What about barrels?

Jerry, I owe you an appology.

I've looked at it and played around with loading the longer bullets to mag length with dummy rounds but disregarded it as too unsafe to even try (also basing that on what manufacturers print).

Several questions remain though.
The SL8 - Are you using AR mags with a max. oal of 2.260" or are the HK mags similar to the sig ones and you can load a fair amount longer (sig mags allow around 2.330")?

Do you have any idea of the presures these loads are producing?

What muzzle velocities are you obtaining with benchmark?
 
The 10rds LAR mags were used so standard AR OAL.

The pressures must have been well within normal spec cause the ejected cases landed a few feet from the rifle in a nice pile. Zero dings or stretching so must be working at expected port pressures and cycling speeds. Cases were reloaded several times without problems.

We never Chronied the loads but given the drop, was within expected velocity norms.

My SWAG would be around 2800 to 2900fps. SAAMI max would be 2950fps.

Give it a try. I never would have believed it could work so well but there it was dropping bullet after bullet on a small target at 1000m.

When working up, go in very small powder increments. 0.2gr is the normal step. When you find a good load, go around that load in 0.1gr increments to fine tune. Semi's can be real finicky about load pressures.

Jerry
 
Jerry I am concerned that while it shows no outward signs of overpressure in the SL8 the oposite could be true in the Direct Inpingment system of the AR 15.This could result in at worst a Catastrpohic Failure as the dwell time of powder's burn rate becomes a factor in the DI guns.
 
That is why you start low and work up your loads slowly looking for pressure signs.

The AR's across NA have digested factory ammo in the billions of rds. NONE is designed specifically for gas guns yet, these rifles just keep popping along.

As long as the ammo is kept within SAAMI specs, which also mimics NATO specs, you shouldn't have a problem. The gas system was designed around modern powders and pressures.

Only when shooters feel their gonzo bolt rifle loads can work in a gas gun, will they run into serious trouble.

Using commercial factory ammo in an AR is a whole lot better then using commercial in a M1A/M305.

Jerry
 
SAAMI and NATO pressures are not identical.

Any barrel longer than 20" in an AR is foolish - the receiver starts to flex - this can also happen with very heavy 18-20 barrels.

16.5" barrel with a midlenth gas system in a 5.56mm/.223 Wylde Chamber in 1:7 is about the ideal General Purpose AR barrel you can produce.


I doubt anyone is going to go out and by a
 
KevinB said:
Any barrel longer than 20" in an AR is foolish - the receiver starts to flex - this can also happen with very heavy 18-20 barrels.
Click to expand...
Target guys run thick-walled uppers (from DPMS, JP, and so on) - I figure this effectively allows for longer barrels.

For general purpose with a stock-dimensioned upper, I'll go with your 20" max.
 
A little off topic but my name was mentioned

I had problems trying to fit the heavier bullets in my 223 cases. I had a full sizing die to begin with but the cases would not hold the bullet pushed in for mag length. I then got a collet necksizing die and it provided enough tension to grip the tapered surface. Thanks to Jerry's suggestion.

I tried the SMK 77's but I think the AMax 75's are the best. I shoot them out of my HK SL-8 and my Tavor...both 1:7 twist. I was last shooting my Tavor, with the stock red dot, out to 700 yards. Jerry will atest to its amazing accuracy. I was on a rest, sitting but still I did not expect to be so close on target. The only restriction was my old eyes trying to see the target. The HK did better when I took off the fore end and tripod. I then rested on the solid frame, not the barrel. Still, its not a benchrest gun but can push to 1000 yards no problem. Lots of fun.

With my powder load I didn't get any case dents but with the commercial 55 grain ammo I got a small ding from ejecting.

bulletsJan2009_1.jpg


bulletsJan2009.jpg


bulletsJan2009_2.jpg
 
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GR, those two rifles should not shoot anywhere near as good as they are. Sure, we may be 'gifted' shooters but still. Very impressed.

Praying for more warm weather so things can melt and we can get out there again.

As for longer barrels being foolished, there seems to be hundreds of service rifle shooters who don't think so. Seems to work for them and their set ups.

And as for pressures specs, you are absolutely right. NATO specs are substantially HIGHER (62,366psi) given how it is measured. SAAMI holds to 55,000psi. Why 223 ammo should never cause your AR a problem unless there is something seriously screwy in the gun.

Also, the NATO leade is much longer rendering the 223 ammo a lower pressure at firing.

http://en.wikipedia.org/wiki/5.56x45mm_NATO

You guys might get a kick out of this.

By the way, this is about barrels so let's get at it. Who wants them? Who wants to make them? Lots of blanks to offer at inexpensive pricing.

Jerry
 
General Ripper said:
I had problems trying to fit the heavier bullets in my 223 cases. I had a full sizing die to begin with but the cases would not hold the bullet pushed in for mag length. I then got a collet necksizing die and it provided enough tension to grip the tapered surface. Thanks to Jerry's suggestion.

bulletsJan2009_2.jpg
Click to expand...


So you are not full length sizing, and just neck sizing?
It also looks from the photos that there is no crimp on the bullet; is it just neck tension holding it in the case?
Can you even place a crimp on a 75 amax at that oal?
Is the powder compressed?
Are you at all concerned with bullet setback?
 
Gents:

I find this discussion on reloading very informative and helpful. I would very much like to see this discussion continued, however with out trying to be the hall monitor, perhaps it is better continued in another thread.

Respectfully your

AbH
 
AbHobbyist said:
Gents:

I find this discussion on reloading very informative and helpful. I would very much like to see this discussion continued, however with out trying to be the hall monitor, perhaps it is better continued in another thread.

Respectfully your

AbH
Click to expand...

Agreed, perhaps a mod could split the posts into another thread?
 
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