69gr Nosler BTHP + Ramshot Tac loads/experience?

As the title suggests, I am curious to hear about peoples experience with 69gr Nosler BTHP loaded with Ramshot Tac, particularly out of a 5.56 chamber.

In the past I have had a lot of cases not fully seal my chamber when loading to max 223 specs, resulting in carbon on the sidewalls of my cases. So I am going to be cooking all my loads at the upper end of 5.56 loads so long as accuracy and pressure signs are permitting.


Planning on shooting ladder loads in .5 increments from 23gr of tac to 25.5, using CCI450 primers seated to mag length. Once I find the best accuracy load with no pressure signs or non fully sealing signs in that range, I will tinker with things like seating depth.

I would suggest a smaller increment between the charges, something like 3/10's would be better as pressure is sure to be much higher as you approach your rifles maximum. Secondly i think the suggested maximum you have mentioned might be a bit extreme... YMM and no I haven't check manufacturers recommendations for that powder.

Note the difference between a .223 chamber and a 5.56 chamber is not the case body portion, but rather the throat.

Quote:

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Originally Posted by 308sako

I would suggest a smaller increment between the charges, something like 3/10's would be better as pressure is sure to be much higher as you approach your rifles maximum. Secondly i think the suggested maximum you have mentioned might be a bit extreme... YMM and no I haven't check manufacturers recommendations for that powder.

Note the difference between a .223 chamber and a 5.56 chamber is not the case body portion, but rather the throat.

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Here is Ramshots load data for Tac with a 24'' barrel

http://www.ramshot.com/wp-content/up...2016_Web-1.pdf



5.56

RAMSHOT TAC
49 LHG B-L 25.0 3,294 27.8 3,589 61,076 2.220 C
50 NOSLER B-TIP 25.9 3,288 28.7 3,588 61,289 2.260 C
55 HDY BT-FMJ 24.5 3,159 27.3 3,450 61,335 2.200
62 MIL M855 23.6 2,940 26.2 3,219 62,350 2.260
62 BARNES TSX-BT 24.1 2,965 26.7 3,244 61,196 2.255 C
65 SIERRA SBT 23.7 2,922 26.3 3,184 62,202 2.210
68 HDY BTHP-M 23.4 2,851 26.0 3,133 61,995 2.250 C
69 SIERRA HPBT 22.9 2,775 25.4 3,049 61,607 2.260
70 BARNES TSX-BT 23.1 2,796 25.6 3,037 61,273 2.260 C
75 HDY BTHP-M 23.2 2,738 25.8 2,994 62,145 2.260 C
77 SIERRA HPBT MK 22.3 2,648 24.8 2,902 61,500 2.260
80 SIERRA HPBT MK 23.2 2,638 25.8 2,903 61,307 2.260 C
90 SIERRA HPBT 21.8 2,436 24.2 2,688 61,794 2.260 C



223

RAMSHOT TAC
34 MSS VNX 27.4 3,636 30.4 3,974 54,960 2.125 C
35 NOSLER BTLF 25.8 3,529 28.7 3,862 54,633 2.260 C
40 BERGER FBV 24.6 3,389 27.3 3,704 54,170 2.216
40 HDY V-MAX 24.9 3,419 27.7 3,737 54,760 2.260
40 NOSLER B-Tip 25.2 3,405 28.0 3,721 54,390 2.260
40 SIERRA BK 24.8 3,399 27.6 3,715 53,940 2.260
40 NOSLER BTLF 24.8 3,310 27.5 3,667 54,799 2.260 C
42 SF WTP 25.6 3,331 28.4 3,648 53,846 2.200 C
45 SIERRA SPT 24.3 3,276 27.0 3,580 54,690 2.222
45 BARNES BAND-S 24.5 3,255 27.2 3,557 54,450 2.216
45 BARNES TSX-FB 24.5 3,210 27.2 3,508 53,750 2.208
45 SF WTP 24.7 3,177 27.4 3,530 53,987 2.224
50 BERGER FBV 22.7 3,065 25.2 3,350 54,400 2.260
50 HDY SPSX 23.0 3,057 25.5 3,341 54,620 2.165
50 HDY V-MAX 22.5 3,103 25.0 3,391 54,990 2.260
50 HDY SP 23.0 3,074 25.6 3,360 53,220 2.226
50 NOSLER B-TIP 24.3 3,130 27.0 3,412 54,158 2.260
50 SIERRA BK 23.8 3,137 26.4 3,428 54,690 2.260
50 MSS VNX 23.1 3,088 25.7 3,375 53,690 2.187
50 BARNES VG 23.3 2,964 25.9 3,293 53,151 2.180
50 BARNES TSX-FB 23.1 3,030 25.7 3,311 54,750 2.184
52 BERGER FBV 22.2 2,983 24.7 3,260 53,800 2.260
52 NOSLER HPBT-CC 22.5 3,003 25.0 3,282 53,250 2.226
53 BARNES TSX-FB 22.9 2,977 25.4 3,254 54,550 2.202
55 BERGER FBV 22.1 2,927 24.5 3,199 54,730 2.244
55 HDY BT-FMJ 23.2 3,018 25.8 3,293 54,894 2.200
55 HDY SPSX 21.6 2,879 24.0 3,146 54,450 2.195
55 HDY V-MAX 22.2 2,909 24.7 3,179 52,660 2.260
55 NOSLER B-Tip 23.1 2,987 25.7 3,265 54,950 2.260
55 SIERRA SBT 23.0 3,002 25.5 3,281 54,995 2.215
55 SIERRA HPBT GK 23.2 3,000 25.8 3,279 54,925 2.160
55 MSS VNX 22.3 2,931 24.8 3,203 53,130 2.162
55 BARNES TSX-FB 22.5 2,887 25.0 3,155 53,940 2.183
55 SF WTP 23.1 2,929 25.7 3,254 54,177 2.244
60 HDY V-MAX 22.0 2,810 24.4 3,090 54,950 2.250
60 NOSLER PART 22.3 2,845 24.8 3,109 55,010 2.205
60 SIERRA HP 22.1 2,838 24.6 3,102 54,120 2.232
62 MIL M855 22.5 2,800 25.0 3,078 54,947 2.260
62 BARNES TSX-BT 22.5 2,804 25.0 3,066 54,333 2.255
65 SIERRA SBT 21.9 2,743 24.3 2,986 54,122 2.210
68 HDY BTHP-M 22.0 2,699 24.4 2,964 54,191 2.250
69 SIERRA HPBT MK 21.9 2,671 24.3 2,921 54,687 2.260
70 BARNES TSX-BT 21.6 2,658 24.0 2,884 54,544 2.260
75 HDY BTHP-M 21.7 2,582 24.1 2,820 54,337 2.260
77 SIERRA HPBT MK 21.1 2,483 23.4 2,759 54,500 2.260
80 SIERRA HPBT MK 21.9 2,500 24.3 2,749 54,308 2.260
90 SIERRA HPBT MK 20.5 2,313 22.8 2,546 54,700 2.260

Update:

I tested ladder loads from 23.8-25 grains of Tac. None of the loads were hot enough to fully seal the brass, resulting in excessive carbon on the case walls down to the rim.

I've tried two different sizing dies with the same results. Looks like I'll have to load a bit hotter than 25grains to get a proper seal with my brass.

I see that with IMI 69 also. I have velocity data with TAC will post later. The problem with home rolled in this case, I cannot source 69 with a factory cannelure like I can in 77, so lose that benefit.

Black Hills 5.56 clocks 2833 FPS @79°F out of a Noveske 16" SS NM Mod0. In my rifles the TAC equivalent is 25.2gr.
20" NM Mod0 Nosler 69gr OTM 25.2gr TAC LC brass 2.245 OAL CCI 41 taper crimp 2900 @78°F.
These are on the warm side. As always, work up your load. My data is for reference only.
Some sooting in shoulder area but see that with CBC 77 and IMI 69gr factory loads to a degree.
Attempted to use A2230, velocity was good, ES was erratic.

Note burn rate adjusted to match measured velocity for lot and temp. Note Lake City case volume is on the large size which effectively lowers pressure for a given powder charge.
Cartridge : 5.56 mm NATO - 5.56 x 45 mm
Bullet : .224, 69, Nosler CC HPBT 17101
Useable Case Capaci: 26.684 grain H2O = 1.733 cm³
Cartridge O.A.L. L6: 2.250 inch = 57.15 mm
Barrel Length : 20.0 inch = 508.0 mm
Powder : Ramshot TAC ? BR=.6100

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% 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

-20.0 75 20.00 2293 805 29773 6748 84.4 1.286
-18.0 77 20.50 2348 845 31681 6973 85.7 1.252
-16.0 79 21.00 2404 885 33711 7196 87.0 1.219
-14.0 81 21.50 2460 927 35869 7414 88.2 1.187
-12.0 83 22.00 2516 970 38166 7628 89.3 1.153
-10.0 85 22.50 2572 1013 40609 7836 90.5 1.121
-08.0 87 23.00 2628 1058 43209 8038 91.5 1.089
-06.0 89 23.50 2684 1103 45978 8234 92.5 1.058
-04.0 90 24.00 2740 1150 48927 8422 93.5 1.028
-02.0 92 24.50 2796 1197 52070 8602 94.4 1.000
+00.0 94 25.00 2852 1246 55423 8774 95.2 0.972 ! Near Maximum !
+02.0 96 25.50 2908 1295 59002 8936 96.0 0.946 ! Near Maximum !
+04.0 98 26.00 2963 1345 62826 9089 96.7 0.920 !DANGEROUS LOAD-DO NOT USE!
+06.0 100 26.50 3019 1397 66916 9231 97.3 0.895 !DANGEROUS LOAD-DO NOT USE!
+08.0 102 27.00 3075 1449 71294 9362 97.9 0.871 !DANGEROUS LOAD-DO NOT USE!
+10.0 104 27.50 3131 1502 75988 9481 98.4 0.848 !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 94 25.00 2989 1369 65053 8872 99.1 0.906 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 94 25.00 2678 1099 46107 8327 88.2 1.058

Any load that can cycle your action is generating plenty of pressure to fully expand the brass and provide a seal. A primer alone can generate enough pressure (6000psi) to move the bullet before the powder ignites fully and the brass seals. This may the reason you’re seeing carbon on your brass. In any case, I would not worry about what your brass looks like, I’d just focus on the performance of your load.