6x45 (6mm-223) AR15

Bits are coming together. Barrel extension and 6x45 reamer are now on hand.
Should be able to find time next week to work on the barrel.
Tomorrow through Sunday I will be on the range.
 
One of the easiest wildcats to load for even if your 223 brass is fired many times you can anneal the shoulder/neck of that old brass then tip it into water and move onto the next one then just put the brass thru a 6mmX223 die, clean and load.

You can even load these on most progressive presses.


:)
 
tiriaq said:
Thanks for the lead.
That's what I've done previously - start small, keep opening the port until reliable function is achieved. It is interesting to watch the changes. Breech opens, but no ejection; then it opens and ejects, but doesn't feed. Next step is opening, ejecting and feeding, but it won't lock open on the last round. One size larger, and away she goes.
Given that all ammunition is going to be handloaded, experimentation is going to be required.
For ammunition with which to start testing, I have the tools for 6x47 (based on .222Rem.Mag). I will take sized .223 brass, use the taper expander to open the neck, and then use the 6x47 seater die.
Click to expand...

Another option is to make the gas block adjustable. JP and others simply put a bolt into the airway restricting gas flow. Simple and elegant.

I have seen the 6-223 shoot in a true benchrest rifle from the 80's and it shot really well but it really was for the 65 to 68gr bullet weights. I am sure you could stuff 70ish gr bullets but I really don't think an 87gr Vmax is going to work.

Having seen 75gr 22cal Amax loaded and shot in a HK, Tavor with zero problems and super LR accuracy, I favor the much higher BC of the 22cal.

But look forward to hearing how this goes.

My interest would be in a 6.5 SOCOM?

That would be fun...

Jerry
 
but it really was for the 65 to 68gr bullet weights
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I'm missing what you are saying or are you saying that the barrel on that rifle had a faster 1 - 12" twist rate because a 1 - 9" or 1 -10" twist would shoot up to 105gr 6mm bullets very well.
 
The rifle I am talking about was for SR BR and had a slow twist catering to that need.

Most SR BR rifles still wear slow twists cause they have no need for heavier bullets.

Setting any rifle with a faster twist will allow the use of heavier bullets.

So this AR could launch heavier bullets if so desired but I wonder if heavier bullets will fit at the reduced mag length.

Most building F class 6mm chamberings will use an 8 twist for the heavies. I am sure a 9 twist will work but is marginal. A 10 twist will not work with the heavy VLD's.

Jerry
 
6x45 and 6x47 would be very similar cartridges when used in a 1:14 barrel, which would be about standard for BR use, optimum for the 68gr range bullets generally used. I have a Hart built, sleeved 700 LV in 6x47. 6x47 or .222 Remingtom Magnum cases don't exactly grow on trees, while .223 are ubiquitous.

With a quick twist barrel, bullet options are much greater. The barrel I am using started life as a .243, so the twist is faster.

Threaded the barrel and fitted the barrel extension yesterday, hope to cut the chamber today, and to turn the barrel to final profile. Going for a medium weight.

This is all just an experiment. If I like the cartridge, I might make up a bolt rifle. Have a NOS 6x47 LV barrel I might alter to 6x45 and install on the Hart/Remington.
 
I have seen the 6-223 shoot in a true bench rest rifle from the 80's and it shot really well but it really was for the 65 to 68gr bullet weights. I am sure you could stuff 70ish gr bullets but I really don't think an 87gr Vmax is going to work.

Having seen 75gr 22cal Amax loaded and shot in a HK, Tavor with zero problems and super LR accuracy, I favor the much higher BC of the 22cal.
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Jerry:

With respect, I will concede to your greater knowledge than mine, of shooting in the Bench rest world. If you say that a slow twist works and that it works best with 65-68 grain bullets so be it.

However from an AR's shooters perspective, If I wanted to shoot those weight, I would simply stick with 22 cal bullets, and forgo the retooling.

However for my use in AR's (which I believe is what the original thread was aimed at) bullets in the 80 grain plus category that fly well from 16 - 20 inch barrels, that can get near 6.8 SPC performance out of the 5.56 cartridge with better accuracy is what really holds my interest.

tiriaq:

Please do keep us in the loop as I very much look forward to sharing your results.

Thanks for your time.

regards and all the best

AbH
 
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Breeching is done. I had measured from the front face of the barrel extension to the bolt face, then reamed the chamber until the Go gauge protruded .002" less than this measurement. Reamer is a PT&G. With the extension torqued on, the bolt will turn over on the Go, will not turn at all on the No Go.
Located the shoulder against which the gas block will seat, then turned the barrel in front of the gas block to .700", the gas block seating to .750", turning toward the breech at .800". Will leave the area over the chamber at .900". This will produce a medium weight barrel. Muzzle is threaded standard 1/2x28, a Smith Enterprises brake screws right on. Using a Brownells clamp on gas block with upper rail for a front sight, if I choose to ever install one. The block can have three rails added to it, although I doubt I will ever do that. Still have to install the locating pin through the barrel extension. Waiting for a DPMS tubular handguard, which is en route. Barrel will be assembled to a DPMS LoPro Upper receiver. This is a plain upper, no door or foreward assist, but is much heavier walled than a standard flat top. Gas port will be about the last thing to do before test firing.
 
AbHobbyist said:
However for my use in AR's (which I believe is what the original thread was aimed at) bullets in the 80 grain plus category that fly well from 16 - 20 inch barrels, that can get near 6.8 SPC performance out of the 5.56 cartridge with better accuracy is what really holds my interest.
Click to expand...

I think the only way to get more bullet mass is to go with a larger cal ie 6.8SPC, 6.5 Grendel, 7.62X39, KURZ.

The 6mm is marginally bigger and an 80gr is 3gr heavier then the generic 77gr MK load that is already in use. I believe this is a big reason why any new cal is dying a slow death.

with the AR mag so small, there really aren't alot of ways to increase performance without new cartridges and bolt heads.

If you look up the TCU family of 223 wildcats, you can see that even the 7mm can be made to work on the 223 case. That would be interesting.

I personally think the next cal step should be the 25cal or 6.5. You can now get into the 90 to 100gr family with decent ballistics to boot.

I can see why the US developers wouldn't choose the 6.5 cal - metric is just wrong you see.

But the 25cal puzzles me. Maybe it also didn't offer much more ooophm then desired????

Tiriaq, looks like you are well on your way to making noise. Sounds great.

Jerry
 
I feel that the 6mmx45 or 6mmx47 is the cartridge that the US military should have adopted instead of the 223...

I would load it with 85gr to 105gr bullets and I would want a 1 - 10" twist rate...
 
Well, got the barrel work just about finished. Once the tubular handguard w/barrel nut arrive, I'll be able to do final assembly.
With my dialup, posting pictures is slow and painful, about 20+ minutes each. If anyone is interested, pm your email address, and I'll send photos.
 
Barrel is now installed on an upper, index pin in, tubular handguard in place. No gas port yet.
I may test it as is, to get an idea of accuracy, what the 6x45 cartridge is like.
 
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