AR COMP & 308

[Rtheurer]

Liltank You inspired me to go out and do a test. I went to the man cave and loaded some ammo for a 308 Tactical rifle that I have. Its a copy of the Army M24 with the exception of having a 6.5X20 LRT with M1 knobs on it. Everything else is the same right down to the 24.5" Rock Creek 5R barrel. 11.25 twist. HS stock Iron sight bases.. ect ect.

Loading components are: 9X fired Lapua Brass, Tula Large Rifle primer, .001 neck tension, Powder measured to the kernal on a Denver Inst lab scale. Berger 175gr BT Long Range bullet. jumping .0015 to the lands.
This is the first time out with the Berger. My usual load is Varget and 175gr Sierra.

Right off I noticed the ES and SD numbers are real good. I tested four loads 43gr, 44gr, 44.5gr and 45gr. with SD of 8, 2, 5, & 8 respectively. Thats a big load range with that good SD across the board I thought.

This Chamber is the M852 Chamber and has a pretty long throat and the bullets are seated WAY out there. the OAL is 3.00" just barely in the case and the base of the bullet right at the shoulder NK junction. This left some room for and kept the pressure down a little. At 45gr was about max as i started to get a little harder bolt lift and slight signs of ejector marks. At 44 and 44.5gr there was non at all. Temp was 54* and Humidity @90% recorded by a kestral 3000.

all groups are five shot groups, from a bench. Let me say Im NOT a benchrest shooter and this is no bench gun. Its a tactical Field rifle and gets shot that way.

Any gun that shows a group in the .2's is a good starting point for further investigation. 5 rounds dont prove a thing. But you can bet Ill be looking at this load again.

 

[liltank]

I'm surprised you could go that high in grain weight. It seemed a 43.5 was my limit for the 168's and I saw primers start to flatten. I also started to notice cratering with tight bolt lift. Do you just neck size for full length size? Don't know if I posted the pic here or not, but this past Tuesday I printed a 1.5" group at 718yds. ;D

Tank

 

[Rtheurer]

I ussually Full Length size with a Die that closely matches my chamber. In this case however I just used the Forster bump bushing die and plucked a few cases from My Palma rifle box of shells to use in the test. I have a bunch of new brass (600 pieces) now after the Australia trip so these old 9X fired brass is getting moved over to the Tactical rifle which sees little use.

As far as powder charges, keep in mind my LOOONG throat ( freebore) The bullet is just hanging on in the case mouth. maybe only a 1/4 of the neck holding the bearing surface of the bullet.

Talked to a couple of 600 yard bench rest guys today and mentioned my ES and SD numbers... alot of heads nodding up and down in aggreement. Good SD numbers and a good accuracy node = good CONSISTANT long range loads. ( 600 to 1000 and beyond) As you very well proved in your very very nice picture.

Bad part about this load is the long cartridge length. I will not be able to stick these in a Magazine. Single feed only as they are too long.

RussT

 

[jscandale]

When you loaded the AR Comp. what percentage did you back off from the RL 15 loads?

JS

 

[A_Gamehog]

Let me say Im NOT a benchrest shooter and this is no bench gun

With single digit SD's you really "know how to load", very few are able to do that.

Congrats

 

[Rtheurer]

JS

I scaled it back 5%. In hind sight I should have gone a little more. Not that this load was hot by anymeans in my rifle. Look at Tank's.. he mentioned he was about max at that 43gr area with a bullet of lesser weight ( 165 class) Looking at my data Im getting about the same speed as Varget with one grain less powder. This could and might very well change with the bullet seated farther into the case as the load gets closer to being compressed. In past experience it has anyway.

G Hog
Just got lucky this time out... blind hog some nuts or something ; ) Ha.

Just cleaned up this rifle and Borescoped it. Throat looks almost new yet. All squeeky clean with a thin coat of protective lube inside ready for winter hibernation.

RussT

 

[jscandale]

Russ,

5% is exactly what I was thinking after looking at the loading tables. I am going to try it in a new wildcat developed for the AR tomorrow morning. I'll let you know what happens.

JS

 

[jscandale]

Russ,

I just got back from the range and used up some AR Comp in comparison to my steady favorite, RL15. I did scale back 5% as a baseline and got some very pleasing results. In fact, I got slightly higher velocity than the RL15 of greater charge weight with no noticeable pressure signs. I am pretty optimistic about this new powder so far considering I am working with relatively small case capacity of around 30-32 grains of powder weight.

JS

 

[Rtheurer]

JS

Good deal. Is this something thats being produced like the RAT or Turbo 40 AR? Or something completely difrent? I was really thinking hard about doing a 6mm on my AR Match rifle... I sat down and added up the pros and cons, the out come for ME was to stay with the 223 version. Or atleast for now, maybe down the road Ill chamber it in a 6mm of some sort. I finished pretty good in the HM class at Perry this year using it against 6mm, 6.5mm and who knows what else. This current barrel may last a while yet so when the time comes Ill make that descision then.

How did the SD's look, Better -about the same- or worse than the R15 loads?

RussT

 

[jscandale]

Russ,

This is a cartridge that John Holliger and I have been collaborating on for about 6 months. We are calling it the 6mm WOA Imp. The 6mm WOA is a 6.8 Spc necked down to 6mm, the improved version is nothing more than the standard Ackley improvement of pushing the shoulder forward and changing the shoulder angle to 40 degrees. The standard WOA is very good and Carl Bernosky shoots it very well here in some local matches, but it doesnt have the capacity of the Hagar which will yield 2900 fps which he takes to nationals. I shot the team match this year at Perry with Carl and practice with him sometimes at our local club and I can tell you that I am convinced the 6mm is the way to go. I have also had a 6 Hagar and it shot fantastic, but brass was a problem, but it is currently underway and hopefully without a hitch. I am confident that the Hagar brass will be available by next spring due to who is making it happen this time around. At least I sure hope so, cause I just got the reamer. I would like to start chambering in both calibers. Currently the SPC brass is available from multiple manufactures. I am currently using Hornady.

Before the brass deal came together for the Hagar, the WOA Imp got started. So far, I am very happy with the results of the Improved cartridge due to the case capacity of about 32 (correction, 29.5) grains of powder. Other than more meat on the bolt and less bolt thrust, the reason we went with the .421 case head size rather than just using the several Grendel based cartridges was to eliminated the feeding problems sometimes associated with the larger head diameter. I have no personal experience with it but have friends who have and have admitted to feeding problems. As you know, even the hint of a feeding problem is a no go for a course gun. So, the 6mm WOA Imp was born on this day.

JS

 

[Rtheurer]

Dont you like it when you write something only to have the internet disconnect right when you post.. Arrrgh.

JS

Very intresting, I have always liked the thought of using the 6.8 case in a AR platform. Just not in 6.8. A 6mm or 22 version has always intrieged me.

I would think with that case capacity that a smaller kernal powder would be of an advantage. Something like XBR 8208, AR Comp, even Leverevolution, which the later proved to gain some velocity in my Palma rifle with the same load in the standard Varget/ 2156 Lapua, CCI load. If memory serves me right it was ~ 70fps faster with Leverevolution. The Kernals are a real small extruded design looking through a magnifying glass, and look just like Hodgdon Super performance.

FlatLander is playing with the Magpro Series here soon if not already and Im excited to see his results too.

Good Gosh what is with all the propellant choices now??? Remember when you took your 308 Match rifle and loaded IMR 4895 or 4064 into a LC case and put a 168gr SMK on top and went and shot! Its like going to a resterant with huge menu..

I played with the 95gr Sierra Match king. After seeing it i thought what a wonderful looking bullet from the Sierra plant. Perfect for application at 200 and 300. Even 600 if you have a easy range to shoot at.

Russ T

 

[jscandale]

Yes, there are tons of choices these days. Tough to make a decision on them.

I have had cartridges like tis in .22 cal. I had a .22PDK. Couldn't get it to shoot very well, and had a .220 Thunderbolt which shot very well. The later was of my own curiosity and was simply a 6 Hagar necked down to 22. Shot like it had eyes, but again, the brass problem.

Now that I have some shoulders blown out as in the picture above, I am looking forward to loading to full capacity with both RL15 and AR comp with the 107 Sierra.

JS

 

[liltank]

I'm kind of interested in your WOA. Sounds like a cool caliber. Never heard of the 6 Hagar. Didn't know it existed. Not to up to date on all the bench wild cats.

Tank

 

[jscandale]

I'm kind of interested in your WOA. Sounds like a cool caliber. Never heard of the 6 Hagar. Didn't know it existed. Not to up to date on all the bench wild cats.

Tank

Tank,

Actually, this cartridge and others like it are designed for across the course use in an AR15 platform which is kind of limited on the length and diameter. After all, the AR was designed for the much smaller .223.
So far, I am pretty optimistic with this caliber, but only time and testing will tell.

JS

 

[liltank]

Tank,

Actually, this cartridge and others like it are designed for across the course use in an AR15 platform which is kind of limited on the length and diameter. After all, the AR was designed for the much smaller .223.
So far, I am pretty optimistic with this caliber, but only time and testing will tell.

JS

Can't wait to hear the results. Looks like it could make for an interesting little carry bolt gun too.

Tank

 

[spclark]

Russ,

This is a cartridge that John Holliger and I have been collaborating on for about 6 months. We are calling it the 6mm WOA Imp. The 6mm WOA is a 6.8 Spc necked down to 6mm, the improved version is nothing more than the standard Ackley improvement of pushing the shoulder forward and changing the shoulder angle to 40 degrees. (snip) I have also had a 6 Hagar and it shot fantastic, but brass was a problem, but it is currently underway and hopefully without a hitch.

Before the brass deal came together for the Hagar, the WOA Imp got started.

Yeah, the brass issue was what prompted me to order up a re-barrel in 6RAT late last year from John H. Preserve what accurate barrel life remains on my WOA 6HAGAR upper and the stash of Jamison brass I have on hand as long as possible.

Attached is the photo I took a year ago September when I was toying with the idea of making 'short' 6HAGAR-capacity cases out of 6.8SPC. Problem here is shooting this stuff in a 6HAGAR chamber would pretty quickly toast the chamber throat I fear, precluding use of the real thing later on. Then there's the investment in a new reamer and dies, which I was unwilling to undertake on my own.

News that 'factory' 6HAGAR brass will become available sometime early next year changes all the plans. I suspect we'll see a lot more of them in the field once the brass issue is history.

In this pic, a full-length 6HAGAR case is on the left, a 6.8 SPC case with a false shoulder formed to 6mm at the point where it ought to be to fire-form to 6HAGAR. Neck's about 0.070" shorter as shown but no less than that of the 6RAT & some others.

 

[jscandale]

Yeah, once the brass arrives, the Hagar will thrive. It truly is a good cartridge worthy of the effort especially when the brass comes through. Hornady is now contracted to make the brass, and they make an excellent product from what I have seen so far. I am using Hornady brass for this 6mm WOA Improved and it forms and sizes very nicely. I would say as good as Lapua at this point. I am still going to move forward with this cartridge even when the Hagar brass is available. I plan on chambering for both cartridges and so does John Holliger. It will probably be available in the spring.

Just to be clear, I am not promoting a race between the cartridges, I hope that they both get an audience.

JS

 

[liltank]

So what are the differences between the performance of the Hagar, WOA, and 6mmAR (6x223??? Right?)?

Tank

 

[jscandale]

Tank,

The major differences between the cartridges that you listed are:

The Hagar is a case that was based off of the old .30 Remington (.421 dia). It was shortened and necked down to 6mm. The big show stopper there was the making of the brass, huge pain in the butt, but Hornady is now on board for making brass for this cartridge which should be available in the spring. It is arguably the king of the hill for the 6mm AR15 platform based cartridges.

The 6mm WOA is a cartridge that John Holliger of White oak Precision developed that just necked a readily available 6.8 SPC (.421 dia) down to 6 mm and shoot it. Good cartridge, shoots great, and brass is o' plenty from multiple sources. It is about 150 fps slower than the Hagar, but is capable of extreme accuracy.

The 6mm WOA Improved (.421 dia) is nothing more than the 6mm WOA with the shoulder blown forward and increased from 30 to 40 degrees. No rocket science here, just more powder in the case. John and I have been in collaboration on this since the summer and so far its been a real success in testing. It ought to rival the Hagar in velocity, but the big advantage is, like the standard WOA, brass available from several sources and forming is not a problem. I particularly like Hornady brass for it's high quality and small primer. I will be trying Remington brass next week. Silver State, not so much, too much variation in QC which resulted in cracking and splitting.

The 6mm AR & 6mm Rat are cartridges based on the 6mm PPC or parent case, 7.62x39 Russian. Its base diameter is .445". These also shoot very well. In fact, I think its pretty hard not to get a 6 mm not to shoot well. I have no experience with any of the cartridges based on the 6 PPC case, however, I know people who are very please with their performance although they are slightly slower than the Hagar, but I think to lean on that fact would be splitting hairs.

The 6mm/.223 (6x45) is simply a .223 case necked up to 6mm. Same shoulder angle and headspace. It also displays very good accuracy, but pales in comparison in velocity to the larger cartridges due to the limited powder capacity. That said, I have a friend who uses it across the course and does very well, however he is a very good shooter who knows how to read wind. Easy to load and brass is made by everybody!

The physical advantages that I see from using a .421 base diameter cartridge over the .445 base diameter is feeding and bolt strength. It doesn't sound like much, but that extra .024" means a lot when you are increasing the feed angle from the mag to the breech. I have never had a feeding issue from a .421 diameter based cartridge (I have had 5 in total) while using a mag designed for the popular 6.8 SPC. Also the bolt of a .421 dia cartridge has more meat in it which results in less lug breakage (AR15 bolt lugs). I have seen broken bolts and it ain't something I want. With that said, keep in mind the 7.62x39 is has enjoyed success among shooters for several years, but it does operate on a slightly lower operating pressure.

I'm sure all of this is open to conjecture and varying opinion, but I am trying to keep this as factual as can be. I hope this was informative and answers your question.

JS

 

[jscandale]

To stay within the bounds of the thread title, I am very optimistic that AR Comp will prove to be a great powder for all of these small AR type 6mm cartridges. So far, so good. 8)

JS