TAC + 123g SST

[ragedracer1977]

Data as follows:
Ramshot TAC. CCI #41. AA Brass. 2.25 OAL. Fired over a CED M2 Chronograph ~15' from muzzle.

28.0g
2338
2475
2379
2412
2365
High: 2475
Low: 2338
E.S.: 137
Ave.: 2393
S.D.: 47

28.2g
2362
2345
2393
2358
2416
High: 2416
Low: 2345
E.S.: 71
Ave.: 2374
S.D.: 25.9


28.5g
2463
2438
2453
2440
2432
High: 2463
Low: 2436
E.S.: 27
Ave.: 2445
S.D.: 11.2


28.8g
2401
2427
2435
2401
2455
High: 2455
Low: 2401
E.S.: 54
Ave.: 2423
S.D.: 20.7


29.0g
2437
2458
2432
2466
2439

High: 2466
Low: 2432
E.S.: 34
Ave.: 2446
S.D.: 13.1


The brass from all the loads appeared essentially identical. No swipes, cratered primers, or any marks on the case head.

Unfortunately, I didn't really get to shoot for accuracy. My barrel nut had come loose at some point and I re-tightened it. I didn't think it was going to throw off point of aim as much as it did, so I only brought 20 rds to sight in. I fired all of them and never got on paper at 150 yds. This was out in the desert, with no assistance, so I couldn't really accurately tell where my rounds were even hitting. I should have at least bore sighted at home. So, I just said oh well, and fired the new loads for chrono readings.

Most interesting to me is that 28.5 and 29.0 are nearly identical, except for the deviation. I think I'll be working in the 28.5 area for accuracy testing.

[LRRPF52]

What barrel length is this from?

[ragedracer1977]

What barrel length is this from?

Sorry, 16" 1/9 Black Hole Weaponry, .264 LBC chamber

[Kikn]

Hope you don't take this the wrong way... and this is only my opinion...mostly

Those loads are pretty hot for TAC Bill A. I had a conversation about a year ago with Bill A. And he was pretty certain that onesshouldn't go past 28.5 with TAC but wasn't quite able to find the data. And was very concerned when I told him that I thought I may have loaded some rounds to 29 and said he wouldn't recommend it at all.

Just proceed with extreme caution.

Also my personal best load with TAC was 27.9 and I was getting 2415FPS average. From my 16" barrel. Just not really sure your gaining much but seems like you could be risking a lot more than you are gaining.

Nosler shows 120 nosler max load at 28 gr.
Nosler 123 hpbt at max 27.5
Hornady 9th edition shows 123 amax maxes out at 27.8

[ragedracer1977]

Hope you don't take this the wrong way... and this is only my opinion...mostly

Those loads are pretty hot for TAC Bill A. I had a conversation about a year ago with Bill A. And he was pretty certain that onesshouldn't go past 28.5 with TAC but wasn't quite able to find the data. And was very concerned when I told him that I thought I may have loaded some rounds to 29 and said he wouldn't recommend it at all.

Just proceed with extreme caution.

Also my personal best load with TAC was 27.9 and I was getting 2415FPS average. From my 16" barrel. Just not really sure your gaining much but seems like you could be risking a lot more than you are gaining.

Nosler shows 120 nosler max load at 28 gr.
Nosler 123 hpbt at max 27.5
Hornady 9th edition shows 123 amax maxes out at 27.8

I browsed through several resources and thought I was in line. It's difficult to find published data for Grendel, at least on line.

I saw data from 27.5-29.0 through various searches. Am I really that out line?

[Kikn]

Nosler has their data published online. I do think the are a bit on the conservative side. There is another post on this forum with the data / photos from hornady's 9th edition. Where I pulled that info from.

I just wanted to make sure you kept a close eye on what you are doing. At a certain point loading hit it can really take a toll on your bolt as well since it is designed to be the weak link from what I understand.

There are quite a few on here far more knowledgeable than me. Perhaps others can chime in with more info.

[LRRPF52]

If you look in the 6.5 Grendel Reloading Handbook Volume I, AA data only goes up to 120gr pills with TAC.

In Volume II, we have some data for the 123gr SST at 28.4gr from a 16", using Remington 7.5 primer, 2.250" COL, with a mv of 2335fps.

I browsed through several resources and thought I was in line. It's difficult to find published data for Grendel, at least on line.

I saw data from 27.5-29.0 through various searches. Am I really that out line?

You're not too far out of line, just be aware that you are .2gr over max published loads for a 120gr NBT. You can see if you have more COL available before you jam the lands, and give yourself some more leeway.

What diameter is your de-capping pin, BTW? I'm wondering if your flash holes are the same as my brass. If you want speed, try CFE223 or LVR under the 123gr SST.

[Kikn]

I looked at one of AA published data for 120noslers from 2006 and it does show a max load of 28.8 with TAC

[VASCAR2]

I loaded 28.5 grains TAC with Remington small rifle primers in Hornady brass with the 120 grain Pro Hunter. My 16" J&T Shaw 1:9 twist barrel gave a velocity of 2355, temperature 80 degrees 450' ASL. I have shot several groups which were MOA in of my 16" 6.5 G.

[Drifter]

Since the average velocity of the next incremental charge weight is less than the preceding load in a couple of your examples, and ES is all over the place, I think all of your listed loads are potentially excessive. For example, the 28.2 load is slower than 28.0. ES for both is quite high.

Data as follows:
Ramshot TAC. CCI #41. AA Brass. 2.25 OAL. Fired over a CED M2 Chronograph ~15' from muzzle.

28.0g
2338
2475
2379
2412
2365
High: 2475
Low: 2338
E.S.: 137
Ave.: 2393
S.D.: 47

28.2g
2362
2345
2393
2358
2416
High: 2416
Low: 2345
E.S.: 71
Ave.: 2374
S.D.: 25.9

I suggest another test with charge weights between 26.8 and 27.8 grains if you wish to safely use TAC and not break bolts with that load in that barrel.

ETA- Also be sure that you're not into the lands with the 123gr SST loaded to 2.250" COL. Factory loads are reportedly shorter. If you're jamming the bullet, that can increase pressure and skew the data on your chronograph. (With the same bullet, I'm into the lands with one barrel at ~2.242". I load to ~2.230" COL.)

[LRRPF52]

Yeah, I don't like those Extreme Spreads either. I think TAC is a better powder for the 100gr NBT, and bullets in the shorter bearing surface class.

I've worked with it a bit in the Grendel, and have no plans to ever use it for 123gr.

[ragedracer1977]

Since the average velocity of the next incremental charge weight is less than the preceding load in a couple of your examples, and ES is all over the place, I think all of your listed loads are potentially excessive. For example, the 28.2 load is slower than 28.0. ES for both is quite high.



I suggest another test with charge weights between 26.8 and 27.8 grains if you wish to safely use TAC and not break bolts with that load in that barrel.

ETA- Also be sure that you're not into the lands with the 123gr SST loaded to 2.250" COL. Factory loads are reportedly shorter. If you're jamming the bullet, that can increase pressure and skew the data on your chronograph. (With the same bullet, I'm into the lands with one barrel at ~2.242". I load to ~2.230" COL.)

My maximum COL is 2.305, So at 2.25 I'm .055 off the lands. It actually looks like I could be loading them just a hair longer (seems like I've read between .010-.015 off the lands is a typical 'sweet spot'.)

On another note, I fired 20 rds of my standard load (27.3g of H335 -E.S. of 33, SD 9.7, AVG Velocity of 2341 FPS) just before I fired these. I have a JP Adjustable gas block. All 20 of my 'standard' load cycled the bolt, fed a new round, and locked back on last round. On the TAC stuff, I had to open the gas port a little. It was ejecting, but not picking up a new round. Is that just a difference in the impulse?

BTW, looking at the 28.0 loads, something was off there. I'm not confident of the 2475 reading, as I had an error on the chronograph. It read that velocity, but was also flashing ERR.

Another thing to keep in mind, I am loading on a progressive press (RL550B) so I do often see powder drop variations of .1 gr +/-. Would that be enough to explain the variations? It's also possible I mixed up the 28.5 and 28.8 loads when I was shooting. I don't think I did, but I can't discount the possibility.

I'm attempting to duplicate Hornady's 123SST load for my rifle. When I chrono'd factory stuff, I was getting ~2430 FPS, with ES of ~45 and a SD of 12 (from memory, don't have it written down).

Speaking of which, what IS an acceptable ES and SD?

[LRRPF52]

Use CFE223 or LVR if you want to duplicate the factory load velocities, and pay strict attention to your load process on the progressive, maybe run it like a single stage and weigh your charges individually. The ball powders meter well, but I never have a warm and fuzzy for mass-production on a progressive, especially if we're at or around max charges.

For a pressure ladder, when you see an excursion outside of 40fps, that usually means you are in unpredictable territory when loading with ball powders using .3gr increments. When I did my pressure ladder with CFE & 123gr A-MAX, I saw very predictable, textbook velocity increases until it finally departed, where I then stopped. That was in the mid-2600's for speed with a 16" barrel. You see why I don't have any plans to screw around with TAC when you see what speeds I was getting. 31.0gr of CFE has been very accurate too for me, with 1/2" vertical and under 1" horizontal in extreme winds, but I'm going to accuracy-test some of the 31.2-32.0gr loads with the A-MAX and SST with round robin OCW, or just shoot them at distance.

Are you saying you can load the 123gr SST to 2.305" without touching the lands? Did you color the projectile with permanent marker or Dykem when checking maximum COL? That will allow you to load longer if you really have that COL.

[ragedracer1977]

Use CFE223 or LVR if you want to duplicate the factory load velocities, and pay strict attention to your load process on the progressive, maybe run it like a single stage and weigh your charges individually. The ball powders meter well, but I never have a warm and fuzzy for mass-production on a progressive, especially if we're at or around max charges.

I've been loading on a progressive for close to 20 years. I know i'm not going to win any 1000yd competitions with ammo loaded on it, but for my uses, I feel comfortable with it.

For a pressure ladder, when you see an excursion outside of 40fps, that usually means you are in unpredictable territory when loading with ball powders using .3gr increments. When I did my pressure ladder with CFE & 123gr A-MAX, I saw very predictable, textbook velocity increases until it finally departed, where I then stopped.


Can you tell me what that would be? I don't have a clue.

That was in the mid-2600's for speed with a 16" barrel. You see why I don't have any plans to screw around with TAC when you see what speeds I was getting. 31.0gr of CFE has been very accurate too for me, with 1/2" vertical and under 1" horizontal in extreme winds, but I'm going to accuracy-test some of the 31.2-32.0gr loads with the A-MAX and SST with round robin OCW, or just shoot them at distance.

Sounds like some CFE223 needs to find it's way to my bench.

Are you saying you can load the 123gr SST to 2.305" without touching the lands? Did you color the projectile with permanent marker or Dykem when checking maximum COL? That will allow you to load longer if you really have that COL.

2.305 would be touching the lands, assuming I measured correctly. Here's how I did it. Closed the bolt. Took a brass rod and inserted it into the barrel until it touched the bolt face. Marked the rod at the muzzle. Removed the bolt, inserted a bullet and used a rod to hold it into the lands. Inserted the brass rod again, then marked the rod - again at the muzzle. Measured the distance between the marks, got 2.305. I did verify, with a marked dummy round, that my current COL is not into the lands. Keep in mind, this is a .264 LBC chamber.

Thanks for your help!

[LRRPF52]

Ok, now work out your magazine allowable COL, and load to that. I found that all my mags have a raw internal maximum length of over 2.300", so if the bullet will allow it, I load a bit long. With the 123gr A-MAX, I loaded to 2.275".

For .3gr increments, I usually see 12-28fps increase in velocity. That's why a 40fps or more departure from the trend rubs me the wrong way, and I personally will stop and look at what's going on at that point. Almost every load development trip, I return with cartridges that are marked:

"DO NOT SHOOT!" with my permanent marker. I take them home, and pull them, then re-charge them with a safe weight.