Thanks Fritz...

The 5.56 chambering is a must, so I will have to give up a little accuracy there. My brother was very specific that he wants/needs to be able to run good quality/self-defense 5.56 ammo through this gun. He wants that versatility.

If this were a pure target gun, we would have gone with a bolt gun in a different caliber I believe.

Have the two of you chrono'd comparable 5.56 and .223 ammo side-by-side in the same rifles? Then have you run the ballistics, say through JBM? Have you compared down-range accuracy and flight?

Fritz and crew know way more than me.

But if you are running bulk off the shelf ammo through it. Take that into account. I would never buy a super high end barrel just to run $0.30 a round bulk ammo through it.

I would only buy a Shilen, Krieger or some other $500 barrel if I was going to be running hand loads/Match ammo through it.

Right now we do not load. I am considering getting a Dillion 650 and learning to load, but that will not be until fall.

We will use high end, match grade factory ammo for shooting groups. We will try several different types to find what the gun likes best.

For a self-defense loading, my brother will use a high-end factory load like TAP, Gold Dot or some other reputable factory loading.

We will not be using Federal bulk, steel cased or any other cheap stuff through this barrel. I know better than that. I have PSA uppers for training and running crap ammo through. I also have Colt, Noveske and other uppers/rifles that only eat quality ammo.

quote:

Originally posted by bozman:
We will use high end, match grade factory ammo for shooting groups. We will try several different types to find what the gun likes best.

For a self-defense loading, my brother will use a high-end factory load like TAP, Gold Dot or some other reputable factory loading.

The TAP line appears to have been phased out of Hornady's line. I've shot both 5.56 and .223 factory loads of TAP, with both 55 and 75 grain bullets. The 223 loads were noticeably more accurate than the 5.56 loads for me. Most likely the additional velocity made the accuracy worse -- and this was in guns chambered for 5.56. The 5.56 loads' additional powder effectively acted like adding 3-4" of barrel length, compared to 223 loads. I felt the additional velocity of the 5.56 wasn't a noticeable advantage -- both in down range target ballistics and in close range self defense situations.

I have not shot ammo loaded with Gold Dot bullets. But a quick search on the webz shows the majority of Gold Dot factory loads are 223, not 5.56.

Factory 5.56 loads seem to be gravitating to a small selection of bullets. Generally 55/62 FMJ, 62 green tip, 69 HPBT, 77 HPBT. The 55 & 62 grain bullets aren't optimal for HD, IMO. The 69 & 77 would work, however I don't see any realistic advantage over similar 223 loads for HD. From an accuracy standpoint, I've shot Black Hills' versions of 69 & 77 match loads, comparing 223 to 5.56 -- the 223 loads were better.

What I'm saying is that unless one desires higher muzzle velocity 55 or 62 grain FMJ loads (my rifles clock a 125-150 fps MV increase), I don't really see any real advantage to 5.56 loads.

Now for a hand loader who really wants to maximize velocity from a 223 bore, then the 223 Ackley Improved chamber makes sense. Not certain that the 223 AI works in an AR, however.

Fritz... I appreciate the info. Like I said, my brother has 1 rifle currently that is chambered in 5.56. Most of the ammo he has now is 5.56 (except for a case of Wolf Gold I gave him when I gave him the rifle for blasting/plinking that is marked as a .223 loading).

He wants to be able to run 5.56 through the new gun if needed. So a 5.56 compatible chamber is one of his criteria. He does have a good quantity of IMI 77 gr and 69 gr ammo as well as some Gorrilla, Black Hills, and others (mostly OTM bullets of different weights). He likes these loadings as they are giving him decent results in his current gun.

I am not arguing that .223 chamber may provide better overall accuracy, but this is one place he did not want to compromise on. So, I need a chamber compatible with 5.56 pressures.

After we get done with this gun, then he may decide to go for more accuracy with a different gun and chambering.

quote:

Originally posted by bozman:
He wants to be able to run 5.56 through the new gun if needed. So a 5.56 compatible chamber is one of his criteria. He does have a good quantity of IMI 77 gr and 69 gr ammo as well as some Gorrilla, Black Hills, and others (mostly OTM bullets of different weights). He likes these loadings as they are giving him decent results in his current gun.

I am not arguing that .223 chamber may provide better overall accuracy, but this is one place he did not want to compromise on. So, I need a chamber compatible with 5.56 pressures.

After we get done with this gun, then he may decide to go for more accuracy with a different gun and chambering.

The .223 Wylde chamber would allow him to safely shoot both .223 or 5.56 ammo. And since the Wylde chamber is usually more accurate than a 5.56, almost a no brainer.

Update on the SPR build...

I will have the barrel, BCG and rail on Monday.

I went with the White Oak Armament 18" SPR barrel with a 1/7 twist (with a Wylde chamber). I had it bead blasted along with the low profile stainless gas block (performed by White Oak Precision, who also test fit and double dimpled the barrel for the gas blocks).

I went with the BCM BCG for now, but may upgrade that with a coated/plated BCG in the future. I have been reading a lot about upper end/high cost BCG's and my head is spinning. Not sure what to make of all of the reviews and opinions about the various offerings. I have always used Colt, BCM, Noveske or PSA Premium in the past. Not sure I really need to look any further than those, but opinions would be appreciated.

For the rail I went with the Geissele Mark 4, 15" in Desert Dirt. Even though I am using a billet upper, it appeared to me that Geissele had changed their Mark 4 design based on the pictures on their website. I called and confirmed that they have removed the lower anti-rotation tabs from the design and have moved them to the top (like most other rails). My Mega upper is milled to accept anti-rotation tabs at the top of the upper, so I will probably not have to modify the rail as has been required with the old style Mark 4 and most billet uppers.

I will be putting everything together on the 12th with my brother.

Everything above I purchased in sets of 2 because both me and my brother are building identical rifles.

Last 2 items I need are a bipod and a 1-8 scope (or better) with a good reticle and exposed turrets. For bipods I am looking real hard at Atlas, but I have no experience, so thoughts would be appreciated.

As for scope, I have no clue. I want a value scope and will want to stay under $1,200 or so (I already have a NF NX 3.5-15×50 on my LMT MWS, so I don’t need another high dollar scope as I do not make a living shooting things/bad guys).

So… that is where I am at as of today. I will update the post and provide pictures after we put the guns together.

Again, any thoughts on bipods, value scopes or plated/coated BCG’s would be appreciated.

Excellent choice on the WOA 18" SPR barrel. You will not be disappointed. I paired mine with a 2.5-10 Vortex PST and enjoy cutting tiny little holes at 200 and 300 yards with ease.

honestly, I dont get what all the hype is about with the atlas bipods besides being able to cant them forward. I just put one on a rifle and compared to say a harris, I don't really see the appeal for 3x the money.