N550 with 185 Bergers .308 Win

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Clint E.

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Hello all,
I am looking for anyone that can share there thoughts and experience with Berger 185 Grain Match Target BT Long Range bullets and N550 powder in a 308 win.

I did a search and most of the results were in regards to 200 and up grain bullets, but showed some impressive results velocity wise and got me thinking. Since my rifle has a 1:12 twist stabilizing the 200's might be questionable, will the N550 give me the extra performace I am looking for with the 185's?

Thanks in advance,
Clint
 
Stabilizing will not be questionable at all. A 12-twist will easily stabilize any bullet you can realistically shoot out of a 308, up to and including 210 grain Bergers.

Over-twist will result in excess torque and that affects shooter accuracy. I always suggest a 12 twist in 308. It does everything.
 
Ok thanks Obtunded, I was just going with what was on the Berger site.

That being said I will change my question to:
Who is using N550 in the .308 win with target/long range bullet types of any weight?
What is your load and what kind of velocity are you getting?

Clint
 
Clint E. said:
Ok thanks Obtunded, I was just going with what was on the Berger site.

That being said I will change my question to:
Who is using N550 in the .308 win with target/long range bullet types of any weight?
What is your load and what kind of velocity are you getting?

Clint
Click to expand...

I shoot 190 SMKs from my 308s using Lapua brass BR2s and 45.25 gr of Vit N550. I get 2690 fps
Strat lower and work up as the pressure sneaks up REAL quick!!
 
alberta tactical rifle said:
I shoot 190 SMKs from my 308s using Lapua brass BR2s and 45.25 gr of Vit N550. I get 2690 fps
Strat lower and work up as the pressure sneaks up REAL quick!!
Click to expand...

Thanks Rick,
What barrel length gave you the 2690?
How do you find the N550 is for temperature stability compared to Varget?
Do you have any N550 in stock right now?

Clint
 
The 190 SMK shoots beautifully out of a 308 Win. It, with 42.3 gr. Varget is my preferred load.

N550 gives great velocity and nice groups, but it also gave me some weird secondary pressure spikes.

P1040672.jpg


N550_hump.jpg


I don't know that the secondary spikes were real pressure, they were possibly some kind of mechanical effect from the muzzle blast. If you fired near dusk, the muzzle flash was ridiculous, even out of a 26" barrel. There was a lot of unburnt powder being ignited when the bullet left the barrel. It didn't seem to effect accuracy in the slightest though. Groups were still amazing. Above are the traces and the actual target for the lower barrel node.

48.0 gr. gave 2777 fps. avg. when the primary pressure hump peaked at 60k. It was a fun powder to play with, but hard to get and not very temperature stable.
 
Also tried it with the 208 AMAX. No pressure spikes, but groups and velocity were not as good as with RL-17.

P1030951.jpg


P1050229.jpg


Some pressure data for both in this report

RL-17 isn't very temperature stable either...
 
Wow thanks for all the info kombayotch!

I wonder if you secondary pressure spike was not caused by N550 being a bit slow for the 190 smk??

It now has me thinking that N540 might be worth a try with the 185/190 weight bullets.

On a side note how do you like your RSI pressure trace system?

Thanks,
Clint
 
It is slow for the 190 IMO. But, I don't think its an actual pressure spike. PT is strain gage based, so it is possible for it interperate a vibration or impulse in the barrel as a pressure spike. Strange that groups are not affected by it though.

I love the PT system, it has paid for itself in time and component cost several times over. You only have to fire a handful of shots, then analyse the data in a spreadsheet and you will know where the load tops out and where all the barrel nodes are. I've on occasion performed the work-up of half a dozen different loads in a single afternoon.
 
kombayotch those post-exit curves also look like artifacts to me (e.g. reflected bending waves in the barrel). The fact that they have a smooth ramp up, rather than an instantaneous spike, makes them look very unthreatening. Did you see this with any other powders, or is this an N550 oddity?

I am curious what your "(0.5U, 0.1L)" notation indicates, can't quite figure it out but I am sure it is interesting.

With the N550 at 48.0 and 60Kpsi, were you getting good accuracy and good SDs?

I only ever got a single kg of N550, tried it a bit in for 6PPC/105-Lapua, never did get very good results with it. I did then and still do like the idea of a high performance powder, I guess there is still some work to do before it's easy to use a higher performance powder.

Thanks for that report on your evaluation of the 210s. (looks the first two tables on pg. 4 have a minor error, the columns labelled "COAL" seem to be the bullet comparator measurement. The third table on pg. 5 says "...loaded to magazine length", which probably is a mistake)
 
I've seen it before, always when the powder is really slow for the bullet weight being used.

"(0.5U, 0.1L)" is the scope correction to zero the 210 gr. loads (from my standard 190 or 155 gr. load zero). I didn't re-set the EREK or windage knob for the 210s.

P1030952.jpg

Bottom group is 48.0, don't recall what the top one was... think it was 46.5, but would have to check my note for that and the SDs. I don't usually worry too much about SDs during initial load work-up.

Yeah, to create this report, I recycled a previous one I did comparing 155 gr. bullets. There are a few things that got missed.
 
Clint E. said:
Thanks Rick,
What barrel length gave you the 2690?
How do you find the N550 is for temperature stability compared to Varget?
Do you have any N550 in stock right now?

Clint
Click to expand...

My barrels are 22" long
So far temp insensitivity seems good.
Currently out of stock but have LOTS enroute.
The 190s seemed like a good next step up in weight, I am experimenting with the 208s as soon as I get he time.
 
Thanks Rick,

I picked up some 185 BT Bergers the other night. I am going to give them a try with some Varget and then with some N550 when I can get my hands on some.
 
N-150

I use 42.0 gr of n-150 , lupa brass , 210 m primers and .175 smk's in my .308 and it shoots good groups with this load , I just started to make up some loads with the .175 berger vld's same powder and charge , i will post results after i range test them and chrono them.




BigFlint said:
Has any one tried N150 instead of N550?
Click to expand...
 
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