Differences in JHP and FMJ for same load?

[txaggie]

Let’s say I have a load that I really like (felt recoil, POI/POA) using 147g FMJ bullets, what differences would I expect to see if I used 147g JHP? Assume using same weight/type powder, same OAL, etc...

In other words, if I liked the load for my target rounds, could I expect the same performance in a defensive round of the same load?

And my final question for this thread, do you use hand loaded ammo for your defensive carry rounds?

[BigDave]

You need to measure the OAL of the bullet itself to give you an idea. If they are the same OAL, there should be no difference.

I used to shoot Star 180 JHP's (40). Those bullets were about 0.010 longer than the 180 FMJ's I was using? If seated to the same OAL, the JHP decreases case capacity by 0.010" over the FMJ = higher pressure. Currently, under the same primer and powder charge, the JHP's make 175 PF, the FMJ's, 169.

YMMV depending on how sensitive your powder is to case capacity.

[BritinUSA]

And my final question for this thread, do you use hand loaded ammo for your defensive carry rounds?

<{POST_SNAPBACK}>

I would advise against hand-loaded ammo for defensive uses. If you ever had to shoot someone, a case could be made that you had made the rounds 'more lethal' by hand-loading (ie. increased velocity etc.).

I think it's better to stick to factory ammo, just to be on the safe side.

[Larry White]

I dont use reloads in my carry gun, enough legal problems there without that one. I use JHPs for my match load, in fact everthing. No exposed lead at the base, no smoke and a cleaner gun. You may have to adjust OAL because of bullet length or nose profile.------Larry

[txaggie]

Thanks for the answers and advice.

[kevin c]

There is a difference in case capacity between the same weight and length JHP vs FMJ loaded to the same length. All the JHP's I've seen have a flat base made up of the bottom of the jacket. All the FMJ's I've seen have the end of the jacket crimped over the exposed lead core. This creates a little extra volume in the case because of the area that in the JHP would be filled in by the base of the jacket.

I did the calculations for the 180 grain 40's I shoot. For the long loaded (1.200") rounds I use: to adjust for the difference made by the different bullet base, the COL would have to be about .005" different. A small change, I admit, but it might make some difference in the load's ballistics.

[George]

The same OAL WILL NOT always produce the same velocity/pressure UNLESS the base of the bullet sits at EXACTLY the same depth as Kevin is saying.

The other part of the equation is in the diameter and length of bearing surface of the projectiles in question. Any difference at all here and the pressure will vary and therefore the velocity will vary.

Make the projectile weight, diameter, bearing surface and base seating depth EXACTLY the same and then you can be sure of duplicating the load, any variances in any of these variables and all bets are off.

BTW, factory ammo is so much more defensible in court that it just isn't worth it to consider hand loading for defensive use IMHO.

--

Regards,