155gr Scenar velocity

[cheshirelad]

Anyone using 155gr Scenars and Vhit140, interested in what sort of velocities you're seeing.

Looking at loading around 44.0

[Popsbengo]

43.5gr gives me 2730fps in my 24" 1:11 barrel

44.0 gives me 2763fps

[cheshirelad]

Have you tried either 44.2 or 44.4

[Popsbengo]

2 minutes ago, cheshirelad said:

Have you tried either 44.2 or 44.4

No, 44gr was just showing pressure signs on warm days and 43.5gr is my optimum harmonic choice

 

[bolte]

I use 155 scenar, 44gr N140, 24" barrel, 1:12 twist, 2833 fps.

[cheshirelad]

Looks like I'll be trying 44.0 as my starting point then, thanks for the help.

[Popsbengo]

41 minutes ago, cheshirelad said:

Looks like I'll be trying 44.0 as my starting point then, thanks for the help.

Don't you think that's a bit risky without understanding the seating depth of those using this solution?

[cheshirelad]

I don't mess with seating depth as they can only be mag length in an AR308, I do intend to start low and work up, my 167gr load started at 43.2

[Popsbengo]

54 minutes ago, cheshirelad said:

I don't mess with seating depth as they can only be mag length in an AR308, I do intend to start low and work up, my 167gr load started at 43.2

My loads are long, too long for a magazine.  Best of luck

[cheshirelad]

Spotted a typo, meant to say 43,0 as my starting point, not 44.0, 🙂

 

[duey]

From my experience I found if you can get them running at 2850fps that works really well 

however you will be starting to push the pressure envelope at this speed so caution in development 

[VarmLR]

On 5/21/2020 at 1:53 PM, Popsbengo said:

Don't you think that's a bit risky without understanding the seating depth of those using this solution?

Yes.  

The idea for safety's sake and to make sure that you are safe not just for yourself but also for those who may be shooting next to you is to start low and work up, not start close to max, which can be inviting trouble!

I haven't shot the 155 Scenar but have loads developed for Sierra's 155 MK in both tangent Ogive and Secant Palma using both N140 and RS50.  My experience with this bullet and an 11 twist 24 inch barrel was that 44gr was flattening primers and resulting in the odd stiff bolt lift on really hot days (above 26C) and on warm days at about 24 or 25 degrees was resulting in a fair few flattened primers (CCI200) with the bullets loaded to magazine length (2.800).

I backed off by a full grain to allow for pressure spikes and found an accuracy node at 43.1 grains resulting in similar groups but at 100fps less (2650fps).  At 20 degrees I was getting an average of 2750fps with 44gr N140 and about 2770fps with RS50.  RS50 disn't show as much pressure spiking...it did show some, but it was more predictable....whereas N140 would be "...nothing....nothing....nothing.....KICKI!" .  That's the thing with N140.  If your ammo gets really hot the pressure and velocity spikes massively, not uniformly so loading close to max when load developing can become a fools errand.

Laurie has pointed out over on another forum though that Vhitavouri are releasing updated recipoes for their "N" range of powders to address some of the temperature sensitivity issues, and I'd say better late than never, as it has turned me off N140 as have the price rises.  I can now buy RS50 cheaper so it's a no brainer for now to stick whith RS.

I remain though a huge fan of N133 for 223 hand loading and have no plans to change any time soon.