Why Hornady HAP (XTP) OAL so Short?

[Steve D.]

Just curious why I see so many refferences to 1.120, 1.125, 1.115, etc. in the Forum when Hornady's Manual lists 1.060 for the 125 Gr. HAP in 9mm (Hornady told me over phone to just use the XTP OAL). I loaded a couple hundrd to a length of 1.066 last night over 4.3 of W231 but I hope the accurcy doesn't suck because they are so short compared to what dimensions other people are loading to.

Any feedback / comments please?

Thanks as always

[Cheesewhiz]

Hornady's 124gr XTP/125gr HAP factory loads are at 1.070", that's so they can be used in a variety of different guns. I load XTP/HAP bullets at 1.075" for my CZ's, that leaves close to a .015" clearance from the rifling in those guns. I imagine that the length can be stretched some with pistols that don't have short chambers. I would recommend buying some factory Hornady and just to see how well your gun(s) like that as it is loaded from them.

Edited June 15, 2012 by Cheesewhiz

[Sin-ster]

Most folks will tend to load as long as their chambers and magazines will allow. Many CZ owners for example go so far as to ream their chambers to be able to run longer (typically heavier) projectiles. For rifles, this can often be directly related to achieving maximum accuracy-- and in all of my pistols to date as well. Furthermore, longer rounds afford better feeding in the vast majority of cases-- provided you don't go too long, of course.

As to why the manual writers load to such odd lengths for certain projectiles-- beats the crap out of me! I see loadings on the edge of the commonly accepted maximum (that won't even fit in Glock mags without nose dives and dragging) in some manuals, and those like the ones you list that are way short. I'm sure there's (probably) a good reason for it, but... Don't let those guidelines be the limiting factors for your loads.

Determine the maximum length for the projectile as dictated by your chamber, and give yourself a cushion for variance or screw ups with the press. You want them to chamber reliably and not be sitting on the rifling, as this can cause pressure spikes in many cases.

Next, ensure that optimal chamber length will actually fit and cycle in your magazines (at full capacity, BTW).

Start with a low and safe load and work up to your desired velocity/PF, being aware of pressure signs in the process. (Note I didn't say the "listed minimum in your manual"-- conceivably, if you stretch the OAL out far enough from a super-low one that they were using, you may actually be better off starting a bit higher, yet still at the bottom of their listed acceptable range.)

Whether you're loading with a purpose or just for plinking, it behooves you to have a chronograph-- or at least borrow one when working on a new load. Realistically speaking, that's the only way to really measure what's going on in the cartridge after you drop the hammer/striker on a live primer.

[Cheesewhiz]

The listed "short" load is the minimum safe length at those powder weights and with that bullet(particular or generic). It isn't normally a recommended length, that would be almost impossible with the variety of pistols and configurations, it is just a "don't go shorter than this" length.

[Recoil45]

I always looked at it as the starting OAL. As mentioned, the minimum safe OAL.

Edited June 15, 2012 by Recoil45

[Steve D.]

Great Input as Usual...Thanks very much gent's.