Bolt Action Subsonics and Tinstar/N32C

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LFOD603
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Bolt Action Subsonics and Tinstar/N32C

Post by LFOD603 »

I've started reloading for my RARR. I tried the 90gr XTP over Trailboss and now I want to try some heavier projectiles.

I have N32C I'd like to try out for some subs. I haven't found much reloading data for it, and I've seen a few people say to try and stay between 50-70% fill. Has anybody else had experience with this powder?

I plugged some projectiles I have into Gordons Reloading Tool and here's what I got:

With the Hornady 165gr SST loaded at 2.10" OAL, GRT shows 5.5gr of N32C at 86% fill to get 1054 fps and max pressure of 33,407psi.

With the Hornady 135 FTX loaded at 2.040" OAL, GRT shows 4.9gr of N32C at 62% fill to get 1059 fps and max pressure of 19,505psi.

With the Hornady 125 HP loaded at 2.10" OAL, GRT shows 4.6gr of N32C at 56% fill to get 1053 fps and max pressure of 16,074psi.

I think I'll stay away from the 165gr SST for now. The lighter bullets are what I'll start with.

If any of you guys have experience with this powder, I'm all ears.
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bangbangping
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by bangbangping »

I like it for light and medium weight subs, and have consistently seen lower ES numbers with Tin Star than with Trailboss. As a side note, due to its potential for high pressure, I use it with heavy bullets to blow out cases with short shoulders. A little bit goes a long way. It is possible to max out pressure while remaining subsonic with heavy bullets, so some care is needed.

Your listed loads look reasonable and safe, though you might find the 125 grain load to be a little slower. I load 125 SMKs long (2.278" COAL) for my CVA pistol. 5.7 grains for 1050 fps.
LFOD603
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by LFOD603 »

Thanks bangbangping,

I'll give them a try. My fear with the heavier bullets was the pressure. I'd like to work down to ~1050fps safely without fear of pressure issues before I get there.

I'll have to do some measurements with the bullets to find where they touch the lands. I have Hornady's 300BLK modified case, but my fire formed supersonic cases have measured longer than my modified case, when using the headspace gauge. I believe this is common for the earlier rotary mag RARR. I have a 223 modified case on the way and plan to cut and size it closer to my chamber. Then I can feel confident experimenting with the OAL.

Once I get around to loading some of these up and shooting them, I'll post results.
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bangbangping
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by bangbangping »

Yeah, not a fan of the modified case sizing. I bought a 5/16 X 36 tap and make my own cases.
LFOD603
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by LFOD603 »

Do you just drill and tap a fire formed case?

What is it about the modified case that you're not a fan of?
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dellet
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by dellet »

LFOD603 wrote: Wed Oct 12, 2022 6:37 pm Thanks bangbangping,

I'll give them a try. My fear with the heavier bullets was the pressure. I'd like to work down to ~1050fps safely without fear of pressure issues before I get there.

I'll have to do some measurements with the bullets to find where they touch the lands. I have Hornady's 300BLK modified case, but my fire formed supersonic cases have measured longer than my modified case, when using the headspace gauge. I believe this is common for the earlier rotary mag RARR. I have a 223 modified case on the way and plan to cut and size it closer to my chamber. Then I can feel confident experimenting with the OAL.

Once I get around to loading some of these up and shooting them, I'll post results.
Then work up, nothing says you have to work down with a high pressure powder.

I use Tin Star with any where from 50-105% density, it works pretty well through that spectrum, with bullets anywhere from 85-220 grains. For the smaller bullets I prefer a bulkier powder, but it works.

It’s my go to powder for solid copper, sub sonic bullets. They need the high pressure to seal the gas behind the bullet. So it’s perfect for bullets in the 175-220 grain weight class and pressures over 40,000 psi.

6.5 grains under a 208 AMax @ 2.150 is good for around 1020 fps in a 12” barrel. Run the numbers in the program you are using and see where it comes out for you.
300 Blackout, not just for sub-sonics.
LFOD603
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by LFOD603 »

Thanks for the input. Working up makes a lot more sense in this situation.

I have some 190gr Sub-X but that's the heaviest bullet I have on-hand at the moment.

I plugged the 208 AMax into GRT and here's what it showed:

With the 208gr Amax(30712 Flat Base) 2.150" OAL, 5.9gr N32C, 99.5% load density, 956 fps and 43977 psi. This was with the 12" barrel.
With the 208gr Amax(30712 Flat Base) 2.150" OAL, 5.9gr N32C, 99.5% load density, 989 fps and 43709 psi. This was with the 16" barrel.

With the 208gr AMax(30732 Boat Tail) 2.150" OAL, 4.5gr N32C, 100.6% load density, 863 fps and 41335 psi. This was with the 12" barrel.
With the 208gr AMax(30732 Boat Tail) 2.150" OAL, 4.5gr N32C, 100.6% load density, 889 fps and 40736 psi. This was with the 16" barrel.

This was with the case volume @ 24.40gr H2O. I realize GRT is a simulation and may not match reality exactly.

I'm going to measure case volume of the brass I have to get a more accurate simulation in GRT. I have some MAST headstamp brass left to play with, maybe 20-25 cases. The rest are 500 Starline factory cases. From everything I've read, the Starline is known to have less case volume. Do you remember the brass you used for that load and the case volume?
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dellet
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Re: Bolt Action Subsonics and Tinstar/N32C

Post by dellet »

Take a fired case with the primer still in or put a used one in to plug the hole. Drop in powder until the COL with the bullet resting on the powder is 2.150”. That will be no more than 95-97% fill. You can not get 100% because you can’t fill the space between the bullet and the case wall 100%.
300 Blackout, not just for sub-sonics.
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