AR-15 Build Advice Sought

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10 years 10 months ago #33213 by SOC
Replied by SOC on topic AR-15 Build Advice Sought
Sorry to contradict OleCowboy, but here goes.

You want as much twist for a short barreled rifle round as possible especially if you want to use bullets like the 77gn SMK, 75gn Hornady or 80gn Berger.

The twist desired for a bullet depends on the bullets length and speed.

Since your getting less speed from a short barrel the bullet won't be spinning as fast.

Bullet WEIGHT has little to do with stability.

This is why short fat pistol bullets use less twist than rifle bullets of the same weight.

I have seen bullets fired so fast at such a high rate of spin that they don't survive to hit the target, but I have never seen a loss of stability due to "too much" spin. I have looked at many claims of such but once examined in person or via pictures it always turned out there was another reason for stability issues, NOT "too much twist."

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10 years 10 months ago #33215 by jtallen83
Replied by jtallen83 on topic AR-15 Build Advice Sought
You and OleCowboy are not the only ones that have different ideas on the topic! My Sig has a 1-7 proclaiming it to be suitable for all bullet sizes while most of the pistol uppers and barrels I'm finding run 1-9 with the same claim :huh: :dry: :S
Guess I'll have to run a comparison for myself ;)
or find a 1-8 and split the difference! :usa:

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10 years 10 months ago #33219 by faawrenchbndr
Replied by faawrenchbndr on topic AR-15 Build Advice Sought
Once again,......research and go with a respected short barrel upper builder. Trying to figure out all this shit yourself gets expensive, and frustrating very fast. Do not care to get into a barrel rifling debate, however, a 1:7 barrel is what you want.

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10 years 10 months ago - 10 years 10 months ago #33222 by OleCowboy
Replied by OleCowboy on topic AR-15 Build Advice Sought

SOC wrote: Sorry to contradict OleCowboy, but here goes.

You want as much twist for a short barreled rifle round as possible especially if you want to use bullets like the 77gn SMK, 75gn Hornady or 80gn Berger.

The twist desired for a bullet depends on the bullets length and speed.

Since your getting less speed from a short barrel the bullet won't be spinning as fast.

Bullet WEIGHT has little to do with stability.

This is why short fat pistol bullets use less twist than rifle bullets of the same weight.

I have seen bullets fired so fast at such a high rate of spin that they don't survive to hit the target, but I have never seen a loss of stability due to "too much" spin. I have looked at many claims of such but once examined in person or via pictures it always turned out there was another reason for stability issues, NOT "too much twist."

LOL, No problem SOC, always willing to listen to an opposing view. Besides, here, we can talk with each other without screaming, calling names, and getting pizzed off and never talk to each other again. This is a good place to be, folks can really learn something...

That said its not the weight, its the inertia catching up with the bullet and if it does it post muzzle you induce instability. I gave an example of acceleration in a car, its not the weight of the car. If the inertia does not make a smooth transition, which it does in a long bbl weapon you can induce instability, can't fight the laws of physics.

Not too much spin, but rather the time to distance for the spin...long bbls are more accurate all things being considered.

1:7 on a 7 in bbl will at best give you one full rotation, depending upon the throat and if they use a progressive twist. I personally like progressive twist for several reasons but that is another topic.
Last edit: 10 years 10 months ago by OleCowboy.

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10 years 10 months ago #33273 by jtallen83
Replied by jtallen83 on topic AR-15 Build Advice Sought
:banghead: No stripped lowers at the gun show or any of the LGS's. I'm going to have to order one in and have Dad pick it up and my wife bring it to me in February.
Any advice on what brand or supplier to use?
I'm tempted to try out a polymer version??????
I'm noticing a HUGE variety of prices, from nearly $500 for a matched upper and lower from Wilson Combat to a $49 polymer lower.
Being my first build I don't want to spend high dollar and then make an irreversible error. :naughty:

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10 years 10 months ago #33274 by faawrenchbndr
Replied by faawrenchbndr on topic AR-15 Build Advice Sought
Personally, I do not care for polymer lowers. I would suggest sticking will a well known company, avoid lesser known companies. Many of the smaller companies that sell cheaper lowers are actually selling the receivers that many of the larger companies would consider blemished or rejects. Kinda like how Caspian labels the flawed 1911 frames Foster Industries.

Call me nuts, but I would love to fins a few Armalite M15 stripped lowers

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10 years 10 months ago #33301 by MrMarty51
Replied by MrMarty51 on topic AR-15 Build Advice Sought

faawrenchbndr wrote: Kinda like how Caspian labels the flawed 1911 frames Foster Industries.

SOOOoooo, could that be relabeled to "Flawedster Industries" ???? :busted: :rotfl:

faawrenchbndr wrote: Call me nuts, but I would love to fins a few Armalite M15 stripped lowers

I tooh wuld like to build Me an AR15 variant of some sort.

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10 years 10 months ago #33302 by OleCowboy
Replied by OleCowboy on topic AR-15 Build Advice Sought

jtallen83 wrote: :banghead: No stripped lowers at the gun show or any of the LGS's. I'm going to have to order one in and have Dad pick it up and my wife bring it to me in February.
Any advice on what brand or supplier to use?
I'm tempted to try out a polymer version??????
I'm noticing a HUGE variety of prices, from nearly $500 for a matched upper and lower from Wilson Combat to a $49 polymer lower.
Being my first build I don't want to spend high dollar and then make an irreversible error. :naughty:

Just say NO to poly.

Go with milled lower rather than forged. Forged is just another term for stamped, not always but often you will find a lower grade of Alum in forged units vs milled from billet stock. Forged will be cheaper and its fine otherwise but not mil spec grade and I would not build to less than that unless the weapon is more of a sporter for a kid, woman or anyone who does not need the higher grade. Thus I recommend 7075 with a temper to T6 standards or mil spec.

Buy a fully milled and ready to assemble lower from one of the top makers and you cannot go wrong...
The following user(s) said Thank You: jtallen83

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