New load development

[Beardog]

Started a new load today for my 308 using N150 with Berger 185g. 26” Sassen barrel. VH gives max load of 40.6g with N150 in a 308 for those rounds.  

So loaded up the below rounds with the given velocities. I went slightly over the manual max load. The early rounds were really sooty for some reason. As the loads increased the rounds were less sooty. No pressure marks or stiff bolt or any warning signs. I feel I’m still under my max load. Rounds are loaded quite long. 

So I think I will go up a bit more. Was really hoping to hit around 2600-2650 FPS, which is what I was getting with varget. 

Any ideas why I got sooty loads? Barrel was filthy. 

 

Reloading phase 1 - Pressure test and OCW. 

1. 38.  2237
2. 38.3. 2273
3. 38.6.  2282
4. 38.9. 2255
5. 39.2. 2372 
6. 39.4. 2352
7. 39.6. 2375
8. 39.9. 2393
9. 40.1. 2409
10. 40.3 2421
11. 40.5. 2403
12. 40.7. 2423
13. 40.9.  2439
14. 41.1. 2448
15. 41.3. 2439

Apart from Rounds 1 and 4, the rest where all a ragged hole.  

Cheers. 

 

[GeorgeB]

N150 is a slower burning powder than Varget, so you will probably need more of it to equal your velocity with Varget 🙄

[No i deer]

Probaly 2 or 3 grains short and the smokey cases arn't expanding and sealing the chamber 

[Beardog]

Not enough bang then. The VH website lists COAL 2.795 with there data.  I load at 2.968. More powder then and hopefully better seal and more bang. Cheers. 

[Chanonry]

9 hours ago, Beardog said:

Not enough bang then. The VH website lists COAL 2.795 with there data.  I load at 2.968. More powder then and hopefully better seal and more bang. Cheers. 

Similarly I used Reloader 17 with the luxury of loading to 2.950 and was seeing 2700.  It was full mind.

[VarmLR]

Sooty = insufficient obturation = too low a load.

 

Think very carefully before pushing it further than you have.  I'd say that from a 24 inch barrel, 2439 is a bit on the slow side and N140 might give you a bit extra, better still, RS50 which doesn't have the same tendency to pressure spike as it is more linear with charge.

You should  safely achieve 2550fps with that powder.  You may not be getting the velocities you want from N150 because of barrel length.   You may not get complete combustion using N150 from a 24 inch barrel PLUS you'd be tempting fate on chamber pressures by continuing to load above recommended max.  The weather is currently quite cool.  Viht is well known (both N140 and N150) for pressure spiking when temps pick up, especially when loads are hot to begin with.  The smarter approach might be to select a different powder to get your intended terminal ballistics rather than try and push your current bullet by upping pressures above manufacturer's stated recommended max load.  I would have thought that the Berger should shoot fine in that barrel length.

Sierra is usually a very reliable indicator of max loads and they state that you should never exceed 41.8gr with a 180gr bullet shot at 2500fps.  I'd say that you're currently taking chances I wouldn't care to with my own .308 by pushing past that.

I shot 190s to 2600fps with a very stiff N140 load.  It spiked horribly past 42.6gr (not the right powder but all I had).  Would't go there again.  At around 42gr it shot fine and grouped well at 1000yds.  Based on that, and the RS50 being less likely to spike plus giving a little faster burn rate, you should be closer to Varget results over N150.  If you're anywhere close to me (Gloucestershire) you'd be welcome to come over and try some as I have some on the shelf.

[Beardog]

Many thanks for the replies. My barrel is actually 26”  my mistake. I think I will go up a bit more my rounds are loaded very long , just 10thou off of the chamber, plenty of room left in the case yet. No high pressure signs. Getting the low pressure indicator with the sooty cases, would that not say it’s ok to go up more? But take on board on the comments. Getting powder is a nightmare and I’ve got two tubs of N150 lol 

I did put a thread on hear a few weeks ago for advice for this load with Berger 185 and N150 came up a few times.  I do have N140 at home which I use on my hunting load with Hornady 165SST.  

There was very little in it between the varget 185 and the N140 165SST loads, only about 10fps on average, which was purely coincidental as I didn’t have a chronograph when developing those loads. VarmLR thanks for the offer.