6.5: 123s vs. 139/140s for medium range shooting..

[Swan]

Curious as to why I see a lack of 6.5 shooters using the lighter 123s, and am wondering if they are a better choice for shooting medium range (to 600yds), especially for tactical matches? After running JBM numbers a bit the wind drift is negligible and the lighter projectiles fly noticably flatter.

We see many .308 shooters opt for the 155s vs. 175/178 projectiles for match shooting and long range work. But this is not as apparent with 6.5 shooters. Why?

Opinions?

 

[wnroscoe]

Re: 6.5: 123s vs. 139/140s for medium range shooting..

For distances past 500 yards, it's all about BC & Velocity

All else is a moot point.

 

[Swan]

Re: 6.5: 123s vs. 139/140s for medium range shooting..

I realize that. I'm wondering for distances under 600yds.

 

[wnroscoe]

Re: 6.5: 123s vs. 139/140s for medium range shooting..

Same thing. I run a 260 and have built more than my fair share of them. The 130/139's (.595/.615 BC's) can reach 2,900+ fps with ease. Since most will run their 260 to 1k their already shooting the .595+ BC bullets. I feel that the 123's (.547 BC) are better suited for the 6.5x47's but, they would work well in a 260. I'm not ready to give up 48 to 68 BC points just yet and think most share that same mind set. IMHO, for the 260 or 6.5x284, the heavier, higher BC bullets are where it's at, 100 or 1000 yards. As with everything else, YMMV

 

[Swan]

Re: 6.5: 123s vs. 139/140s for medium range shooti

Good point. I guess if you can get those velocities with the heavies there is no need for high velocity 123s so much with regard to a .260.

 

[pdogdown]

Re: 6.5: 123s vs. 139/140s for medium range shooti

How much more velocity would it take for the .547 BC to surpass the .615 BC. 175 FPS? Just curious

 

[pdogdown]

Re: 6.5: 123s vs. 139/140s for medium range shooti

Also curious about the JLK VLDs? Any real drawbacks? What loads are people shooting with them?

 

[rksimple]

Re: 6.5: 123s vs. 139/140s for medium range shooti

Inside 600, the lighter bullets make elevation dope less important. Wind is about the same. Flatter bullets have the advantage.

 

[Swan]

Re: 6.5: 123s vs. 139/140s for medium range shooti

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rksimple</div><div class="ubbcode-body">Inside 600, the lighter bullets make elevation dope less important. Wind is about the same. Flatter bullets have the advantage.</div></div>

That was kinda my point with the original post. And one we discussed after the match. It would seem that running the light bullets for match conditions would be beneficial in a few ways. Barrel life would be the main concern pushing the heavies at 2900 fps, no? The lighter ones should yield longer barrel life if you are not pushin em hard.

I guess it really depends on what shoots well outta your barrel. Which reminds me, Know anyone who can chamber my 6.5 blank in .260 in a reasonable amount of time?

 

[Sleeper]

Re: 6.5: 123s vs. 139/140s for medium range shooti

I guess some of us consider inside 600 short range

Figuring drop is the easy part. Its all about the wind!

 

[Sleeper]

Re: 6.5: 123s vs. 139/140s for medium range shooti

I guess it really depends on what shoots well outta your barrel. Which reminds me, Know anyone who can chamber my 6.5 blank in .260 in a reasonable amount of time?

He was the first one to answer your question.

 

[81sfo]

Re: 6.5: 123s vs. 139/140s for medium range shooti

What barrel lenght is needed to reach the 2900 fps mv with the 260 and 139-140grn bullets.?

 

[ChadTRG42]

Re: 6.5: 123s vs. 139/140s for medium range shooting..

Inside of 600 yards, the lighter bullets would be fine. They are faster and flatter, with similar wind drift. The cost is increased barrel wear and less energy. The happy medium from 100 to 1K is the 140 weight. If you look at the energy of the 140's at distance, it makes a difference when hitting steel. I've seen 243 Win's push the 115 DTAC's fast, and not knock over steel, and miss out on the score. You still need "ass" behind the bullet, and I think the 140's is as light as I'll go. I still would rather have the energy of my 190 SMK out of my 300WM, but then again!

 

[crumpmd]

Re: 6.5: 123s vs. 139/140s for medium range shooting..

Inside 600 the 123 in my 6.5x47L is awesome. Past that it does not really shine but is not too bad. Don't kid your self about barrel wear. You will want to find a good charge at or above 3000fps for the 123 in a 260. I pushed them at just over 2900 with my 6.5X47L and got real good performance but past 3000 they are like a laser. But it is a smokin hot load. I run the 139 scenar now at 2730 out of a (now) 22 inch barrel with silencer. I do ok at 1000 yards. If I could push to 2900 I could do better, but the cartridge is not suitable, it is a hot load as it is.

 

[wnroscoe]

Re: 6.5: 123s vs. 139/140s for medium range shooti

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81sfo</div><div class="ubbcode-body">What barrel lenght is needed to reach the 2900 fps mv with the 260 and 139-140grn bullets.? </div></div>

I'm running a 26" Bartlien 1-8 4 groove. 44.5 grains of H4350, RP Hulls with full match prep, CCIBR2's, .002" NT, 139 Scenars @ 2.847". 2,920ish fps.

Work up to this load, it's GTG in my rifle but over max in others.

 

[wnroscoe]

Re: 6.5: 123s vs. 139/140s for medium range shooti

Just for grins and certainly not real world data;

123 Scenars @ 3,000 fps

MOA to 1k = 27.19
TOF to 1k = 1.402 Seconds
5mph wind drift @ 1k 3.54 MOA
Energy @ 1k = 646 ft. Lbs.

139 Scenars @ 2,927 fps

MOA to 1k = 26.9
TOF to 1k = 1.382 Seconds
5mph wind drift @ 1k 3.14 MOA
Energy @ 1k 809 ft. Lbs.

Playing with the numbers it looks like the 123's would need to be driven to 3,050 fps to give the same results as the 139's. At 3,050fps, the 123's energy is still under the 139's, they're at 674.2 ft lbs @ 1k. I know guys running the 123's at 2,950 in a 6.5x47 so 3,050fps in a 260 should be easy.

If they float your boat I say pull up anchor and sail away

 

[DocB]

Re: 6.5: 123s vs. 139/140s for medium range shooti

Good day,

I shoot the 123s in my 6.5-06, since they are more accurate than the other 6.5 bullet weight classes at the same speed. I'm getting 3150f/s, 1k is not a problem; except at HR where I'm having to cut the speed to 3000f/s. I'm looking for accuracy, not knockdown.

HTH,
DocB