Load data from VV n320 Very odd readings

[glock10mmman]

Hey all. I got alot of suggestions in my thread about using n320 for my 40 major loads. So I went to work and made 6 different loads all with OAL of 1.130 out of my GLock 35 with stormlake barrel.

Started off with 4.0 grains as there is no load data in my Lee book, but I seen alot of people loading between 5-6 grains so I want to be on the light side to start with.

Here is my findings 20 rounds of each load were fired and cronoed. Mixed once fired brass, federal small pistol primers and all from the same gun. Temperature was around 60 with no wind and low humity. All from 550 press with dillon dies. Nothing but the powder dial was changed during loading.

4.0 Average was 855. High was 866 and low was 853

4.4 Average was 834. High was 877 and low was 781

5.1 Average was 961. High was 995 and low was 933

5.4 Average was 1020. High was 1047 and low was 1011

5.6 Average was 1100. High was 1130 and low was 1075

6.0 Average was 1032. High was 1059 and low was 1017

Now I am more confused than I was the day I was taught how to load. I have never had such weird readings such as these before. Why would the FPS of 4.4 grains drop from 4.0? Same as with 6.0. How is this possible? I got alot of deviation in velocity with all the loads except from the 5.4 load. It seemed to work out well over all. The 5.1 load made majorand was a dream to shoot except that some loads jumped down to 933 which makes 167 PF

I am up-in-arms. Can anyone help?

Thanks in advance

g10

[dfwmiket]

What brand of chrono? With screens on, or infrared? Did you verify the charge consistently each time you changed the amount of powder being used?

Just FYI, these are my chrono readings, using a CED (match style) chrono:

Glock G35 4.5G -V V n320 180 Zero JHP

948

924

936

925

953

932

943

923

936

928

934.8 168.264

5.1 sounds awfully hot......... I always ran 4.6, and knew I had a few FPS to give me breathing room.

-Mike

[G-ManBart]

I'll go out on a limb and say that the mixed brass is what caused the variation you saw.

I only have two kinds of .40 brass....Winchester that I pick up once-fired after our qualification days (so I know it's really once-fired) and Starline that I bought new.

If I use everything identical but the cases, the Win loaded rounds will have a higher PF (like 6-7 points). So, my match load in Starline cases is at PF171. If I accidentally get a Win case in there, it's like PF177. I've tested this several times and it's always the same.

Oh, the load is 180gr Zero JHP, 4.7gr of VV-N320, Federal small rifle primer, 1.195oal out of an STI Edge.

[glock10mmman]

What brand of chrono? With screens on, or infrared? Did you verify the charge consistently each time you changed the amount of powder being used?

Just FYI, these are my chrono readings, using a CED (match style) chrono:

Glock G35 4.5G -V V n320 180 Zero JHP

948

924

936

925

953

932

943

923

936

928

934.8 168.264

5.1 sounds awfully hot......... I always ran 4.6, and knew I had a few FPS to give me breathing room.

-Mike

Mike it was CED crono. The screens were not on and I verified each charge weight after it was dumped by the powder measure. I used my RCBS 510 beam scale each time with a the scale being zeroed between loads.

g10

[glock10mmman]

Bullets were X-treme plated bullets too. Brass was a mix of once fired Remington Federal and Wichester all fired from duty loaded ammo from Glocks, Sigs and Hk's This was all picked up by myself after the shoots so I know its once fired.

g10

Edited September 16, 2007 by glock10mmman

[HoMiE]

Mixed brass can do that. And just because you picked it up doesn't mean it has been once fired. Some ammo manufacturers use once-fired brass as well. Try using the same headstamp for brass when working up a load, then see how different brass changes your expected results.

[Coolduckboy]

4.6gr with 180gr FMJ was perfect when i was running N320.

[Joe4d]

X treme???? there is your problem, bullets are garbage, check a bunch of em's diameter