who here has used these two bullets in their gas guns and what results are you getting with it? which do you prefer to shoot more? and what are your loads for both rounds??
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Re: 155 scenars vs 175SMK's in a gas gun????
I don't have one, but my neighbor has a DPMS 308 LR with a 16". He tried the 175 SMK but would not generate enough velocity. So he tried the 155 scenars with N560 and gets good velocity. Depending on the length of your barrel, if you want to reach out there, I would at least get a 20" barrel and 18" is a minimum. At least with his 16" barrel, it seems that he is not getting good groupings at 100 yards with the 175 SMK as compared to the 155 scenars.
I don't have one, but my neighbor has a DPMS 308 LR with a 16". He tried the 175 SMK but would not generate enough velocity. So he tried the 155 scenars with N560 and gets good velocity. Depending on the length of your barrel, if you want to reach out there, I would at least get a 20" barrel and 18" is a minimum. At least with his 16" barrel, it seems that he is not getting good groupings at 100 yards with the 175 SMK as compared to the 155 scenars.
Re: 155 scenars vs 175SMK's in a gas gun????
It depends on the twist.M1A 175 work great on a 1-11 twist while the 155 work best on the 1-12 Both will reach out to 1 k with no problems. I prefer the 155 across the course in a 1-12 krieger.
It depends on the twist.M1A 175 work great on a 1-11 twist while the 155 work best on the 1-12 Both will reach out to 1 k with no problems. I prefer the 155 across the course in a 1-12 krieger.
Re: 155 scenars vs 175SMK's in a gas gun????
my m1a prefers 155 scenars. both the 175s(42g varget), and the scenars(45g varget) produce good groups, but the 175s seem to batter the rifle a bit. its just a feel thing, and might be my imagination. i tried to tweak the 175 load up a bit, got no additional velocity, just groups opened up a bit, ES went up, and the brass began to jam under the scope mount on extraction. now imho the m1a performance, likes and dislikes vary more gun to gun than other rifles. sooo many mods, levels of build etc. i dunno...just gotta feed her what she likes
my m1a prefers 155 scenars. both the 175s(42g varget), and the scenars(45g varget) produce good groups, but the 175s seem to batter the rifle a bit. its just a feel thing, and might be my imagination. i tried to tweak the 175 load up a bit, got no additional velocity, just groups opened up a bit, ES went up, and the brass began to jam under the scope mount on extraction. now imho the m1a performance, likes and dislikes vary more gun to gun than other rifles. sooo many mods, levels of build etc. i dunno...just gotta feed her what she likes
Re: 155 scenars vs 175SMK's in a gas gun????
I just had my DPMS 308 Re-barreled with a Rock 5R 24" barrel it is a 1-11.25 RH twist
I just had my DPMS 308 Re-barreled with a Rock 5R 24" barrel it is a 1-11.25 RH twist
Re: 155 scenars vs 175SMK's in a gas gun????
Out of my DPMS LR-308 16" and 24" barrels I have had best luck with 155 SMK, 5/8" groups @ 100 and 1.5 @ 200 (old palma 2156 I think) the 175 shot next best then the 155 lapua. Used RL-15 for powder and CCI BR primers.
Out of my DPMS LR-308 16" and 24" barrels I have had best luck with 155 SMK, 5/8" groups @ 100 and 1.5 @ 200 (old palma 2156 I think) the 175 shot next best then the 155 lapua. Used RL-15 for powder and CCI BR primers.
Re: 155 scenars vs 175SMK's in a gas gun????
The 155 Scenar has the definite advantage at longer range...
If you are talking about the <span style="font-weight: bold">old</span> design Palma bullet, the 175 has the edge in that the 175s only have to be run to to around 2550 in the gas guzzlers...and that is easy enough on the moving parts. Powder burn rate is the more critical concern, and that needs to be in the 4895 area. That load combo is equivalent to Fed GM and is well suited to the gas system.
The high BC 155 grs like the Scenar or the <span style="font-weight: bold">new</span> Sierra and Berger designs all have the ballistic edge over the 175 because of their higher BC compared to their lower weight.
In other words, they are more streamlined so they cut through the air better, and because they are lighter, they can be launced faster. I am only talking about the new improved 155 designs here like the Scenar, not the <span style="font-weight: bold">old</span> Palma bullet design.
Higher BC is free downrange velocity.
Accuracy is dependent on the rifle and load development. Usually accuracy is the bottom line, and none of this ballistic stuff is an over-the-top critical factor when shooting under 1000 yards. At 1000 yards, it matters a lot.
I like the 178 Hornady too, but theoretically speaking, there is no reason why a good shooting load can't be worked up for one of the new 155s, and I generally like shooting them better in my gas guns.
TC
The 155 Scenar has the definite advantage at longer range...
If you are talking about the <span style="font-weight: bold">old</span> design Palma bullet, the 175 has the edge in that the 175s only have to be run to to around 2550 in the gas guzzlers...and that is easy enough on the moving parts. Powder burn rate is the more critical concern, and that needs to be in the 4895 area. That load combo is equivalent to Fed GM and is well suited to the gas system.
The high BC 155 grs like the Scenar or the <span style="font-weight: bold">new</span> Sierra and Berger designs all have the ballistic edge over the 175 because of their higher BC compared to their lower weight.
In other words, they are more streamlined so they cut through the air better, and because they are lighter, they can be launced faster. I am only talking about the new improved 155 designs here like the Scenar, not the <span style="font-weight: bold">old</span> Palma bullet design.
Higher BC is free downrange velocity.
Accuracy is dependent on the rifle and load development. Usually accuracy is the bottom line, and none of this ballistic stuff is an over-the-top critical factor when shooting under 1000 yards. At 1000 yards, it matters a lot.
I like the 178 Hornady too, but theoretically speaking, there is no reason why a good shooting load can't be worked up for one of the new 155s, and I generally like shooting them better in my gas guns.
TC
