FTF with N330 and 125gr HAP in Glock G34

[cwsanfor]

I am developing a load using Vihtavuori N330 under 125gr Hornaday HAP bullets In new Starline brass. I used an OAL of 1.1 after finding that 1.125 touched the rifling in a Glock G19, G26, and G34. That OAL passes an L. E. Wilson case gauge, and will both drop out of and spin in all three barrels.

I loaded 4.1, 4.3, and 4.5 gr N330. All three loads chambered and fired well in the G19 and G26, but I got repeated FTF in the G34 except with the 4.5gr load. QuickLoad predicts 31,139 psi and 1,133 fps for the 4.3gr load, and 34,853 psi and 1,172 for the 4.5gr load.

I don't mind loading to +P pressures, but thought it odd that I apparently anything below the SAAMI maximum pressure with these components won't cycle the G34, or presumably a G17. It caused me to wonder about the OAL, but I know several people loading HAP to 1.10, and the lack of FTF in the two shorter barrels suggest that the heavier G34 slide just needs more power. Anybody load this combination, or have any experience that would care to comment? Thanks.

[lll Otto lll]

G34's do have heavier slides. You may want to read this thread on recoil springs.

http://www.brianenos.com/forums/index.php?showtopic=101834

[cwsanfor]

Thanks.

It just seemed odd that since N330 at 4.7gr yields (according to QuickLoad) 39,162 psi and 8.9% compression, so for a load that will reliably cycle but not blow up the G34, I am limited to 4.5 and 4.6gr in a powder that was "designed for 9mm". I guess that since N330's range between starting and maximum load is usually only about 0.6gr (VV and Hornady data), this is just the nature of the beast.

[Darrell]

A bullseye load is 4.8 to 5.0 of N330 with a 115 at 1.085. 4.8 gr with a 124 shot best for me in my gun with N330 but I prefered 4.8 to 5.0 of N340 which mad 131 PF and shot a 1.5" group, N330 best group was 2.20".

[cwsanfor]

A bullseye load is 4.8 to 5.0 of N330 with a 115 at 1.085. 4.8 gr with a 124 shot best for me in my gun with N330 but I prefered 4.8 to 5.0 of N340 which mad 131 PF and shot a 1.5" group, N330 best group was 2.20".

Darrell, are all those at a COL of 1.085? I ask because QL shows 4.8gr of N330 under 125gr HAP a 1.085 COL giving 45,773 psi and 17.3% compressed, which is hotter than I am comfortable with.

[cwsanfor]

I believe I'll load 50 cartridges from 1.07-1.10 COL, vary the powder to keep the pressure and velocity about constant, and chrono that batch in all three guns, and I should be able to tease out whether it is the power factor or OAL that is causing the misfeeds. So I'll load:

COL, gr N330, psi, velocity

1.07, 4.1, 1124, 32972

1.08, 4.2, 1134, 32980

1.09, 4.3, 1143, 33015

1.1, 4.4, 1153, 33073

[Darrell]

I believe I'll load 50 cartridges from 1.07-1.10 COL, vary the powder to keep the pressure and velocity about constant, and chrono that batch in all three guns, and I should be able to tease out whether it is the power factor or OAL that is causing the misfeeds. So I'll load:

COL, gr N330, psi, velocity

1.07, 4.1, 1124, 32972

1.08, 4.2, 1134, 32980

1.09, 4.3, 1143, 33015

1.1, 4.4, 1153, 33073

1.085 is what I tested at. No pressure signs for me in my gun. I also tested at 1.080 really no change.

Edited May 10, 2011 by Darrell

[cwsanfor]

Thanks for the replies.

My chronographing this weekend was rained out, but I went to the range yesterday and shot 50 Win NATO 124gr and 50 Federal 115gr through the G34, G19, and G26 with zero problems. That seems to vindicate the guns. I'll return to the reloads this weekend. I loaded a ladder with the same predicted pressure but various OAL, and a ladder with the same OAL but varying powder charges.

I'm thinking the FTF issue may have been related to some combination of:

1) Lower power factors, since only the softer rounds gave a problem,

2) I used Imperial Sizing Wax (which I usually do not) on those rounds because I was using a new set of dies, and I did not tumble or wipe the finished rounds, so they may have been a bit sticky,

3) Possibly a OAL issue,

4) I had just installed Match Grade Slide Locks in all guns and had run fewer than the suggested 200 rounds through them (this seems like an unlikely cause).

I usually try to only change one thing at a time, and here I changed four (new dies, new load recipe, using sizing wax, and changing slide locks). We'll see. My current batch of reloads was tumbled after seating, each one chambered in a Glock barrel, tested in a Wilson case gauge, and manually cycled through a Glock, so I bet they all shoot fine.

[cwsanfor]

I finally got to chrono these rounds this weekend. I shot

1) 10 each in the G34, G19, and G26 with a fixed 1.1 COL, with loads of 4.1, 4.3, and 4.5 gr VihtaVuori N330,

2) 10 each with 1.1 COL/ 4.5 gr, 1.08 COL/4.3 gr, and 1.065 COL/ 4.1 gr (for a roughly constant 35,000 psi predicted),

3) 10 each Hornady Steel Match 124 gr (which I'm trying to duplicate)

4) 10 each Winchester NATO and Federal 115 gr for a comparison and chrono verification, since I know their velocities).

All rounds were delubed this time, and I had previously fired 100 each of the NATO and Federals through each gun with no malfunctions.

I got two FTE and two FTF in the G34 with 4.1 gr N330 at 1.1 COL, and one FTE in the G26 with 4.1 gr at 1.1 COL. These two guns are newer than the G19, and probably a bit tighter. If the G19 were new, I suspect it would not have reliably run the lowest charge.

What I think happened is this: QuickLoad underpredicts the velocity from N330 under HAP much more than with 3N37 under Delta Precision 124 gr FMJ RN. Rather than the predicted 1,094 fps from the G34, a 4.1 gr 1.1 COL measured only 862 fps, a 232 fps difference, and only 108 Power Factor. I think this is just not enough to cycle the action in a fairly new G34. The COL does not seem to be a factor, and probably not the lube.

So this weekend I'll chrono 1.1 or 1.09 COL HAP over 4.4/4.5/4.6 gr N330 and see what that does. QL predicts the hottest of those at 39,000 psi, but I'm pretty sure it is high by at least 10%, so I'll work up to that load looking for overpressure signs.

In the unlikely event that anyone wants to see the data from this past weekend, it's at https://spreadsheets.google.com/spreadsheet/ccc?key=0ApfazXeV8cnBdGlTWHJaMWNHV3hlTjZTWWlEc3ZDWEE&hl=en_US&authkey=CPuW35sF .

Thanks for the feedback.