XTP vs. Jacketed Load Data

[duxfearme]

I'm new to reloading and have a question regarding load data in my Lee manual. I've noticed that in the different bullet categories, it singles out XTP bullets from Jacketed bullets. Can someone explain this to me? Do all jacketed bullets fall under the category of "Jacketed" bullets except for Hornady XTP's or does XTP refer to a more generic JHP.

For example, if I were to buy some Montana Gold JHP's, would I use the "Jacketed" load data, XTP load data or both? I've noticed that if they have a common powder, they are usually very close in charge amounts.

[10fcp]

I'll take a jab at this but hopefully someone else chimes in. I went through this a while back. Someone on another mesage board was saying some styles of hollow pionts have a deep hollow section. These I believe seat deeper in the case when loaded to the standard OAL. I think the differance between XTP's and others will be XTP's being seated deeper leaving less case capacity between bullet base and powder. I hope this helps. Best bet is to get lots of sources, manuels from bullet makers and powder manufactures.

[merritt]

Part of this is that not all bullets are made equally and the sources of load data want you to know who's they are using. XTPs are a popular hollow point so they show up in load tables often.

Sometimes data points will be more vague like "cast lead" and "jacketed" which will tend to show up when there is a relatively standard bullet that can be sourced from many places (for example most 230gr .45acp hardball rounds are similar)

Frequently you will have to guess when you use a bullet and just look at all relevant data points (in this case probably use the lower starting point of XTP and JHP) and use pressure signs and performance as the ultimate determination of how you will load your rounds.

hollow points (esp. for pistols) seat and load differently. they tend to be longer than similar weight JRNs (again for pistols) so things like case capacity and velocity will be different

[duxfearme]

Thanks guys. It sounds like if I'm using a JHP, the load data will probably be somewhere between the generic "Jacketed" load and "XTP" load... maybe even closer to the XTP since the JHP bullet will probably be longer than standard ball.

Since I'm looking for a low-recoil practice load anyway, it sounds like I get to have fun playing with some lighter loads until I find one I like (that won't kB! my gun!) :D

[mike100]

The XTP is a common/popular enough JHP design to merit load data in manuals. Also, hollow-point load data goes higher as it seems that the mass of the bullet is more rearward and on the circumference with the middle being hollow and all. My theory is that they engage the rifling and don't resist the twist as much as a solid bullet design. they spin easier-basically.

[Black_Talon]

It's about bearing surface. JHP's with big 'ol hollow points have longer bearing surface than the same weight bullet without a hollow point displacing internal volume. Longer bearing surface equals higher friction, higher friction equals higher pressure, all other things being equal.