I am about to load some 150gr Sierra Gameking with some Ramshot Tac. Other info: Federal Brass, CCI 200 and will be shot out of bolt gun and hopefully also works well in an ar10.

The following is the data i got from Western (maker of Ramshot) and Sierra for the 150 gk. Both listed COAL's are 2.750" :
MIN CHARGE (min velocity) - MAX CHARGE (max velocity)
Western: 41.9gr (2693fps) - 46.6gr (2947fps)
Sierra: 38.6gr (2500fps) - 41.8gr (2700fps)

I know about shooting from the bottom up and watch for pressure signs as I go. Assuming all normal safety protocols in place, should I consider the Western maximum to be safe? Both sets of data looks right because the associated velocity to the weight is roughly correct tome. I don't wanna stop at 41.8-9gr because i feel like i should aim higher than 2700fps.
Maybe not 46.6gr, maybe something like 44 to 45gr seems about right to me, but I definitely want as much speed as accurately possible.

It’s not uncommon to see different data from different sources and some are know to be consistently high/low compared to others but I don’t recall ever seeing that wide of a gap. I would not limit myself to 44-45 unless I saw abnormal velocity leading up to it or pressure signs. As you know every chamber is different so you may low velocities at 46.8 or high at 45. I’ve heard people laugh at the “safe in my gun” phrase as simply a disclaimer but what is safe in your gun may blow mine up. I know I’m being long winded to cover the basics of reloading which you already know but sometimes we (me) get confident our knowledge and do not start low or at least in the middle of data.

I would start loading singles in the 41-42 range up to 47 in .3 increments watching velocity and brass carefully. This doesn’t take long and will give you an idea of your limits with that combination. If you do this you may find upfront that TAC is not the powder for you. Or maybe it’s perfect. Some will have pressure long before reaching desired velocity while others will achieve it with no issues at all.

Now that I’ve reinforced basics I’m sorry that all I have to offer.

You're more helpful than you think. I want to be on the higher end of the Western data. Sounds to me your first gut instinct is to go near the max and then a bit more, I usually go 0.6gr to 0.9grmore than max published for my 308 so far.

The lower end does not seem that appealing to me. I may start somewhere in the 43-44gr range and up to 47.0 (maybe).

Since the rifle was brought up, it's a Savage bolt with a brand new bolt head and fairly new Shilen barrel in a varmint profile. I haven't had any rifle issues yet in my brief reloading career.

Sierra posts their reloading data as one of the most conservative I know. So, there certainly is room North of the listed 41.8 grains Sierra max charge. (How they are claiming 2700 fps with only 41.8 grains of powder beats me!) I'm showing you should be ok up to about 47, even 48 grains, but I'd keep it a little more sane with less powder. And a lot depends on which brass you run (for internal case capacity volumes). But FC brass holds close to normal reload data. The main negative to FC brass is the loose primer pockets and the excessive case neck flow after sizing (i.e. needing to be trimmed).

TAC is one of my favorite 308 powders for the heavier bullets. It does very well.

I wouldn't load my initial load above the Sierra max...just in case they are correct. I'd probably start at 41.5 and go up from there.

or ignore everything I said and pay attention to Chad

Start below max and watch your chrono.

I used 46 grains of TAC with 150 NBTs in 2 different 20" bolt actions, a Tikka and a Savage. They were good for 2860 FPS in both rifles. I never had any pressure issues. Didn't go higher because 2850 was fast enough for me lout of a 20" barrel.

You can also see that type of range if you are comparing a service rifle ( M1A ) vs a .308 and did not notice the different call out. You don't want to over gas the service rifles. Typical Service rifle load is 2550 FPS with a 168 Sierra and somewhat faster with the 150, cant remember the exact number because I only shoot the 168 currently. In a bolt gun you don't have that concern and indeed for my bolt gun I am loading several grains more with the exact same components. Just to be clear, I am using IMR 4895 not RamShot.

First of all, thanks for the info., Your comfort level with 46gr makes me feel better.

Secondly, really about the heavier bullets? Again as a layman, I thought the general rulle was slower powder for heavier. Varget, W760 and RL15 are all slower than Tac so that was the rationale for using Tac with a 150gr bullet. For example, I tried Tac in 223 with the 75 max and terrible results (factory tikka varmint circa 2011). The same with 65gr gameking did remarkably better. I assumed it was because the powder was too fast.

Just looking at some other data: Hornady lists TAC for 1787-180gr bullets and does NOT list them for the 165-168 weight class. I only got a couple pictures of the latest manual in my phone. Interesting!

The 223 and 308 Win are almost identical with which powders work well with the lighter and heavier bullets in each caliber. Meaning, if a powder works well for a 77 grain bullet in the 223, it should (generally) work well for the 308 with a heavier bullet, like a 175+ grain, and vice versa. TAC is a double base ball powder and has good energy to excel the heavier bullets. I used it a lot in some of my personal and customer ammo (for bulk 223 or 308). But it will also work well for the medium to lighter bullets, if needed. It's a great powder.

In you Tikka Varmint model, I have the exact same rifle. If you loaded the 75 grain A-max at max Tikka mag length, the ogive of the bullet is seating deep into the case. So the 75 grain A-max has an insane long jump to the rifling. It's not an ideal bullet for mag feeding out of a Tikka. TAC can certainly work and work well, but you would need to seat the bullet out long close to the rifling and single feed the rounds. This will give you better results.

Here's a pic I found on line of a 223 with 75 grain A-max loaded to mag length. You can see that the bullet is seated awkwardly deep into the case to fit and feed at mag length. It's not the best set up for gaining accuracy, but sometimes it can be made to shoot well. I would not use this bullet and just go to the 75 grain BTHP to fit properly in the mag.

Here's a good over the top picture of what I'm talking about. The bullet is too deep into the case.

I ended up doing a home modification on the magazine to give me length. I was able to maesure out the lands and gave it like a 0.005-0.010 jump. Magazine length was not alimiting factor. I assumed it was the powder. Been mulling over trying it again since A) I got a BUNCH of Tac and B) use the newer eld around the 75gr class.

Chad,

What would be your recommendation for 77 TMK and TAC in 5.56? It would be 223 brass loaded to mag length in an AR.

It's your rifle. Go to the range and figure it out.

Haha, and it's funny because it's true.

Legit a-hole comment aside, below is what I've been using for Ramshot Tac. I think what he is saying is that published data from a credible source is always a good place to start; such as info direct from powder or bullet manufacturers. And then all standard safety protocols should be in place so you can do as fireman suggested. This thread was because what I thought was a huge discrepancy in published data from 2 different sources.
http://www.accuratepowder.com/wp-content/uploads/2010/09/WesternLoadGuide1-2016_Web.pdf

If you look at your link, AA has 2 different loads. They have the 223 Rem data at 55K psi and the 5.56 data at 62K psi. TAC with a 77 grain SMK shows 23.4 grains with 223 Rem and 24.8 grains for 5.56, with a difference of 1.4 grains hotter for the 5.56 data. Most of the time the 5.56 data is about 1.5 to 2 grains more than the 223 data. (I think the 24.8 grains of TAC is still a little light for 5.56 data). But if you are loading a 77 Tipped MK at mag length, then the bullet most likely will be seating deeper than the BTHP SMK bullet, which will reduce your case volume some and increase your pressure. So, the load data for the 77 SMK (BTHP bullet) may be slightly more powder than the 77 grain Tipped MK that is seated deeper. So keep that in mind.

Oh, and where's the other guy that argues with me and says there's no pressure difference between 223 Rem and 5.56. That's a good link to show!