Heavy .224" and over-stabilization.

redshooter

redshooter

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I'm working up a load for a 30" long 1 in 6.5 twist JC barrel on my 223 Rem 783.

Best group so far was at about 2800 fps, ~2900 was about 1/2 moa larger, another 0.4 gr, larger still, at this point I'd expect it to be getting smaller, but it's not. Could this be due to the 1 in 6.5 twist?

Still have some room to go faster, I'm seating them at 2.450", still have a little room in the mag, no pressure signs at 27.1 grains.

Projectile is Hornady 88 ELD, powder is CFE 223, Starline 5.56 brass, and CCI 450's, reamer was a Manson T-15.

Any suggestions?
 
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I shoot 223 at some stupid ranges with some success. I also had a 300m competition load that was Hornady 53gr Vmax going about 3400 which I still shoot my leftovers of out of a 1-7 barrel and they shoot absolutely fine. We've fired up to 3600 ft/s out of it and again, no problems other than pure fear of the eldritch horror we'd created. Overstabilization is not a problem except for people doing ELR operations, as the bullet simply resists turning into the headwind most efficiently as it arcs through the air. In 2005 the 90gr Sierras used in high power competition were prone to just blowing up even when properly spun. It has been fixed since 2016 at the latest and tested at least to 2800 ft/s with no problems today, but it was enough to start people freaking out about the phantom of overstabilization.

I'm not familiar with the JC barrels but assuming it's quality stuff your best bet is to keep an eye on your cleaning. My stock Tikka barrel fired 80gr SMKs into nothing worse than 3/4" groups, and I was disappointed when I jumped to a Bartlein whose best groups were no better. The problem turned out to be cleaning: stock Tikka barrel was so smooth it never fouled, but for the cut barrel even the usual solvents like Hoppes were cleaning the loose stuff but still left the lands looking like lava rock. If you're confident that your loading is good I'd throw a borescope in and ensure that everything is cleaned down to bright, shiny metal with no black crust and definitely no copper flakes. Thoroclean and a stiff new bronze brush is what eventually got my barrel going. Sierra Match King 80s, 90s, and Berger 85.5s have all been fantastic with the 90 A-Tips on standby for when I'm feeling brave.
 
Not sure what cartridge you are using, but if it is a standard .223, depending on what your net case capacity is, your loads are running 63,000-80,000 psi, using 30.8 grs. of H20 as the net case capacity. QL shows bullet length of 1.208", while GRT shows 1.2457".

How close are you to the lands at 2.450"?

IF your cases have a case capacity different than 30.8 grs., you might want to bring your charge down to 26.5 grs. which GRT shows as the next lower OBT node.
 
How’s your technique and equpiment? Do you consistently shoot the same size groups? Or are you going off of one good group you shot at 2800fps? How’s it bedded? What kind of stock? Trigger? Bipod? Rear bag? I’ll attach a picture I had on my phone of my wife doing some load development. The rifle puts 5 groups of 5 shots into similar sized groups so that’s what I consider that load to shoot at rather than one “good” group. There’s a few ways to get here and one is to use your chronograph to look for speed devaition or the old ladder test. In my opinion the gun in the picture is shooting good enough and I’m going to make some small changes and see if scores consistently improve rather than burning out a barrel chasing the best my gun can do.

I shot with a guy who was blowing up 6mm eldm a couple years ago and I suspect he was spinning them too fast and that’s likely what the outcome would be for you. I’ve shot some 88 eldm out of my 223 to 900metres with good success and my barrel is 1-7.5” twist. I was debating about going 7 or 7.5 and I figured the 88 hornady or the 85.5 berger would work in the 7.5 so I stuck with that. My experience is the 88 hornady and 85.5 berger shoot similar, but the odd hornady (maybe 1 in 10) seemed to hit a touch low and it wasn’t drastic.

Eric cortina put out a video I watched that really simplified reloading. I’ll see if I can find it, but I think it went along the lines of vertical spread had to do with ignition and roundness had to do with harmonics. I think he went with getting extreme spread and deviation down to an acceptable level and then work on seating depth.

My kestrel says the 88s are going 2780 and the 85.5 are 2820 out of a 29” barrel. I’m using 24.0 grains of varget for the 88 and 24.3 for the 85.5. 85.5 is 2.006” to ogive and the 88 is 1.978”. They’re both a few thousands of an inch off of the lands.
 

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redshooter said:
I'm working up a load for a 30" long 1 in 6.5 twist JC barrel on my 783.

Best group so far was at about 2800 fps, ~2900 was about 1/2 moa larger, another 0.4 gr, larger still, at this point I'd expect it to be getting smaller, but it's not. Could this be due to the 1 in 6.5 twist?



Any suggestions?
Click to expand...
I wouldn't worry near so much about max velocity as I would CONSISTANT velocity which tends to equal better accuracy at long range .
The reason the groups are opening up could be any number of reasons, accuracy node could be one.
No matter the reason , if it shoots better at 2800, leave it there and enjoy the accuracy of that little mouse gun😁
Cat
 
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Every combo will have a sweet spot that it wants to shoot... and that might not be where you want it to be.

If things are getting worst the higher you go, it is telling you that that is not the direction that works. Try lower powder charge, pressure and see if things shoot better... I suspect they will.

for powders, Varget, N150 and 160 is where I would look for best consistency and you might even get the speeds to where you want.

I have never seen consistent and repeatable accuracy using ball powders... at least, competition level performance.

Jerry
 
I have a .223 FTR with a 1-7 twist 29" barrel using either 80gr eldm or bergers 80.5gr bullets have been very good to me I'm also using CFE .223 and have had some nice groups at 1000 yrds all depending on wind lol
 
I haven't even got the Comparator out yet, just finding the nodes, was hoping to find one in the 3000 fps range, but around 25.4 gr was the last decent one, and haven't ran that one past the radar (25.0 was 2800-2810). Next 3 over 25.4 just got bigger, I would have expected one of them to be smaller. 3000 fps for the projectile shouldn't be a problem, but maybe spinning it too hard is, I'd read a bit of that when I bought the barrel, just limited info on it. Never had a barrel run out of speed so to speak, only copper fouling, and pressure have left me short of a decent node, this might be something else.

Why CFE 223? I have lots, still have over 9 lbs of the stuff, love that ####, and Hdy 62 gr FMJ for my semi-autos. I've been shooting semi-auto's unsupported for the last 2 years to prepare for the opportunity to shoot Service Conditions again, thanks for that parting gift of banning all my semi-autos, but the SKS Dear Leader...

I've got some Varget, and IMR 4895, and since it doesn't look like I can exploit the extra speed of the CFE may as well give the Varget a go.
 
Interesting. Hodgdon only has data for a 90 gr pill w/cfe223, max 22.8 gr for vel 2554
for 82 gr, max 23.5gr for 2,724
and you are chasing 3000?
interesting
 
Hornady's 5.56 data, 88 gr ELD seated at 2.390" col, max is 25.0 grains of CFE223. I'm seating these at 2.450", also I'm getting some extra fps from the 30" tube.

26.7 grains gave me just over 2900 on the lab radar, didn't run the 27.1 so I don't know the speed, but if the jumps were consistent 2950ish is likely.

27.1 grains of CFE 223, that primer looks nice and round, no marks on the brass, and the cases just slid out. I think 3000 easy, but if it's grouping at 2 MOA what's the point.
 

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IMO if you want to push a heavy bullet at 3000fps, use a different cartridge

Sierra manual states for a 24" barrel:
*requires 1:6.5 or faster twist, 95gr HPBT match @ 2450fps and max 22.8 of cfe223
*requires 1:6.5 or faster twist, **requires 1:7" @ 2650fps and faster, 90gr HPBT match @ 2550fps and max of 23.2 cfe223
*requires 1:8 or faster twist, 77-80gr @ 2800fps and max 24.6 cfe223

Accuracy loads:
90: 21.8 of varget at 2500fps
95: 2450fps 23.3 RE17
77-88's: 2550 22 N140

25.6 of cfe223 under a 55gr pill does 3k fps. 27.6 for 3300, 1:12 or faster

Key point here IMO is faster than 2650 = 1:7 barrel, and 3k is out of the wheel house

Also at a certain point, the length of the barrel is going to get diminishing returns on an increase in velocity and would likely only be changing harmonics. That is to say, if you add 1" of barrel longer than 20 should get X fps increase, but 1" longer than 21 wont be the same as the increase from 20 to 21. And going from 24 to a 48" barrel isnt going to make any of these FPS numbers double.
 
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fiftycalforsquirrels said:
IMO if you want to push a heavy bullet at 3000fps, use a different cartridge

Sierra manual states for a 24" barrel:
*requires 1:6.5 or faster twist, 95gr HPBT match @ 2450fps and max 22.8 of cfe223
*requires 1:6.5 or faster twist, **requires 1:7" @ 2650fps and faster, 90gr HPBT match @ 2550fps and max of 23.2 cfe223
*requires 1:8 or faster twist, 77-80gr @ 2800fps and max 24.6 cfe223

Accuracy loads:
90: 21.8 of varget at 2500fps
95: 2450fps 23.3 RE17
77-88's: 2550 22 N140

25.6 of cfe223 under a 55gr pill does 3k fps. 27.6 for 3300, 1:12 or faster

Key point here IMO is faster than 2650 = 1:7 barrel, and 3k is out of the wheel house

Also at a certain point, the length of the barrel is going to get diminishing returns on an increase in velocity and would likely only be changing harmonics. That is to say, if you add 1" of barrel longer than 20 should get X fps increase, but 1" longer than 21 wont be the same as the increase from 20 to 21. And going from 24 to a 48" barrel isnt going to make any of these FPS numbers double.
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MDT did a video experiment on increasing the barrel length out to absurd lengths. As I recall, it does keep speeding up the bullet every inch by a similar amount.
 
MisterVRT said:
Any particular reason for CFE 223? IMO its not a powder known for super accurate loads. Double base will get you speed but not as steady numbers as a single base powder
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found most accurate load with CFE223 and 69gr hornady HPBT in 1:9 twist, but only in cold weather, with temperature higher the group opens up
 
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