22 Grendel 40? IMP

[Es 350]

If anyone wants to see an amateur (lol)vid of me and cousin shooting 10" plate at 571 yds yesterday... he posted a 4 min on youtube..... "AR banging steel at 571 yds"

[flatland1]

I recently re-barreled one of my Howa Mini 6.5 Grendel rifles with a Bartlein 1-6.8tw bbl chambered in 22 Grendel. I thought seriously about asking PTG to grind a reamer for me that would essentially be a 22 RAT, as I'm a long-time fan of the 6 RAT, and have AR15, Howa Mini, and CZ 527s with 6RAT bbls on them that I've chambered. Have only just started shooting the 22 Grendel Mini, and haven't done enough chronograph work to have a feel for what range of velocities are possible with it, out of the 24" Bartlein bbl. But I can't stop thinking about doing a 22RAT....and Es 350, seeing photos of your loaded rounds isn't making it any easier to stop thinking about it!

[Es 350]

Sorry for being a bad influence...lol

I got some Norma PPC brass waiting on me at home.... i read on net a guy with a reg. 224 Grendel say with Norma brass he had 35.3 gr of H20 capacity which is considerably more than unfireformed/necked down Hornady brass.
So once i get home and have a chance to neck down and check capacity will know for sure if the Norma brass will offer a performance increase .

[Es 350]

Anyone that shoots 224 Grendal, LBC or Predator,
Could you give me an actual (weighed) H20 capacity on a fired case? Would be much appreciated.

[windsage]

I use Hornady cases and they hover around 34.9 to 35.0 in the .224 Predator.

Edit: The above is after necking down the 6.5 brass but prior to firing. After firing, the brass volume is 35.3-35.4 before sizing.

[Es 350]

I use Hornady cases and they hover around 34.9 to 35.0 in the .224 Predator.

Edit: The above is after necking down the 6.5 brass but prior to firing. After firing, the brass volume is 35.3-35.4 before sizing.

Thank you!
According to your capacity i didnt really gain that much with my improved version.
Fireformed , resized my case holds 35.7 gr .
Have read on another forum a guy with a 224 Grendel/hornady brass was at 34.2gr.

When I first necked down a few 6.5 Hornady cases i checked the capacity and was right at 34 gr, from my understanding "normal" 224 Grendel/LBC/Predator is a straight necked down 6.5, same neck length etc.
So may be lot#'s of brass.
But with my brass i only have .7 gr more capacity than you with my IMP version.

[windsage]

My Hornady brass measured .0125" thick at the neck before forming. After I necked them down They measured .014". The neck in the chamber is .255" but I still got higher than expected pressures. When I checked the fired cases, some of the necks had gotten thicker as they fired. and were showing .254" OD and .222" ID. So, I am going to neck turn them and try again.

The shoulder on the .224 Predator appears to be exactly where the 6.5 Grendel shoulder was. Since the shoulder taper now goes to .224" the actual neck is slightly shorter. You can hold them side by wide with the 6.5's and see the difference.

The most common powder seems to be CFE223 and it's only filling the case about 90-95% with the 75gr ELD. I bought some 95gr SMK on sale, and hope to try them to see if they like slower powders. Just doing some Quickload estimates, it looks like we get close to H4350, RL16 or RL17 territory with the 95's. With those I can make real use of the larger volume. My goal is to get the 95gr to 2800 fps. This would closely mirror the trajectory of the 6.5 Creedmoor.

[Es 350]

Have you annealed your brass after fireforming?

What signs do you have as far as higher pressure?

Neck walls on my Hornady brass is .013 , i machined my reamer at.2555 neck dia. My "full power" loads have an outside neck of .2535 and inside of .2252.
I did notice that my lower pressure fireforming loads do not expand the necks and a bullet will not slip into case. At first i thought i screwed up by not making neck dia. Large enough but after annealing brass and or higher preassure loads it expands the neck to the chamber. Cases really need annealed after "working" in the necking down process for consistent neck tension/seating pressure and accuracy.

This may not be your problem but is what i found in my barrels.

As to the heavy bullets..... the bullet i built the 7 twist for was mainly the 88 gr ELDM.... i shot a ladder this weekend with 88's/ R16..... According to quickload .... 29.6 gr of R 16 behind an 88 ELDM " SHOULD " produce 2939 fps @ 56,318 pressure in a case of 35.0 gr of H20...... from a 24 inch barrel
This is a Quickload "PREDICTION" and as everyone should know every barrel and lot of powder is/can be different and why loads NEED WORKED UP in their gun!

But ... i shot the ladder in my 27 inch barrel and got up to 3015 fps..... while i do not plan to shoot loads this hot i was not seeing any excessive pressure signs . The primer pockets "pin gauged" same as new 6.5 Hornady brass.... AR cannot withstand pressures of a bolt gun and sometimes case measurements and primer reading can be misleading as to pressures actually produced...... again this was in my barrel and not suggesting anything for anyone elses barrel!

[windsage]

I was getting flattened primers and clear ejector smears with 28.4 gr of CFE223 and 75gr ELD even after I turned the gas way down. The velocity was 2915-2935 fps. I did not anneal them after I necked them down. I was hoping to get through fire forming, and then anneal. I started with the Hornady brass as it was about .001" thinner than my Starline brass I normally use in the 6.5. I don't expect top velocities since this is a gas gun and the barrel is 22".

[Es 350]

What length gas system do you have?

You may try turning the gas completely off, if bolt is cycling too fast it will show higher pressure than you actually have... you may know this but maybe some dont.

A trick i use on guns that dont have adj. Gas block and showing high pressure with loads that are less than what they should be is to add a buffer weight, it helps keep bolt closed long enough for pressure to bleed off , not yanking case out of chamber while barrel pressure is still high causing signs on fired brass of a high pressure load..... just a thought, you know more about your barrel/situation.....

[windsage]

It's a Rifle +2" gas system with a full weight BCG and the same H2 buffer that I use on 6.5 Grendel's. At one point I had the gas off thinking that same thing. The final setting on the gas tossed brass at about 3:30-4:00 which is where I like to set it. I generally go about half a turn open from where it won't cycle on the Superlative Arms adjustable. The cases were actually clean below the neck similar to how bolt gun brass looks, so it was sealing at the neck. I am sure the necks are tight after the forming, but there isn't a crimp on them. Even for my PRS rifles I've never neck turned, so this will be new for me. I think I'll turn them back to .013" and then anneal them and load another ladder to see what that does.

[Es 350]

I used a dial caliper to measure my neck wall and neck OD quickly , didnt get out the micrometers....it is close but not exact... but with your measurements .254 - .222 = .032÷2 =.016 neck wall ..... which is pretty thick.
If you dont have a bunch of this lot of brass and dont want to neck turn im sure a different lot of Hornady brass would be thinner like mine .
But adding neck turning to your bag of tricks is not a bad thing either.

On annealing brass... i anneal after fireforming. Some guys anneal before neckking down or up, unless using used/fired brass it should be annealed from factory when using new brass which is what i use .

[Es 350]

My Hornady brass measured .0125" thick at the neck before forming. After I necked them down They measured .014". The neck in the chamber is .255" but I still got higher than expected pressures. When I checked the fired cases, some of the necks had gotten thicker as they fired. and were showing .254" OD and .222" ID. So, I am going to neck turn them and try again.

The shoulder on the .224 Predator appears to be exactly where the 6.5 Grendel shoulder was. Since the shoulder taper now goes to .224" the actual neck is slightly shorter. You can hold them side by wide with the 6.5's and see the difference.

The most common powder seems to be CFE223 and it's only filling the case about 90-95% with the 75gr ELD. I bought some 95gr SMK on sale, and hope to try them to see if they like slower powders. Just doing some Quickload estimates, it looks like we get close to H4350, RL16 or RL17 territory with the 95's. With those I can make real use of the larger volume. My goal is to get the 95gr to 2800 fps. This would closely mirror the trajectory of the 6.5 Creedmoor.

The 22PPC brass has thinner necks than Hornady, with Hornady brass loaded i am at .2515 , PPC .248 which would not require turning for your chamber.
Imagine annealing often would be the ticket with the added working of the neck.
The 22 PPC Also adds .4- .5 gr more H2O capacity vs Hornady.

Word of caution on the 22 PPC brass, because of thinner neck a smaller bushing will be needed to maintian proper neck tension on bullet and the flash hole in Norma brass is smaller diameter than Grendel brass like Lapua brass , both requiring smaller decapping pin.

But like the Hornady brass (just checked) the Norma PPC brass does not fully form to chamber on initial fireforming (which is normal) after couple firings the Hornady is at 36.1 gr H2O and the Norma is at 36.8 gr. After a second firing and may increase a little more with more firings/completely forming to chamber. This gives me a loaded case capacity (Norma brass at current capacity) .5 gr more than a 22 BR with a 53 gr bullet @ my aol vs Nosler 22 BR data.

[Es 350]

Finally got gas port drilled and machined a gas block for the 22" 14 twist, am running a +3" gas system.
As i suspected it feeds and ejects fine.... in the 30 or so rnds i put through it.
Just need to remove some machine marks and apply finish this one is ready for some predator/varmint hunting.

[betolatinlu]

Wouldn't that be similar to the .224 Valkyrie ?

[Es 350]

Grendel brass is stronger than Valkrie (from my understanding), and more capacity which equals more velocity for a given weight bullet.
My chamber which is basically a 22 Grinch has 3.2 gr (Hornady) or 4 gr more capacity with Norma brass, which offers a considerable performance increase over 224 Valkrie.

One of my cousins has a couple 224 Valkrie AR 15's , so am familiar with it .

[Caleb]

How is that thing shooting? That 14 twist will be a grest varmint and predator barrel

[Es 350]

It shoots better than i expected, especially from AR platform.
I think the largest 5 shot groups were still under 3/4"@100 yds. And this was with foreform loads right after chambering.

Barrel wasnt new but dont look to have had many rnds in its former life as a 22 250. After 10 or so rnds (smoothing up throat) it has been a solid under 1/2 moa gun with any bullet, powder or load combo i have thrown at it.
So could not be happier with this project.

Coyotes are kinda scarce in my area these days.... hope to get on a few before long if it will quit raining long enough to get after them!
Would like to put the Grendel to the "test "!

[Es 350]

The load i settled on pushes the 53 gr Nosler/CFE out of the 22.5"/14 twist barrel @right at 3800 fps (3797 av. To be exact)
Case measurements ,primer pocket measurement and reading primers "indicates" pressures to be inline with AR platform.
This load rarely results in the slightest shiny spot where ejector is , majority of fired brass looks pristine.

Also shot a ladder with 50 gr Vmax/CFE , top load was 3893,3887and 3889, this load produced an ejector mark on brass .
Will back off charge weight to that of the 53 gr load above and should both should be fine as a "winter load" both will need backed off for summer heat with CFE's temp stability.

CFE is dirty, temp stability SUCKS but produces great velocity vs pressure and delivers awesome precision.

Above loads are in Hornady brass, Norma with almost 1 gr more H2O capacity will offer more performance but will shot the Hornady for time being.

Project is complete as far as i am concerned and consider it a success, 22 250 performance from an AR platform and being able to feed 88 gr bullets from AR mag!

[Caleb]

Great results,

I think i seen you say before in here or on f.b. if you were to do it all over again would you, meaning the cost, trouble, time and all?

Vs a straight 22 grendel