AR shooting 6mm

[tonysnoo]

Russ was very helpful getting me started down the fat rat road. He really knows the round well.

I found that the 87 Berger bullet liked the exact same CFE load as my 108s , but ended up about 140fps faster.


I am also reluctant to try and give a load for a straight 6mm ar since they obviously don't have the case capacity of a fat rat or a 6mm turbo40. I do however use the exact same 108 load in my fat rat as in my turbo40, not necessarily mag length. Ive only tried and run the 87s out of the rat. I have no reason to think they wouldn't work just the same in the turbo.

Two of my buddies...1rat ...1turbo...both shoot the same 108 load successfully. My rat buddy won't load anything but mag length and he has done the lions share of winning our local steel matches.

My suggestion would be a half grain less than your 105 load as a starting point for your 87 load test.

Good luck.

 

[SG4247]

It's hard enough getting good Grendel load data, and any wildcats based on it have even less info available as you fellows are well aware.

So, as another data point, would you guys care to share barrel lengths and MV with the 87 Berger?

I know the quantitative MV improvement the FATRAT and 40 Turbo provides over the 6AR.

I should be able to reliably interpolate that MV data to the 6AR and my barrel length.

I would expect very fast numbers with CFE, 87 grainers and the shoulder forward case mentioned. May be a real barrel burner.

If you guys provide this reference data point, I will know if light 87 grain bullets
are worth pursuing any further.

Thanks
Glenn

 

[Cakes]

I usually don't like to list "full power" powder charges but rather list a velocity that works for my particular load. I have two 6AR Turbo 40's, 8 twist & 24" 5R Bartlein & Krieger. All the 87's seem to prefer approximately 2920' and the 75's use H335 @ 3045'. I do fire-form with 87's and 27.3 of H4895 if that helps.I only use Tula SRM's. 90 Berger BT's also shoot very well but are more $$$. I also shoot a Hagar which seems to prefer 8208 with the 87's and 75's at approx. 175' faster and it would seem that the 6AR platform "should" also like 8208. I just need to wait until the highpower season is done to find time to play with it. Good Luck, Eric in DL

 

[tonysnoo]

So, as another data point, would you guys care to share barrel lengths and MV with the 87 Berger?


I would expect very fast numbers with CFE, 87 grainers and the shoulder forward case mentioned. May be a real barrel burner.

Thanks
Glenn

Hey Glen,

I run a 26" barrel on my newest fat rat. It has a shorter throat than my first fat rat. It runs coated 87s right around 3020 or coated 108s at 2860 with a little over 31 grains of CFE. My buddy's rat uses the same load on coated 108s with about 50fps less speed... so go figure

Other than fire forming my first barrel has 1500+ 105 - 108class bullets at around 2860-2890 fps through it. A bore scope inspection was quite surprising. There were no signs of heat checking at all.

Take care and good luck.

Ps take a look at the thread I linked in one of my earlier posts. There is a ton of rat data in it.

 

[SG4247]

Thank you guys very much! This is very helpful.

I really enjoy shooting the 6AR. Its very accurate with comfortable recoil, fairly simple to set up also.

I did not want to go thru the fire forming process with the FATRAT and T40, even though I knew there is a speed penalty with it.

I use the Redding 6AR die purchased from RW, and it will form the neck on new Lapua 6.5 Grendel brass in one operation on my press.

Glenn

 

[DJ111]

Glen,
Old post but was doing some load testing on a 6ar today.
20" barrel 1-8" twist.
87 vmax col 2.220
Hornady brass
CCI 450
29.5 grains 8208 xbr @ 2925 fps .24" 3 shot group @100

Might be a little hard on brass but it's a yote gun and I don't care.

 

[SG4247]

Thank you DJ,

Might load that down a little, and give it a try.

I have had primers blow out from Hornady Grendel Brass using 8208 in hot weather, so I know its a little tricky.

Appreciate the data!

Glenn