VV N120 220gr subsonic help

[dellet]

If you want to use the Hornady data instead of the Sierra

The Sierra 220 SMK is 1.490",
The Hornady 225 is 1.565"

To seat the SMK the same depth as the 225 Hornady data of 2.250", you would seat the Sierra at 2.175-80". That would give you the same basic relationship of powder fill ratio.

[mauidiver]

Hey Dellet, whats the shortest COAL you ran with 208 grain Hornady ELD Match and N120? I ask because after making 100 rounds the other night I have about 6 that apparently went below suggested COAL in the book, and I don’t have a bullet puller yet. I just separated from bundle until I do. I think they are in the area of 2.240ish?

Thanks for all your help sir.

[jgieske]

Hey Dellet, whats the shortest COAL you ran with 208 grain Hornady ELD Match and N120? I ask because after making 100 rounds the other night I have about 6 that apparently went below suggested COAL in the book, and I don’t have a bullet puller yet. I just separated from bundle until I do. I think they are in the area of 2.240ish?

Thanks for all your help sir.

I'd guess the ELD-M is a pretty consistent bullet but keep in mind bullet meplats can vary a few thousandths from round to round, causing what can appear to be inconsistencies in OAL when measuring from the meplat.

I'd venture to say that those "short" rounds are a lot more consistent with the other rounds if you measured OAL from the ogive, which is a more accurate/important indication of OAL anyway.

[dellet]

Hey Dellet, whats the shortest COAL you ran with 208 grain Hornady ELD Match and N120? I ask because after making 100 rounds the other night I have about 6 that apparently went below suggested COAL in the book, and I don’t have a bullet puller yet. I just separated from bundle until I do. I think they are in the area of 2.240ish?

Thanks for all your help sir.

Trick question, what’s the powder charge?

I rarely if ever use the same length if the charge changes a half grain in this cartridge.

Just went back and saw your other data. If this is the 10.3 load, shoot them and compare with those that are 2.250, they might be a bit fast.

You might find a very nice load with 10 grains in that 2.240-55 range.

[mauidiver]

I actually loaded most of them with 10.2. I also loaded about 10 rounds with 10gr. Hopefully will get out Monday morning. Thanks again guys.

[mauidiver]

Dellet, you forced me to buy a Forster Ultra Micrometer Seater Die. It adjusts in 0.001” increments.... The RCBS seater die was driving my ocd crazy!! Hopefully this will make it a bit more enjoyable. Thanks again for your suggestions.

[Freedom1973]

Dellet, you forced me to buy a Forster Ultra Micrometer Seater Die. It adjusts in 0.001” increments.... The RCBS seater die was driving my ocd crazy!! Hopefully this will make it a bit more enjoyable. Thanks again for your suggestions.

Maui,
You are not the only one. You will really enjoy using it.

[mauidiver]

Shot off another 50 rounds today, extreamly happy with how they ran, Bolt opened every time mag was finished. I did run 15 sig 220’s just because but when I got home and cleaned, I found a little bit of blue/greenish residue on the end of charging handle and bolt. It easily wiped off, but never seen this before. I use CLP to clean bolt prior, nothing else. Anyone ever seen this blue from N120 before?

[dellet]

Thank you both for the responses. I contacted vihtavuori and this was their response:

Thank you for contacting us at Capstone PG. Unfortunately the use of N120 will not be a good match for this type of an application. This is due to the fact that this would have to load to fill ratio of 114% due to the slow burn rate of the powder for the application and would simply be an issue of having to use more powder than would be able to fit inside the case and still be able to properly seat the bullet even with very heavy compression of the powder charge. Please do not hesitate to get back with any of us with the Capstone Tech. Team if we can be of further assistance.

Could have sworn N120 was highly recommended around here for subs.

Wondering what you all think about this.

Just to remove any lingering doubts. I contacted Kevin through another forum about this and shared this post with a link to this thread, below is his response. Asked about posting this and his response was they want to sell more of their powder in this application.

Hi,

Appreciate your bringing this to my attention. Not sure who wrote the response, but it seems a bit odd in that we plainly list N120 as being a very well-suited powder for this particular application. It is one of only three (3) powders we currently list in the 300 BO data, and would be my first choice for this combination. I'm currently building a 300 BO in a 10.5" SBR to be used with a suppressor, and this will likely be one of the first powders I work with in that rifle. I'll do a bit more digging on this end regarding the response, but rest assured, the N120 is an excellent choice for this task.

N120 hasn't been heavily imported in the past, simply because of the relatively unique niche it fills. Most of the cartridges that are naturals for this powder have a rather small fan base, so it wasn't a really big demand item. With the intro and popularity of the 300 BO, it now has a much broader range of support. With Capstone being structured last January, increasing imports and knowledge of some of these lesser known powders has become a priority for us. More to come in the future, I assure you!

Thanks,
Kevin
Kevin Thomas
Capstone Precision:
Lapua, Berger, Vihtavuori, S-K

[jgieske]

Just an update for all those interested in this powder/bullet combo.

After several test rounds I landed at 9.3 grains with an OAL of 2.09 (.250 at the mag rib rule of thumb). This gave me an average velocity of 980 fps unsuppressed with a 20lb crimp from the Lee factory crimp die.

At that seating depth and charge weight, the powder begins to crunch/compress a little but does not completely compress to a stop. There were no signs of overpressure. This is common in my other extruded powder loads such as varget so I'm not too worried.

I had cycling issues and bolt lock failures unsuppressed. Everything worked fine suppressed. This is a brand new gun, less than 100 rounds, which may or may not be a factor:

9" ballistic advantage pistol gas barrel
Standard carbine buffer spring w/H2 buffer
ALG-ACT trigger group
PSA premium bcg
SLR GB7 gas block aligned and dimpled with the SLR gas block jig.
Aero Precision m4e1 upper/handguard combo

I'll have to put a couple hundred rounds through it before I can decide if the powder or the gun is the issue when shooting unsuppressed.

I haven't done any accuracy testing yet so I have no idea what kinds of groups it will shoot at the moment.