N133 versus N135 Powder

[SS427]

The 6BR website cartridge guide doesn’t list N133 as a powder for light bullets. Not a single “Favorite Varmint Loads” for the light bullets are with N133. The Sierra reloading manual lists an N135 load for 70 grain bullets, but no N133 load.

Yet several of the 6BR forum members have suggested N133 loads for my 13.5 twist barrel and they have shot extremely well. I got one Nosler 70 grain Ballistic Tip group that measured .175 during load development, and several Sierra Matchking groups in the low .2s.

In reading my VihtaVuori manual, I’ve found some interesting facts. The grain size of N133 and 135 are the same size. Energy content is the same at 3600 joules per gram as well as bulk density at 880 g/l. It appears these two powders are essentially the same. The relative burn rate for N133 is 72 and for N135 it is 70. I assume some sort of coating slows the burn rate for the N135.

N133 doesn’t fill the 6BR case completely with the few recommended loads I’ve found, while N135 probably would, or come very close. My understanding is a full case or close to full case often gives better accuracy.

Since I’m getting such good results with the N133, should I even bother with the N135? I’m on the verge of buying 8 lbs of N133, but before I commit the funds I want to make sure N133 is the better choice over the N135. My gut tells me to get a pound of N135 and try it, but maybe someone else has already been down this road.

 

[fdshuster]

Otter: I have, and use a lot of both powders, using the N133 for the lightweights, 58 to 70 gr. with 6ppc and 6BR's. The N135 is driving the 75 to 85 gr. bullets in 6BR. Both my favorites, can't say one is better than the other, but always make sure I have a good supply on hand. Price has taken a jump over the past year, from $165 out the door a year ago for 8# of N133 to $240 recently.

 

[SS427]

Thanks Frank. I knew you would have an answer. Thought about just sending you an email but figured someone else might be interested in an answer too.

I think what I will do is order the 8lbs of N133 and at the same time order a pound of N135 too. The N133 works great in my .223s, so I know I will use it.

 

[johara1]

Hey Frank, get some old 8208 and it will make that PPC.sing........jim

 

[MarkS]

Otter,

N133 is on the fast side for a 6BR. It should be find for lighter bullets. But you need to try N135. I have shot it in 6 different 6BR, and shot the best in all of them.

Mark Schronce

 

[SS427]

Mark - thanks for the info, but was kinda hoping I wouldn't hear this. Locally I can get N133, but no one carries the N135. I will have to order it if I want to try it. :-\

 

[jo191145]

My 14 twist 6BR liked both 135 and 133 with the 58gn V-Max(Its favorite bullet). The nod going to 133 as a little more accurate.
In the end a good stiff shot of Benchmark outperformed both of them.
Next time I screw that barrel on I'd like to try X-Terminator and IMR-8208. My 6ppc likes both those powders. I'm thinking the BR with a light pill would too.

 

[COLT45SA]

I had a custom built light weight sporter in 6mm PPC that made one very slightly ragged hole using 27gr of N-133 over a 62.5gr Watson bullet.

 

[SeabeeKen]

Youre right SS, 133 130, and 135 are same grain size and the coating changes the burn rate.

 

[Laurie]

Youre right SS, 133 130, and 135 are same grain size and the coating changes the burn rate.

Bofors does the same thing with Norma 201 and 202 - identical apart from the weight / thickness of the deterrent coating. Makes sense with powders in this category, and allows the handloader to fine tune combinations.

 

[DocBII]

Bofors does the same thing with Norma 201 and 202 - identical apart from the weight / thickness of the deterrent coating. Makes sense with powders in this category, and allows the handloader to fine tune combinations.

Laurie,

So would you be willing to make custom loads by loading first one then the other powder? What about mixes of the powders?

I'm not recomending either process, just curious if you are aware of the results of others experimentation. Send PM if you would prefer to keep this discussion private.

Thanks,
DocBII

 

[Laurie]

I'd never mix powders - with the range we have today with modest steps in burn rates, the risk far outweighs any possible benefit. I'd never be happy that a perfect and repeatable mix takes place either.

There's a large enough step between N133 and N135 for me not to have many (or even any that I can remember) overlaps between them. In my 223 lighter bullet days, I used N133 pretty exclusively for 52-55gn bullets; N135 for 68-70s; N140 and Re15 for 80s. These days I mostly use N133 in 6.5 Grendel with 120/123s and will try both it and N135 with 123/130s in that cartridge later this year.

Re the OP's first post, I'd have thought N133 a bit 'quick' for the 6BR with all but the very lightest (as in 55-65gn) bullets, and would personally try N135 first. TBH, N135 has never been a great performer for me though across several cartridges with the exception of the 223/69. Others on Accurate Shooter are much happier with it though, so who am I to disagree with what works for them! As is often the case with Viht powders, QuickLOAD default settings (and burn-rate charts too) appear to show N135 as a considerably slower burning powder than it turns out in practice. See here:

http://www.targetshooter.co.uk/?p=3934

So far as the difference the coatings make to the Bofors / Norma powders, you can see how they worked out in practice in a long-throated 223 F rifle with the 77gn SMK in an examination of possible Reach-compliant alternatives to H4895 in our market:

http://www.targetshooter.co.uk/?p=3956

Note the mention of the large discrepancies found in different burn-rate charts for N201 both in relation to its N202 sibling and also grades from other marques, also my lack of trust in QuickLOAD results in this instance.

 

[Doom]

I've used N135 with 52gr Berger Match Target in 223 and have been pleased with it. The issue is getting enough in the case to keep the velocity but I get 3300+ fps with 25.4 gr in a Lapua case. 26grs fill the case to the top.

 

[jcm24m]

Viht powders burn so much cleaner, you’ll be happy with either 133 or 135

 

[DocBII]

Laurie,

I appreciate and respect your response. I've found barrel length matters more for any velocity result forthose powders. Optimum complete powder burn tuning to barrel length for night matches appeared to provide the best performance.

Thanks,
DocBII