Swage or Cut crimp in 5.56/.mil brass and MK262 suggestions?

[OzzyO20]

Anyone have any suggestions or sound arguments why one is better than the other?

I've been reloading 6.5 CM exclusively, but took inventory of some other brass the other day and I have a ton of Lake City 5.56 and IMI 5.56 brass I'd like to load up for my MK12 Mod 0. I've read a few articles about each one, but nobody really gave a reason why they do one or the other (other than swaging being a little less messy).

I have a RCBS case prep center, so I can attach a cutter do it if that makes a difference.

I've almost exclusively ran 5.56 77 grain ammo though it (Black Hills, IMI, Magtec, Federal, etc.) and I know trying to replicate that is difficult/dangerous but if anyone has something close to a MK262 recipe they want to throw out, that'd be a huge help as well.

Thanks fellas.

 

[padom]

I cut the crimp out of LC brass. I've had too many issues with primers not going in on swaged brass in the past. Get yourself a RCBS Trim Mate Military Crimp Remove - Small off Amazon and put it on your case prep center and cut away.

Why is it difficult/dangerous to replicate MK262 ammo? Get yourself 8208XBR and 77smk, 77cc, 75 BTHP, etc. and do load development in 0.2gr increments from 23.2gr to 24.0g. Most people find their node at 23.6gr. Out of a 20" 1:7 that usually yields 2800fps and clover leafs if your barrel is capable.

 

[OzzyO20]

I cut the crimp out of LC brass. I've had too many issues with primers not going in on swaged brass in the past. Get yourself a RCBS Trim Mate Military Crimp Remove - Small off Amazon and put it on your case prep center and cut away.

Why is it difficult/dangerous to replicate MK262 ammo? Get yourself 8208XBR and 77smk, 77cc, 75 BTHP, etc. and do load development in 0.2gr increments from 23.2gr to 24.0g. Most people find their node at 23.6gr. Out of a 20" 1:7 that usually yields 2800fps and clover leafs if your barrel is capable.

I've heard the velocity is tough/impossible to match without pressure signs due to unicorn powder used in most loads. I'll certainly give it a shot though. I actually had that tool in my Amazon cart so I'll probably go ahead and order.

What dies do you use @padom?

 

[MtnCreek]

I either cut with a hornady hand tool or swag with a dillon bench tool. Hand cutting is more precise, but slower. The bench tool is faster, but not as consistent. Case head thicknesses and even the burr left from flash hole punching effect the swag. I typically cut 7.62 for bolt gun use and swag 5.56 for autoloaders because of the quantity of brass I'm prepping.

 

[OzzyO20]

I have a flash hole uniformer I don't hardly use on 6.5 since I switched to Lapua brass. Would it be worth hitting both sides of the flash hole with it at the case prep center? Are they even universal?

 

[natdscott]

Swaging is materially (noun) better. It serves to further work-harden the head of the casing, which is much more positive that physically removing metal from the casing.

That being said, e'rybody has been doing both for so long that it may not be material (adjective) to the situation.

I would PERONALLY buy a Dillon SuperSwage. Well. Actually, no I wouldn't. I'd just use uncrimped brass, which is what I DO do.


Oh, and as far as high-speed, lowidrag Mk 262 loads: Alliant 2000-MR is your huckleberry. It's FASssssstttt...

 

[Precision Underground]

I cut the crimp out of LC brass. I've had too many issues with primers not going in on swaged brass in the past. Get yourself a RCBS Trim Mate Military Crimp Remove - Small off Amazon and put it on your case prep center and cut away.

Why is it difficult/dangerous to replicate MK262 ammo? Get yourself 8208XBR and 77smk, 77cc, 75 BTHP, etc. and do load development in 0.2gr increments from 23.2gr to 24.0g. Most people find their node at 23.6gr. Out of a 20" 1:7 that usually yields 2800fps and clover leafs if your barrel is capable.

Can you really get 2800 from a 77 gr? Is the 8208 that fast? I'm maxed out with varget just below 2700 with an 18".

 

[natdscott]

Can you really get 2800 from a 77 gr? Is the 8208 that fast? I'm maxed out with varget just below 2700 with an 18".

If it can be done, 2000-MR will be the one to do it.

Note that I am not saying it is the perfect powder. I'm just saying it's fast as shit.

I'm staring down 0.0037" erosion per 100 rounds using it though. If a guy had chrome or melonite, and could still get 4,000+ rds out of a match barrel with it, man, it might be super-ideal.

-Nate

 

[MarinePMI]

Can you really get 2800 from a 77 gr? Is the 8208 that fast? I'm maxed out with varget just below 2700 with an 18".

I'm getting 2960fps with 75gr ELD-M's, so yes, it's that fast...

 

[natdscott]

I'm getting 2960fps with 75gr ELD-M's, so yes, it's that fast...

What barrel length, what rifle type, whose casing, and how long are you seating?

 

[OzzyO20]

Just to be clear, I'm talking gas guns not bolt guns. I think everyones on the same page but anyone reading that isn't I want that to be known so you guys don't try and cram a hot bolt gun load in your gasser.

 

[MarinePMI]

24" barrel, Tikka Varmint, NAMMO (Lapua) brass. Seating about .010" off the lands...

 

[Precision Underground]

I'm getting 2960fps with 75gr ELD-M's, so yes, it's that fast...

Damn I gotta get me some of that!

 

[natdscott]

24" barrel, Tikka Varmint, NAMMO (Lapua) brass. Seating about .010" off the lands...

Well god DAMN Marine.

We're not even talking about the same game.

---You have a BOLT rifle. (We are discussing an AR.)
---You have SIX INCHES more barrel. (He is stuck with only 18", and that's at LEAST 125 fps difference alone).
---AND, you are seating LONG. (We assume he's asking about mag length, seeing as Mk 262 is a spec load.)

Hell, I can do over 2,650 with the 90 Berger out over 2.600" OAL, but that doesn't mean I'd recommend it to some random dude on the internet. I think it's a bad idea to do so when you're talking about hot loads for an AR in particular.

Just this week, a dude blew up his Tubb rifle just down the line from me, and that's a BOLT rifle... Shit really does happen.


Ya gotta speak in the same terms, or the internet gets the idea that THEY should get 2,900+ from the same bullet. Then they blow their shit up, and wonder why.

-Nate

 

[padom]

Can you really get 2800 from a 77 gr? Is the 8208 that fast? I'm maxed out with varget just below 2700 with an 18".

All day long. No pressure signs at all. this has been pretty standard from 20" barrels both 1:7 and 1:8 with 23.6g 8208 with 77smk. Both my 20" 1:7 WOA or Rainier Ultramatch get this and my buddy gets the identical speed with same load and bullet out of his Shilen 20" 1:8.

Keep in mind these are from a new barrel with 50rdds on it getting 2791. Sped up to 2806 after 125rds..

 

[MarinePMI]

Well god DAMN Marine.

We're not even talking about the same game.

---You have a BOLT rifle. (We are discussing an AR.)
---You have SIX INCHES more barrel. (He is stuck with only 18", and that's at LEAST 125 fps difference alone).
---AND, you are seating LONG. (We assume he's asking about mag length, seeing as Mk 262 is a spec load.)

Hell, I can do over 2,650 with the 90 Berger out over 2.600" OAL, but that doesn't mean I'd recommend it to some random dude on the internet. I think it's a bad idea to do so when you're talking about hot loads for an AR in particular.

Just this week, a dude blew up his Tubb rifle just down the line from me, and that's a BOLT rifle... Shit really does happen.


Ya gotta speak in the same terms, or the internet gets the idea that THEY should get 2,900+ from the same bullet. Then they blow their shit up, and wonder why.

-Nate

LOL! It was an example of 8208 being fast. As to the internet and people doing something stupid, you'll note I didn't include the actual load. At some point, people have to think for themselves, or shit will happen.

 

[FishDr]

Nate -
I’m also using 2000-MR. Can you elaborate a bit more on the throat erosion issues. I havent measured mine, but did chase an accuracy node in a previous barrel. Perhaps this is why.

Also, my loads are 69smk at ~ 2920 FPS and 77smk at ~ 2790 fps.
Thanks.

 

[natdscott]

Oh, I just think the powder is really hot. I'm never anywhere NEAR that with RE-15, but then, I don't get the same performance.

I am only using the 2000-MR to try to maximize speed with the 90 VLD while keeping pressure in a relatively manageable bracket. RE-15 and many others are NOT able to do that with the heavier bullets.

If you are running only mag-length ammo, there's not a lot you can do about it but to carefully chase the tune with powder charge adjustments, and to simply track the issue. When you've seen about 0.100" erosion (less in a .223), or +1.0 grain-to-get-the-same-speed (again, probably less in a .223), then the barrel is toast, if not before. (the 'before' part is individual to the barrel. Some just quit shooting earlier, and the really good shooter has to know when to honestly assess the data in front of them, and trash it when it's done. Or shoot better.)

Now about the loading long, I'm loaded to something like 2.616" OAL, where I WAS at 2.574" to start with, for the same tune. This only took 1,120 rounds.

VLD bullets can be a real pain in the ass to keep tuned, and the slower the barrel's leade surface moves, the easier that is to do.

A barrel of this nature would usually do 4,000-5,000 rounds of top-grade accuracy with 65-80 grain loads with a powder like Varget or RE-15.

The barrel I am talking about is Bartlein's best work, but is still flying forward at 0.0037" per hundred, which is about as bad as a .260 or 6.5 Creedmoor. I attribute that to the powder and to the nature of the loads, and I assumed that would be the case, so it's alright.

Now to be clear, it can still work just fine, provided the lands are washing evenly, and fire-cracking is minimal. My load adjustment tests on Sunday evening showed two groups at 0.013" Vertical, and 0.206" vertical, at the same two jumps as had tuned at 200 rounds, and a slightly heavier powder charge put two groups in at about 1/2 and 9/10's MOA, with the same jumps. So it's not like I'm complaining about an AR that will lay down that kind of vertical...it's just that a fast-moving leade requires work and tracking.

High performance has it's costs, and not just money.

-Nate

 

[FishDr]

Thanks for th explanation Nate. I certainly agree. This fits almost exactly what I observed in the previous barrel. Hopefully the new one will last a bit longer.

 

[natdscott]

...thinking about maybe meloniting the next $450 blank.....

 

[MarinePMI]

Sure hope you do that after its chambered, and not to the blank.

 

[Crang]

Dillon Super Swage has always done right be me. Used to have to clean up a lot of LC brass when I was into M14s

 

[natdscott]

Sure hope you do that after its chambered, and not to the blank.

LMAO!

Yeah, that would suck!

 

[OzzyO20]

...thinking about maybe meloniting the next $450 blank.....

H&M does great work: http://blacknitride.com

 

[Precision Underground]

All day long. No pressure signs at all. this has been pretty standard from 20" barrels both 1:7 and 1:8 with 23.6g 8208 with 77smk. Both my 20" 1:7 WOA or Rainier Ultramatch get this and my buddy gets the identical speed with same load and bullet out of his Shilen 20" 1:8.

Keep in mind these are from a new barrel with 50rdds on it getting 2791. Sped up to 2806 after 125rds..

I gotta get me some of that!