What's special about the 300 GR. Hornady XTP?

[Don1357]

I just got two pounds of H110. While looking at the Hodgdon reloading data I noticed this:

240 GR. NOS JHP: start 23 grains, max 24 grains.
300 GR. HDY XTP: start 18 grains, max 19 grains.
325 GR. BTB LFN GC: start 20 grains, max 22 grains.
330 GR. BTB LFN GC: start 19 grains, max 20.8 grains.
355 GR. BTB LFN GC: start 17.5 grains, max 18.8 grains.

How come the 300 and the 355 are just about the same charge? And the 325 and 330 is listing more powder than the 300 bullet?

[waco]

Where is the canalure? How much of each bullet is seated in the case?

[Don1357]

The Hodgdon website doesn't go into those details.

[NSB]

The Hornady XTP is a jacketed bullet and the other ones are lead. There is more pressure build up with the jacketed bullets.

[stubert]

The XTP also gets seated lower than a lot of lead bullets, I have a Ruger which has a longer cyl. I can seat lead out to 1.71"

[Don1357]

Jesus...

I have two .44 molds, a Lee C430-310-RF 310 grains and a Lee 429-200-RF 200 grains one. Given that this powder is as easy to screw up on both ends of the spectrum (and that the spectrum can be one grain wide to begin with) what powder load should be safe?

[NSB]

Jesus...

I have two .44 molds, a Lee C430-310-RF 310 grains and a Lee 429-200-RF 200 grains one. Given that this powder is as easy to screw up on both ends of the spectrum (and that the spectrum can be one grain wide to begin with) what powder load should be safe?

This powder is perfectly safe. It's used for hundred of millions of rounds a year. Use the loading manual and follow it and there will be no problems. I've been using H110/WW296 (same powder) for many, many years with not problems what so ever. The only way it's "easy to screw up" is when someone can't follow directions or gets creative. This is a powder designed for magnum loads. If you want lighter loads there are a lot of other choices.

[dkf]

COAL for the 300gr is 1.600"

COAL for the 355gr is 1.710"

Thus approx the same amount of bullet is protruding below the case mouth into the powder space. That is why the powder load is similar. The COAL is very important, if data doesn't list the COAL then don't use the data.

[fredj338]

Probably more about bearing surfaces. The XTP has a very long bearing surface. Cast bullets with grooves have 30-40% less bearing surface. The small diff in OAL isn't moving the pressure needle, especially with very slow powders.

[mdi]

The Hornady XTP is a jacketed bullet and the other ones are lead. There is more pressure build up with the jacketed bullets.

I'd figger the same...

[runfiverun]

xtp's are shaped different.
they take up more case shape for the same oal.

if you want a huge illustration of this difference look at the data for the 9mm XTP in the Hornady book and then compare it to a sierra manual.
if you use sierra [or anyone elses] data and substitute in an xtp at the same oal your pistol probably won't last too long.

[Larry Gibson]

The Hornady XTP is a jacketed bullet and the other ones are lead. There is more pressure build up with the jacketed bullets.

This is the reason........

[44MAG#1]

I tested the 44 caliber Hornady 300 grain XTP IN A RSB 4 5/8 th gun. With the bullet seated in and seated out.
Using Win LP primers and H110 it took exactly 3 gr more H110 to equal the velocity of the lesser charge weight with the bullet seated deep when seated out. Since I am not allowed to post charges I will say XX gr charge with the Bullets seated deep took XX +3 grains to equal the same velocity with the bullet seated out. Nothing in ballistics is free.

[David2011]

The Hornady XTP is a jacketed bullet and the other ones are lead. There is more pressure build up with the jacketed bullets.

I once believed that because "everybody knows and everybody says so." Manufacturers' load data does not reflect this old wives' tale. The powder chosen seems to be a factor as well. As a quick reference I looked up 240 grain .44 bullets with all powders on the Hodgdon site and with the same powder charge sometimes the jacketed bullet developed more pressure and sometimes the lead bullet with the exact same charge developed more pressure.

Here are two examples chosen because the JHP and lead maximum loads were the same.

Hodgdon Titegroup .429" 240 gr JHP 1.600" 9.0 gr. 1,219 33,500 CUP 10.0 gr 1,292 37,700 CUP
Hodgdon Titegroup .430" 240 gr LSWC 1.620" 4.7 gr. 801 11,100 CUP 10.0 gr 1,288 38,400 CUP
Lead with Titegroup at 10.0 gr produces a marginally lower velocity at slightly higher pressure compared to the JHP.

Winchester 231 .429" 240 gr JHP 1.600" 8.0 gr 1,021 23,800 CUP 11.0 gr 1,272 37,800 CUP
Winchester 231 .430" 240 gr LSWC 1.620" 5.5 gr 800 12,000 CUP 11.0 gr 1,334 38,100 CUP
Lead with 231 at 11.0 grains produces slightly higher pressure and 62 fps more velocity compared to the JHP.

[Larry Gibson]

David2011

Understand also your looking at CUP figures with only 700 difference in the 1st example and an even less difference of only 300 in the 2nd example. A back to back test of the same loads could easily be the reverse. You're also using an example with very fast burning powders (231 and titegroup) in comparison to a very slow burning H110. With the faster burning powders you are using as an example the rise to peak pressure (peak pressure; that which CUP only measures) is much quicker and closer together.