Anyone shoot 155 Scenars out of a 16" barrel? Performance?

[bm11]

I asking because I have a gasser coming, and while it has a 20" barrel, I'm going to shorten it up to make for a handier, suppressed package. I have seen all kinds of posts about how "155 Scenars need to be pushed fast (2900 fps+) to perform." My personal experience does not agree. I have found that the like to be pushed HARD, but if the barrel is too short to develop crazy velocity, they still shoot. My bolt gun load is 46.5 grains of Varget with a Lapua case, it makes 2800 fps and shoots a consistent half moa. I make good hits out to a thousand yards, out performing a buddies 26" barreled .308 (TRG-22) that shoots 175 SMK's at 2650 fps (in drop, drift, and hit percentage as a result of both.)

My question is- if you go shorter in barrel, and down in velocity further, does this continue? It seems as though in spite of case length issues and the shorter barrel length I should still be able to get an honest 2700 fps, which with 155 Scenars still makes this a decent long range gun.

Anyone tried it? Seems as though everyone is stuck on 175 SMK's going 2450 fps or so, but this seems to be a better solution, at least on paper!

 

[Brasscow]

Here's what I've found

16" rainier ultramatch
Winchester Commercial Case
CCI BR2
155 scenar
Varget

43gr: 2418fps average
43.5gr: 2455fps average
44gr: 2512fps average
44.5gr: 2528fps average
45gr: 2543fps average
45.5gr: 2572fps average
46gr: 2604fps average

Can't say much about the accuracy, but I think it shoots well around 45.5gr. I was able to keep them into about .75 MOA. 2-3" groups at 200yds. I don't ever do load development inside of 200. Usually at 600.

I wouldn't push much more powder into the case IMO in a gas gun. Keep in mind this is with a winchester case. Equivalent load with mil brass is probably a full grain less. I'm working on other guns at the moment and I only built this rifle up to shoot the 130 tsx into hogs. I only loaded up the scenars for my own knowledge and because I stock large quantities of them for my bolt rifle.

I'll probably try them with 8208xbr to see if I can't get a bit more velocity out of them, but highpower season is upon us so I probably won't do that for nearly a year. Keep us updated on what you find!

Edit: Wanted to add I want to try 8208 because its a bit faster burning. I suspect I can get greater velocities in the shorter barrel without having insane gas port pressures. The reason for the 46gr max I listed was port pressures - feels like the rifle is getting beaten up. No idea how much more velocity you can get, but I think 2700 is definitely optimistic. My rifle has a JP low mass BCG and JP retained silent capture system FYI.

 

[bm11]

Yeah, I was thinking that pressure would potentially be a limiting factor. Both the short mag length and the fact that it is a gas gun.

Still, 2600 fps would still be decent, certainly better than a 175 at 2450. Only if it shoots though!

 

[Brasscow]

Yeah, I was thinking that pressure would potentially be a limiting factor. Both the short mag length and the fact that it is a gas gun.

Actually, I'm not sure that jumping the scenar is an issue at all. I don't think it minds. 3/4MOA is good IMO. My rifle has a geissele s3g and I'm sure as hell not used to a single stage or a gas gun, so all things considered it shot pretty good IMO.

Actually if you have an LR-308 I have a rainier ultramatch barrel with about 150rds through it I'd be happy to sell you. It's actually the barrel I worked these loads up with. Long story, but I bought two and sent one in for dimpling and did load development on the other figuring when I had finished that I'd put my dimpled barrel on and send the other in for dimpling and build one for my father. Turns out he's going to go another route as he had shoulder surgery and doesn't care for the 308 recoil.

 

[bm11]

I don't think its an issue with jump, but the shorter seating depth results in less case capacity and more pressure than a long loaded round.

Thanks for the offer on the barrel! It would require quite a bit of work to work with my MWS though, a lot more than the simple chop and thread it needs now.

 

[Brasscow]

I should have figured that's what you meant since we were discussing pressures.

As for the barrel, don't be lazy about it. It's just a little machine work on one end vs the other

 

[bm11]

Both ends vs just one. My suppressor is threaded 18x1.5 metric. Which means if your barrel is 16" and 5/8x24, I can't use it without registering my MWS as a SBR!

 

[Dogtown]

Personally, I find the 175SMK performs better out of a 16". The 155 Scenars rule at distance is you can get them to about 2900+ fps, which is easy in a 22-24" barrel. But when I moved to a shorty the 155s started falling apart on me while the 175s retained the performance at distance that I was expecting. For that reason I think the 155s are still top performers, but within a narrow window of conditions while the 175s will shoot well regardless of barrel length.

 

[bm11]

Gotcha. I guess I may have to try both and find out! The new 168 hybrid looks good too, but may be a bit on the long side for an LR20 PMag.

 

[Unsichtbar]

Dogtown Is giving you some accurate information "Personally, I find the 175SMK performs better out of a 16". The 155 Scenars rule at distance is you can get them to about 2900+ fps, which is easy in a 22-24" barrel. But when I moved to a shorty the 155s started falling apart on me while the 175s retained the performance at distance that I was expecting. For that reason I think the 155s are still top performers, but within a narrow window of conditions while the 175s will shoot well regardless of barrel length."

I shoot a lot of 155L from a DTA 22' barrel 8208 XBR 2900+ fps at 80F 8.4 Mil to 1000, you have to shoot 155 at 2900 at least to get the performance, you might look at 178s or 185 with 8208, I get some very fast fps with MR 2000 but have not tried that powder in a 16" barrel

 

[bm11]

Why though? The BC is the same and you can push them faster. Physics is physics. Explain why 2900+ needs to be achieved? Mine work great at 2800 out of my 18.5". The 2900 fps scenar is going 2800 fps after 50 yards and 2700 at 100 yards. Does it know how fast it was launched or that it was launched a hundred yards ago and not 50?

Again, I have read this time and time again on the internet, but if the BC is .505 and so is the BC for the 175 SMK, on paper the 155 beats it in every case. WHY does the Scenar NEED to be launched at 2900? Factually or anecdotally I mean. Because I have a rifle that launches them at 2800 that has been doing so for almost 6000 bullets, is still averaging .5 moa, and makes hits at 1000 yards with less drop and drift than a rifle shooting 175's at 2650 on the same day and same conditions (in the real world I mean, not just on paper.)

 

[Unsichtbar]

The real BC for 155L is lower 0.459 a SMK is .495 BC G1 http://www.appliedballisticsllc.com/index_files/Lapua_Scenar.pdf The BC for Hornady 178 HPBT is .505 BC or higher G1 Berger 185 is some what higher .530 +. I like the 155L which I shoot most of the time but when there is a tail wind the heavier better BC bullet is not as effected by the wind.

 

[bm11]

Ok thanks for the reply. I looked up Litz' G1 numbers for the Scenar, Sierra, and AMAX, and I guess they are in Shooter now (I always used Litz' profile but it never showed the number so I referenced "advertized number."

Here are the Litz numbers:
155 Scenar: 0.462
175 Sierra: 0.475
178 AMAX: 0.469

If we are going to use Litz' numbers for this debate, we are going to have to use them for the other bullets as well.

Numbers comparing the Scenar at 2600 and the Sierra at 2450 to follow!

 

[sinister]

bm11, what is it exactly you want the gun and projo to do? A short and handy suppressed rifle may not be the best tool for 800-1,000 yards at sea level.

You've selected the Lapua 155 for a suppressed 16-incher. Everything in life is a compromise.

Do you shoot a lot at 1,000? Are you trying to get a quiet shooting 308 for deer under 300 Meters? Are you just trying to make the gun go bang?

There are literally tens if not hundreds of bullet/powder combos available for the 308 without overstressing the gun, a suppressor, or your patience.

 

[bm11]

All numbers calculated at 0 density altitude (varies from -800 to +2000 where I shoot depending on time of year, but I figured I would give the sierra as much advantage as I could, so I used 0.) Wind drift in 10mph/90 degree standard.

Sierra at 2450 fps (0.475 BC)
500 yard drop: 3.9 mil
500 yard drift: 1.3 mil
1000 yard drop: 13.3 mil
1000 yard drift: 3.2 mil

Scenar at 2600 fps (0.462 BC)
500 yard drop: 3.4 mil
500 yard drift: 1.3 mil
1000 yard drop: 11.9 mil
1000 yard drift: 3.1 mil


Scenar at 2900 (.469 BC) QUOTED FOR REFERENCE
500 yard drop: 2.6 mil
500 yard drift: 1.1 mil
1000 yard drop: 9.1 mil
1000 yard drift: 2.6 mil

My conclusions, short of confirming scenars still group at 2600 fps- Scenars still have an advantage, despite a small deficit in BC, the difference in velocity more than makes up the difference.

 

[bm11]

bm11, what is it exactly you want the gun and projo to do? A short and handy suppressed rifle may not be the best tool for 800-1,000 yards at sea level.

You've selected the Lapua 155 for a suppressed 16-incher. Everything in life is a compromise.

Do you shoot a lot at 1,000? Are you trying to get a quiet shooting 308 for deer under 300 Meters? Are you just trying to make the gun go bang?

There are literally tens if not hundreds of bullet/powder combos available for the 308 without overstressing the gun, a suppressor, or your patience.

My goal is to turn a 16" gasser into the most versatile semi auto precision rifle it can be, within its own limitations. It's not going to keep up with my .338 Lapua or even my .260 bolt gun, and if the primary purpose were to shoot it at 1000 all the time, I'd go with a longer 6.5mm option. But, knowing that its a 16" .308 gasser, I'm trying to get the most performance I can out of IT, which at least on paper means the 155 Scenar is the bullet to use.

 

[Unsichtbar]

See these two links will assist you

Heavy Bullets for Long Range

http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf

 

[bm11]

See these two links will assist you

Heavy Bullets for Long Range

http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf

Both good reads and I enjoyed them both! However, using numbers generated with a good ballistic program, with realistic muzzle velocities for a 16" barrel and ballistic coefficients generated by Bryan Litz, tell me where above in my ballistic chart I gain a benefit with the heavier bullet?

No doubt the higher BC pays off when the velocity is higher, but again, if my choice is a 175 SMK at 2450 fps or a 155 Scenar at 2600 fps, and the above data is correct for drop and drift both being less with the 155 Scenar, where do I gain an advantage with the 175?

Lets keep this going because I do enjoy a good, informational debate!

 

[archad]

I use the Nosler 155's CC in my 16" .308. 2600 fps easy acheived with IMR 8208 great accuracy works good to up 800 meters.

 

[Brasscow]

I have a thousand 155CCs I've been planning to give a shot, but when I compared them side by side with the scenar I didn't think they would offer much stability past 600yds.

See attached.