Vihtavuori N32C (TinStar)

[LeaderOfThePack]

Hi.

Finally got that silencer. Pic of rifle will be coming, yes.
I have need for subsonic load to save ears of my dog. Only decent powder available here for that purpose is probably Vihtavuori N32C which is originally meant for CAS loads like TrailBoss is.
I have loaded normal loads for 9mm, 38, 357mag, 45-70, 222rem, 30-06, 338WM, etc during last 30 years and did read most of data available in web, but can't find actual data for this rifle with N32C.
Does anybody have access to Quick Load and could check if same rules go with this, as with TrailBoss? (I mean that volume thing, measure where bullet ass lies and that's 100%, then start with 80% of that)
Or if I make this clear: can I go BOOM with this powder? Is it possible to overload?
I've been thinking to load it with 300gr XTP to get decent terminal ballistics with near sound velocities. Is that ok, or should I go with something lighter?


Test results:
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Temp outside -4C
Bullet: XTP 300
Powder: Vihtavuori N32C
COL: 2.138 (54,3mm)
charge | Speeds (4 shots) | Average
14.5gr | 1109, 1105, 1103, 1064 | 1095
14.0gr | 1070, 1054, 1098, 1065 | 1072 Smallest group so far.
13.5gr | 1020, 1053, 1082, 1074 | 1057
I think optimum sub-sonic might be around 13gr, so I will test that also. Bad news is that group size seems to be growing when I go under 14gr. In my opiminion charge weight change affects suprisingly little to speed.
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Added 22 feb 2019 - Longer COL:
Temp outside +4C
COL: 2.154 (54,7mm)
charge | Speeds (4 shots) | Average
13.5gr | 1016, 1001, 1001, 1006 | 1006 Group about inch. 3 of them little over half inch. (About 15mm)
13.0gr | 984, 1002, 1008, 983 | 994
I probably load rest of that bullet box with 13.5gr mentioned above. Sound is about same level with un-silenced 22LR.
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Added 26 feb 2019 - Test with shorter COL:
Temp outside +3C
COL: 2.000 (50,8mm)
charge | Speeds (3 shots) | Average
13.0gr | 1023, 994, 991 | 1003
12.0gr | 894, 919, 913 | 908
Totally doomed idea, jump to lands just destroys accuracy. "Groups" were over 2" @50 meters.
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[LeaderOfThePack]

Same weight of N32C is about 67% of volume of TrailBoss, so NO you CAN NOT use full volume loads with it.

[Hoot]

Per QuickLoad, with a 300gr XTP, 2.26 COL, a 16 inch barrel and a bolt action, you need to load the case 50% full and 50% empty to keep the velocity subsonic. You can go to 60% fill with a 325gr bullet and stay subsonic.

Hoot

[LeaderOfThePack]

Thank you for that info. Have to cross check still if that is in line with what I also found (using Google) from old topic about this powder, from here http://www.450bushmaster.net/viewtopic.php?f=5&t=15365

[Herker]

Per QuickLoad, with a 300gr XTP, 2.26 COL, a 16 inch barrel and a bolt action, you need to load the case 50% full and 50% empty to keep the velocity subsonic. You can go to 60% fill with a 325gr bullet and stay subsonic.

Hoot

Hoot, I am working on a similar project in a 1:16, 16" AR platform with a 46 HYBRID I am waiting on.

Can you please continue to extrapolate the Tinstar in Quickload as to what would stay subsonic with tinstar?
For example only, 1,050fps:
350g - 70%?
400g - 80%?
500g - 90%?
525g - 100%?

These things are usually never linear with regards to pressure/weight and of course there are other variables. Just curious what Quickload has to say.
I am looking to go as heavy as I can so long as I can have accuracy, action and safety.

Read a couple other posts that put 16.5gr of tinstar under a resized (.458 to .452) rem. 405gr at 1,056 and overpressure, so that may be our limit with tinstar.

I would think the .450BM could push a 500g at 1,050fps with the right combination of components given the .458 socom does so.
525g pile driver would be fun resized .

Hoot,
Given case capacity of the .450bm is 59g of water and .458 socom is 61.6g (with larger bore), what are your opinions on using .458 socom low end data as a starting point for .450bm when going heavy? Hard to find heavy bullet data on the .450bm.

Thanks for all of your work and information here!

Herk

[Bmt85]

From what I have seen, Tinstar and Trailboss can work for subs, but won’t cycle an AR. Your probably going to run powders that are a bit slower than what we typically use in the 450B. Not a lot of people are running subs in this cartridge, even less in an AR. Even then, we don’t really have data. I want to venture down the sub route, too. I custom ordered a 10.5” barrel for it, received it about a week ago. I’ve been looking for a place to start, but not a whole lot to go off of. I came across some data for the 45 VRap, which is similar, and they were looking to cycle the action. Powders tested were h110, aa2200, and shooters world blackout. However, they were using cast bullets, so again, a bit different. I know I’m planning on working on the 425gr Maker’s bullet, then maybe something for cheaper sub plinking. That won’t be for quite a while though.

For someone to give you load data, they need specifics on the bullet, c.o.a.l., and useable case capacity. Might need some other info, too.

[Hoot]

From what I have seen, Tinstar and Trailboss can work for subs, but won’t cycle an AR. Your probably going to run powders that are a bit slower than what we typically use in the 450B. Not a lot of people are running subs in this cartridge, even less in an AR. Even then, we don’t really have data. I want to venture down the sub route, too. I custom ordered a 10.5” barrel for it, received it about a week ago. I’ve been looking for a place to start, but not a whole lot to go off of. I came across some data for the 45 VRap, which is similar, and they were looking to cycle the action. Powders tested were h110, aa2200, and shooters world blackout. However, they were using cast bullets, so again, a bit different. I know I’m planning on working on the 425gr Maker’s bullet, then maybe something for cheaper sub plinking. That won’t be for quite a while though.

For someone to give you load data, they need specifics on the bullet, c.o.a.l., and useable case capacity. Might need some other info, too.

Herk;

For these heavier bullets, QuickLoad needs at a minimum, the bullet length. It can extrapolate the rest.

Hoot

[Herker]

Have only done a few size downs and need to get the details together.
On the mic for example a 400g Speer Jacketed lengthens almost .02" after sizing down to .4515.

Will start a new thread once I get my info. around...don't want to hijack this one more than I already have...sorry!

Thanks guys...looking forward to more!

Herker

[LeaderOfThePack]

Finally some progress. I changed title a little.

I measured max COL by putting spring inside used brass, then bullet on top of it. I just barely was able to put it in chamber, and in both cases bullet needed just a touch with rod to drop out after measurement. I think it's nearly perfect measure, but ones mentioned below are rounded up to safe side.
Hornady XTP 300 max COL = 55mm/2.17"
Barnes TSX 275 max COL = 60.7mm/2.39"

No actual loads yet, but plans as follow:
Bullet: Hornady XTP 300
C.O.L: 54,2mm/2.15"
Powder: Vihtavuori N32C, 15grains
Primer: 7 1/2
Still under consideration if I make this shorter for better fill ratio. I tested that this volume fills about half of whole brass without bullet.
Amount of powder was in safe scale in one users test with resized Remington SP 405grain. Will see what speed this gives and then some adjustments maybe needed.

Bullet: Barnes TSX 275
C.O.L: 60.2mm/2.37"
Powder: Vihtavuori N120, 36grains.
Primer: 7 1/2
This gives speed of 1700 fps with XTP 300 in hornady original info, so I think it's on safe side. Hornady was using normal primer, not magnum, but that info is for AR anyhow so I have safety tolerance with RAR.

Updates:
- Tests for N120 moves for later time because I seem to be out of it for now.
- I loaded 4 of N32C loads and maybe test those today. Hornady bullet seater threads differs from RCBS, so COL is changed a little.

[LeaderOfThePack]

Previously mentioned load for 300 XTP (Vv N32C, 15.0 gr) tested now.
Temp outside +4C, gun and cartridges didn't have time to cool down to that temp. Estimate over +10C, so will be quite near hunting season opening temps

First one Hornady factory load for reference: 2126 fps. Actually shot 2 of those, but other one did give ERR because lining wasn't right.
Speeds: 1151, 1111, 1124, 1128. Average 1128.5
Sound was quite near what shotgun shooting upwards sounds like. Recoil was friendly push instead of someone throwing a brick on your shoulder, 308 in slowmotion
Accuracy was amazing. 4 shots under 20mm on 50 meters with 2.5x scope. It's under what those two factory ammos did!
I think I test same lenght with 14gr of N32C next. If accyracy is still same, COL seems to be perfect. If velocity drops too much or hits spreads, I maybe try shorter COL to shrink powderless space on brass.