PNTC Intro to Long Range AAR

erwos · Jul 8, 2019

squaregrouper said:
I am by no means an expert, but this is my understanding...
The trajectory is predictable as long as the projectile is supersonic; once it is subsonic, all bets are off. EX- In the same conditions, a bullet travelling at 3000fps at the muzzle will repeatedly have virtually the same velocity at 100yds, 200yds, 500yds, etc- until it becomes subsonic. At subsonic speeds, the trajectory is much less repeatable, thus much less accurate.
Most .308 bullets leave the barrel faster than 6.5CM, but they can't maintain velocity as well.

What I've read from people who sound like they know what they're talking about is that the 168gr SMKs in particular have a design problem where their transonic profile is especially not good. Other 308 bullets are more predictable when they go trans- and then sub-sonic - this is one of the reasons you pay all that money for the fancy version of Applied Ballistics with the transonic bullet profiles.

I don't know what I'd bump up to from 308. Probably something like 300 PRC or 338 LM. I don't think 6.5CM really gets me far enough into the next range category to be worthwhile.

Speed3 · Jul 8, 2019

erwos said:
What I've read from people who sound like they know what they're talking about is that the 168gr SMKs in particular have a design problem where their transonic profile is especially not good. Other 308 bullets are more predictable when they go trans- and then sub-sonic - this is one of the reasons you pay all that money for the fancy version of Applied Ballistics with the transonic bullet profiles.

I don't know what I'd bump up to from 308. Probably something like 300 PRC or 338 LM. I don't think 6.5CM really gets me far enough into the next range category to be worthwhile.

You can try 155gr .308 bullets, palma shooters have been shooting those for years at 1k. Cheaper than rechambering to a different round.

davsco · Jul 8, 2019

if you want to shoot a .50, check out 340defense.com not too far from charles town wv. been a few years since i've been there, but they had a .50 you could rent and you could shoot .50 out to 400yds there. call first just to be safe.

yeah as speed noted above, get a 300 win mag (or norma). that's pretty much the max caliber that is allowed at most long range competitions. bil has one and shooting at and past 1k with 230g bullets, you KNOW when the targets are hit, vs the 140g 6.5 creedmoors and the like.

engineerbrian · Jul 8, 2019

I checked their web site and it looks like the next class is on my sons B day. I emailed them to make sure minirs are ok, so if the answer is yes, we’ll be there on August 31st.

rbird7282 · Jul 8, 2019

erwos said:
What I've read from people who sound like they know what they're talking about is that the 168gr SMKs in particular have a design problem where their transonic profile is especially not good. Other 308 bullets are more predictable when they go trans- and then sub-sonic - this is one of the reasons you pay all that money for the fancy version of Applied Ballistics with the transonic bullet profiles.

I don't know what I'd bump up to from 308. Probably something like 300 PRC or 338 LM. I don't think 6.5CM really gets me far enough into the next range category to be worthwhile.

What do you mean by far enough into the next range category? If you’re talking 1200 yards and under, there’s a reason why most long range shooters are using 6.5CM.
Obviously.338LM is in the next category but at $5 per round that gets expensive quickly

Sent from my iPhone using Tapatalk

davsco · Jul 8, 2019

https://precisionrifleblog.com/2018/12/14/rifle-caliber/

Speed3 · Jul 8, 2019

davsco said:
https://precisionrifleblog.com/2018/12/14/rifle-caliber/

There is a reason why people stick to the 6/6.5mm catridges…. lots less recoil.

Downside, less splash and energy downrange. For paper energy doesn't matter, steel it does to a point of diminishing return (subconscious flinching or shooting hard recoiling rifle in awkward spot).

dist1646 · Jul 8, 2019

Speed3 said:
You can try 155gr .308 bullets, palma shooters have been shooting those for years at 1k. Cheaper than rechambering to a different round.

This! A buddy of mine who is a really top level shooter recently admitted that 155gr bullets are superior to the 175's @ 1000yds.
Less recoil too. If handloads are not allowed, take a look at Berger ammo.

edit, Target Sport USA has Berger 155.5gr Full Bore ammo for less than $27 box.

erwos · Jul 8, 2019

dist1646 said:
This! A buddy of mine who is a really top level shooter recently admitted that 155gr bullets are superior to the 175's @ 1000yds.
Less recoil too. If handloads are not allowed, take a look at Berger ammo.

I think it should be clarified that it's very specific 155gr high BC bullets we're talking about, such as the Berger and the Lapua Scenar.

rbird7282 said:
What do you mean by far enough into the next range category? If you’re talking 1200 yards and under

Like 1000yds to one mile. 6.5CM runs out of steam around 1200, which isn't bad, but if I'm going to invest in a new rifle, I want more than 200yds more effective range.

4g64loser · Jul 8, 2019

I run 155 Palmas (sierra 2156) in my Bisley chamber .308 and I have zero trouble at 1000yd. 24" bbl and lapua brass gives me 2910avg with good case life. I know the Palma guys push em a lot harder but if I need more speed I go to a larger case. Be careful trying Palmas or Scenars (the lapua version of a Palma bullet) in a standard/factory .308 chamber as they have a short bearing surface (part of why they will run faster than most 150/155 designs) and can be somewhat cantankerous if there is a long jump. FWIW I have found that both bullets tolerate about a .020 jump in .308/.30-06/.300RUM.

The 173/175 sierras were created because the 168s sucked so bad when transitioning to subsonic flight. They are great at short ranges but are generally not worth loading if you shoot past 500 regularly (the Berger 168VLDs do NOT get lumped in this statement but they are a totally different design). 155 Palma type bullets can be driven faster and offer a BC close to most traditional 175 tangent ogive designs. the 175s aren't as fast out of the gate but are a readily available factory load that will do 1000yd in MOST good rifles. the 185 Berger Juggernaut is another factory option to look at (check out Berger factory ammo offerings) if you don't handload.

dist1646 · Jul 8, 2019

erwos said:
I think it should be clarified that it's very specific 155gr high BC bullets we're talking about, such as the Berger and the Lapua Scenar.

The 2155 Sierra will get the job done. Some have switched to the 2156 and that one works too. Berger is just the current 'gold standard". Their loaded ammo has the benefit of Bryan Litz's input.

Speed3 · Jul 8, 2019

dist1646 said:
The 2155 Sierra will get the job done. Some have switched to the 2156 and that one works too. Berger is just the current 'gold standard". Their loaded ammo has the benefit of Bryan Litz's input.

And so does Berger's daughter lmao

rbird7282 · Jul 8, 2019

erwos said:
I think it should be clarified that it's very specific 155gr high BC bullets we're talking about, such as the Berger and the Lapua Scenar.

Like 1000yds to one mile. 6.5CM runs out of steam around 1200, which isn't bad, but if I'm going to invest in a new rifle, I want more than 200yds more effective range.

Got it. Yeah that’s a different class altogether

Sent from my iPhone using Tapatalk

PNTC Intro to Long Range AAR

The #1 community for Gun Owners of the Northeast

Member Benefits:

erwos

The Hebrew Hammer

Speed3

Ultimate Member

davsco

Ultimate Member

engineerbrian

JMB fan club

rbird7282

Ultimate Member

davsco

Ultimate Member

Speed3

Ultimate Member

dist1646

Ultimate Member

erwos

The Hebrew Hammer

4g64loser

Bad influence

dist1646

Ultimate Member

Speed3

Ultimate Member

rbird7282

Ultimate Member

Users who are viewing this thread

Latest posts

Forum statistics

Latest threads

Forum statistics

Share this page