18" vs 20" velocity

[jluna575]

Hello Everyone,

I am very interested in building a 6.5 grendel upper. My plan is to run it suppressed and use 123 ELDM handholds. Ideally, I would like to achieve a minimum of 2500 fps to shoot steel at 800 yards. Would I be able to achieve that velocity with a faxon 18" barrel or would I need to step up to the 20"?

[StoneHendge]

[jluna575]

Thanks for the heads up. I wanted to know what kind of numbers people were getting in these barrel lengths. I'll mostly be using this at the range so the 20" makes the most sense.

[Arkhangel5]

+1 to what SH said.

My Brownell's/Satern 18in shoots 123 ELD's at ~2465fps. Shoots 1/2moa easily. Never tried to push it harder.

That said, when it was available, factory Amax 123's were close to 2500fps, but only sub moa.

20in will make your quest a little easier.

SY

[Kilco]

Stonehendge put it well.

[SDet]

My 18 odin works normally gets 2450ish with factory ammo. Though there was one lot I was getting closer to 2600 with. Pressure signs on every piece of brass, terribly hard on the gun, but the ballistics were great. Have maybe 20 rounds left, might ask the shop if they have another case from the same lot.

[NugginFutz]

With the factory Hornady Black, my 18" Larue will spit those out at 2481 fps. Hand loading the 123 ELD with some of the newer powders, such as Alliant Power Pro 2000MR (mentioned on another thread) could very well put you up there at 2500 fps, but I would tend to agree with SH - 20" or even 22" will allow you to load something less hot to do it.

At the same time, thought, I would like to point out that an 800 yard shooter is very much in reach with a factory 123 ELD running 2450-ish. At 800 yards, an extra 50 fps will amount to only an additional 25 Lb/Ft of energy at the target (443 v. 468) at sea level.

[Sticks]

All things being equal at 800 yards, sea level, 59*...all the basic starter info from JBM Ballistics. Those difference between those numbers gets smaller the higher in elevation you are.

It may or may not be worth chasing faster FPS than factory. I try to at least match it, but often the accuracy node is below factory ammo speeds.

[Niles Coyote]

Found this with some light searching on cfe223

This is what I found.

Lilja 18" , 81*F
CFE223, Nosler 123 custom competition, new AA lapua brass, Wolf SRM primer, COAL 2.255

29.5gn-2376fps-es14-sd4.7
29.8gn-2399fps-es12-sd4.4
30.1gn-2427fps-es19-sd5.7
30.4gn-2423fps-es49-sd15.4 chrono showed an error reading?
30.7gn-2442fps-es21-sd7.7
31.0gn-2483fps-es21-sd7
31.3gn-2508fps-es27-sd9 Best Group .57 inches
31.6gn-2528fps-es19-sd5.8

This morning was a nice morning to shoot so I headed down to my range by the river.Got my Crony set up and started running some 3 shot groups over it using Hornady 123 gr.ELD Match bullets and some CFE223 powder and Rem 7.5 primers.I did all my shooting at 200 yds.The temperature was sitting right at 32 degrees.My Crony does not like the cold so I would have to warm it up regularly in my truck when I walked down to my target to check it out.My COL was set at 2.310" for my Howa 20"HB.
Earlier I started some load development with some 123SST's and CFE but ran low on bullets that I needed to hunt with so I continued with the 123ELD's starting at 31grs. and increasing the charge .3 grs. at a time.Average velocity increase was 26fps.At 32.2 grs I reached average 2607 fps with 22fps extreme spread and a 1.25" group.That was the best I could get.I took the charge up to 33.1 grs.,quite compressed and received 2679 fps. with no issues.

I have not used it my self, but I know LRRPF52 played with it a bit, maybe he'll be by in a bit.

Some additional data point can be found here.

https://forum.snipershide.com/forum/sniper%C2%92s-hide%C2%AE-advance-marksmanship-unit/sniper-s-hide-reloading-depot/6710153-6-5-grendel

[Texas]

Hello Everyone,

I am very interested in building a 6.5 grendel upper. My plan is to run it suppressed and use 123 ELDM handholds. Ideally, I would like to achieve a minimum of 2500 fps to shoot steel at 800 yards. Would I be able to achieve that velocity with a faxon 18" barrel or would I need to step up to the 20"?

I am missing something here. Why do you have to have 2500 fps to hit steel at 800 Yes? With an average increase of 20 fps per inch of barrel, you may find a 20 barrel with a lower velocity than an 18 inch barrel. We choreographed three different 20 inch barrels on the same afternoon with the same lot of ammo, and there was 120 fps in the barrels.

[Kswhitetails]

I am missing something here. Why do you have to have 2500 fps to hit steel at 800 Yes? =

Been thinking this the whole time. 2400 gets you there with a resounding whang... Seems like I'm missing something...

[dammitman]

people obsess with FPS when what they need to do is obsess with accuracy

[SDet]

It's a balance, 2400 fps has over a half moa more wind drift at 1000yards than 2500. Yes, both will get there, but unless the 2400 groups 0.5moa smaller, 2500fps is the better load.

[41bear]

people obsess with FPS when what they need to do is obsess with accuracy

Amen brother, the only interesting gun is an accurate gun.

[jluna575]

I am missing something here. Why do you have to have 2500 fps to hit steel at 800 Yes? With an average increase of 20 fps per inch of barrel, you may find a 20 barrel with a lower velocity than an 18 inch barrel. We choreographed three different 20 inch barrels on the same afternoon with the same lot of ammo, and there was 120 fps in the barrels.

2500 fps is one of those made up requirements by an OCD person haha. I plugged the numbers in the ballistic calculator and liked the drops so I kinda of wanted something in that range. What barrel manufacturer do you recommend?