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Discussion Starter #1 (Edited)
Wildcat 6.5mm bullets in a 6.8 case-
Now that I have a few less irons in the fire I can get back to testing the SIX5. If you have any loads you have found to be accurate please post up if you care to share.
By trimming the 6.8 case back to 1.620-1.625 max the 123 Amax or SST can be loaded to the cannelure of a 41mm long 6.8 case and fit in the Magpul pmags or PRI 6.8 mags that allow loading to 2.31". Still there is enough full diameter bullet to properly align the bullet in the freebore.
IMO this combo fixes a few problems the Grendel/264 has.
We don't have problems with the weaker extractors.
The 6.8 bolts are stronger than the Grendel/264 bolts so they can run at a higher pressure.
Pmags or 6.8 mags that allow loading to a longer length and feed better than the Grendel mags.
More brass choices between Hornady, SSA, Federal, S&B, Nosler and Remington. IMO the Hornady and Federal will work better without neck turning.
6.8 bushing dies with a .288 bushing and trimming the case to 1.620" is all that is needed. A 6.8 or Grendel seating die will work fine.

With the case capacity being the same we are getting the same performance with 123 gr bullets and more with 100gr and lighter bullets. We aren't held to a 52,000 PSI max like the Grendel is.
The PRI mags allow loading to a COAL of 2.3" or 2.31" with that in mind and keeping the bullets .010-.020" off the lands for best accuracy.
The length of the case and freebore were designed to work best at 2.31-2.32 with the most popular bullets for a case this size. Bullets like Noslers Custom comp and Sierra's appear to touch the lands near 2.33". That makes me think they will shoot better loaded out to 2.31-2.32. Will test soon.

What I came up with allow most of the bullets below to have the full diameter body of the bullet outside the case mouth to properly align the bullet on the bore. The more I shoot this thing the more I like it. 16" barrel velocities are 100gr-2750-2800fps, 123gr bullets 2450-2500fps
Try these loads-they have been tested for accuracy using Hornady brass, Wolf magnum primers and all shoot under 1 MOA some under 1/2 MOA
100gr Barnes TTSX -OAL 2.3" 28gr 10x ---max load, do not use more than 28.5 10x--sub half MOA --most accurate load tested.
95Vmax 2.3" oal-28gr 10x
100gr Hornady Amax -OAL 2.3- 28.gr 10x ---max load
100 Nosler Partition-2.248oal-28gr 10x
120gr Barnes TSX--OAL 2.32-30gr AA2520---max load
120 Nosler BT-OAL 2.3-2.31"-30gr AA2520---max load
123gr Amax OAL 2.31-2.32-30gr AA2520---max load
123 Amax OAL 2.31-28.4gr Xterm
All 100 gr bullets work well with 28gr 10X
Drop 1/2-1 gr if using CCI magnum primers or Federal brass. All of those loads above are compressed but shoot very well.


16" production barrel. 123gr SST loaded to 2.3"-
----------------------32gr Lever, SSA brass, CCI 450 primer 2486fps. Max load due to fill no where near max pressure.
----------------------27gr AA2200--------------------------2512fps
----------------------28.5 8208-----------------------------2481fps
----------------------32.5 CFE------------------------------2541fps
100amax----------------32grH335-----------------------------2825fps
100Amax----------------29grAA2200--------------------------2805fps

CFE and Lever work with the 100gr bullets but is slower than the 2200, 1200R and H335.
The 100 gr Amax bullets when zeroed at 300 fly flatter and have less deflection than the 123 Amax.
The top 6 bullets should show the best performance, bullets touch the lands at:
123 Amax ------------2.325
123 SST--------------2.318"
100 NBT----------------2.328
100TTSX---------------2.325
120TSX----------------2.305
120NBT----------------2.288
100Amax---------------2.295

123SMK----------------2.385
123 lapua---------------2.360
100 & 108 Lapua------2.390

All loads should be considered max. Start 1-2 grains lower and work up while looking for accuracy.

123gr Hornady A-Max, SSA Brass, CCI 450 primer, 2.295" COAL
IMR-8208 28.5gr = 2401fps (56,400psi)
AA-2520 30.0gr = 2456fps (57,800psi)
AA-2200 26.0gr = 2410fps (58,200psi)
VV-N530 27.5gr = 2475fps (57,500psi)
Hodg. CFE 32.0gr = 2493fps (54,500psi) --- Max fill
X-Term. 29.5gr = 2508fps (59,422psi)

100gr Hornady A-Max, SSA Brass, CCI 450 primer, 2.295" COAL
VV-N530 29.5gr = 2788fps (59,700psi) --- 29.0gr MAX
IMR-8208 29.8gr = 2684fps (56,669psi) --- Max fill
Norma N200 27.5gr = 2738fps (59,460psi)
Alliant RL-7 26.5gr = 2705fps (58,200psi)
AA-2200 28.0gr = 2720fps (59,730psi)
Alliant 10X 28.0gr = 2763fps (57,500psi)
H-335 31.0gr = 2747fps (56,100psi)
Hodg. CFE 33.0gr = 2697fps (52,000psi) --- Max fill
X-Term. 31.5gr = 2775fps (56,388psi)

Tried h335 and 2200 & 100gr bullets again with no luck.
28.5 gr 10x with 100 ttsx, nosler and amax. All 3 bullet types with that load shot under 1/2" at 100. The best load I have found for 100gr bullets is 28.5gr 10x, best load for 120 gr bullets 30gr 2520.
I think the following bullets will work best because of the load lengths. The load lengths shown is where I found the best accuracy.
100 Nosler BT-2.32
100 Amax-2.32
100 TTSX-2.31"
120 Sierra Prohunter
100 Sierra Varminter
85 Sierra Varminter
95 Vmax
90 TNT
120 Nosler BT-2.3
120 TSX-2.31
The Hornady 123 Amax and SST can be accurate but from what I have seen they need to be loaded to 2.32 or 2.325 to get the best accuracy.
Any bullets with a longer ogive than the 123 Amax like the ones below will need to be loaded to a longer OAL to get accuracy.
123 Amax -2.325
123 SST-2.32
123 Nosler CC
120 Sierra HPBT
107 SMK
100 Lapua
108 Lapua
123 SMK
123 Lapua
 

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Got a couple good ones going.
120 NBT, Hornady brass, CCI 450, 27.5 gr 8208 xbr, OAL 2.30", 2400 fps. Accurate load when tested several times.
123 Amax, SSA brass, CCI 41, 29.1 gr 8208 xbr, OAL 2.30", 2500 fps. Was shooting fist sized groups at 300 yds.
Working on some long loads now. 123 SST isn't touching lands till 2.38". Tested with Lever loaded to 2.36" I am getting 2600+ fps with good pressure. Got 130 AR hybrids on the way to load long. Also picked up 2 lbs of TAC to try as well. I would love to see this chambering in an 18" or 20".

As always, what works in my barrel may not work in others. Work up slow and watch for pressure.
 

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Got a couple good ones going.
120 NBT, Hornady brass, CCI 450, 27.5 gr 8208 xbr, OAL 2.30", 2400 fps. Accurate load when tested several times.
123 Amax, SSA brass, CCI 41, 29.1 gr 8208 xbr, OAL 2.30", 2500 fps. Was shooting fist sized groups at 300 yds.
Working on some long loads now. 123 SST isn't touching lands till 2.38". Tested with Lever loaded to 2.36" I am getting 2600+ fps with good pressure. Got 130 AR hybrids on the way to load long. Also picked up 2 lbs of TAC to try as well. I would love to see this chambering in an 18" or 20".

As always, what works in my barrel may not work in others. Work up slow and watch for pressure.
VERY interested in your upcoming report on the AR Hybrids and TAC powder.

I'm guessing the Hybrid bullet will still be too long out-of-case, which I see you noted ("loading long").

I'm headed out of town for a few days, but now that the rifle is done, I plan on starting load development with TAC. (I have a lot of it...). I hope in the next couple weeks to have data to report.
 

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Some 100 yard testing with 100 gr NBT. Using fresh made SSA brass ( not fire formed or neck turned yet ). Loaded long with cut mags. First is H-335, CCI 450, COAL 2.355"



Next is CFE 223, CCI 450, COAL 2.355"



Definitely some accuracy there. Did not chrono. Just fire forming some brass so I can play with the 130 Bergers loaded long. Also coming up will be 120 NBT in Hornady brass loaded with TAC (mag length).
 

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tbready, I must say you are getting better results than I am. Tried your 120 NBT and 8208; had to drop down by a 1/10 for it to close up. Using Federal brass and federal primers by the way. Keep up the good work. Intrested in the 130 Berger results.
 

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tbready, I must say you are getting better results than I am. Tried your 120 NBT and 8208; had to drop down by a 1/10 for it to close up. Using Federal brass and federal primers by the way. Keep up the good work. Intrested in the 130 Berger results.
Did you get a better trigger yet? I'm running a Geissele SSA, want to change it to a SSA-E.
 

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tbready, I must say you are getting better results than I am. Tried your 120 NBT and 8208; had to drop down by a 1/10 for it to close up. Using Federal brass and federal primers by the way. Keep up the good work. Intrested in the 130 Berger results.
Using Federal pulled brass with the Fed AR primers I've noticed a much lower velocity compared to the same brass and powder load but with Wolf SRM primers.
 

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As far as I'm concerned, SSA and S&B are probably going to the best brass option as far as raw performance goes. I wanted to try Nosler brass but I don't think that is happening anytime soon. Hornady does really well in the accuracy dept. but I can not match my speeds using SSA. From here on out I'm sticking with 120-130 gr. because the numbers are phenominal in the 16" barrel. I just built an upper for a buddy that runs the local 1500 yard range. He is very excited especially with the weight of it using a 13" BCM KMR. He is a Grendel man and this cat has him excited.
 

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Did you get a better trigger yet? I'm running a Geissele SSA, want to change it to a SSA-E.
Yes I did. I have a Hipertouch 24E in it. like it so much I bought a second and may buy a third and fourth!

The Federal brass I am shooting is the pulled brass from RMR. Using Wolf 223 primers for the second go around.
 

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Berger 130's touch the lands at 2.41" COAL. Just finished cutting out the magwell to get a longer COAL. I'm gonna be able to get these loaded right to the lands now. Results this weekend.
 

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Discussion Starter #12
Berger 130's touch the lands at 2.41" COAL. Just finished cutting out the magwell to get a longer COAL. I'm gonna be able to get these loaded right to the lands now. Results this weekend.
I never thought a Berger would work in it. I based the design on the 123 Amax and made the decision based on LWRC saying we could load to 2.32" using the magpul mags. I shouldn't have done anything until I had a mag in my hand because we can only load to 2.3. That hurt the accuracy and ability to use some bullets unless the front of the mags are cut. The 120 Nosler and 120 Sierra produced good accuracy but they are not what I wanted to shoot. The Amax doing 3/4" isn't want I wanted either...good enough to hunt with but I still need to do some more work with that one.
Good luck with the 130s
 

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Bergers' twist rate calc. is giving me a 1.66 SG @2400 fps. Applied Ballistics app is is giving it 1000 ft/lbs out to 800 yds using G7 drag model.
 

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Here's the Berger 130's (OCW test) @ 2.40" COAL with Lever. 31.6 gr looks good (just over an inch) running just over 2500 fps. Getting warm. COAL adjustment may tighten it up a bit. Not done with this load yet. Going to step it down and run a OCW from 30-31gr.

 

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130 Berger AR Hybrids @ 2500 fps, COAL: 2.40", 600' asl, 1369.7 fps, 541.6 ft-lbs, 7.3 mils, "900 yards" Applied Ballistics G7 drag model. Still above transonic. 120 NBT and Tac at mag length tomorrow. Loaded some up from 27-28gr of Tac and speed and pressure were low. Loading some tonight with 28-29gr. Speed at 28gr was 2360 fps and pressure wasn't even close to pushing it. Were's everybody at? I know I'm not the only one loading for this cat.
 

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130 Berger AR Hybrid. Loaded to 2.40" with a speed of 2500 fps @ 600' asl, Applied Ballistics G7 drag model is giving me a result of 1869.4 fps, 1008.9 ft-lbs and 5.7 mils up at 900 yds. Damn!! 120 NBT and Tac at mag length tomorrow. Loaded some up from 27-28gr of Tac and speed and pressure were low. Loading some tonight with 28-29gr. Speed at 28gr was 2360 fps and pressure wasn't even close to pushing it. Were's everybody at? I know I'm not the only one loading for this cat.
I think you have some settings wrong in your ballistic calculator. With those numbers I'm showing 939fps and 391 ft/lbs at 900yds with a 14.6 mil correction.

Bad numbers - ignore.
 

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I think you have some settings wrong in your ballistic calculator. With those numbers I'm showing 939fps and 391 ft/lbs at 900yds with a 14.6 mil correction.
Which drag model? I've been through my settings a dozen times and can't find anything wrong. The G1 shows similar to what you are stating but these bullets do not follow a G1 model.
 

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Which drag model? I've been through my settings a dozen times and can't find anything wrong. The G1 shows similar to what you are stating but these bullets do not follow a G1 model.
I went back and did have an error with what I input, but it still doesn't work out to the same numbers. Using a .560 G1 shows 1260fps/458ftlbs, .287 G7 shows 1242fps/445ftlbs. That's using JBM Ballistics which has been fairly accurate compared to my real world results. I ran the numbers on Hornady's calculator with very similar outputs.
 

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I'll go through it again. Your numbers sound about right. Was scratching my head with what AB is giving me but I can't find anything wrong with the data.

Update: seems like the Applied Ballistics app is still screwed up from months ago. Calculations seem to bevall over the place.
 

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I'd love if your numbers were right, but they we're better than what my 6.5-284 does with a heavier, higher b/c bullet and a lot more speed.
 
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