Why are factory loads a lot hotter than max reloading published data

B

Balance

CGN Regular
Rating - 100%
26   0   0
Hey, so I've been trying to understand why factory loads are made a lot hotter than reloads at published max charges for the same bullet weight. If I were to buy a box of standard range ammo 9mm or 45acp then compare them to my reloads they seem to be a lot hotter. My reloads are mid range loads but even at the published max in reloading books and on the Internet they would seem to have to go above the data charge weights to get similar power to the factory ammo. I understand most reloading data is very conservative for safety reasons and have read that companies use proprietary blends of powder and so on.....

An example would be a 9mm 124gr plated bullet with titegroup as the powder. Hodgdon data shows 4.1gr of titegroup as the max yet I'm using 4.0gr and cheap factory range ammo of the same bullet weight feels a lot hotter.
 
It's the burn rate of the powder. A slower powder might give more recoil and blast. Titegroup is very fast. Your OAL with your reloads, mixed with bullet type can have an effect too. The only way to truly tell is to chronograph them. For softball loads in 45 for example, you want the fastest powder (bullseye/titegroup) for the least recoil.
 
Medium burn pistol powders seem to work better for me in 9mm. A max load of clays (fast powder) for example with a 115/124gr bullet barely cycles the action, where HS6 (medium) is very reliable even at start loads.
 
It also has to do with marketing. They are maxed out and designed to get high fps because that is what sells to the average joe.
I have a rifle that has really flat primers with almost any factory ammo. My reloads are only 50-100 fps less and only minor flattening.
 
Balance said:
...An example would be a 9mm 124gr plated bullet with titegroup as the powder. Hodgdon data shows 4.1gr of titegroup as the max yet I'm using 4.0gr and cheap factory range ammo of the same bullet weight feels a lot hotter.
Click to expand...

What factory ammunition with 124gr plated bullet are you comparing it with?

Got a chronograph?
 
Ya I need to chronograph them to know for sure. I did load some 124gr plated 9mm with a middle load of 6.3gr of the slower hs6 powder and it is alot more like factory 9mm ammo. On hodgdons website it show 6.6gr as a max.
 
Balance said:
Ya I need to chronograph them to know for sure. I did load some 124gr plated 9mm with a middle load of 6.3gr of the slower hs6 powder and it is alot more like factory 9mm ammo. On hodgdons website it show 6.6gr as a max.
Click to expand...

Wouldn't mind to hear the results, I would not be surprised if the manufacturers have a custom powder to save money that is not what we can buy.
 
I have chronographed 9mm 124gn factory ammo and found it pretty close to what I had to hand load to achieve minor power factor for IPSC. Generally between 1050 and 1100 fps, and below maximum loads shown in Lyman manual.
 
Geoff B said:
I have chronographed 9mm 124gn factory ammo and found it pretty close to what I had to hand load to achieve minor power factor for IPSC. Generally between 1050 and 1100 fps, and below maximum loads shown in Lyman manual.
Click to expand...

What powder, bullet and manufactured rounds?
 
Balance said:
Hey, so I've been trying to understand why factory loads are made a lot hotter than reloads at published max charges for the same bullet weight. If I were to buy a box of standard range ammo 9mm or 45acp then compare them to my reloads they seem to be a lot hotter. My reloads are mid range loads but even at the published max in reloading books and on the Internet they would seem to have to go above the data charge weights to get similar power to the factory ammo. I understand most reloading data is very conservative for safety reasons and have read that companies use proprietary blends of powder and so on.....

An example would be a 9mm 124gr plated bullet with titegroup as the powder. Hodgdon data shows 4.1gr of titegroup as the max yet I'm using 4.0gr and cheap factory range ammo of the same bullet weight feels a lot hotter.
Click to expand...

I have a naive question: how do you determine the kind of powder used in the factory loads? Without that info, how can I say it's hotter than this or that other powder? Muzzle velocity for a given bullet weight is one data point, but the powder burning rates also affect the chamber peak pressure and I'd have no way of finding that without one of those specialized pressure gages, no? Going by "feel" when reloading... that's scary to little me! :)
 
VanMan, about that ~20 FPS difference, were those barrels rifled to the same twist rate? Same number of lands/grooves? Heck, same exact inside diameter and length? Shot on the same day at the same temperature and air pressure? :)


OP: I've just finished sacrificing 10 rounds of 9mm Fed Am Eagle RN 115gr so I could use them as spare parts/dummies to set up my dies. Aside from finding out that those bullets usually weight 114gr, I found that they use 4.7gr of some powder (flakes shape). That would be overload with Bullseye or Titegroup or Hodgdon 700X but underload with most slower burning powders like Power Pistol, Blue Dot, VV N350 or 3N37, Hodgdon HS-6 or Accurate #5 or #7.
 
You must log in or register to reply here.
Back
Top Bottom