[Graham Smith]

Having only dealt with loading for two guns (one 9mm and one .40), I never realized how big a difference there could be between guns. But I do now.

Because of problems I have been having with inconsistent loads in my Glock 35, I bought some .40 major from Atlanta Arms and Ammo. At the same time, I got a KKM barrel for my gun. After shooting one match with the Ammo I found it seemed a bit hot to me compared to the load I had been using before. So I took my own ammo plus some of the AA to the range and ran the two through the chrono.

I was astounded to see that the AA ammo was clocking over 1000 fps which, with a 180gr bullet, gave me a PF of over 180. I contacted Danny Wisner at AA and he sent me a different batch of ammo to try. I ran that through this weekend, and it was a little lighter, but not much. Just to be complete, I ran both the original and the new through both barrels this time and got a surprise. Here is the data:

Glock 35 with KKM barrel
Original ammo - Avg FPS 1041 SD 45 PF 187
New batch ammo - Avg FPS 1007 SD 11 PF 181

Glock 35 with original factory barrel
Original ammo - Avg FPS 996 SD 35 PF 179
New batch ammo - Avg FPS 976 SD 8 PF 175

So, there is a definite difference between the original barrel and the KKM because the load they use should be running between 170 - 175 in most guns.

But here is the really strange thing, when I looked at the chrono readings for my own reloads, they were actually running slower with the KKM barrel than they had been with my stock barrel. I've now got to work up a new practice load (180 gr MG over N320) using more powder than before.

I have no idea what could possibly account for this kind of difference but it is patently clear than no load data is complete without details about the gun it was shot through. I think that next month, I need to load up a whole series of test rounds and shoot comparison readings between the two barrels and try and narrow this down.

[Will_M]

Could it possibly be that the KKM barrel is slightly tighter, and therefore pushing the bullet faster?

[charliez]

If the barrel is tighter, would that make any ammo run slightly faster? Curious minds want to know why the reloads ran slower in the barrel where AA ran faster ... chrono hickup maybe?

[G-ManBart]

What was the sample size...i.e. how many rounds did you shoot of each load through each barrel? If it wasn't 20-40 of each through both barrels the difference might not be as big as it seems. R,

[Graham Smith]

The original batch in the G35 with the KKM barrel was a 20 round batch. Subsequent batches done after I got the new ammo were 10 round batches but I repeated the same tests through two cycles. I'm going to repeat the same tests this weekend along with more handloads through each barrel.