158 XTP, N110, and unusually high velocity

Quailman84 · Sep 3, 2020

Been experimenting with loads in my 66-8 with 4.25" barrel, and I had some really unexpected high velocity with N110 loads. Working up to this load, velocity was pretty impressive, primers liked normal, and extraction was easy. I stopped when I got to this point even though it's still 1.4 grains below vihtavuori's max and no pressure signs. Here's the load:

158 XTP
14.8 gr. N110
Winchester brass
CCI550 primer

Averaged 1346 fps for 5 shots, and accuracy has been excellent with all loads! This seems way higher than I should be getting from a 4.25" barrel, but it still extracts easily and primers look normal. Thinking I may have a chronograph problem, I tested some other known loads and the velocities were about what I expected.

This is my first experience with N110. I'm just looking for opinions whether this load is safe (used sparingly) or if anyone has had similar experiences with this powder. Is N110 just magical?

Golphin · Sep 3, 2020

I have never used that powder so no help really. Is it supposed to be like H110? If so those are not really high numbers at all from what I see on the Hodgdon site using H110.

rwsmith · Sep 3, 2020

I'd expect good results.....

I've heard that their powders are top notch, but the price sure reflects it.

Did you say 158 gr??? Holy Moly!

Quailman84 · Sep 3, 2020

Yeah 158 grain, at 1346 fps. It's a butt kicking load for sure. That's 635 ft-lbs of energy from a 4.25" gun. N110 is close to H110 in burn rate, but I never quite got this sort of velocity with H110. I went up to 16.4 grains of H110 (16.7 max according to hodgdon) and only got 1210 fps. N110 produces less flash and concussion than H110 too.

505Gibbs · Sep 3, 2020

Your primer appearance is a reasonable judge of the pressure so it appears you have a WINNER!!

Funflyer · Sep 3, 2020

I typically see about 70-75% of rated(10" barrel)velocity from my 4" 357 using H110. Looking through the VV manual your XTPs appear to be in the 85-90% range which is fantastic!

Last time I was in the LGS I almost picked up can of N110 but ended up with IMR4227, AA1680 and 4100 instead. I know what I'm going to try next though.

ddixie884 · Sep 3, 2020

I believe the burn rate and charge weight is close to, but not exactly the same as 2400. All I ever loaded with it is .38spl 158gr +P at 10, 10.5 and 11gr. I was just trying it for grins and giggles as I also load 11gr 2400 in this ctg. I haven't chronoed it or had it tested but I fired a few of them in a LCRX and got easy extraction and pretty regular primers, even tho I was using Rem 1 1/2 primers which are known to have very soft cups.........

tdan · Sep 4, 2020

My old Speer #12 lists max load for their 158 gr jacketed bullets and N-110 is 15.0 grains. COL for these cartridges is 1.570-.575. This powder gave higher velocity than H-110. Velocity in their test gun, a 6” model 19, was 1253. These results come from using a small pistol primer.......not those magnum 550’s. You don’t need magnum primers to light off N-110 which is a stick powder. In this Speer data, they only use the 550’s on H-110, Win-296, 2400, and HS-7. Try the regular small pistol primers. I bet your velocity drops a bit with a possible increase in accuracy. XTP’s have always shot well in my Smith’s, especially the 44’s. Excellent choice of bullet!

Paul105 · Sep 5, 2020

ddixie884 said:
I believe the burn rate and charge weight is close to, but not the same as 2400. ........

Pretty much been my experience also. Never used N110 in the .357 Mag (only in .44 mag).

Different guns give different velocities. For example, I have two 66-8's, one 4 1/4" and the other 2 3/4". The 2 3/4" gun gives equal and sometimes higher velocities vs. the 4 1/4" (depending upon load). Also, temp will impact velocity.

Here are results for 158gr XTP, 15.0gr A2400, Starline cases and standard small pistol primers.

4 1/4" M66-8
Competition Electronics
Velocity at 5 Long Paces from the muzzle
40 deg F

1,294 fps avg for 5 rounds

2 3/4" M66-8
LabRadar
Velocity at Muzzle
60 def F

1,316 fps avg for 5 rounds.

Different chronos, diff distance, diff temps noted on above.

FWIW, VV lists 16.3gr N110 as max with the 158gr XTP -- however, they are using "All the loads on these pages are pressure tested according to the C.I.P. method" vs. SAAMI for A2400.

Anyway, chronograph results can drive you nuts - at least that's been my experience.

Paul

Quailman84 · Sep 5, 2020

Thanks everyone who shared their thoughts and experiences.

I worked up some more N110 loads using Federal 200M primers (only ones I've been able to find in the past couple months) and they are over 100 fps slower than equivalent loads with the CCI 550. Maybe these 550s are a particularly hot batch. Anyway, I found 14.4 gr N110 with the 200M gave me the best accuracy I've had so far from this gun. Two 5-shot groups at 25 yards measured 1.38 and 1.75 inch. They averaged 1156 fps for 15 rounds. I'll probably just stick with that load for the times I want a jacketed hollow point.

Oh and I realize magnum primers aren't required with N110, but vihtavuori shows small pistol primers in their 357 data and I'm trying to reserve my CCI 500s for 9mm and 38. I may try a few to see what difference, if any, they make.

chris1961 · Sep 7, 2020

Vihtavuori N 110 is very accurate and smooth in comparison with the H 110. I reload myself my .44 and .460 magnum with this powder. You will have less recoil with vihtavuori powders.

158 XTP, N110, and unusually high velocity

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