6mm RAT powders for NRA HP

[Rtheurer]

I have some more Data on the 6mm Fat RAT. For some reason we are not able to get all the velocity some other folks have been getting, maybe do in part to the 26” barrel vs some 28” barrels folks are using.
Tried the 87gr Berger hunting bullet at Mag Length for the heck of it and low and behold this is going to be my 300 yard match load with either Varget or R15. Both powders shot real well. Vertical in the .2’s in a five shot group.
Varget got the velocity up to 3042fps but the accuracy node for my rifle was at 2952fps. Same for R15 witch reached 3028fps but the accuracy node for my rifle was at 2964 shooting into the .2’s here as well. A Quarter minute gun for 300 yard rapid fire is awesome. We will see if it holds up this summer when I really ring it out.
Also tested where the 105gr Berger hybrid’s R17 showed some promise early then sucked at 600 yards while shooting a string of ten showing a vertical around 10” …. Yuk. Here R15 and Varget again proved consistent in my rifle and shot a wide charge ratio well. Pretty wide node powder wise and jumping them .020 off the lands. Both powders performing well at the top end of the pressure for this rifle. Accuracy node at 2796fps with Varget and 2778fps with R15. Again slower than a lot of folks are posting but if they go into less than a ½ MOA at 600 yards I am happy. Quick Load is showing a 97% fill with Varget and 105vld’s .010 in the lands. 101% with Varget and 87gr VLD hunting bullets at Mag length. (2.230”)
Russ T

 

[NateG]

"Accuracy node at 2796fps with Varget"

That's *exactly* where my space gun shot best with 105VLDs and 8208--also with a 26" tube.

 

[dfry]

Gary, I just wanted to follow up on neck clearance of the brass in the regular RAT chamber. Also, I am talking about sling or F class shooting here with ARs, not benchrest or bolt guns. Looking at the neck on the RAT chamber of .274, the bullet diameter of .243 and the brass neck thickness on my AA Lapua brass with a thickness of .014-.015 after forming, you end up with a neck of .271-.273. Much to tight for high power, and absolutely to tight for an AR IMHO. The mouths of my brass are so tight it is very difficult to push a bullet in the fired brass, and yes, it is trimmed to minimun. I discussed this with German Salazar, and he agrees that is too tight, .004-.006 is the prefered range for clearance on an AR from what I've seen. So, I am turning my necks down to .013 or .012 to give me at least .004 clearance (actually at .012 getting .267 loaded necks, .243+(.012x2)=.267). I know, I'm sure there are people who will not agree with me on this, but having only .001-.003 clearance in an AR will bite you sooner than later. I really wasn't to happy with having to turn brass in a xcourse gun, but really with power it hasn't been a big deal. I think a .276 neck would be much better in the RAT and would solve some of the pressure issues people are having. It is noted that this is the same issue I was having in the 6WOA with SSA brass and why I stuck with R-P brass so I wouldn't have to turn necks. Straight SSA brass with unturned necks was giving me all sorts of pressure issues. But what the heck, even though I haven't shot much of the turned brass yet, it does seem to at least give me a little better X count, and I'll take any X that I can get! Also, as Steve has said, he has seen better accuracy in the Hagar and RAT with .011 neck thickness, Dave

 

[jscandale]

Dave,

You have touched on a subject that several folks have had concerns about with regard to neck clearance. You are correct in stating that the AR needs about .002-.003" per side in order to be worry free. I have opened up a few necks for folks with a .276" neck reamer.

JS

 

[Rtheurer]

Got Some more Data today.
CFE 223 was tested in the 6mm FAT RAT. I have two solid loads with R15,and Varget in a short range 200 and 300 yard load and a 600 yard load. Bullet seating depth was kept the same, as was the primer, brass and neck tension for the CFE223 test.
At 30.0 and 30.5grains of CFE223 the 105gr hybrid reached 2772fps and 2790fps which got it into the same sweet spot as Varget and R15. Brass showed no pressure signs what so ever. The R15 and Varget loads are on the upper end of pressure at that speed with the 105 bullet. Accuarcy was in the 3/8 MOA and below.

87gr Berger VLD Hunting bullet at magazine Length. Yep this little darling has been showing some great promise with just about every powder choice. Im really excited to see it is working so well at mag length ( 2.230)
Again some steller ( for a Gas Gun) results have been found with R15 and Varget with this bullet. It can be pushed over 3000fps pretty easy. My rifle likes it at 2970 to 2997fps depending on the powder used.
CFE223 shot well at 30.0 gr to 30.6 grains all under .500 with no signs of over pressure again.

So what I am seeing with this powder is that my ammo could be charged with 30.5gr of CFE223 powder and seat either a 105gr bullet for 600 yards or the 87gr Hunting bullet at Mag length and be well inside the X ring. Might be a great choice for a progressive set up?

It will get some testing in a Match Format to see if it all holds together. Ill keep you posted.

RussT

 

[Michaël T]

Hi Russ,
at which distance is your tesing done?


Michael

 

[Rtheurer]

Load testing is all done at 100 yards first with the chronograph and then a good load is selected and tested agian at 100 and then it goes to the actual yard line for which it is intended to shoot. 105's are shot at 600 and the 87gr Berger VLD at 200 and 300yards.

If I had my own range I would just test at distance right off the bat. Sigh..... But no such luck, and I didnt win the LOTTO.

RT

 

[spclark]

That's pretty much my practice too: vary load to determine grouping while also getting an idea of velocity / SD @ 100 yards. Pick what I believe has potential & load up enough for a match.

Sometimes I'll do a second series with a good load but varying seating depth. Over the last couple years I've found a 0.020" jump seems to work well with just about every bullet meant for 600 yards or beyond in all of my rifles.

 

[Michaël T]

Russ and Steve
thanks guys,

i am off to the range to test my fat rat.
report tonite or tommorrow if ya'll are interested.

Michael

 

[Michaël T]

i went to the range but found it closed due to fire(Mc.Miller sports park in Eagle wisconsin).
got home and cleared some property for 100 yards and 200.
finally i shot my fat rat with 95 smk @mag length(2.25) 2782 ft/s grouped 0.600" vertical
107 smk's(2722 ft/s) at mag length grouped 1.1" vertical and my 107smk's(2722 ft/s) seated 0.020" of lands grouped 0.25" vertical
load data was 28.3 of 8208
AA brass fireforming with BR4
used Oehler 35p for speed check.
later i will try 28.8 with 95 at mag.length and 107's with 0.020" jump .
tomorrow 200 yards

 

[dfry]

Shot 95 SMKs mag length today in the RAT benched, maybe it is just me since I don't shot the match rifle benched that well, and I have a hard time seeing the 100 yd reduced target, but they shot over an inch. 90 Bergers, 15 rounds rapid fire were 1/2", the new 105 BTHP Hornady shot about 1/2", iron sights, Dave

 

[Rtheurer]

Dave
It looks like your in the same boat as me. I really really wanted to shoot the 95gr SMK and the 107gr SMK in the Fat Rat. But testing has showed that it is always the looser of the bullet selection. I plan on shooting this thing in mass volume soon and with The sierra plant but a half day dirve for me, I can pick up seconds for pretty cheap on my way to a match. Of course my rifle likes the most expensive bullets out there... but boy does it like them. As mentioned above the 87gr VLD Hunting bullet at Mag Length jumping a pretty good amount is the clear winner for my rifle. The 90's looked good but not as good. Nate is a true believer of the 90's and that should be a great combo. Rumor has it, Berger is working on a mid weight 6mm bullet and that may be the cats butt for 300 on down when and if it ever shows up.

CFE223 was tested today at 300 yards. Looks like another winner edging up on the r15 load and edging Varget by a little bit. Ten shot groups at 300 look real good. My rifle ( do your own work up please) likes 31.5 and now 32gr of CFE223 with no pressure signs. I think it cold go a little more as well putting it just shy of 3000fps with the 87's. As it stands with 31.5 is at 2942fps

900 rounds on the gun now and have not shot a single Match with it!!! Got a hell of a spread sheet though!
I take that back two 600 yard matches have been shot with it.

RussT

 

[dfry]

Ha! I hear that on the spread sheet! The 90s have always shot well for me mag length, just don't need them that much since my home range shoots 300 reduced at 200. Yeah I was hoping the 95 SMKs would shoot at mag length, they shoot well seated out but I can't drive them fast enough to out shoot the 107s and 108s. I would still like to try the hybrids to see how they do. I will also probably shoot the 105 BTHPs in a match in a few weeks to see what happens. The 87 BTHP still shoot great for me and are cheap to boot! So I think I'm set, now, if I can just get my off hand back!

I really wish Sierra would have made a 90s gr. bullet with a good BC for mag length when they came out with the 95. They just don't have a good BC 300 yd. bullet. Oh, by the way, I know Gary Yuen shoots the 107 mag length at 300 with good results. I haven't tried it yet though,
Dave

 

[spclark]

i went to the range but found it closed due to fire(Mc.Miller sports park in Eagle wisconsin).

There's a shooting range near Eagle? Never knew that! What kinda facilities? Open to non-members? Eagle's not much farther than Bristol / KCCC for me but they're only open Friday afternoon & weekends, no holidays.

 

[Michaël T]

yes open to the public no membership and hey go out to 300 yards and every range has a range officer the place is always packed owned by the state but operated by civilian company.
i am shooting the match next week sunday at bristol.
i now have a 300 yards range at the house where i rent.

 

[Michaël T]

so i shot at 100 yards:
load:AA fireformed brass BR4/30.0 RL15
95 smk @2.26 (mag)vertical 0.623" speed:2782 es =34fps
107smk@0.025 jump vertical 0.780 speed: 2722 es=22
107smk @2.26(mag) vertical 1.409 speed:2722fps es=41

At 200 yards
95smk@2.29 vertical (1.136/2.2=0.516moa) speed:2863 es= 22 fps same load as above
107smk@0.005 jump (0.531/2.2=0.241moa) speed:2840 es=24 same case prep but 30.3RL 15
no press issues
warning: the oehler 35p was left at the same distance , i cannot explain the 100 fps increase, can you?

 

[spclark]

Hmmm.... All 3 sensors properly aligned? Shades on? Any shadows from overhead baffles? Those play hob with my 35p @ Bristol with the newest one they put in last year right in front of the firing line.

I'd have expected more of a spread between the 95's & the 107's for loads that similar, but then I can't recall exactly where mine was pegging from year before last. I never got the 107 SMK to shoot as good as Berger's 105VLD either.

 

[Michaël T]

the 95 smk's were shot with 30.0 grains RL15 and the 107's with 30.3
i expected to more speed from the 95's

 

[bpm990d]

Have yet to get the chronograph to work. Brought it to the range Friday but forgot the tripods.

6mmRAT by WOP & a heavybuffer.com AR10 buffer. Substantially heavier than standard.

28 gr. ARCOMP dumped with Redding BR measure
AA Grendel brass - fireformed (second firing)
Rem 7 1/2
Sierra 107s and Hornady 105 HPBT last match

600 yard MRP match - bright sun, wind gusting from 7-8 O'clock to 7 mph with some direction changes. Mirage was running pretty good. 75 degrees ambient but hot in the sun.

match 1.....194-8X
match 2.....199-9X
match 3.....197-8X

I think the Hornady's shot better but the score was a little lower. Primers were a little flatter with the Hornady bullets. Same exact zero as 107s, first shot with them was a dead nutz X.

Same load will function the rifle with Sierra 95 HPBTs for rapid fire.

HTH,

B

 

[Rtheurer]

B

Looks like you have a winner combo with the Hornady AMP 105gr bullets. Ussually as the day goes on its harder in wind conditions so I can see what you mean.

My rifle finally has a match under its belt as well. My buddy Doug shot a match with it unfortunatly the wind reared its uggley head as tornado's ripped across the middle part of the country. I was watching the weather on the internet via NOAA web site. It started at 12mph and worked its way up to 20-24mph by the time they where done. Doug managed a 780-15X in some real tough conditions. Fireforming brass at 200 yards, and shooting the CFE223/87gr Berger VLDS at 300yds. He said he shot an X ring group on each side of the X ring at 300yds. loosing 3 points total.
Then at 600 everyone got destroyed with a fishtail 20mph wind at 6:00... Yet the 6mm Fat Rat came out on top, he was clean in his first ten and then dropped 3 in a row... while the 6XC in a Tubb 2000 where shooting 8's and 9's in the hands of another High Master shooter.
600 yard load is 29.7gr Varget with a Berger 105gr Hybrid jumping .020. CCI 450 primer and Alaxander (lapua)brass.
Three diffrent powders, three diffrent bullets at three separate yard lines.= 780/800 got to love that.