22 fat rat reamer needed

[RampedRaptor]

Hello,

Looking at replacing my 6mm fat rat barrel with the 22 version. The goal is to shoot the 75gr elds and Berger 80.5s.

Didn’t know if anyone knew of a reputable Smith with a reamer on hand?

I already have dies on hand; I’d like to stick with the fat rat dimensions and not veer off course.


Thanks in advance for any input

 

[RampedRaptor]

To the first page. I know it’s a long shot

 

[Reddman]

Did you ever find one? I am having one made....

 

[ES 350]

Would be interested in dimensions of Fat Rat chamber.
I machined my own reamers for 22 Grendel IMP, basically a Grinch from what little info i can find.

I can tell you Norma 22 PPC brass will offer 1+ gr capacity increase over Hornady and Starline and others from what info i can find from others.
Necks are thinner on Norma, I machined my reamers based off Hornady brass as is what i had at time, so have like .008 neck clearance with Norma which doesnt seem to shorten brass life or cause any issues.

Originally this was a "feed 88 ELDM From AR mag " project...... i now have a 14 twist AR, 7 Twist AR ,8 twist bolt gun and will be finishing up a 7 twist bolt gun this weekend to stabilize 88 gr bullets.

Shot the 8 twist bolt gun at 1000yds (80 ELDM @3120) last weekend, was very happy with results. Hits and misses were easily spotted . Crazy switching winds prevented a hit on 4"×6" plate @1000YDS , 1/2moa plates were easy enough at lesser ranges

Posting on another forum promted atleast one other to have PTG grind him a reamer , so far he loves it.

My reamer has a shorter neck , slightly more capacity than what they came up with .

53gr and 50 gr

 

[Reddman]

Where would you put your freebore for the 88's?

 

[Reddman]

Or if you could give me base to ogive of a loaded cartridge with the bullet above the neck shoulder area for the 88's? I'm having a very difficult time figuring freebore.

 

[ES 350]

What neck length will your reamer have?
Assume this will be for a bolt gun ? If you want base above shoulder.....

My reamer has a .2 neck , and because i knew i would more than likely chamber several barrels for different bullets..... i machined reamer with a short throat and also machined a throating reamer to lengthen throat for which ever bullet/oal i wanted to shoot in that barrel at same time/set up as chambering.

7 twist AR is at .140 freebore and load 88 ELDM 2.27 , obviously not going to get base above neck in AR platform but still get decent velocities and feed from SS AR mags no problem.... could load out to 2.31+ (in SS mag) but left some room for growth of throat.

On 7 twist bolt gun oal is 2.385/1.775 BTO and puts base of 88 right at neck/ shoulder junction for my reamer , this works out to .255 freebore.

Here is shots 57,58 and 59 from 7 twist bolt gun (88 eldm@ 2965 fps from 123 yd), first 56 were fireforming loads with 50 gr bullet for barrel break in.

 

[Reddman]

Nice little group there. Here is my reamer so far. It was done by JGS. I believe the neck would be 0.214 using the given measurements. 0.255 freebore sounds like a lot! Maybe you could give me some advice on my reamer?

 

[ES 350]

.255" is alot.... but 88 is 1.24" long -.175 for BT =1.065 of bullet above BT+ 1.52 ,case length=2.585 -.2 neck length (my reamer) = 2.385"

Long bullet and short neck = long freebore to be at/above neck shoulder junction.


Your neck length (of loaded rnd) should be @.207 IF your brass is at 1.52", if trimmed shorter or use Norma brass actual neck length will be less but not an issue other than possible carbon ring ... something i am keeping my eye on with Norma brass as it is 1.505 after forming in my chambers, but as already mentioned i only had Hornady 6.5 brass when i machined reamers for size die and chamber...... so far all is good with shorter Norma brass.....

Other than small differences your reamer is really close to mine ...

What size die will you be using?
For life of brass should make sure it will not size brass down too far (dia) that fired brass grows more than 1.5 to 2 thousandths at .200 line and shoulder.

.254 neck should work fine.... mine is .2555, which is larger than i prefer for Norma brass but what i wanted for no turn Hornady....

Not sure how easy it is to see in pic ... line around bullet (towards bottom of black sharpie) is start of bearing surface of 88 ELDM , there is ..872" of bullet outside of case @ 2.385" oal.

 

[Reddman]

Makes sense. I put some dykem on a bullet and just did the same measurements. Came out pretty close to your measurements. There is a little eyeballing involved. Lol.

Would I be better off borrowing your reamer?

I haven't even thought about dies yet. I plan on reaming the chamber myself. How hard is it to make dies?

 

[ES 350]

With a mic. and depth mic. You can get exact measuements on bullet.
I did the above pic for reference.

The reamer print you have is fine, (sorry , i dont loan or rent my reamers/tools) i would just prefer to have size die/sized case or have reamer manfacture also grind a size die reamer of correct dimensions to ream size die blank or machine your own blank.

Dies are not hard to make , just need a reamer couple thou. Smaller to ream size die.
Use mandrels to expand neck for proper neck tension/ necking up to form false shoulder to fireform, these are easily machined as well

I use a seating die (Hornady 223 in this instance) to seat bullets. Hornady seat dies are same per caliber...ie. 223 is same die as 22 250 etc....

If building a bolt gun 22BR or one of its offspring would be easier/cheaper as dies are available . Only reason i built bolt guns is this started as a ultimate (for me) AR caliber to push 88's as fast as possible and feed them from mag.
All started when at range with 223 AR single feeding 80 handloads.... found 6.5 Grendel case on ground.....

 

[Reddman]

Sounds like me. I have been wanting to do this ever since they came out with higher bc 22 Cal bullets. I thought maybe the Valkyrie would be close and so I bought 2 (one in bolt one in AR). I can get 80 eld's at 2950 fps in the AR which is no sloach but my mind kept going back to how perfect the Grendel case would be for an AR. The guys at federal missed the boat on that one. Why totally hack up a 6.8 SPC case for the Valkyrie when a slightly modified Grendel case is even better? I think they got caught up on making something totally new . It was brave but the case length makes no sense. Not when you can get 4-5 more grains in a shorter Grendel case.

Now look what Hornady did with the 6 ARC...makes way more sense. Although I think they should have went 22 Cal. The sectional density along with the ballistics are better in 22 Cal. (22 Grendel). Hornady claims they did so much engineering and research because of military applications...um guys you necked down a Grendel and bumped the shoulder back. Lol. The ARC seems to be slightly less a ballistic performer than the Valkyrie but had the advantage of better brass and a more inheritantly accurate cartridge design being close to the 6ppc. Better bullet seating too with the shorter case so you can get the bullet out of the case further and out of the powder.

 

[Reddman]

BTW thank you for your help so far. What kind of setup do you have for grinding reamers? Have any pics? I find it very cool that you are able to make your own.

 

[ES 350]

Quite welcome....
I actually turn them between centers on lathe, mill flutes , heat treat then hand stone sharp.

 

[Reddman]

Quite welcome....
I actually turn them between centers on lathe, mill flutes , heat treat then hand stone sharp.

Coolio - Teach me obiwan

 

[Reddman]

Can we call this cartridge the 22 Rush? Because it is very 6 Dasher-esque

 

[Reddman]

Deleted

 

[ES 350]

I have been trying to think of a good name for it.... just been referring to it as 22 Grendel IMP.....

Here is a pic of the 7 twist Savage

 

[Reddman]

Very nice man! I'm pretty excited about getting mine done. What kind of groups are you averaging with the 88's? I know you had that great one in the pic but what do you think your average would be?

 

[Reddman]

I'm toying with putting mine on a savage target action repeater. They have the trigger you can dial way down and look very solid. Only down side is that they are large shank only so if I ever wanted to switch barrels on it, they would have to be large shank. I have a 6.5 x 47 lapua with a criterion barrel and a regular savage action currently. Which is of course small shank. The accutrigger isn't bad at all. I also have a bighorn origin action with a Valkyrie barrel on it which is also the same size as the savage small shank and threading. It would be nice if all my rifles were interchangeable.

 

[ES 350]

I havent had a chance to shoot it much..... but varget seems to be the powder in this 7 twist....
What ive seen so far i think it will be a 1/4" gun. I know that gets thrown around alot on forums but we shall see.
I shot 5 of the varget loads after the ladder below....first 4 went .193 ctc..... i said to myself dont screw this 5th one up..... like an idiot i repositioned and dropped it low left ......

I did a ladder with R16 , not as accurate as varget in this barrel...but i started too low on charge weight . The last 4 increments were all less than .5" for 3 shots, lots of testing to do and little time to do it.

I like the Savage actions, not the greatest by any means but for my purposes they work great.

This was a 243 Win , replaced the bolt head with a PTG 223 that i opened up to PPC size. Had to modify the extractor also.

The internal mag (unmodified) feeds decent except second to last round.... need to massage the feed lips and think it will cycle fine.

 

[ES 350]

Here is a pic of a 3 shot group at 650 yds from the 8 twist Ruger
80 ELDM @ 3120 (load i shot at 1000 yds couple weekends ago)
I obviously missed the wind correction .... but could have been a heck of a group!!!!

Same load (5) at 100yd....

 

[Reddman]

Very nice. The one group at 650 is still very nice fyi. haha

 

[ES 350]

Yeah, not dissapointed...... just could have been better! Lol

As you can see .5 MOA plates (except 1000 yd) was almost easy as long as i did my job at guessing the wind or had one shot to figure the wind out.......
But is a very accurate chamber across 4 barrels i have chambered for it.
Of course good handloading does help out with precision.... and with the size die i machined (my design) my brass and loaded rnds have zero run out ... occasionaly .001.

 

[Reddman]

Did you do something different on your dies? Are the bushing or just cut to exactly where you want them?

 

[ES 350]

Ancient Chinese secret .....
I machined the reamer exact dimensions i wanted (actually machined die first , then chamber reamer to match) but is also different design than any i have seen before..... might try to patent it or sell idea to die maker.....

 

[Reddman]

You are a lot like me. I have an invention I'm working on for reloading too. If you want me to test your dies and give you feedback I could sign a non compete non disclosure agreement. I'm going to do this with my invention too. I want feedback before I put it into production.

 

[ES 350]

You are a lot like me. I have an invention I'm working on for reloading too. If you want me to test your dies and give you feedback I could sign a non compete non disclosure agreement. I'm going to do this with my invention too. I want feedback before I put it into production.

Sent you a PM.

 

[ES 350]

Took my 14 twist AR and 7 twist Savage to WY to shoot some Prairie Dogs.
While they were few and far between i managed to find a couple small dog towns.

Mostly used the 7 twist with 88's as winds were as high as 18mph which played havoc on 53 gr bullets at longer ranges.

Furthest opportunity was somewhere around 450 yds (398 was closest sage brush that i could range) in 18 mph wind .

Only rnds put on paper since last post was 3 to check zero before going afters dogs, 3 went .2".

Love this chamber! Has become my favorite round to shoot.

 

[Reddman]

Sweet! Sounds like a lot of fun!

Work and deer hunting have kept me busy. I haven't had time to order the reamer. Question: How much do you have to trim your cases after fireforming? I am curious if you could spec the neck length a little longer because of brass stretch being that it is sizing down to 224 cal. Have you thought about using the starline un-formed grendel cases? I was thinking that these might allow you to get longer necks?

 

[ES 350]

Grendel brass is 1.52 max length, 1.515 trim length. After necking down to 22 cal ,brass is less than trim length.
22 PPC is 1.505 IIRC before forming which also is less than trim length.
So no initial trimming is needed and because of 40° shoulder, hardly any trimming is ever needed,another reason i love this chamber!
Some of the hornady brass has 8+firings , Norma is at 6 firings.
I do have a couple of each brand with loose primer pockets load testing 8208XBR powder which gets crazy up top.....

When i drew up my reamer..... i wanted max capacity, doing a little measuring..... 223/556neck length is .203" i figured if it works on 223 should be fine on Grendel.
Which have no reason to think i need a longer neck length.

The 40°shoulder keeps the flame intersection inside the neck of case vs in the throat, ( if you draw a straight line continued up shoulder angle through neck) my thinking is this should help with throat wear.....

I machined my reamer with a .2" neck length for a case length of 1.52".....

 

[Reddman]

What are you to the shoulder? Have you seen the grendel casings I'm talking about? They are straight walled and unformed.

 

[ES 350]

I had not previously seen the brass you speak of.
It would require many steps to get down to 22 caliber. It could be done and would result in a longer case. Also would require several annealing steps before actual firing, seems like lots of extra work ...
More than one way to skin a cat as they say.....
I am pretty happy with the reamer i have now..... if i see problems later down the rd with earlier than expected throat wear/barrel life i may change my mind.....but for a AR and bolt gun chamber i think it should be pretty good as far as performance vs barrel life....

Base to shoulder is 1.23" .

 

[Reddman]

Adding it all up it looks like you left 0.017 space from the end of your brass to the end of the neck chamber? I used 0.107 as the length of the brass from the shoulder to the neck. For your chamber I had 1.537. Minus 1.52 = 0.017

 

[ES 350]

My compound scale is off a bit, shoulder is actually sharper than 40°.
As i said before i machined size die reamer first without giving that a thought..... so instead of machining another reamer and die ...i just used same angle on chamber reamer so they would match.....

So a little longer neck for a 40° shoulder would "probably" be beneficial to keep flame intersection inside neck instead of outside in throat...... this is all "thinking" have not actually tested..... but makes sense in my mind.... unfortunatly Norma brass with shorter neck puts flame deflection point right at/just in front of case mouth until it grows.

Shoulder is 1.23, base of neck is 1.32 for .09 or .290" shoulder to end of case.

Total chamber length is 1.526 to try and keep a carbon ring from forming at end of case.... so with this reamer cant run a longer case anyways.
This was dimensions for hornady brass, the Norma neck length is less than .2" , measured after 6 firings and is growing some, but doubt i will ever have to trim other than for consistency in length .

I know we are not talking lots of gain in case length, but making case longer (in AR platform) is heading towards Valkrie short comings but no problem in bolt gun.
Like i said more than one way to skin a cat.... this is my way, not saying its the right way.

 

[ES 350]

I took the 14 twist AR and the 7 twist Savage with me to WY.

Found a couple Prarie Dog towns....
Mainly used the Savage as winds were up to 18-20 mph. 400 +yd shots were pretty easy with the 88's @ 3000 fps.
I used the AR 200 yd and under 53 Nosler @ 3640 fps, talk about vaporizing a dog!!!!

This weekend i had 2 opportunities at coyotes... the first was 450-60 yds, couldnt get a range on yote as he was in a valley and was picking up top of hill at 399 or weeds on other side at 633.... guessed 500 and shot right over him.
Second one was an easy 240 yd.
Yote was facing straight away... almost flipped it over on impact ....flat hammered it. Might call it
22 Hammer or 22 DRT ...lol

There are other 22 cals that will provide same or better performance from bolt gun although IMO makes a great bolt gun round .... to my knowledge is about best you can get from small frame AR feeding heavies from mag.
Was gathering parts to build a 284 Win 40° , which i think will be another good one with decent barrel life.... having so much fun with 22 Grendel IMP it might be awhile putting 284 together.

 

[Reddman]

Very nice update! I'm saving mine as a winter project.

The 22BR comes to mind as probably similar ballistics. Problem with the 22BR in an AR is the bolt would have to be machined that much more making it weak.

Advantage of this round is it will feed better and uses Grendel bolts that are readily available in an AR.

In a bolt gun I think you will see it feed and magazine slightly better than the 22BR and may even be slightly more accurate.

I agree that it is the maximum performing long range cartridge in an AR that is still practical. By practical I mean not having an overly weakened bolt as mentioned above. It's just a barrel swap away from a Grendel or possibly just ream an existing Grendel.

I am assuming "DRT" is "dead in their tracks" or something? Not sure what the R is? lol

I think I will call my version the 22 Rush - being that it is similar to dasher and has a Russian parent case

 

[Reddman]

You should come out to Idaho some time. Like WY we have a lot of open shooting space and a lot of coyotes. I have a pretty nice range close by that goes out to 1135 yds (yes I did smack that steel with the little Valkyrie ). Interested what this round will do. Probably get the 80's up to 3200 I bet. I'm currently 2970 with the 80s in the Valkyrie in the AR, and 5/8" pretty consistently. I would love to see the 88s and 90s up to that speed in the "22 rush hammer DRT"(lol) and possibly a lot better accuracy.

 

[ES 350]

When i began this journey of better performance and brass (know a couple guys with Valkrie) , i really wanted to build a 22 Dasher.... finding a oversize bolt and barrel extension for AR15 was a dead end street barring machining my own...

Figured this was about as close as one could get with commonly available AR parts.

The Ruger was bought as a 6.5 Grendel and plan to use my reamer with proper size pilot bushing to see how much performace the added capacity gains.

22 BR is a pretty good comparison as far as capacity/performance.
I dont have a BR case to compare but have read it is 37.5 - 38 gr of H20 capacity.

The Norma brass from my chambers is at 37.5 after couple firings.

DRT is Dead Right There.... lol Hammer might be a better name... it hammers anything it hits and hammers accuracy wise.

I would think 80's @3200 is possible, i did a ladder with 75's in Ruger over the weekend with H4350 .... got up to 3340 fps.....

 

[ES 350]

Never been to Idaho, would love to see it some time!

"Most" western states have MANY pluses , wide open spaces for shooting long range is one of them!
I can shoot 1000 yd maybe a bit more behind the house in winter months , 900 yd is more convenient so is what i normally shoot.
Im thinking going to have to get some smaller targets than what i normally shoot or 900 will be pretty boring with the 88's.
The 80's was kinda boring at the 1000 yd range on the larger targets or any target under 800 yds. BUT.... shooting is better than working anyday!!!!!

 

[ES 350]

I'm toying with putting mine on a savage target action repeater. They have the trigger you can dial way down and look very solid. Only down side is that they are large shank only so if I ever wanted to switch barrels on it, they would have to be large shank. I have a 6.5 x 47 lapua with a criterion barrel and a regular savage action currently. Which is of course small shank. The accutrigger isn't bad at all. I also have a bighorn origin action with a Valkyrie barrel on it which is also the same size as the savage small shank and threading. It would be nice if all my rifles were interchangeable.

You ever get a 22 Grendel IMP put together?
I recently chambered up a spare 7 twist , this one a 28".
Doing load development it likes same loads as other 7 twist and hammers like all the other barrels cut with same reamer.