hodgdon load data for 124g 9mm: ***

Field · March 30, 2010, 02:29 AM

i am wondering why with a heavier bullet 124g vs 115g they are telling you to have a shorter cartridge overall length with almost the exact same amount of powder and yielding a somewhat similar velocity

115g gdhp
col= 1.125
5g universal
1149fps

125g sie fmj
col=1.090
4.9g universal
1118fps

could someone explain this.?

SL1 · March 30, 2010, 06:36 AM

Just off the top of my head, I know that the Speer Gold Dots have an unusually blunt nose shape, while many FMJs for the 9mm have unusually long nose shapes. So, it seems plausible to me that the heavier bullet is still shorter than the lighter one. If so, then THIS heavier bullet leaves more space for the power than THIS lighter bullet when seated to THESE COLs.

And, it is possible that Hodgdon used different lots of Universal at different times to produce the data for these two bullets. That could mean that they used different lots of powder with significantly different burning rates.

Which brings-up the point that Hodgdon usually publishes the pressures of their loads, but you didn't provide those data in your post. Are these two loads producing the same peak pressure?

And, of course, there are always the possibilities of misprints.

Edit,

Now that I look at the data again, it seems that my first paragraph above makes the situation look more inexplicable instead of less. When I wrote that paragraph, I was thinking Speer GD was the heavier bullet and the Sierra FMJ was the lighter bullet. Still, I would have to know the length of the bullets to begin to try to figure this out. I am used to 125 grain GDs for the 357 Sig, which have almost no cavity. If the 124 grain GDs for the 9mm have a large cavity, then that could make them longer. Without doing a lot of research to find this info, I don't really KNOW. What I was attempting to do is give the OP some things to consider, so that HE can figure it out.

SL1

Sevens · March 30, 2010, 08:02 AM

If you have a shorter COAL and a heavier bullet, you most likely have less internal space inside where the "magic" happens. With less space you have higher pressure, resulting (usually) in a little more velocity than you'd otherwise get if they had the same exact internal space in which to operate.

But we aren't just comparing different COAL's here, we are comparing different bullet shapes and construction, too.

Field · March 30, 2010, 10:57 AM

Quote:

Which brings-up the point that Hodgdon usually publishes the pressures of their loads, but you didn't provide those data in your post. Are these two loads producing the same peak pressure?

And, of course, there are always the possibilities of misprints.

31,200 cup for 115g and 30,600 cup for 125g

no i dont think it is a misprint it shows the same data on hodgons website.

the thing is i am not using either of these bullets. my situation is i am going from 115g hornady round nose to 124g montana gold jhp using universal as my powder

mongoose33 · March 30, 2010, 11:16 AM

First, if it's a new load for you, you should be working it up.

Second, the shape of the bullet may influence how long the COL has to be.

Example: I'm shooting Missouri Bullet's 125gr 9mm Smallball lead bullet. The ogive is really fat; in other words, it causes the bullet to seat into the lands at a long OAL.

So to deal with this, I have to seat it at 1.09 or less, where other bullets like Precision Bullet's TC bullet has no such ogive. The same w/ Precision Delta's FMJ bullets--a more slender ogive.

That can be the issue right there.

A third reason can be the length of bearing surface. Heavier bullets often have a longer bearing surface; this can impact what loads work effectively with that bullet.

Whatever you do, however, work up that load.

March 30, 2010, 02:29 AM	#1
Field Senior Member Join Date: July 11, 2009 Posts: 295	hodgdon load data for 124g 9mm: *** i am wondering why with a heavier bullet 124g vs 115g they are telling you to have a shorter cartridge overall length with almost the exact same amount of powder and yielding a somewhat similar velocity 115g gdhp col= 1.125 5g universal 1149fps 125g sie fmj col=1.090 4.9g universal 1118fps could someone explain this.? __________________ iPSC=A66009 iDPA=A38321 http://www.youtube.com/user/FieldBoy111

March 30, 2010, 06:36 AM	#2
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	Bullet length? Just off the top of my head, I know that the Speer Gold Dots have an unusually blunt nose shape, while many FMJs for the 9mm have unusually long nose shapes. So, it seems plausible to me that the heavier bullet is still shorter than the lighter one. If so, then THIS heavier bullet leaves more space for the power than THIS lighter bullet when seated to THESE COLs. And, it is possible that Hodgdon used different lots of Universal at different times to produce the data for these two bullets. That could mean that they used different lots of powder with significantly different burning rates. Which brings-up the point that Hodgdon usually publishes the pressures of their loads, but you didn't provide those data in your post. Are these two loads producing the same peak pressure? And, of course, there are always the possibilities of misprints. Edit, Now that I look at the data again, it seems that my first paragraph above makes the situation look more inexplicable instead of less. When I wrote that paragraph, I was thinking Speer GD was the heavier bullet and the Sierra FMJ was the lighter bullet. Still, I would have to know the length of the bullets to begin to try to figure this out. I am used to 125 grain GDs for the 357 Sig, which have almost no cavity. If the 124 grain GDs for the 9mm have a large cavity, then that could make them longer. Without doing a lot of research to find this info, I don't really KNOW. What I was attempting to do is give the OP some things to consider, so that HE can figure it out. SL1 Last edited by SL1; March 30, 2010 at 11:23 AM.

March 30, 2010, 08:02 AM	#3
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,756	If you have a shorter COAL and a heavier bullet, you most likely have less internal space inside where the "magic" happens. With less space you have higher pressure, resulting (usually) in a little more velocity than you'd otherwise get if they had the same exact internal space in which to operate. But we aren't just comparing different COAL's here, we are comparing different bullet shapes and construction, too. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

March 30, 2010, 11:16 AM	#5
mongoose33 Senior Member Join Date: June 23, 2009 Location: Wisconsin Posts: 228	First, if it's a new load for you, you should be working it up. Second, the shape of the bullet may influence how long the COL has to be. Example: I'm shooting Missouri Bullet's 125gr 9mm Smallball lead bullet. The ogive is really fat; in other words, it causes the bullet to seat into the lands at a long OAL. So to deal with this, I have to seat it at 1.09 or less, where other bullets like Precision Bullet's TC bullet has no such ogive. The same w/ Precision Delta's FMJ bullets--a more slender ogive. That can be the issue right there. A third reason can be the length of bearing surface. Heavier bullets often have a longer bearing surface; this can impact what loads work effectively with that bullet. Whatever you do, however, work up that load.