Brass for 77 TMK AR15

[treillw]

Managed to get 1500 77 grain TMKs. Now I need brass to go along with them.

I want to load them up to shoot as hot as possible from a 10.5" and 14.5" AR.

I was going to buy bulk once fired Lake City brass (probably 3000), but there are so many inconsistencies in years, lots, etc, etc - probably not the best if you're running a max powder charge to have different case volumes.

The majority of the reloading that I have done in the past is for long range precision - measuring powder to the nearest kernel and seating bullets to +/- .0005". The idea of all the inconsistencies from 1500 pieces of brass wreaks havoc on my OCD, but at the same time I don't want to spend $$$$ on all Lapua brass.

I'd be happy if I can get them to shoot minute groups. The TMK is one of the best projectiles out there, and I don't want to "waste" them by using junk brass and creating poor reloads.

I will probably shoot 100 or so of the rounds to verify function and then store the rest away for a rainy day.

What brass would you use for them? Any good suppliers out there?

Thanks!

 

[LVLAaron]

Before the pandemia there were a lot of good 223 brass makers. I measured 5-10 brands for H20 capacity, consistency, etc.

If you can find Starline 5.56 (not 223 - they sell both) you'll have some really solid stuff to work with.
Sig has also been excellent.

Be advised I dont think you can make 77 TMK's mag legnth.

 

[treillw]

They can be loaded mag length, but they usually run a little hotter than same charge as for regular MK since they will need to be seated deeper. not sure what your accuracy expectations are, but I would use Lake City brass and be happy. Good luck with them. I tried them, and they gave me a tighter “core group” than regular 77s, but I always seem to get a couple fliers with them. Went back to regular 77s which shot a bigger group, but was more consistent and no fliers.

I'd be happy if they gave me 1 MOA accuracy.

 

[RegionRat]

I'd be happy if they gave me 1 MOA accuracy.

What does your 10.5" upper shoot now?

It has been a several years since there was an ability to buy 1000 piece batches of virgin LC brass, and the contractor running the place has changed since then too. Could be a long time or even never before we see them sell virgin brass.

You are faced with just buying the best option for commercial brass you can get, but if I were you I wouldn't worry about it. A 77 TMK in a WOA Service Rifle upper will shoot clean at 300 yards using mixed headstamp brass. Since you are talking about a 10.5" barrel, does that really matter?

https://www.diamondkbrass.com/.223-5.56-Processed-1000.html

 

[AzMandella]

I bought LC brass . But I also bought 1000 Norma 5.56 ammo . And shot half of it for the brass . When they have it it's only .50 cents a round . Pretty cheap for good brass compared to just the brass if you can get it .

 

[dthomas]

I would also use starline if you don't want to run laupa.

 

[PopCharlie]

+ 1 for Starline. You will need a VERY fast twist to stabilize 77 gr TMKs in a short barrel. I shot some of these out of a 9 twist 16" AR. I had to seat them very deep to make mag length (2.27 OAL I'm my gun). Accuracy was very poor. +3" groups at 50 yards. 55 gr Nosler Varmagedan FB bullets shot 1 MOA at 50 and 100 yards out of my gun.

PopCharlie

 

[jrh84]

I was going to buy bulk once fired Lake City brass (probably 3000), but there are so many inconsistencies in years, lots, etc, etc - probably not the best if you're running a max powder charge to have different case volumes.

Plenty of high power competitors using LC brass for their 200-600 yard service rifle loads, and several using LC for 1000 yard prone matches. I used to be super worried about making sure my ammo was all from the same year, but over the last 5 years, I've gradually worried less and less about it, and just loaded and shot regardless of the headstamp (as long as it's LC). My scores have gone up, especially at long range.

For your application, I wouldn't worry about mixing LC years.

 

[JB10]

I use mixed LC brass. Normal prep work, load and shoot. Im not teying to push things to the max but have decent accuracy. Have not had any issues. The bonus is its all free range pick up!!!

 

[jelenko]

I:8 will stablize 77 TMK's.
When the bullet exits the muzzle, it's rpm's are determined by the velocity and the 'local' twist rate.

At 1500 fps and twist rate of 1:8, the 77 TMK is still solidly stable.

 

[treillw]

I:8 will stablize 77 TMK's.
When the bullet exits the muzzle, it's rpm's are determined by the velocity and the 'local' twist rate.

At 1500 fps and twist rate of 1:8, the 77 TMK is still solidly stable.

I've got 7 twists, so I should be good.

 

[jrh84]

The bonus is its all free range pick up!!!

It's a well-known fact that free brass makes the best handloads.

 

[whatsupdoc]

Before the pandemia there were a lot of good 223 brass makers. I measured 5-10 brands for H20 capacity, consistency, etc.

If you can find Starline 5.56 (not 223 - they sell both) you'll have some really solid stuff to work with.
Sig has also been excellent.

Be advised I dont think you can make 77 TMK's mag legnth.

Whats the difference between the Starline 5.56 and the 223 brass

 

[karrarararararar]

Whats the difference between the Starline 5.56 and the 223 brass

The 5.56 brass has a harder case head.

 

[RegionRat]

Whats the difference between the Starline 5.56 and the 223 brass

What karrararar said. The hardness of the 5.56 is worth the difference in the higher pressure loads for an AR platform. The primer pockets and rims will survive a little longer in theory.

 

[SecondsCount]

I load a lot of 223 ammo for my ARs and have found that loading for reliability and accuracy is more important than velocity. You have already crippled yourself with the shorter barrels but the heavy bullets help make up for the loss of velocity.

I use LC, PMC, FC, Wolf, R-P and Hornady brass, sorted by headstamp. I load ten, shoot them, and look at the primers. As soon they start to show signs of flattening is when I know my load is near peak. Nothing will stop your gun quicker than a hot load that goes nuclear and the bolt rips the rim off, or a case ruptures and sends the extractor into orbit.

 

[dc.fireman]

Plenty of high power competitors using LC brass for their 200-600 yard service rifle loads, and several using LC for 1000 yard prone matches. I used to be super worried about making sure my ammo was all from the same year, but over the last 5 years, I've gradually worried less and less about it, and just loaded and shot regardless of the headstamp (as long as it's LC). My scores have gone up, especially at long range.

For your application, I wouldn't worry about mixing LC years.

This.

My service rifle load ( A RRA NMA4) is LC Brass, a 77 SMK, CCI-400, and 24.2 gr of Power Pro Varmint (right next door to TAC on the chart). That's coming from a 1/8 20" stainless barrel. The LC brass is good enough for what you want to do with it. My rule of thumb is no longer than 2.260" COAL - they seem to mysteriously 'grow' at the worst possible time - during your rapid fire strings.

 

[Alaska Bush Man]

Managed to get 1500 77 grain TMKs. Now I need brass to go along with them.

I want to load them up to shoot as hot as possible from a 10.5" and 14.5" AR.

I was going to buy bulk once fired Lake City brass (probably 3000), but there are so many inconsistencies in years, lots, etc, etc - probably not the best if you're running a max powder charge to have different case volumes.

The majority of the reloading that I have done in the past is for long range precision - measuring powder to the nearest kernel and seating bullets to +/- .0005". The idea of all the inconsistencies from 1500 pieces of brass wreaks havoc on my OCD, but at the same time I don't want to spend $$$$ on all Lapua brass.

I'd be happy if I can get them to shoot minute groups. The TMK is one of the best projectiles out there, and I don't want to "waste" them by using junk brass and creating poor reloads.

I will probably shoot 100 or so of the rounds to verify function and then store the rest away for a rainy day.

What brass would you use for them? Any good suppliers out there?

Thanks!

Lake City 5.56 brass
IMR 8208 @ 23.3
MK 262 load 23.8
CCI 41 primers
77MK

Case Capacity diffence between brands is much less in 5.56 with Fed @ 23.5 the most vs 23.3 for LC. I use LC brass for 99% of my 5.56 shooting.
Military 7.62 LC brass and commercial brass a lot more difference involved between the brass.