22 ARC ...Here we go !

[Shotafterdark]

I'll document the load development on this rifle
You can learn form my success and failures ...

What I am working with ...my personally built AR
24" EABCO 416R stainless barrel , 7 twist wearing a Surefire SOCOM RC2 30 cal can
Superlative Arms Gas Block ...turned 18 CCW then back 6 clicks ,,,on the money
ASC Stainless 6.5 Grendel 10 rd mags
Trigger Tech trigger 2 lbs
Magpul Stock
H3 Buffer
Nickel plated carrier AIM Nickel Bolt Carrier
Faxon 6.5 bolt
Arken SHJ4 VHR MIL 6 x 24

Started today with AA2230 powder
Hornady ELD VT 62 gr bullet
Hornady 60 GR V Max flat based
Hornady 6.5 brass formed to 22 arc
Hornady New Dimension 22 arc dies

 

[Shotafterdark]

 

[Shotafterdark]

 

[Shotafterdark]

The two projectiles respectively
60 gr Vmax
and 62 GR ELD VT

 

[Shotafterdark]

 

[Shotafterdark]

 

[Shotafterdark]

All was going well . so I thought ...
I decided to switch up to the 60 GR Vmax after
the 5 ELD VT 62 ...

The ojive is very different as you are aware and I didn't seat the
new rounds back enough ...

I stuffed the first bullet into the rifling and sent that sucker
into dust at 3700 fps ...almost blew the gun up ..

 

[Shotafterdark]

here is where it got interesting
2 things happened

1 I seated the bullet into the lands
2 Bullet vaporized due to new barrel and speed

watch as the bullet turns into a cloud out about 200'

 

[Shotafterdark]

 

[Shotafterdark]

I hit the reset button ..stripped and cleaned weapon
investigated bolt and carrier for any damage
reseated all bullets accordingly ....

3657 is too fast my friends ...

 

[Shotafterdark]

The initial cold bore shot , then 3 were not good
The new seating depth for the 60 gr Vmax
not in the lands

 

[Shotafterdark]

LOL I cursed myself sayin things are going smooth ....dohhh

 

[Shotafterdark]

uploads maxxed out at YT for the day....guess Ill update more tomorrow
as well as Sierra 69 GR TMK loads.....I expect greatness....

The brass fired with the 60 gr V Max into the lands smoked the primer pockets
and trashed the brass ,,,,stretched that shit like a stretch armstrong ....
of course most of you are too young to know what the hell that is...lol

lesson learned today ...check OAL with OAL gauge ...on experimental loads
the 22 arc is still experimental .....we are learning ....

 

[Shotafterdark]

Lessons learned today ....Hornady's load data cannot be correct
I am using the exact barrel they claim to have used for documented data
a 24" match barrel on a gas gun with 7 twist ....

The 60 GR Vmax was loaded to 30 gr , blew up all of them at 200' 3700 fps
I dropped the load to 28 gr ,,,blew em up at 3500 fps
dropped them down to 27 gr and they held together at 3300 fps ..

If only I had a 9 twist .....arghhh!
tomorrow we will push them Sierra TMK to their limit , I guarantee they will
not be blowing up ....

 

[Shotafterdark]

I'm going to keep the 62 gr ELD VT for my 223 AI
Ill be playing with on Tuesday as my KRG Chassis arrives
and the Tikka get's stripped and rebuilt into awesomeness !

That is gonna be a fun one !

 

[Shotafterdark]

So today I have decided to nip this lil issue of seating depth in the butt and not
guess on any further loads by clearance in magazine ...

Those ELD profiles are new to me as a varmint hunter I am not used to
such a sleek and narrow Ogive and it's allowance to be seated out so far.

Made a cup of coffee and then proceeded to make my case from a fired
cartridge yesterday .

It appears Mr Brown makes a very tight chamber for his barrels as I had the same
issue with his 22 CReedmor barrel , tight chamber...
This one is no exception , the bullet would not fit into the neck even after firing
it from an over pressured charge ... I reamed it , didn't work , still needed more removed
then I grabbed a bit from the index and removed .008" from the ID of the neck ..

Proceeded to drill and tap base 5/16" x 36 TPI for my OAL gauge...
Today we do it right !

 

[Shotafterdark]

Here is the vid from yesterday ...60 GR Vmax at 3500 fps
not excessive by Hornady's claimed ballistics from their own testing as
they have a 55 gr Vmax loaded to same fps in the available manual
out of the exact same barrel as mine a 24" gas gun 1-7 twist ..

They do NOT hold together !

<iframe class="rumble" width="640" height="360" src="" frameborder="0" allowfullscreen></iframe>

 

[Shotafterdark]

I wanted to throw in a plug for these lil 3d printed USB battery cases that you can mount
in many ways to your schtick ! for thermal and NV these are the ticket ! I do not wanna
find myself worrying about a dead battery in the field ,,,an Anker USB lithium ion battery
is that assurance,,,,,
This added to the 18650 assures you are GTG !

Mount em forward on your foreend...or right on the scope ...

 

[Shotafterdark]

Once she was backed down to 28 grains of AA2230 @ 3300 fps they
decided to hold together.... grouped like shit ....but there is tomorrow
and we are just getting started ..

probably would help if I was shooting at the same target ..lol

Today we play with the Sierra TMK 69 Gr .....


<iframe class="rumble" width="640" height="360" src="" frameborder="0" allowfullscreen></iframe>

 

[232593]

How did the ELD-VT do?

 

[Bowhunter-tw]

Im shooting a bolt gun I built with a 20” 1:7.5 twist. Loading 60gr vmax with aa2230, started with 31 gr, way over pressure, blowing primers out of the case. Backed it down to 29.5, getting cratered primers but the groups with both of these loads were tight, gonna back down to 29gr

I also loaded some target/fireforming loads with 55gr Fmj over 29.5 gr of aa2230 and they shot great, no pressure.

 

[Ledzep]

The PDF we published has the MAX (gas gun) at 29.6gr with AA2230 and the 62gr ELD-VT at 3300fps. 3500+ is super spicy.

Also, there's a very real thing in lot-to-lot variation in powders. What we publish is what we recorded with the components/lots we had. Start low and work up...

Also, the 60gr V-max has more bearing surface than the 62gr ELD-VT for which the data was created, and will likely reach considerably higher pressure at the same charge weight. Likely won't be able to achieve the same velocity as a VT at the same pressure.

 

[232593]

The PDF we published has the MAX (gas gun) at 29.6gr with AA2230 and the 62gr ELD-VT at 3300fps. 3500+ is super spicy.

Also, there's a very real thing in lot-to-lot variation in powders. What we publish is what we recorded with the components/lots we had. Start low and work up...

Also, the 60gr V-max has more bearing surface than the 62gr ELD-VT for which the data was created, and will likely reach considerably higher pressure at the same charge weight. Likely won't be able to achieve the same velocity as a VT at the same pressure.

Was that with a 24” barrel?

 

[Bowhunter-tw]

The PDF we published has the MAX (gas gun) at 29.6gr with AA2230 and the 62gr ELD-VT at 3300fps. 3500+ is super spicy.

Also, there's a very real thing in lot-to-lot variation in powders. What we publish is what we recorded with the components/lots we had. Start low and work up...

Also, the 60gr V-max has more bearing surface than the 62gr ELD-VT for which the data was created, and will likely reach considerably higher pressure at the same charge weight. Likely won't be able to achieve the same velocity as a VT at the same pressure.

Does bullet bearing surface drastically alter velocity for the same pressure? I understand it correlates to friction in the bore but would have thought it was nearly negligible

Also curious what drives max charge to be lower for gas gun vs bolt?

 

[Ledzep]

Was that with a 24” barrel?

Yes, Bartlein 1:7 5R SAAMI V&P test barrel.

Does bullet bearing surface drastically alter velocity for the same pressure? I understand it correlates to friction in the bore but would have thought it was nearly negligible

Also curious what drives max charge to be lower for gas gun vs bolt?

It will depend on what your definition of "drastic" is, but it can be worth the better part of 100fps or more in extreme examples at the same weight. Bullet construction (toughness/rigidity) and bearing surface are pretty large contributors to the rise rate and peak pressure in a given load/cartridge. In some of the tests we've done bearing surface is worth up to ~25% of the total peak pressure. In other words if you shoot a standard bullet and it creates 60,000 PSI, then you cut the bearing surface away except for a tiny driving band it could be as low as 40-45,000psi with the same load.

Something like a 140gr 6.5mm round nose flat base projectile is 100% guaranteed to produce more pressure at the same charge weight vs. a sleek/sexy 140-142gr boat-tailed match bullet. There are often things that can be done in powder selection to work around some of these issues and mitigate them to an extent, but in as apples-to-apples situation as possible this is generally the case.

In the ARC/Grendel family the "gas gun" data is limited at 52,000PSI to keep the bolt thrust on an AR-15 at a sane level. "Bolt gun" data is 62,000PSI because bolt actions are typically built to handle SAUMs and WSMs with the same lug geometry, so whatever you do with an ARC/Grendel is going to be kosher.

 

[Bowhunter-tw]

Great information; I did not know it had that much influence on pressure. Does larger bearing surface equal better stabilization? Otherwise id imagine bullets would all just have small driving bands to gain velocity

Also good to know on the bolt vs gas gun.

 

[Ledzep]

Stability can devolve into a deep rabbit hole, but as a general statement if you keep the same bullet overall length and bullet A has more bearing surface than bullet B, and they're both of similar construction (same boat tail or both flat-base), you can generally expect bullet A to have a higher SG out of the same twist rate and velocity. However, if you go to messing with boat tail lengths and angles between those two bullets all bets are off.

It can also help to have more bearing surface to get a longer "wheel base" and prevent in-bore yaw, which generally makes bullets easier to get to shoot in a bunch of barrels. Bullets with minimal bearing surface can be a little picky/erratic, especially in roomy throats.

Obviously what I just discussed has tens of variables involved and you can easily find exceptions.

 

[Bowhunter-tw]

Yah it is a very dynamic situation and one that I am very interested in understanding better. That in combination with what the pressure profile looks like from primer detonation to bullet exit.

 

[Bowhunter-tw]

Stability can devolve into a deep rabbit hole, but as a general statement if you keep the same bullet overall length and bullet A has more bearing surface than bullet B, and they're both of similar construction (same boat tail or both flat-base), you can generally expect bullet A to have a higher SG out of the same twist rate and velocity. However, if you go to messing with boat tail lengths and angles between those two bullets all bets are off.

It can also help to have more bearing surface to get a longer "wheel base" and prevent in-bore yaw, which generally makes bullets easier to get to shoot in a bunch of barrels. Bullets with minimal bearing surface can be a little picky/erratic, especially in roomy throats.

Obviously what I just discussed has tens of variables involved and you can easily find exceptions.

For load data estimates, is there a heavier bullet weight with similar bearing surface I can use for a starting point on the 60gr vmax bullets?