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Some AR questions

Discussion in 'Rifle Country' started by Perseverance, Nov 5, 2010.

  1. Perseverance

    Perseverance Active Member

    I'm currently in the process of figuring out what upper to buy and I have run across some things that have got me a tad perplexed. Any info from some experienced people would be helpful.

    1. 1/7 twist vs 1/8 twist - I've noticed most people will tend to recommend 1/7 for a battle rifle but I have noticed some manufactures offering and/or using 1/8 barrels (larue for example). Can someone explain what the difference is and if so what makes one better or worse than the other.

    2. Fixed front sight - a rifle I held at a local gun store was equipped with a full length hand gaurd and no fixed front sight. Instead this rifle had flip ups front and rear. I liked this set up, I plan to use a red dot or halo sight. Should I opt for a fixed front sight or the full rail with the flips.

    3. Stock/lower - I'm planning on buying a complete lower since this is my first AR but I have toyed around the idea of buying an empty lower and building it. If I decide to go that route I was wondering what a good tactical stock would be and also if building up the lower is a good idea for a first timer. And also can anyone recommend a lower kit that ha everything I would need?

    I had some more but can't think of them at the moment I'm sure they'll come to me and I'll add them.

    Thanks for all the help guys I know these beginner AR threads can be a tad redundant.
  2. deadduck357

    deadduck357 Well-Known Member

    1) Go with 1/8.

    2) BUIS.

    3) Complete lower (for your first let yourself get use to the design before diving into something you know nothing about).

    3.5) M4 stock(or something simple like a Magpul MOE, you don't want to get to extravagant).

    Try to stay simple for your first, get to know the system, they are modular and you can change whenever.
  3. mljdeckard

    mljdeckard Well-Known Member

    1. The biggest difference between the old M-16 A1, and more current versions, is the bullet used and the rate of twist. They used to use to use 55gr bullets, and 1/12 rifling. They say the intent was to make the bullet just stable enough to be accurate, but still unstable enough that it would yaw and tumble. It was common for the bullets to hit the target sideways at distance. In switching to 62gr bullets with a longer, flatter 'ogive', (the part of the bullet that contacts the rifling in the barrel,) and tightening the rifling to 1/7, they made it more stable, and greatly increased the range of the rifle. If you are building a defensive rifle, and you want to be able to shoot GI ammo, you will likely want the tighter twist. On a defensive rifle, you can still use lighter bullets, (there are many good commercial defensive loads with lighter bullets,) because you are less concerned with accuracy at distance. You will also likely want chrome lining in the chamber and barrel.

    On the other hand, if you are planning on using it for many different purposes, 1/8 or 1/9 can sometimes do a better job of handling lighter bullets. (Most varmint hunters like 55 gr bullets.) Many say that tighter rifling handles the lighter bullets just fine, but honestly I've never seriously tested them for accuracy.

    2. A fixed front sight is pretty optional. Most optics work just fine with a fixed sight, for most configurations, a backup flip-up rear and a fixed front works fine. But, like you see, there a bajillion ways to do this.

    3. Building a lower is so easy you will smack yourself for not doing it sooner. Seriously, your first one might take an hour, with no special tools. What I would recommend, order the free Brownell's AR catalog. (And get on the lists for them and Midway as well to send you their master catalogs.) This way, you can see lower parts kits, which start at about $58, but you can also see other upgrade options you might want to get BEFORE you put all the mil-spec parts on. This way you won't have to build it and then take it back apart again. I'm talking about things like, oversize controls, ambidextrous controls, self-tensioning takedown pins, anti-walk pins, Magpul B.A.D. lever, etc.

    Here's the bad news. As soon as you see how easy it is, you won't stop at one. :)
  4. TonyAngel

    TonyAngel Well-Known Member

    What sort of rifle are you putting together. If you just want to build or buy a standard M4gery, then your choices are going to be limited to either a 1:9 or 1:7 twist. Of the two, it really doesn't matter, unless it is your intention to shoot heavier projectiles, like 69 or 77gr open tips. If this is the case, then the 1:7 is what you'll want. If all you are going to be shooting is cheap M193 or M855 ammo (55gr or 62gr), then you might want to consider the 1:9 twist. The 1:9 will arguably shoot the cheap ammunition better than a 1:7. Cheap ammo with cheap projectiles tend to wobble a bit. The faster you spin them, the more they will wobble, so the slower 1:9 twist rate could be better. The 1:8 barrels that you see are not milspec and are used in "boutique" builds. They are tough, but more expensive and are geared to delivering above average accuracy. 1:7 or 1:8 doesn't matter. Both will shoot the MK262 round (military 77gr load) that everyone seems to be enamoured with these days. Of course, the 1:8 may arguably shoot the cheap stuff better than the 1:7, but not quite as well at the 1:9. 1:8 is a good compromise twist, but is not available in "milspec" type barrels.

    As for the front sight, I prefer a flip up front, just so that it isn't in the way of the optic. This doesn't mean that you need to get a rifle with a rail. It only means that you need a gas block with a rail section on it for the front sight. Then you can put anything you want on it. Rails are nice, but I've found them to be uncomfortable and often bulky. Don't get 'em if you don't need 'em. A free float tube could do you just as nicely and cost you a whole lot less. I use tubes and just drill and tap them and add rail sections if I need them.

    As for the complete lower, I think you should just buy a complete rifle. The fact that you referred to a stripped lower as an "empty lower" speaks volumes. Get a rifle and learn it. Maybe build your next one. Call either Bravo Company or Spike's Tactical, tell them what you want with a budget number and let them build you something. Or...you could just buy an off the rack upper from one of those places, then buy a lower and slap them together. If interested in the Spike's, check out Aimsurplus.com They actually have better prices on Spike's stuff than Spike's does and they ship more quickly, if they have it in stock.

    As for the stock, pick the one that looks the coolest or feels the best to you. You could opt for a standard M4 which is the cheapest or a Magpul MOE at around $60. I'm running a Magpul UBR. I think I paid $250 for it. Check out the offerings from Vltor too.
  5. kwelz

    kwelz Well-Known Member

    Once again this is personal preference. I buy complete, build them, or even have them built depending on how much time I have and what the requirements are.

    Suggesting a stock is a bit difficult without knowing the intended purpose of the rifle. However it sounds like you just want a good all round carbine. That being the case I suggest you either stay with a normal M4 Stock, get a Magpul CTR, or get a VLTOR IMod.
    All of my M4 style guns have either the CTR or IMod and my SPR guns use EMODS
  6. Varob

    Varob Well-Known Member

    Spikes is running there complete lower with a M4 style stock for $250.00 + shp and FFL fees. Just under $300.00
  7. GunTech

    GunTech Well-Known Member

    The main reason the military went with 1:7 is to stabilize tracers. 1:9 will stabilize M855 ball just fine. The reason that many makers use 1:9 is that it works well with both 55gn and 62gn milsurp. If you are going to shoot exclusively heavier bullets, 1:8 or 1:7 if you are going to shoot really heavy bullets.

    Bullet dispersion by bullet weight with various rifling twists:

  8. Sky

    Sky Well-Known Member

    I have a flip up standby front sight mounted on a Bushmaster Predator.

    The sight cost $106 and mounts on the gas block.

    If you flip the sight up and it locks there is still a slightly larger than infinitesimal amount of fore and aft movement.

    Now when sighting in your iron sights your elevation is adjusted with the front sight. One small turn gives you X moa at X yards. The flip up is not nearly as rigid as a fixed sight. It's OK for a back up and works but to me it is not nearly as accurate or consistent as a fixed sight.

    Fixed front sights co-witness with red dots and really never bother optics as far as field of view or shadowing in my experience. They could (I suppose) depending on what type of optic you were to use but I doubt it will ever be a problem for you.
  9. Tirod

    Tirod Well-Known Member

    What the market offers right now is based on the M4gery fad, which leads in sales. It's not necessarily what will work best for you.

    Problem areas include: carbine gas on a 16" barrel. It works, but midlength is better, and the more appropriate type. People by carbine gas because they want the look of the issue gun, with short handguards. Unfortunately, those came with 14.5" barrels, which require some BATF paperwork to legally own. So they get 16", which makes the action run harsher due to higher pressures. Don't do it, you can't have burst/full auto anyway, get it so it will run the better way.

    Quad rail fore ends: with 40-48" of picitinny rail. Even the supplier to the military of quad rails is quoted on record as saying the average shooter would be better off avoiding them. It's an institutional compromise to offer the maximum options to different users across DOD, who mount old school tech optics with bulky inefficient battery packs. Once that is all clamped on, you have to use a vertical foregrip to hold it up. Avoid the problem, get regular handguards or a tube that accepts bolt on rail pieces. It will be lighter, more user friendly, and possibly quite a bit cheaper.

    Adjustable stocks: Another compromise, largely due to the use of armor and the acceptance of techniques like squared up shooting because the armor doesn't work that well. If you wear armor on a daily basis, get the M4 adjustable. Otherwise, you're better off with an A1 or A2 issue rifle stock, which has a better cheek weld and helps the shooters comfort in year round use. The M16A4 is still in production, most issue weapons are at least A2 pattern, not M4, including the Designated Marksman rifles. Fixed is the tactical stock, not the M4, when you count the numbers.

    There is even a growing opinion the M4 was better left to the Log and Command types to use, like the M1 Carbine in it's day. Combat soldiers on patrol could use the M16 pattern to better affect, with it's longer barrel and ballistics. The obviously misused HMMV as a combat troop carrier, plus all the door knocker and street patrol duty in Iraq are what contributed to the M4's popularity. Afghanistan, not so much. That may change, tho, the game seems to be moving back into town.

    One other consideration is caliber. If someone shoots hundreds or thousands of rounds of ammo yearly, stick to military calibers simply for the cost savings. Using a taxpayer supported caliber with cheap surplus and reject ammo on the market makes financial sense. But if much less ammo will be shot, or reloading is part of the plan, consider an alternative caliber. There are benefits to using something bigger or faster, such as the .300 BLK by AAC, or the 6.8SPC. Either will deliver quite a few more footpounds of force, without a lot of reengineering or expense. The results seem to be preferred if using a short barreled weapon, or hunting in mind.

  10. W.E.G.

    W.E.G. Well-Known Member

    I shot a bunch of 55-grain surplus through a Bushmaster 1:8 barrel at 200-yard SR targets a couple weeks ago. While I don't think the 55's are going to win matches, I found the accuracy to be quite decent. Not like the bullets were flying around the target like buckshot. For offhand practice, I cannot tell the difference between the 55's and the heavy-bullet Cadillac ammo. Shots that I called "center" were in the 10 ring. My crappy shots went where I saw the sights go.

  11. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

    As Azzia said, it just depends on what length bullet you want to shoot. The faster twists will shoot shorter (lighter) bullets; but can spin apart lightweight, thin-jacketed bullets travelling above 3,200fps.

    This is a commonly held belief; but it is not true. None of the twist rates used in the AR15 (1:14 through 1:6.5) are anywhere near what you would need to stabilize a bullet in a human body. The twist rate of the 1:14 spins a bullet at around 165,000 rotations per minute. A 1:7 is 330,000rpm. In order to spin-stabilize a bullet in something with 1,000 times the density of air, you would need to spin it at 95,000,000-100,000,000rpm.

    The benefit to the fixed front sight is that it is pinned instead of clamped or set-screwed and it is always up when you need. The downside is that it is up when you don't need it as well. The pinning means it will be very difficult for the gas block to shift and turn your rifle into a straight-pull bolt action. For most recreational use, pinning is way more than you need. If you are going into a house with someone shooting at you and you wack the front sight on a stone doorframe as you run full-speed with 60lbs of gear on.... the pinned sight base can be a good idea.

    The first thing to think about when you choose a stock is how you want to shoot? Are you shooting for groups from a standing position in a local High Power competition? Or are you shooting while moving in an IPSC 3-gun competition/defensive carbine course? Doing a little of both?

    High Power is going to favor a very solid stock, with a good cheek weld and a longer length of pull. 3-gun is going to favor a stock with a good cheekweld and a short length of pull. A little of both means you need an adjustable stock. For a good affordable, compromise, I think the Magpul MOE is a good buy. It will do both jobs adequately and is cheap enough that you can replace it later when you've got some rounds downrange and know what your personal preference is.
  12. GunTech

    GunTech Well-Known Member

    Just a note on the 14 vs 16 bbl. You can use a 14inch barrel as long as you use a permanently fixed flash hider or muzzle brake that brings OAL to 16 inches - brazing or blind pin. I did this because I happened to get a bunch of M4 barrels at a very good price.

    Tirod did a nice job of hitting the salient point of the 'one size fits all' AR vs the purpose built gun. If you are building a gun, why not tailor it to what you need rather than to every single possible use.
  13. benEzra

    benEzra Moderator Emeritus

    Eh, I'm going to disagree with this one. I don't wear armor (nor do I own any), but I do find that there is no single "right" stock length for me; it varies depending on what I'm doing and what I'm wearing. I run the stock anywhere from full short to two clicks out, so the fixed stock would be too long for me for most uses anyway.

    FWIW, there are adjustable stocks on the market that give better cheek welds than the M4 style and are suitable for precision shooting.
  14. mljdeckard

    mljdeckard Well-Known Member

    I agree with Ben. I have found that if you have the adjustable stock, you have the option. Also, I often have petite females or youths shooting my rifles, and the adjustability is good to have.
  15. Zerodefect

    Zerodefect Well-Known Member

  16. Perseverance

    Perseverance Active Member

    Once again I am so impressed with the level of professionalism and information on this forum, this is definetly the best source for firearms topics.

    To clarify a bit my plan is to run a 16" barrel with a mid-length gas system, as other have mentioned this is good platform and will yeild good reliabilty which is paramount for me.

    As far as ammo is concerned I'm in a bit of a grey area, the rifles current role will be mainly tactical/home defense/target shooting. In the future down the line match shooting may be on the horizon but my thinking is that I may be building a more purpose built rifle for that indevour.

    I'm planning on spending my money in the upper, the lower will probably be a budget job but I want the upper to be top notch. I've been looking seriously at the LaRue uppers, either the tactical with the fixed front or the stealth sniper with a 12" rail. Both these set-ups utilize ss barrels in 1/8 twist. I'm feeling like I may be going overkill for a defensive weapon system but I'd like as much accuracy and reliability as I can get without getting to ridiculous.

    I also saw a BCM upper group that consisted of a Vltor Mur upper and a hammer forged barrel mid length system that looked nice. Came equipped with a DD 12" lite rail for around the same price a the larue units.
  17. benEzra

    benEzra Moderator Emeritus

    Personally, for reliability and durability I would prefer a chrome lined (or nitrided) barrel over a stainless barrel. Stainless is great for match guns, but IMO most guns intended for LE or defensive use go with lined barrels of some sort.

    I think the BCM midlength upper is a very good option.
  18. Al Thompson

    Al Thompson Moderator Staff Member

    Agree. I have two and they run like sewing machines. :) I would advise getting the pencil barrel over the M4 profile, wish I had. Next one will be lightweight.

    Either the Magpul MOE or with some careful shopping, a M16A1 stock is very good value for the money.

    Get some Pmags for feeding your critter and good lube. I like Slip 2000 or Slip EWL, but type is less important than simply keeping it wet.

  19. Quentin

    Quentin Well-Known Member

    Great information above already and I won't comment on the upper as it seems you're already headed in a good direction.

    For the lower, I would build it - and use good parts like a Stag or Daniel Defense LPK and BCM 7075-T6 receiver extension/M4 stock kit/H-buffer. As far as the stripped lower, most are good but consider paying a little more to get a roll mark you'll be proud of since the extra cost is a drop in the bucket compared to the total cost of the rifle. As other have said it's not that hard to build the lower and the main reason to do it is to have complete control over what parts go in it. Don't go cheap here, get quality parts.

    Another option on the lower if you want to cut cost is buy a $270 blemished complete lower from BCM since the parts are top notch and the blemish will be forgotten once you add matching ones yourself.
  20. Perseverance

    Perseverance Active Member

    So is a stainless barrel considered "not good" for a combat rifle? Or is it just considered overkill and too expensive for a tactical rifle. Most of what I've heard says that that the ss barrels are more accurate and last longer so I can't see how this could be a disadvantage. I could very well be wrong and if I am by all means educate me.

    If you didn't have a budget for a defensive AR would you choose a ss barrel?

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