Higher than expected velocity - what do you think?

[Jayhawkhuntclub]

223 Wylde load is based on Hodgdon website recipe below:
90 gr Sierra MK
2.38" OAL
22.3 C gr of Varget max load
2447 fps max velocity
All from a 24" barrel

MY LOAD
88 Hornady ELD
2.5" OAL (jammed - velocity jumped 40 fps jammed when compared to seating 0.005 - 0.120" off the lands)
21.7 gr Varget
2499 fps average - measured with magnetospeed
FROM a 21" barrel - side charging straight pull bolt action on ar15 platform
55 degree weather

No pressure signs that I can see: no stiff extraction, no ejector marks, no flattened primers, no cratering, no pierced primers...etc.
And it's shooting great. Last night I put 8/8 in 0.63" at 100 yards.
My question, any thoughts on why I'm getting 50 extra fps out of a barrel that's 3" shorter?
I feel like I've got everything about right, but that velocity has me questioning myself. Do you see any issues?
Thanks!

 

[TheMammoth]

What kind of brass you using?

 

[Jayhawkhuntclub]

New Starline 5.56 brass, CCI 450 primers

 

[Subwrx300]

Four reasons most likely (could be any combination in part or whole):

1. You have a FAST lot of Varget
2. 88 ELD has different bearing surface length
3. Starline brass has lower internal volume than Sierra's test cases
4. Your barrel is faster than theirs.

Point in case regarding lot to lot variation of powder: Today I tested a new 8lb jug of H4350 and compared it to my old lot with the same load. 30fps slower from new lot than the old lot.

My fast lot was 2770fps avg with 42gr.
The new lot (slower lot) is 2740 with 42gr. 1.1% slower to be exact. +30fps

If I were to shoot same load with fast lot and Starline brass (6.5cm) it tops 2800 (vs 2770). +30fps

My other barrel is also faster than this one by about 20fps. +20fps

Berger VLDs are 10fps slower for the same charge even though both are same weight. +10fps

Combine those and that's almost 100fps different with "same" components but different lots, brands and barrels. Didn't even add primer effect which can also change velocity fairly substantially (+10-15fps).

A 223 is much more sensitive to charge/powder burn rate than say a 6.5CM, so you could get even higher differentials than I've shown here.

 

[b6graham]

also.

reloading books/website per manufacturer is SLOWWWWW and SAFE

Hodgon lists 6.5creedmoor. 140 amax. 40gr as max load at 2660fps. thats not even a starting load or as fast as factory ammo

 

[Jayhawkhuntclub]

Thanks for the advice.
Also, does the 40 fps jump due to the bullet being jammed into the lands seem reasonable?

 

[Subwrx300]

Thanks for the advice.
Also, does the 40 fps jump due to the bullet being jammed into the lands seem reasonable?

It makes sense to have velocity increase when jamming.

However, I (and most others here) don't jam bullets mainly to completely avoid possibility of pulling a live round out and having powder go everywhere with bullet stuck in barrel.

Unless you have a specific need (which is either purely benchrest precision related) I'd forget about jamming bullets if I were you; stick to some level of jump and call it a day.