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Flat shooting round?

G

GRIM

Sergeant
Full Member
Minuteman
Dec 21, 2009
454
1
59
Wisconsin
Ok - so I've gotten consumed lately looking at BC's & velocities. (These ballpark #'s are for around 5500' elevation in summertime).

What is a great round that is flat shooting? Gives good barrel life(if that is possible but most anything is better than the barrel eating 6.5-284)?

7mm 162 AMAX at around 2900 fps drop 22.5 moa / drift 4.5 moa at 1K

260 Rem 139 Scenar around 2750 fps drop 26.7 moa / drift 5.1 at 1K
(What velocities are most guys getting with the 139 Scenar in the 260?)

(For comparison sake):
308 Win 155 Scenar at 2810 fps drop 29.4 moa / drift 6.5 at 1K

So browsing the numbers for the 162 AMAX (.625 bc) in a SAUM is a nice setup. Does everyone else feel that a short action cartridge gives less perceived recoil than a standard cartridge (ie - 7mm Mag)?
 
Re: Flat shooting round?

I just got a 7-08 here on the hide. I might play with some 162amax's as I have some that I shoot through my 7wsm. Doubt you could get the 162 to 2900 out of the 7-08. But with my 7wsm I'm getting 3150fps
 
Re: Flat shooting round?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JCH</div><div class="ubbcode-body">I just got a 7-08 here on the hide. I might play with some 162amax's as I have some that I shoot through my 7wsm. Doubt you could get the 162 to 2900 out of the 7-08. But with my 7wsm I'm getting 3150fps </div></div>

What is the bullet you're using in your WSM at 3150 fps? What is the accuracy?
 
Re: Flat shooting round?

i'll send you a PM. I only have pictures of my 3 shot groups during load testing.
 
Re: Flat shooting round?

7-08 isn't as flat shooting as the 6.5's but with the Amax's and scooting along at ~2700 it will hang wind with the 6.5's, and have a nice long barrel life-not to mention is carries "smackdown" power farther than the little 123 Scenars the 6.5 boys enjoy so much.

A short action mag would definately make it more laser like, but I like barrel life and stretching my powder as far as possible. I get 5% more rounds from a pound of I4895 for my 7-08 than I do for my 308 with 175's, but I dial a 40% less wind.
 
Re: Flat shooting round?

+1 for the 7 WSM. That is one flat shooting mofo. Bad thing is, its pretty hard on barrels (not quite as bad as the 6.5x284). Ever look at the 6.5x47 ? Good compromise between flat shooting/wind drift and barrel life.
 
Re: Flat shooting round?

barrel life on the smaller bores is definitely an issue but this can be helped a bit by cleaning properly which is:

1. get the bolt out and get a wet patch down it just as soon as you can after firing.
2. follow this by wet bronze brush and scrub it hard.
3. follow this with patches till they come out clean.

The name of the game is don't let the carbon cool down as it becomes an abrasive from hell. Fire a cold barrel that is left dirty is like dropping a hand full of dust down the bore.

http://shootersforum.com/showthread.htm?t=63278

Read the above for more info.
 
Re: Flat shooting round?

OK, a few thoughts.

We all discover BC's and begin to worship it the altar of velocity sometime shortly after we become soundly hooked on LR.

It's a phase, usually accompanied by barrel burnouts and puzzlement at why the danged numbers that looked so good on paper aren't translating into winning scores on the target.

Pretty soon, reality reacquaints itself and we realize that flat shooting's really not so much better than whatever it was we were doing before that phase grabbed us by the short and curlies.

As far as velocity is concerned, as long as we're getting to the target with around 1250-1300fps, we're as fast as we need to be.

Drop and drift are just numbers. Whatever they are, they all lend themselves to shooting only in as much as our wind reading skills allow. Wind reading is a binary task, there are two realities, a hit, and a miss. By how much is only interesting from a historical perspective, by the time we know, it's already too late to change the POA, and by extension, the POI.

If you think simply correcting by the amount and direction of the miss will save the next shot, you really don't understand the nature of LR winds. Consistency is about maintaining your zero and your hold and learning how to recognize the same conditions that gave you the last hit. Engaging the wind in a dynamic guessing game is pretty much guaranteed to produce misses.

Investing your belief in the proposition that a faster, flatter trajectory will save your butt when you ain't gettin' it all right is basically a copout. Every time you blow the wind call, you blow the shot, no matter how much mayhem you're generating in the engine room. There is <span style="font-style: italic">no substitute</span> for wind skills.

The best way to utilize the High BC/High Velocity phase is to say thanks, let's not, and say we did.

Greg
 
Re: Flat shooting round?

Excellent post Greg!

B.C. is just a representation for the efficiency of motion.
I usually lean towards efficient if I can.
 
Re: Flat shooting round?

Take two people with the same fundamentals, the one shooting the bullet with the better external ballistics wins.

How good can you read wind?

The difference for a 180g Berger VLD in 7mm at 2950 fps muzzle with a 2mph wind read difference is 1.1 MOA(14.2 inches) at 1000 yards. The same 2 mph wind read error with 175g SMK at 2700fps at 1000 yards is 2.0MOA(20 inches).(Comparing 10mph to 12 mph)
 
Re: Flat shooting round?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 264win</div><div class="ubbcode-body">243 with 115 dtac @ 3000-3100 kicks butt </div></div>

There's the answer. Light recoil, excellent ballistics and cheap components. Also it can be used in any DBM system the .308 can and use 10 round mags and feed fine.

Flat shooting matters if you plan on shooting any UKD as being off with a range by only 20 yards can be a miss but with flatter shooting cartridges will hit. On a KD range it doesn't make much difference as you know the range and just dial it on.
 
Re: Flat shooting round?

I don't disagree with the folks who use the flat shooters. More power to them, they make it work; and making it work is what we all need to do, regardless of which approach we choose.

Greg
 
Re: Flat shooting round?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">Take two people with the same fundamentals, the one shooting the bullet with the better external ballistics wins.

How good can you read wind?

The difference for a 180g Berger VLD in 7mm at 2950 fps muzzle with a 2mph wind read difference is 1.1 MOA(14.2 inches) at 1000 yards. The same 2 mph wind read error with 175g SMK at 2700fps at 1000 yards is 2.0MOA(20 inches).(Comparing 10mph to 12 mph) </div></div>

That's what I'm talking about. Yep - I never said that the high bc/flat shooting round will replace wind reading skills - ever. At UKD the flatter round will help with any mis-reading the wind and no one here is a machine at reading it so there will always be error in reading it. I'd much rather shoot a flatter round than say a 30-30 at UKD.

I've grown up on a .308 and know it well. But I also see that the occasional near-hit could have been a hit with a round that had a tad bit less wind drift so why not shoot something with less drop/drift since all that matters are first round hits. Right?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 264win</div><div class="ubbcode-body">243 with 115 dtac @ 3000-3100 kicks butt </div></div>

There's the answer. Light recoil, excellent ballistics and cheap components. Also it can be used in any DBM system the .308 can and use 10 round mags and feed fine.

Flat shooting matters if you plan on shooting any UKD as being off with a range by only 20 yards can be a miss but with flatter shooting cartridges will hit. On a KD range it doesn't make much difference as you know the range and just dial it on. </div></div>

My thoughts exactly, not neccessarily in 243 but something similar.
 
Re: Flat shooting round?

Grim,

I love post like this. Lots of opinions.

In the above posts we have the following candidates offered for flat shooting rounds:

243 Win @3000 FPS and 115 gr DTAC's
260 Rem @2750 FPS and 139 Gr Lapua
7mm-08 @2700 FPS and 162 gr A-Max
7mm SAUM @ 2950 FPS and 162 gr A-Max



So how do they really stack up at 1kYds? All calc's used G7 BC's.

243 Win @3000 FPS and 115 gr DTAC's
1000 Yds Drop -7.4 Mils -25.5 MOA Drift 1.9 Mils 6.6 MOA

260 Rem @2750 FPS and 139 Gr Lapua
1000 Yds Drop -9.0 Mils -30.8 MOA Drift 2.1 Mils 7.3 MOA

7mm-08 @2700 FPS and 162 gr A-Max
1000 Yds Drop -9.0 Mils -30.8 MOA Drift 2.0 Mils 6.8 MOA

7mm SAUM @ 2950 FPS and 162 gr A-Max
1000 Yds Drop -7.3 Mils -25.0 MOA Drift 1.7 Mils 5.8 MOA

I not going to make a recommendation one way or the other, but merely an observation: The two fastest rounds listed and "flattest shooting", are not a significant order of magnitude better, than the two slowest rounds listed.

As Greg noted above there is a "cost" associated with exceeding 2900 FPS with High BC bullets. Whether that "cost" is worth the "benefit" is for you to decide.

Something to think about, and ponder when considering your build.

Regards,

Bob
 
Re: Flat shooting round?

I haven't got to shoot my 7-08 yet so I can't speak to it. But my 7wsm running the 162gr amax is getting 3150fps out of a 24" barrel.

You want flat without a lot of wind drift, that is it.
 
Re: Flat shooting round?

Reality is, flat shooting equals shorter barrel life, equals better ballistics...and you're gonna have an advantage if you miscall the wind.
 
Re: Flat shooting round?

Well - my 7 SAUM is being shipped next week. Buying it turnkey from a buddy of mine that is thinning his herd. Said it shoots bugholes with 162 AMAX at 2830 fps. Yes..... I am excited.
 
Re: Flat shooting round?

The 7s are the way to go. Shot at 600 and 1k yesterday with the WSM and 180gr JLKs. 2.7 mils to 600 and 6.2 mils to 1,000. About a 5-6mph wind coming in from the east, and only had to dial in .4 mils at 1k
 
Re: Flat shooting round?

I think that when it comes to velocity, it depends, largely on how you're getting that velocity.

You can stoke a case to its limit and blow the bullet the hell out of the bore.

Or you can put a comparable amount of powder into a larger case, run it at part throttle down a longer bore, and get to the same place velocity-wise with maybe less heat and pressure.

Now which would you like to do to your bore for its forseeable future?

Greg
 
Re: Flat shooting round?

Greg, your reply from several days ago sums up long range shooting as well as I have ever read. Every bullet drops and every bullet is affected by the wind. Learn to dance with the wind, dial in the correct vertical and shoot the most accurate load you can develop in a rifle that doesn't kick like a mule. Tom
 
Re: Flat shooting round?

Well - I guess I'm looking for a portable (shootable off-hand) rifle that can perform like my 300 RUM rifle. My 300 RUM is very accurate but it's also extremely heavy as compared to the 7 SAUM I have coming. I'm shoving 190 SMK's in my RUM at 3200 fps and it perfoms ballistically well but it eats barrels at those specs.

I figure I take it easy on the 7 SAUM powder charge (55.0 grains of H4350 is what my buddy said it likes & QuickLoad also says it a mild load) and toss the 162 moly AMAX's at 2830 or so and that will give me better performace than my .308's and be as easy on the fluted Pac-Nor barrel as possible.
 
Re: Flat shooting round?

Here's what's incoming in a week or so... 7mm SAUM.

Rem700_0.jpg

Rem700_5.jpg

Rem700_2.jpg

Rem700_3.jpg

Rem700_6.jpg
 
Re: Flat shooting round?

All in all, the 260 rem does a lot of things pretty well, and is fairly mild on the barrel.

Barrels are expendable, just as brass is.
Prudent reloading practices can do a lot to prolong the life of either, without sacrificing much at all.

If you were to run the numbers for any of the above scenarios, at 75 ft/sec less, you'll see that the drift doesn't really increase very much.
The 260 rem. can push a 140 to over 2800 easy (In a 26" barrel).
The 7-08 would have to be pushed HARD to hit 2700 with a 162.
So in the above scenario the 260 can ballistically match the 7-08, at part throttle.
Short action, lighter recoil, good ballistics, medium barrel wear with typical loads.
The only downside is that your target is getting hit with comparatively light 140 grain bullets, if that matters.
 
Re: Flat shooting round?

Quickload handloading software comes with Quicktarget.

Enter in a cartridge, a bullet, a powder, a charge, a barrel length, and it tells the peak pressure, and the velocity.

Open Quicktarget and accept info from Quickload.
It shows the drop and drift and velocity over range.

Here I have plugged in a 140 gr bullet with 22" barrel in a 260 Rem:
Quicktarget.jpg



I think you can still download a free demonstration.
I have had quickload for ~ 10 years, and I would pay 10 times what ever they want for it.

http://www.neconos.com/details3.htm
 
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