Temp Stable Version of Ramshot TAC?

[jackstrawIII]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

Hey,

I have a great handload for my 308 Win using TAC powder with a 125 grain all copper bullet. It's going 3200 fps out of a 21" barrel.

Which is great, but the problem is that (supposedly) TAC powder is notoriously unstable in temperature change. Considering it gets quite cold up here (upstate NY) during hunting season, I want something more stable.

I just tried to ladder test with Varget and I couldn't get enough Varget in the case to push the bullet over 3050 fps out of my somewhat short barrel.

Do you guys know of any other powders I could try? I'd really like to be able to get at least 3100 fps, if possible.

Thanks!

 

[Unclenick]

I don't think any of the temperature-stabilized powders will get to those velocity levels with a solid bullet in a 21" barrel without exceeding SAAMI pressures, so you are looking for something likely not published. Indeed, there are only a handful of spherical powders that will get to that velocity with a standard jacketed bullet (probably about 3275 fps in a standard 24" test barrel). Throw in the higher bulk (that takes up powder space) and higher start pressure needed to load and fire a solid, and there is a good chance you are above it now.

 

[jackstrawIII]

Unclenick, you are correct. I am definitely looking for something unpublished. Have already checked all the published info I could fine.

Does anyone have experience with TAC powder in cold weather? How dramatic is point of impact?

 

[stagpanther]

I shoot in Maine--often gets down in single digits and even below zero in the winter. Even if the powder is "temp insensitive"--other stuff probably is sensitive, like me. I wouldn't be concerned so much about overall drop in velocity as I would consistency. Point is, I personally don't pay much attention to those temp ratings (or rumors) until I've verified it for myself in my gun in the conditions I intend to shoot in.

 

[tangolima]

I haven't had the need to do that, yet. But that's what I would do. I would adjust powder charge if I expect significant temp change, say summer load and winter load.

Most powder has temperature sensitivity of 0.2 - 0.3% for every 10F change in temperature. Or I can measure it myself with Chrono. MV roughly follows powder charge % to %. Or I can tell from the load development record. Certainly all powder charge should be bracketed by test fire to ensure safety.

-TL

Sent from my SM-N960U using Tapatalk

 

[Shadow9mm]

Might just try using a magnum primer if your not already. Supposed to give better ignition cold temps. And tac is a ball powder which generally like magnum primers.

My suggestion. Put some rounds in a sandwich bag and put them in the freezer about an hour beforeyou go to the range. When you go to the range put them in a lunch pail with some ice packs and see what kind of velocity change you actually get.

You can compare this with your warm weather temps to get a rough extrapolation both warmer and colder.

Some ballistics calculators have places to input velocities based on temps to better calculate your drops depending on the current conditions.

 

[jmr40]

Don't over think this. You might lose 200 fps with TAC in cold temps. But 3000 fps from a 125 gr 308 bullet is still going to be plenty effective. And 200 fps at the muzzle isn't going to make a significant difference in trajectory inside of about 300 yards.

Or you could lose 150 fps using Varget in warm temps and another 50 fps in cold weather. It still loses some speed at cold temps, just not as much. At the end of the day you'll end up with about the same speed with Varget as TAC in cold temps.

The advantage of just using Varget all the time is that it will be more consistent in a wide range of temps. Which is what I'd do.

You already claim 3050 fps with a goal of 3100 fps. That's nothing. If I'm shooting a 308 I don't want to download it too much but chasing another 50 fps just isn't worth the effort.

 

[44 AMP]

My suggestion. Put some rounds in a sandwich bag and put them in the freezer about an hour beforeyou go to the range. When you go to the range put them in a lunch pail with some ice packs and see what kind of velocity change you actually get.

If you are going to try this, I suggest adding a thermometer so you know (approximately) how cold the rounds get. Few home freezers will duplicate the low temps of an Adirondack winter.

I grew up in the Adirondacks, before "Climate change"...

Winter temps varied quite a bit. Some days you can get a high barely above freezing and be -20F at night, I can remember a year (tho I can no longer remember which year) where, from the middle of Dec to the last week in Feb, the warmest it got was -17F. That was a hard winter.

I can also remember a year when they had to make artificial snow for the Olympic Winter games at Lake Placid. A week after that it was subzero.....

We used to go snowmobiling at -20F sometimes.

Best suggestion I can think of is to sight in your rifle with the ammo you plan to hunt with in the cold, and accept what ever changes the cold creates. Just verify you zero with everything as cold as its going to get while you are hunting. In the frozen deer woods, even a couple of hundred fps change isn't going to matter, AS LONG AS your rifle is zeroed for it.

When we did anything longer than a single day trip, a weekend or one time, a full week, the rifles and ammo were stored outside. Not in a heated cabin or a slightly warmish tent, not moved from the cold to warm and back again. This made them consistent, and also meant the rifles didn't have to be cleaned of condensation.

Using the correct oil (or none) was also very important.

 

[Unclenick]

Jackstraw III,

Note, too, that since we figured out we were in unpublished territory, this policy needs to be followed. In this instance, I edited the warning into the starting post for you.

You didn't mention anything about the hunting range you were expecting, but you did mention New York and deer. When I hiked the Catskills in eons past, I didn't see much by way of shots over 100 yards for which I could still get to and recover the game in a reasonable time frame (not across gullies or over cliffs and the like). And deer aren't hard to kill, so unless the bullet maker has said his bullet won't work at 2500 fps, I think your current load has you pretty well covered down to -20°F. Of course, you may have some other reason for pushing the envelope.

 

[jackstrawIII]

You didn't mention anything about the hunting range you were expecting, but you did mention New York and deer. When I hiked the Catskills in eons past, I didn't see much by way of shots over 100 yards for which I could still get to and recover the game in a reasonable time frame (not across gullies or over cliffs and the like). And deer aren't hard to kill, so unless the bullet maker has said his bullet won't work at 2500 fps, I think your current load has you pretty well covered down to -20°F. Of course, you may have some other reason for pushing the envelope.

Good points, and largely true for those who hunt mountainous regions in NY. Most of my shots on deer have been in wooded areas and have been under 100 years. I'm fortunate, however, to have permission to hunt some farming areas and shots across bean fields are quite common. I prefer to have impact velocity as high as possible when using copper bullets, with 2600 fps being a (somewhat arbitrary) golden number.

My current load with TAC gets me 3200, which puts impact velocity of 2600 to almost 300 yards. More than enough for my use...

Following the recommendations of the group here, I might have to do more testing to see what sort of real-world velocity reduction I actually experience with cold ammo. I'm not hardcore enough to hunt at -20 degrees anyways haha. If it's single digits or lower, I'll just wait for the next day #brrrrr

 

[44 AMP]

-20F is pretty extreme, but here's my point, and it applies to hunting any time you get down close to freezing, or far below....

Your ammo is cold. Your rifle is cold. YOU are cold. Maybe for several hours before getting a shot. Things are going to be different than when temps are higher. Are you going to be wearing gloves?? Trigger finger mittens?? hands in pockets, taking them out to make the shot??

Things like that make a difference. Maybe not a lot, always, but maybe more than you think, until it happens.

Cold, stiff, numb fingers and featherweight trigger pulls don't work well together. There are lots of factors at work in the cold that simply don't apply when its warmer.

And no, I wouldn't go hunting in -20F if I had a choice. Trouble is, I've seen years in the Adirondacks, when, by the time it warmed up to single digits, the season was over! Not every year, by any means, but it has happened.

 

[Paul B.]

I can't say about TAC as I never seem to find it on dealer's shelves. I have used W760 in the .308 with 165 gr. Speer Hot Core and in a 30-06 with 165 gr. Accubonds on hunts. The .308 hunts usually weren't that cold rarely reaching say about 32 degrees during the day and on several elk hunts the 30-06 was used in temps running around +4 to +14 degrees at the time a shot was taken. On one hunt I checked the sight setting at the Whittington range near Raton New Mexico. The rifle and ammo had been stored in my truck and the temp at the time of the sight check was 14 above zero. I saw no change on my target from when I left Tucson AZ at 100 yards. I also checked my .35 Whelen at the same time which used RL15 and a 225 gr. TSX bullet with no change in point of impact. Dunno how RL15 is regarding temperature but W760 is supposed to be rather sensitive. I agree the OP should test his load at temps as close as possible to what he might expect on the hunt. That's about the only way to know for sure.
Paul B.

 

[Nathan]

Which 125gr all copper? At what depth?

Ballpark pressures look like 70000 psi and a highly compressed load? Is that where you think you are at?

Nothing including what you are running can safely get to 3200fps, but H322 could see 3150 fps if you don’t run out of room. Reloader 10x, IMR 4198 or H4198 could be all great choices.

 

[MarkCO]

...but the problem is that (supposedly) TAC powder is notoriously unstable in temperature change. Considering it gets quite cold up here (upstate NY) during hunting season, I want something more stable.

Hogwash. TAC is extremely stable. The "term" you are looking for is "Temp Sensitivity" or "Muzzle Velocity Variation".

All you need to do is shoot over the chrono at a few temps, get your average muzzle velocity and then see what the change is. I have a powder that is 1.7 fps/degree and some that are as low as (Hodgdon Extremes) 0.1 fps/degree.

TAC is usually about 0.9 to 1.0 fps/degree depending on barrel length. FWIW, most of the IMR and Accurate powders are over 1. Several are over 1.5. The Hodgdon extreme line is usually under about 0.4, with H4831SC being the best there is, usually under 0.1, which is why I use it in my Elk rifles since I hunt in sub zero to as much as 60F for the Wapiti.

Anyway, use TAC and make yourself some charts for the temps, or, get yourself Ballistic, enter the data and know exactly what you will have.

 

[IMtheNRA]

...but the problem is that (supposedly) TAC powder is notoriously unstable in temperature change..

Wait. What? Where did you get that information?

 

[jackstrawIII]

Which 125gr all copper? At what depth?

Ballpark pressures look like 70000 psi and a highly compressed load? Is that where you think you are at?

Nothing including what you are running can safely get to 3200fps, but H322 could see 3150 fps if you don’t run out of room. Reloader 10x, IMR 4198 or H4198 could be all great choices.

Nathan,

This is the 125 grain MKZ from Cavity Back bullets. It’s a very effective killer on white tails. I’m running the coal at 2.67”

It doesn’t feel like a super high pressure load to me and I’m not getting any major signs. A bit of cratering on the primers, but nothing significant. I’ve shot probably 50 or so of these loads, never seeing any trouble.

What do you think? Am I doing something I shouldn’t be?

 

[FrankenMauser]

Notorious, eh?
News to me. I missed this notoriety and have been using it since at least 2014.
I live in the high desert. Winters average around freezing, with at least one spell of "high" temps below zero for 2-3 weeks. Summers run hot.
I have never heard any complaints about TAC.

Does anyone have experience with TAC powder in cold weather? How dramatic is point of impact?

TAC is one of the go-to powders on my bench for .223-based cartridges. I run a lot of it through 6x45mm and .17-223, specifically.
I have shot it from 0 F to 100+ F.
I haven't noticed any issues, or a big enough change in POI to be attributed to the powder, specifically.

I can shift POI 1/4" down on the 6x45mm by screwing on a suppressor. I haven't seen even that much different caused by temperature.

 

[stagpanther]

Here in Maine I'm much more worried about my rear end freezing to the stand seat than I am about TAC performance degradation. And I only use stands when they are necessary to see above the snow depth. Sometimes it gets so cold the bullet stops in midair and remains suspended there.

 

[jackstrawIII]

Sometimes it gets so cold the bullet stops in midair and remains suspended there.

It’s a different world up there in Maine.

 

[MarkCO]

Here in Maine I'm much more worried about my rear end freezing to the stand seat than I am about TAC performance degradation. And I only use stands when they are necessary to see above the snow depth. Sometimes it gets so cold the bullet stops in midair and remains suspended there.

My January Coyote hunt a few years back, was -10F. I was shoot 77TMKs pushed by TAC. 70 degrees below my zero temp. My Kestrel and App agreed, and I got all my hits right where they were supposed to be. Elk in December is a bit warmer, usually around 10F or so.