Purpose and Idea behind using 155gr pills with a .308?

[jLorenzo]

I've been working up 2 loads for my first .308. 20" Howa heavy bbl in a B&C adjustable target/Comp with Legacy Sports 10 round mag.
Load # 1
155 ELD'S
CCI 200
Fed brass
45.2 Varget
Load #2
178 ELD
CCI 200
Fed brass
Still playing with powder charges.
Have done 42.4 (Hornady book max, which seems conservative), 44.4, 44.8. I shoot a monthly local match that is all positional out to 700y. Rarely does the wind get above 6-7 mph if that.
My question is what we're 155 weight range of bullets designed for? My thinking is slightly less drop to 700, more velocity, slightly less recoil.
The 178s I use for casual shooting out past 1k. Still finding the limits and how they handle going trans.

Am I dumb for messing with the 155s in a PRS setting with a max range of 700 or is there merit to using the 155s? Opinions and experience would be appreciated especially those with 20" barrels.
Thanks guys.

 

[sjc929]

I’m using 155 Hybrids, but the reason I chose them is they have a higher BC than the 168 SMKs I was using before, and I can push them MUCH faster, which is particularly relevant for me because I’m using a 16” barrel which struggles with getting bullets heavier than 155s to a respectable speed. You aren’t dumb for messing with 155s, but you should test to see how much faster you can push them vs the heavier bullets, and see what the actual drop and drift differences are. I suspect with a 20” barrel, you can probably push the 168s and 178s fast enough that the 155s won’t get a chance to shine. Recoil might be a little better, but you’re still shooting a fast .308 bullet, and it’s going to kick no matter what.

In short, what you said the merits of the 155s are is true, but in my opinion is only relevant when dealing with very short barrels that can’t push the 168-185 class bullets fast enough.

 

[Hawk in WY]

The original "idea" came from International Palma Competition.

155 grain bullets were/are mandated. We don't hear much about Palma Matches anymore.

I believe the ballistic coefficient negative versus 178's disappears if you drive the 155's something like 100 fps faster.

Reminds me I must work up a 155 load for 1,000 yards and watch the 6.5 CM crowd cry.

6.5 beats the .308 at 1,000 in general, but it's fun to pop some people's balloons on the 1,000 yard line.

 

[RackOpsTactical]

Test out the various - what if - scenarios using a ballistics software. JBM ballistics is a free online one that works really well. Test out various muzzle velocities with the 155s then see if it is capable of doing what you are wanting to do before going transonic. If it works for what your goal is than go for it. Late haters hate if they want. However if your goals are not met than it's not worth it. Only you can decide. However testing in this manner will save your components and cash.

I think the 168ish and 178ish are around for a reason. But like I said if the bullet muzzle velocity works for you than go for it.

 

[918v]

The original "idea" came from International Palma Competition.

155 grain bullets were/are mandated. We don't hear much about Palma Matches anymore.

I believe the ballistic coefficient negative versus 178's disappears if you drive the 155's something like 100 fps faster.

Reminds me I must work up a 155 load for 1,000 yards and watch the 6.5 CM crowd cry.

6.5 beats the .308 at 1,000 in general, but it's fun to pop some people's balloons on the 1,000 yard line.

A 5% increase in velocity does not overcome a 20% difference in BC.

 

[Hawk in WY]

A 5% increase in velocity does not overcome a 20% difference in BC.

In God we trust, all others bring data.
Here a quote from this Forum a few years back:

155 Scenar @ 1000:
MV: 2,875 FPS (Can be pushed much faster btw)
Drop @ 1000: 345.5"
Drift in 10 mph wind @ 1000: 98.6"
Velocity @ 1000: 1,218.1 FPS
G7 BC: .236

175 SMK @ 1000:
MV: 2,650 FPS
Drop @ 1000: 412"
Drift in 10 mph wind @ 1000: 108.5"
Velocity @ 1000: 1,114 FPS
G7 BC: .243

 

[918v]

You and the OP were talking about the 178 ELD, not the 175SMK. The G7 for 178’s is .276

 

[Shadow_Warrior]

Back in the day when we all shot the .308 here, I was running a 155gr at 2950fps w/ good ol' trusty Varget.
It was a warm load out of a 24" barrel but it never let me down in hot or wet conditions.

 

[rgv]

I ran the 155 Scenars at 2950 as well until the PRS put a speed limit of 2800 fps in tactical division.

I switched to 175 RDF at around 2760 and I believe it’s a toss up, with a slight advantage of less recoil with the 155 and a slight advantage in gusty conditions to the 175.

 

[W54/XM-388]

I ran the 155 Scenars at 2950 as well until the PRS put a speed limit of 2800 fps in tactical division.

So they wanted to handicap commonly used ammunition for yet some other stupid reason. Great.

 

[Long Range 338]

If you are shooting to 800 yards or less the 155 makes more sense than the 168 or 175 for PRS. Remember speed matters! We assume everybody can dial/hold elevation but wind is time of flight based and less time in the air means less time for wind drift.

 

[jLorenzo]

If you are shooting to 800 yards or less the 155 makes more sense than the 168 or 175 for PRS. Remember speed matters! We assume everybody can dial/hold elevation but wind is time of flight based and less time in the air means less time for wind drift.

That was my thinking, less TOF less time to be effected by wind. Well shall see. I've worked up to a pretty damn hot load with the 155 eld, 45.2gr of varget. No real pressure signs but you know when they go off that's for sure.

 

[jLorenzo]

Also the Legacy Sports dbm limits me to a COAL of around 2.79 and change. Don't know if that factors in. I know the 178s would benefit from being seated out further. So far only have the Hornady heads pace comparator, need to get the ogive one. I've jammed bullets but they didn't shoot any better and I'd rather have a jump in theory anyways.

 

[jLorenzo]

Everything considered the 178 ELD M has a respectable BC for a .308 round.

 

[Huskydriver]

The original "idea" came from International Palma Competition.

155 grain bullets were/are mandated. We don't hear much about Palma Matches anymore.

I believe the ballistic coefficient negative versus 178's disappears if you drive the 155's something like 100 fps faster.

Reminds me I must work up a 155 load for 1,000 yards and watch the 6.5 CM crowd cry.

6.5 beats the .308 at 1,000 in general, but it's fun to pop some people's balloons on the 1,000 yard line.

I 100% agree on the source for 155 grain bullets being palma mandated matches. Most palma shooters I know are using 30- 32" barrels to push 155s over 3000fps to make shooting at 1k doable and repeatable.

 

[steve123]

All other reasons aside, I tolerate the recoil of the 155 better, especially in a unbraked rifle.

 

[jLorenzo]

I saw somewhere the guy that set the smallest group at 1k with a 308 was using 155s. Probably did have like a 30" barrel. I'm going to keep playing with them and if I don't get the results I want I always have my 178s which are great bullets, just figuring out seating depth.

 

[spife7980]

All other reasons aside, I tolerate the recoil of the 155 better, especially in a unbraked rifle.

Me too. I actually shoot 150s from my 3006 just because I enjoy shooting them more.

That said, if it were for PRS style shooting then I would go with the 175s just for wind, even at 700 max.

 

[lash]

Me too. I actually shoot 150s from my 3006 just because I enjoy shooting them more.

That said, if it were for PRS style shooting then I would go with the 175s just for wind, even at 700 max.

With the stated winds that he said he’s dealing with, I’d most likely go with the 155s. They are relatively like lasers in comparison. Add that to the lighter recoil translating to better view of splash and I’d choose the 155s every time, for PRS shooting. On belly and at distances longer than 750, or with higher unpredictable winds? Then I’d go 178s. But that’s just my take on it.

 

[918v]

Is the 155 accurate at 2900 FPS out of 24” barrels?

 

[memilanuk]

It's pretty frickin' hard to find a scenario where the 155 isn't accurate. A drunken monkey could fall off a stump, and hit upon a decent load for a 155 on the way down. Great bullet for beginners, both in terms of ease of loading, and as far as having to be mindful of the wind.

 

[918v]

Bullshit

 

[Long Range 338]

Bullshit

Care to expand on which part of the discussion you refer to? Or are you typically able to stifle all discussion with your extensive mastery of debate?

 

[Bender]

A 155 pushed fast will smoke a slower 168 or 175 all day to 1000.

The math proves it.

Don’t be a Fudd and just say bullshit...

 

[Dirty8404]

Don’t forget the 155s pushed at proper speeds is better at unknown distance as well.

 

[steve123]

Me too. I actually shoot 150s from my 3006 just because I enjoy shooting them more.

That said, if it were for PRS style shooting then I would go with the 175s just for wind, even at 700 max.

Sold my 30-06 but I ran 155's in it too. I know where a heavy 30-06 AI is but it's one of those, do I really want to go there again things. The thrill is gone and I don't hunt much so I'd rather shoot my 22rf or 223AI!

40x/308 - Irons, without flags, on steel, it's not easy in the wind with those 155's by 675Y which is the distance we have the steel set at. Pretty much don't bring it out unless the wind is down. Tried a warm load of 178's but the trade off is not worth the recoil without a brake. I try to like 308 but that just left or just right of steel is frustrating....

That 40x might get turned into a 25x47 using blackjacks this year.

 

[OLD308]

Personaly, I never run 155s. I run shorter barrels mostly so I'm not getting the speed to make them lasers (funny, 308 laser) vs the 175. Wind is always and for ever the main issue after fundamentals for shooting distance. So I practices the fundamentals and shoot what bucks the wind the best. As far as recoil is concerned, that's very subjective. To test this take your 22lr and put a clock on your accurate speed shooting at distance, say 100-150 yards. Then compare that to you times with the centerfire at 400-500. I bet your time and precision is not that different. Yes the top shooters are benefiting from minimal recoil systems. The average to above average shooter is lying to them selves about recoil being the reason for their time and precision. Practices in the long run will benefit them/us more than newer toys.

Positional shooting is were the recoil can be seen by everyone. Another reason to train with the heavy hitters. I could get better groups and a faster time with my .223 at 400 verses my 308. Funny thing, the more I trained to mitigate the recoil of the 308, the firmer my position was. Thus both the 223 and 308 groups are the same now. I would not have found the need for a firmer position with the 223 alone. Sounds little contradictory, yes, but try it and see if it works for you. This is exactly what I was prescribed when I spouted off that "recoil is killing me mantra". Just my thought, hope it helps.

 

[ShebasDad]

Good to hear I'm not the only one going down this road. I've got loads ready to test in both 178 and 155 eldm's if the weather would settle down. Good luck I'll post range results when I get to the range.