Grendel vie six8 recivers

[A5BLASTER]

AA2520, CFE223, H4895, and IMR4895 all look like good options for those bullets. QL predicts the four powders will reach max SAAMI pressure before compressing the load. IMR4895 should have the highest charge volume.

Sidenote what does quickload give as a min and max charge with cfe223 at the coal length I have listed for the A-tip and cci450 primers?

[centerfire]

Sidenote what does quickload give as a min and max charge with cfe223 at the coal length I have listed for the A-tip and cci450 primers?

A-Tip is not in QL because it is so new, I ran the model using 150SMK. Here is the QL prediction using my actual measured volume in water; I think QL over predicts pressure and velocity in this model. 2100fps to 2200fps looks reasonable but, as always, work up.

Cartridge : 6.5 Grendel (SAAMI)
Bullet : .264, 150, Sierra HPBT MatchK 1755
Useable Case Capaci: 29.113 grain H2O = 1.890 cm³
Cartridge O.A.L. L6: 2.368 inch = 60.15 mm
Barrel Length : 16.0 inch = 406.4 mm
Powder : Hodgdon CFE223 *C

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.0 90 26.33 1956 1275 38328 9136 90.8 1.211
-09.0 91 26.62 1980 1305 39598 9266 91.4 1.192
-08.0 92 26.91 2003 1336 40912 9394 92.0 1.173
-07.0 93 27.20 2027 1368 42275 9519 92.5 1.155
-06.0 94 27.50 2050 1400 43688 9642 93.0 1.138
-05.0 95 27.79 2074 1432 45152 9762 93.6 1.120 ! Near Maximum !
-04.0 96 28.08 2097 1465 46672 9880 94.1 1.103 ! Near Maximum !
-03.0 97 28.37 2121 1498 48248 9994 94.5 1.086 ! Near Maximum !
-02.0 98 28.67 2145 1532 49882 10106 95.0 1.069 ! Near Maximum !
-01.0 99 28.96 2169 1566 51580 10215 95.4 1.053 !DANGEROUS LOAD-DO NOT USE!
+00.0 100 29.25 2192 1601 53342 10320 95.9 1.037 !DANGEROUS LOAD-DO NOT USE!
+01.0 101 29.54 2216 1636 55175 10423 96.3 1.021 !DANGEROUS LOAD-DO NOT USE!
+02.0 102 29.84 2240 1672 57077 10521 96.6 1.005 !DANGEROUS LOAD-DO NOT USE!
+03.0 103 30.13 2264 1708 59057 10616 97.0 0.990 !DANGEROUS LOAD-DO NOT USE!
+04.0 104 30.42 2288 1744 61115 10707 97.4 0.975 !DANGEROUS LOAD-DO NOT USE!
+05.0 105 30.71 2312 1781 63257 10794 97.7 0.960 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 100 29.25 2313 1782 64635 10343 99.6 0.957 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 100 29.25 2037 1382 43480 9740 87.9 1.138

[A5BLASTER]

A-Tip is not in QL because it is so new, I ran the model using 150SMK. Here is the QL prediction using my actual measured volume in water; I think QL over predicts pressure and velocity in this model. 2100fps to 2200fps looks reasonable but, as always, work up.

Cartridge : 6.5 Grendel (SAAMI)
Bullet : .264, 150, Sierra HPBT MatchK 1755
Useable Case Capaci: 29.113 grain H2O = 1.890 cm³
Cartridge O.A.L. L6: 2.368 inch = 60.15 mm
Barrel Length : 16.0 inch = 406.4 mm
Powder : Hodgdon CFE223 *C

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.0 90 26.33 1956 1275 38328 9136 90.8 1.211
-09.0 91 26.62 1980 1305 39598 9266 91.4 1.192
-08.0 92 26.91 2003 1336 40912 9394 92.0 1.173
-07.0 93 27.20 2027 1368 42275 9519 92.5 1.155
-06.0 94 27.50 2050 1400 43688 9642 93.0 1.138
-05.0 95 27.79 2074 1432 45152 9762 93.6 1.120 ! Near Maximum !
-04.0 96 28.08 2097 1465 46672 9880 94.1 1.103 ! Near Maximum !
-03.0 97 28.37 2121 1498 48248 9994 94.5 1.086 ! Near Maximum !
-02.0 98 28.67 2145 1532 49882 10106 95.0 1.069 ! Near Maximum !
-01.0 99 28.96 2169 1566 51580 10215 95.4 1.053 !DANGEROUS LOAD-DO NOT USE!
+00.0 100 29.25 2192 1601 53342 10320 95.9 1.037 !DANGEROUS LOAD-DO NOT USE!
+01.0 101 29.54 2216 1636 55175 10423 96.3 1.021 !DANGEROUS LOAD-DO NOT USE!
+02.0 102 29.84 2240 1672 57077 10521 96.6 1.005 !DANGEROUS LOAD-DO NOT USE!
+03.0 103 30.13 2264 1708 59057 10616 97.0 0.990 !DANGEROUS LOAD-DO NOT USE!
+04.0 104 30.42 2288 1744 61115 10707 97.4 0.975 !DANGEROUS LOAD-DO NOT USE!
+05.0 105 30.71 2312 1781 63257 10794 97.7 0.960 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 100 29.25 2313 1782 64635 10343 99.6 0.957 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 100 29.25 2037 1382 43480 9740 87.9 1.138

Awesome thanks. I was planning on starting the lever and the cfe223 at 25 grains and working up in my normal fashion of .2 tenth increase, 5 rounds at each charge.

I typically work up like this until I find the velocity spike or dump and then look at my 5 round data under that to find my accuracy node and then adjust the seating depth.

The A-tip from best I could measure is right at 25 thousands less in the case then the smk.

I also was thinking from the 16 inch barrel I would probably end up in the 2150 to 2200 fps range.

Will be fun to try this out. Hopefully before deer season gets here.

[A5BLASTER]

Well bringing this back to life.

Ran into a problem and it's unfixable and kills this setup for me.

The mags work fine with factory ammo. The problem is the rifle will not feed with handloads at all.

The slight increase in case size on the resized cases makes the mag swell just enough that the rifle will not feed from the mags.

Got several loads worked out and can set the gas to lock the bolt back but nothing can get it to strip a second round if running handloads.

So guess I'm going to sell of the six8 recivers and mags. Don't want a rifle that can only run factory ammo.

[Daveycrockett]

Well that's a total bummer! Especially since most of us run hand loads probably. I'm wondering why the difference? How much of a difference is the resized case?

[A5BLASTER]

Well that's a total bummer! Especially since most of us run hand loads probably. I'm wondering why the difference? How much of a difference is the resized case?

Hardly nothing at all. But it is just enough increase too make it swell the mag and not feed.

It was a funny experiment and if I had a rifle I would only feed factory ammo, I would keep them but since I handload for all my rifles, this just ain't going to work and I will have to move them.

[Lastrites]

I for one really thought you were on to something and it's a shame it didn't work out for you. Not surprising that the 6.8 mag would pose a problem, needs a dedicated 6.5 mag for that receiver set and you would think someone would run down that rabbit hole.

[A5BLASTER]

I for one really thought you were on to something and it's a shame it didn't work out for you. Not surprising that the 6.8 mag would pose a problem, needs a dedicated 6.5 mag for that receiver set and you would think someone would run down that rabbit hole.

I guess it depends on how you look at it.

From a factory ammo only view it works great. If someone was wanting this type of setup and they didn't handload and only ran factory ammo. Then it would work great for them as it did me.

But since most folks handload as do I then yes it's a failure. I don't want to be hamstrung into only factory ammo. Granted my 16 inch AA barrel is a great pipe and shoots everything but sst's into small groups, I still don't want a factory ammo only setup.

I may sell them or I may put them away for a diffrent build someday.

I may when I have time take one of the mags and see if I can mill down the follower and bullet guides 5 to 10 thousands and see if that fix's the issue.

[kmon]

Haven't read the whole thread but A5 are you running polymer mags or steel mags? Reason I am asking is the Polymer mags tend to be thicker with a little less internal capacity than steel, at least in many instances. If not running Steel mags, your might give them a try if available before abandioning the project

[A5BLASTER]

Haven't read the whole thread but A5 are you running polymer mags or steel mags? Reason I am asking is the Polymer mags tend to be thicker with a little less internal capacity than steel, at least in many instances. If not running Steel mags, your might give them a try if available before abandioning the project

No one makes metal mags for the six8 revivers. Only mags that are made for it is the six8 pamgs.

Like I stated they work fine with factory ammo but the sized reloads are just a bit more then it can take.

Might take one out to the shop and see if I can mill off say 5 to 10 thousands from the running surface of the guide rails and see if that will allow enough room to let the sized cases of my reloads fees properly.

The guide rails aren't rounded like in normal mags, their running surface is flat. So it maybe possible to mill off just a hair from each one and relieve the pressure from my sized cases.

As to the internal capacity of the polymer mags, they and the magwell are designed to allow a coal length of 2.300.

[A5BLASTER]

So decided I wouldn't try modifying the mags.

I put in a order for a kit for a diffrent cartridge and will be building it up on these recivers when I get it in a couple of months.

Going to be fun comparing the two diffrent rounds.

[A5BLASTER]

So time for a update.

Been working my majic and modifiyed the mags to work with grendel handloads and still work with spc based cartridges.

Here is a pic of my 12 inch grendel sbr. Just got back from the range putting the finishing touches on the mag mods and also doing some ladder for the wildcat cartridge that shares this lower.

What I had to do is inside the mags, there is 6 this rails. 2 big ones and 4 small ones. The big rails has 1 per side up front and small rails are 2 each side in the back.

What I did was take my lil craft belt sanded that uses 1/2 wide sanding belts and sanded the small rails down to ruffly 5 thousands tall and the bigger guide rails up front it took them down till they just stopped touching the neck bullet section of a loaded round.

Once I did that it all but ended the mag swelling and handloads started working perfectly. So now they work with factory ammo and handloads plus still work just fine with my apc based wildcat round I'm working with.

I got my 12 inch barrel from BFT bout 2 weeks ago and as of today I'm at almost 3000 rounds down pipe.

And yes it's as badass as it looks, nothing like dumping 29 rounds of wolf fmj from a polymer mag on a steel man target at 200 like it's stupid easy.

One of these days I'm going to get it on film, just for the haters

[m796rider]

That's badass.

[A5BLASTER]

That's badass.

Thank you sir.

[VASCAR2]

A5 I assume this is the GB 12" barrel with 1:7.5 twist. Sounds like your liking this new 12" barrel can you give any accuracy reports. Has the barrel shown any preferences or does it shoot everything pretty decent?

[A5BLASTER]

A5 I assume this is the GB 12" barrel with 1:7.5 twist. Sounds like your liking this new 12" barrel can you give any accuracy reports. Has the barrel shown any preferences or does it shoot everything pretty decent?

Only real good test for groups I have done with it has been to see how my 120 gold dot load for my 12.5 did.

Velocity difference averaged 9 fps less, group sizes were a lil larger but still under moa. Didn't measure but between half to 3/4 moa

Wolf fmj shoot from the bags is 1.5 to 1.75 at 100. I can shoot almost as fast as I can pull the trigger and drop all 29 rounds on a steel plate that's 12 inch wide by 24 tall at 200 yards with a red dot.

Next full day at the range I will set some time to the side for shooting groups and taking pics. I will put the 1-6 pst gen2 back on for that.

[VASCAR2]

Looks like a great build and thanks for the info!

[Lastrites]

A5 you need to post a better of that lil black blasting beauty!

[A5BLASTER]

A5 you need to post a better of that lil black blasting beauty!

Next range trip I will see what I can do for pics. I really need to get it on vid.

[FRB6.5]

Nice! Hopefully Six8 and Magpul notice.