300 PRC 220gr A-Tip COAL

[gtarplaya2k]

Hello there, I'm new to handloading and wanted to make some rounds for my Browning Xbolt 300 PRC. After shooting ~100 rounds of Hornady ELD-M I took a few of the brass. Everything with the brass looks good on size. The issue is, if I seat the A-Tip with a COAL of 3.663, which matches the measurement I took of the factory ELD-M, the bolt will not close all the way. I need to bring the COAL to 3.552 to get it to fully chamber. Is this normal? My biggest concern is if they are even safe to shoot.

 

[DaveTooley]

You have to load to fit either the magazine or the chamber. Not knowing your powder charge, myself or anyone else can't say whether it's safe.

 

[gtarplaya2k]

I loaded up a ladder from 76.3 to 78.7 in .3 increments of retumbo powder.

 

[gtarplaya2k]

My concern is more the why the rounds don't fit when the ELD-M's do and are longer. Could the bullet not be straight? I assume that would be catastrophic.

 

[Mike TackleBerry]

Hello there, I'm new to handloading and wanted to make some rounds for my Browning Xbolt 300 PRC. After shooting ~100 rounds of Hornady ELD-M I took a few of the brass. Everything with the brass looks good on size. The issue is, if I seat the A-Tip with a COAL of 3.663, which matches the measurement I took of the factory ELD-M, the bolt will not close all the way. I need to bring the COAL to 3.552 to get it to fully chamber. Is this normal? My biggest concern is if they are even safe to shoot.

A-tips are not ELD-M and have different bullet geometry, You need to get a headspace comparator tool and find touch in your barrel with the A-tips, then decide if you want to jump them or jam them.

 

[gtarplaya2k]

Conveniently, I have an OAL gauge and modified case coming today. I guess that will help confirm?

 

[Mike TackleBerry]

My concern is more the why the rounds don't fit when the ELD-M's do and are longer. Could the bullet not be straight? I assume that would be catastrophic.

The 230 A-tips have a BOAL of 1.762 and a B2O of around 0.940. The 225 ELD-M have a BOAL of 1.656 and a B2O of .890 i believe. While technically a secant ogive, the A-Tip features a refined profile that leans toward the behavior of a hybrid ogive more than a secant.

 

[Mike TackleBerry]

Conveniently, I have an OAL gauge and modified case coming today. I guess that will help confirm?

Absolutely, it's not going to be 100% perfect, but it will get you close. I do 3 separate measurements, then take the average, and that's my bullet touch measurement. Find that measurement and jump the bullet .020 and use that to begin your load development. If you want to jam the bullets, take the touch measurement and add + .010 to + .020, and go from there, but make sure to start the powder charges by 5% less and work your way back up.

 

[gtarplaya2k]

Just measured out to 3.834 touching. So I'm assuming something is definitely not right.

 

[Mike TackleBerry]

Just measured out to 3.834 touching. So I'm assuming something is definitely not right.

That's the COAL, That sounds about right to me for a 300 prc with 230 a tips. Take .020 off the 3.834 (3.814) and use that as a starting point for your load development.

 

[gtarplaya2k]

I do have a bore gauge that the brass fits in without a bullet. Once the bullet is added at say 3.663 it no longer fits in the bore gauge until I make it ~3.552. Could the bullet not be seating correctly? I'm using a Lee Bullet Seating Die with the micrometer. From what I've read, the die is very universal in bullets and shouldn't be an issue with the A-Tips.

 

[gtarplaya2k]

Doing some more digging, it seems maybe my neck is not getting expanded enough by the sizing die and is causing compression and bowing of the case.

 

[gtarplaya2k]

Ah ha so documentation says the neck should be .341 for the 300 PRC but after running through the lee decapping and resizing die it seems the neck is only 0.336. Do I need to get an additional die to expand the neck? It seems my full lenght resizing die makes the neck too small.