muzzle velocity 20"vs13.9" with CFE223

[v4lu3s]

I have developed 2 loads for a 20 in rifle, one with h335 and the other cfe 223. I recently picked up a second upper, and since the CFE223 load was my range/training ammo load I used it to test out the shorter barreled rifle. In the 20" I am seeing 2640-2660 FPS with about 31 grains of powder. Out of the 13.9 though I was seeing 2540-2580. Not nearly as low as I expected. Have ya'll seen anything similar? Is this typical of the grendel or is solely due to the CFE233 being a so called relatively fast rifle powder? It would appear that H335 is even faster, so I will likely be trying that on the 13.9 barrel soon. Just kind of curious since I expected to see 150-300 fps slower not ~100 less with 6 inches less.

[VASCAR2]

A Friend and I chronographed several loads in our 6.5 Grendel AR-15’s a few years ago using a Magnettospeed Chronograph. Your velocities with CFE223 were significantly higher than we recorded on a 70 degree day in the midwest. Usually it is hard to match factory velocity with most powders except for CFE223 or LeveRevolution. You didn’t mention the bullet weight you’re using with CFE 223 power and the particular brass. If your using a 107 grain or lighter bullet your velocities might be within the normal range. We chronographed other ammunition that day but the 123 grain Nosler Custom Competition is the only load tested using CFE223 powder.

Hand Load 123 Grain Nosler CC, 31.0 grains CFE223, CCI 450

16" 2449

18" 2471

20" 2526

24" 2619


123 Grain SST Hornady

12” 2277

16" 2430

18" 2493

20" 2511

24" 2583

At the end of the chronograph session I decided to test this load in just two different barrel lengths.

Hand Load 107 Grain SMK 28.5 IMR8208XBR, CCI 41 Hornady cases.

20" 2658

24" 2729

[grayfox]

That is interesting. CFE powder is different from most, in the pressure curve it produces, kind of "not so high" but "longer duration". It is the area under that curve that is responsible for the MV. What could be happening is that the portion cut off by the 6" "lopped of" is less of a contributor to MV than the remaining piece still driving the bullet.

[v4lu3s]

I am using 123gr Hornady ELD-M and Hornady brass. Prior sessions where I used the chrono I was seeing the 2600-2660 range for my handloads with the CFE223 AND the factory SST and ELD-M loads from Hornady. This was my break in day for the 13.9 inch barrel. I am using a Magnetospeed chronograph. Both rifles were shot with a YHM Resonator suppressor in place as well. Hodgdon is saying 2600 fps out of a 24 inch barrel, at 31.2 grains, perhaps the suppressor is helping add a few more fps. I am very surprised to see the velocity out of the 13.9" barrel (even if the suppressor helps velocities), but it is a pleasant surprise as that could help extend the effective range if I decide to hunt with the SBR.

[grayfox]

Those loads, CFE, bullets and hornady brass at 2600 MV are over the Saami pressures. Max MV for 123-120 class bullets in a 20" AR should expect to see 2500 give or take.
You can do it of course if you want to, but be advised that you are more than likely over-pressure.

[v4lu3s]

Interesting that Hornady factory ammo is over SAAMI pressure, they even say on the box they do 2580 or 2590 FPS and their reloading manual uses an 18" barrel for reference. My handloads are 0.2 grains under maximum load in the Hornady manual as well. I am seeing the factory loads and my handloads with 20 FPS of each other.

No signs that I can see of over pressure, and I have flattened primers before, as well as damaged cases from the ejector on the shell base on a .308 load that shoots great from one rifle and is very over pressure in a second.

[Bonas]

Hornady Black 123 grain ELDM factory ammo lists 2,580 velocity. That's from a 24" barrel. Hornady lists a max load of 31.2 grains for CFE223 for a 120 grain bullet, at least when I made my notes. All rifles are different. Your velocities indicate you're running high pressures. Many knowledgeable people here say Grendel doesn't show visible pressure signs until it's past max pressures.

I would expect about a 200 fps drop from a 6" shorter barrel. That's general experience, not specific to CFE223.

[biodsl]

In my experience with CFE, I gain about 15-20 fps per inch of barrel length (with my two barrels). A drop from my 22" to my 16" is around 110 fps, roughly.

More of a factor is temperature. My load of 31.2 of CFE with a 123 grain bullet from my 22" barrel produces a velocity of 2500 fps at 40 degrees fahrenheit. At 90 degrees that same load results in 2670 fps. Roughly, and I mean roughly, you can expect 1.8 fps per degree of temperature increase with CFE.

31.2 grains of CFE in hot summer temps is probably too much for my barrel.

[LRRPF52]

Hodgdon’s data is for 123gr SMK as well, not the ELD-M, A-MAX, or SST, which are all shorter bullets that don’t intrude as much into the case.

They maxed out at 48,700psi with a full case.

24” barrel

Bullet: 123 GR. SIE HPBT

Diameter: 0.264"

Case: Hornady

Primer: Federal 205, Small Rifle

Hodgdon

CFE 223

2.260"

28.4

2,352

36,800 PSI

31.2

2,602

48,700 PSI

What barrel are you using? Different rifling types can yield faster mv and the suppressor will give you a little bit of boost, but nothing earth-shattering.

[mulyhuntr]

Fwiw, I've tested quite a bit with the 123 eldm with cfe223 and LVR.

Velocity from 18" Odin Works barrel with 31.0 cfe223 using Starline brass and cci450 averages 2420fps (Garmin xero). LVR mirrors the velocity of cfe223 but with better accuracy. I'm sure my velocities are kind of slow as the barrel just barely hit 100rds, but op's seem wayy too high.

[v4lu3s]

The Hornady reloading manual does NOT specify a 24" barrel, it uses an 18" Alexander Arms 1:8 barrel. It would be odd imo to spec that barrel in their reloading manual yet use a different setup for their factory loads. But I don't work there. Even then 2580 on the box with 24" but 2500fps in the manual at 18" is an 80fps difference for 6 inches.

The 20" barrel is an Odin Works barrel (about 300 rounds down it) and the 13.9" is a Sons of Liberty Gun Works match barrel.

If Hornady was being consistent using an 18" barrel for all testing, going from 2580-2590 fps on factory ammo to 2650 with a 2 inch longer barrel and a 7 inch suppressor seems within reason. The 13.9" with its minimal velocity drop is weird to me.

[v4lu3s]

Anyway all that being said I will definitely keep it under advisement and do a bunch of double checking to make sure that the Dillon powder drop did not somehow get out of spec when reloading normally when doing a batch I way each load and measure it until I'm satisfied it's consistent and then once I get there I might only check one out of 20 or 1 out of 50. So I won't argue that it's not entirely possible that I may have loaded my last 40 or 50 in this batch too hot.

[grayfox]

Vendors (and their lawyers) seem to know what you're not willing to concede... MidwayUSA has the specs for both the sst and the eldm ammo, both of which are listed at 24" barrel length:

hornady-ammo1.png

hornady-ammo2.png

What you don't seem to realize is that speed sells (so, 24" barrel spec for ammo - people like to buy higher MV ammo, Marketing 101), but reloading folks only care about honesty (which is why Hornady switched to 18" barrel length for their books. This happened, what, 2 or 3 versions ago).

Like I said, you are free to shoot however you choose, but when you're doing it, I don't want to be in the next shooting lane. Could just be you have a humdinger of a "fast" barrel... or something else.

[mulyhuntr]

Have you chrono'd without the suppressor?

[LRRPF52]

The Hornady reloading manual does NOT specify a 24" barrel, it uses an 18" Alexander Arms 1:8 barrel. It would be odd imo to spec that barrel in their reloading manual yet use a different setup for their factory loads. But I don't work there. Even then 2580 on the box with 24" but 2500fps in the manual at 18" is an 80fps difference for 6 inches.

The 20" barrel is an Odin Works barrel (about 300 rounds down it) and the 13.9" is a Sons of Liberty Gun Works match barrel.

If Hornady was being consistent using an 18" barrel for all testing, going from 2580-2590 fps on factory ammo to 2650 with a 2 inch longer barrel and a 7 inch suppressor seems within reason. The 13.9" with its minimal velocity drop is weird to me.

In Hornady’s 8th Edition, they used a 14.5” AA Grendel AR-15.

For the 9th-11th Editions, they used 18” AA Grendel AR-15.

Factory box ammo velocity info is from a 24” barrel.

I found when I did my first ladder testing with CFE223 from my 16” AA Grendel barrel that I could easily get some crazy velocities with 123gr A-MAX loaded to 2.275”.

9th Edition said max was 31.2gr of CFE223, but they were including the 120gr GMX copper monolith as well, lumped in with 120gr A-MAX and 123gr A-MAX.

Here’s the ladder I did:

16” AA button-rifled ER Shaw barrel
CFE233
123gr A-MAX
Lapua brass
Rem 7 1/2 SRP
2.275” COL
All velocities measured 15ft from the muzzle, so mv is actually faster.

31.1gr 2489 (45,711psi)
------------------------------------- Everything below this line exceeds Hornady’s max loads, so it was just an excursion test, not meant to be mass-produced.
31.4gr 2520 (47,302psi)
31.7gr 2532 (48,893psi)
32.0gr 2553 (50,484psi)
32.3gr 2572 (52,075psi)
32.6gr 2598 (53,666psi)
32.9gr 2612 (55,257psi)
33.2gr 2640 Cratering of primers was observed at this point

If your powder measure is letting out a few extra tenths of a grain, that would explain your velocities, along with the suppressor boost.

A good news about pressure with this powder under a 123gr Hornady is that even with 31.2gr, it’s well under 50,000psi. Hodgdon’s data shows that under a 123gr SMK with 31.2gr, it’s 48,700psi.

Increasing my COL to 2.275” and adding a little more powder under a 123gr A-MAX allowed me to continue pressing forward without any velocity excursions until I hit 33.2gr.

I have never, nor do I recommend loading those charges, and my go-to is 31.2gr of CFE223 under 123gr Hornady cup and core bullets, which is only around 46-47ksi doing 2460-2490fps in 16” and 18” Grendels. CFE223 is very forgiving under a 123gr Hornady.

I’m thinking your powder measure kicked out a little more. Due to variations in powder from powder measures, it makes sense to control your charge weight setting to stay away from going above MAP. The velocity isn’t going to make much difference down range when only talking even 100fps.

Try sampling your powder measure with a digital scale to see what kinds of weights it’s kicking out and adjust.