on a couple of RCBS sizer dies)

The best way to seat those type of softnose JHP bullets is to make a custom seating stem.

If you have access to a lathe it's not that much trouble, If have no lathe, you might try the following:

1.Drill the original seating stem deeper and degrease it very well when done.

2.Set the seating stem upside down in a vise and fill the cavity with epoxy glue (resin).

3.Oil the bullet you want to use, and push it into the epoxy. Let dry and harden.

Carefully pry the bullet out, it get off easy because of the oil and clean up the epoxy.

4. You have now a custom made seating stem to the exact bullet shape.

This is however a sort of temporary help, the stem might wear out after couple of thousand settings...

Hope this helps.

Posted By: firingpn
Date Posted: 11 Oct 2023 at 11:54pm

Thanks Luc.V

I thought about doing that but figured there was an easier fix. Which appears to have solved the problem. Being a bit more accurate in my record keeping. Although, I do suspect the bras played a part in the issue.

Thanks again,

Jaay