6mm RAT powders for NRA HP

[NateG]

"I need to fire form some more brass for the RAT before I shoot it in a match, I just don't want to fire form that brass in rapids."

Why not? It works just fine. (Just set up the for normal resizing, and run with it) Heck, I shot fire-forming loads on the 200 yard line at Perry last year when my RAT upper was new and I didn't have enough brass formed yet.

 

[dfry]

I have thought about it Nate, just a little concerned since I wasn't quite sure if I had the false shoulder down pat where it should be. I had one round during testing that the case was not quite fireformed all the way and it failed to fire on the first hit. I'm sure the shoulder was just not quite enough forward and there was a little to much headspace left. I have not had that problem while fire forming because of the false shoulder holding the case back well. Your right, should be fine, Dave

 

[NateG]

One you have your die set up to bump the shoulder .00X (I think I'm about .003, but don't remember), that runs just fine for fireforming, too.

 

[spclark]

0.003" bump works for me too; annealing helps with consistency here and for good results when fire-forming. I had bad luck trying to f'form when points were at stake (changing to a new buffer spring after a couple matches didn't help) so now do that only at practice.

Curiously, f'forming works great @ 600 yards! I do it mostly in offhand now when I want to form up new cases but after a season's shooting I don't see much need for that.

Some folks report pressure issues with their 6RAT; I'm a believer when it comes to neck turning though, which might account for the few instances I've seen with my upper.

On an off-topic note, if the factory brass for 6HAGAR becomes a reality soon (last word I got is very positive!) I'll be using it over my 6RAT for 2012.

 

[jscandale]

I do the same thing (fire forming with a false shoulder) with a similar cartridge and have done it with other wildcats and fire forming during rapids works great while the accuracy does not indicate that the fire forming effects it one bit. The only drawback is that you can't get the same case capacity as the formed case, but who cares, it's rapids. The formed cases are needed for the case capacity for the 600 yard brass.

JS

 

[dfry]

yep it worked fine, set it up with about .003 shoulder bump and also sized new cases, they shot fine. Looks like I am going to have to replace the buffer spring, I got the failure to lock back in slow prone on a few shots like several others have experienced with this round. I don't have this problem with the 6WOA on the same lower, but I'll change the spring to see if that fixes it. The AR-Comp shot great, standing was just terrible with the 15+ mph wind gusting over 20, the hard blowing wasn't as bad as the sudden left offs, had several people cross firing due to the sudden drops in wind. I has some sight adjustment issues but I was able to correct those with the sighters. Shot a 195 in slow prone, a little under my average, but with the wind, I was still happy. Dave

 

[GWY]

I just wanted to thank everyone for sharing their experiences with the 6mm RAT. This thread has been very insightful and interesting as there is not alot of published information on this cartridge.

I've been shooting a 6mm RAT for alittle over a year and have 2 complete spaceguns chambered for it. Both have 26" Krieger 7.5 twist barrels. I'm using H4895 with Remington 7.5s and 90 Berger BTs for 200 and 107 SMKs for 300 and 600. Accuracy has been superb. A few notes;

1) I experienced function issues and like many on this thread solved it with new buffer springs (Tubbs flat wire)

2) My initial experience led me to think the RAT's chambering in the neck might be tight (an unfired bullet would not slide easily down a fired case's neck, it had to be pushed in). I chalked it up to brass springback, but after reading this thread, my initial suspicions may have been correct.

3) I made the same initial mistake as a previous poster in thinking the RAT was the ballestic equal of the 6mm AR Turbo 40 Degree Improved and got into pressure problems and had to reduce my loads. I think ballestically, the RAT is somewhere between the 6mm AR and the 6mm AR Turbo. The only references I could find on case water capacity listed the 6mm AR at 36, the 6mm RAT at 36.7-37, the 6mm AR Turbo at 37, and the 6mm AR Turbo 40 Degree Improved at 37.5-38.

My 107 SMKs move around 2750fps. I never have been able to get more velocity without excessive pressure signs and problems in either of my RAT rifles, but the accuracy is so good, I felt no need to be greedy on velocity. Overall, I am very pleased with the RAT, although like many on this thread, minor issues had to be tweaked.

Thanks again to everyone for sharing your experiences.

GWY

 

[dfry]

Hey Gary, glad you chimed in, I agree, case capacity wise the RAT is on par with the 6 Turbo and not the 40 degree turbo. Also, agree with Steve that the necks are a little thick and for top pressure loads, neck turning may be a good idea. My AR Comp loads so far do not seem to be over pressure.

Iwill say that AR Comp is also a little dirty about like Varget or RL15. I still need to test more with H4895 to see which is more accurate in my rifle. I also want to turn a few necks just to see what the results may be,

Merry Christmas all,,,,,,,


And its Merry Christmas, not happy holidays,,,,,Geez

 

[Rtheurer]

All

Those of you shooting the 6mmRAT or Fat Rat. what primer have you gone with for your Short Line loads?

I haved alot of CCI 450's

Great thread fellas, awaiting delivery sometime in the new year.

RussT
Merry Christmas to all.

 

[spclark]

I'm using up a variety of SR primers for fire-forming at offhand; most anything works fine here. For everything else I've settled on the Wolf / Tula KVB-223 REM product. Works great in Lapua Palma brass too....

 

[dfry]

I have been using Wolf SRM primers, I know Gary is using Remington 7 1/2s for at the least short lines. I have a lot of those also so I may test those and use them up on short line also. The wolf shoot great and when I buy more primers I will still use those, they are really economical also! My rapid prone at the last match (my first time out with the RAT at a match, shot at 200 on the reduced target) was a 197, the 3 points was on the first string and was me, the second string was a 100 with like 4 Xs and very tight. Anytime I shoot a 100 with some Xs on that target I know the group is tight (that target is tough to me anyway), so the AR Comp and Wolf are a great combo. Seems that the RAT is not very picky about primers to me, Dave

 

[Rtheurer]

With a new match upper in Fat Rat on the way I was wondering if anyone has shot the 87gr BTHP from Hornady for 200yds or fireforming. There about the cheapest Match bullet I could find, and I have seen them shoot bug holes in a friends 240NMC bolt gun.
Any thoughts on this bullet and maybe a good powder choice?

RussT

 

[NateG]

You knew I was going to suggest 8208...

By the way... where'd you get the fat-rat from? And how does it differ from the RAT? (a couple extra thousandths in the neck, perhaps?)

 

[Rtheurer]

Indeed I have a 8lb jug of it. Have you had a chance to play with the 87gr Hornady? Any thoughts?

Im getting it from Lee Wells of Accurate and reliable and you are correct the neck is bigger. ( .276 ) It should arrive around Friday.

RussT

 

[dfry]

Since we don't have a 300 yd. line anymore at my range and shoot the 300 reduced at 200, the Hornady 87 BTHP is what I shoot on shortline.
I just shoot my 600 yd. load for shortline but you can go up in charge if you want, but they just hammer with the 87s. I shoot them in
my 6mm WOA also, they are cheap, can take a lot of jump and have been very accurate for me (with Varget, H4895, 8208, AR-Comp), Dave

 

[NateG]

Indeed I have a 8lb jug of it. Have you had a chance to play with the 87gr Hornady? Any thoughts?

I've been using the 80FB Berger at 200 or less, (Whether OH/SR or the prone stages at reduced distances) but the 90 Berger at 300. For either one, I just use my 600 charge (28.0 8208) under the 80 or the 90. With the slightly more generous chamber, you might get a bit higher under the 105s, but 28.0 was mild under the 90s, and probably a nice spot for the 87s, I'd guess. (2900 fps, though--2800 with the 105, 2900 with the 90, and 3000 with the 80s from the same charge)

 

[Michaël T]

I have received mine(6mm Fat Rat) today and it looks just like Lee said it would, great gentleman to deal with.
now put it together and wait for warmer weather Hi of 38 deg. )
all posting here were very helpfull but have not made a decision yet on powder and bullets.
i have 32#'s of RL 15

 

[dfry]

If you have 32 lbs of RL15, that's an easy decision, start there!

 

[Rtheurer]

Mine has arrived as Well. ;D

Release the Houndsssssssssssssss. let the testing begin.

 

[Michaël T]

i will have to wait till late Feb for testing.
Russ did you buy a complete upper?
i just bought the barrel and accessories