Difference between 20" upper and 20" Varminter

[megavolt121]

I'm trying to decide between a 20" flattup upper or a 20" varminter but can't really tell the differences. Here's what I've noticed.

Flattop vs. Varminter
- "standard" barrel vs. bull barrel.
- freefloat vs. non-freefloat handguards.
- front sight post vs. front sight block

Can someone else chime in on differences?(Let's ignore barrel twist rates right now). Also, will a varminter be that much more accurate than a standard 20" build? at 100 yards? 200 yards?

[mike452]

What brand are you talking about?

I have noticed varminter = bull stainless barrel without front sight.

That's all. All other configurations can be changed. Bushmaster free floats theirs. Accuracy should be the same. It just dissipates heat faster.

[maxicon]

A lot depends on how much you're spending. The barrel makes a huge difference, and a high-quality standard barrel can outshoot an inexpensive bull barrel. Bull barrels are not inherently any more accurate, and mostly spread the heating and cooling profiles (that is, it both heats up and cools down more slowly) and add weight for recoil control.

Weight is another big deal. Most varminters are heavy, so if you're going to be shooting a lot of offhand, lugging it around, shooting with noobs, etc, light weight is more fun.

Freefloat makes a big difference if you're going to be shooting with a sling (that is, providing tension with the sling for stability, not just using it to carry the rifle), if you're going to use a bipod, if you're going to be shooting for very tight groups at long ranges, or if you're going to be hanging a big pile of tacticool gear on your handguard. For plinking, the difference isn't huge, though a heavy barrel will typically deflect less than a light barrel when it's not freefloated. Most freefloats are heavier than standard handguards, as well.

A railed gas block can be put on any rifle. It provides more flexibility, as you can use flip-up sights, no sights, whatever, but it's another possible point of failure. You also have a bit more flexibility on handguards if you don't have a standard front sight tower. There's not much sturdier in front sights than a one-piece, if reliability is an issue. If you're using magnified optics, the front sight won't be an issue, but for red dots/holosights/low mag optics, some people get distracted seeing the front sight post, and prefer a flip-up.

Really, it all depends on what you want to do with it. For a first AR, I wouldn't recommend a varminter, but if you've got a relatively light one already, a varminter's a good addition to the stable.

[bobfried]

Ar 100 or 200 yards a Superlight carbine with a decent barrel will be more than enough. I still don't understand why anyone would want a HUGE stainless steel barrel to shoot a tiny bullet at 300 yards or less. Remember that an SPR is only a medium contour 18" barrel firing the Mk262 at well over 600 yards accurately.

With the advances of barrel technology I can't think of a single reason to go above an 18" medium contour unless you are restricted from doing so.

[ocabj]

The difference between a lightweight barrel and a heavy weight barrel is going to be seen specifically in weight and accuracy in a long string.

Firing 10 rounds in a lightweight barrel in a short amount of time (2-3 minutes) will probably result in a larger aggregate group size than 10 rounds out of a heavy barrel. This is due to heat (as mentioned) and the flex of the barrel as it heats up.

Free floating in an AR has no bearing on heat disipation. The only point of contact of a non-free floated handguard is going to be at the gas block. A free floated hand guard will eliminate this contact with the glass block / front sight. Even if you don't use any accessories that contact the handguard, it is still advisable to get free floating handguards / tube since any heat flex that occurs in the barrel or in the handguards will translate to different pressures at the contact point of the handguard / gas block area in various conditions. This will affect accuracy. You want to eliminate this.

As far as wanting a heavy SS barrel to shoot 22cal at medium range, it is necessary in order to maximize accuracy. Heavy equates to more material. More material equates to a stiffer barrel. Stiffer barrel equates to better performance while hot. Hot conditions include firing several rounds in a couple minutes. Varmint hunters do this. Competion shooters do this.

[megavolt121]

Free floating in an AR has no bearing on heat disipation. The only point of contact of a non-free floated handguard is going to be at the gas block. A free floated hand guard will eliminate this contact with the glass block / front sight. Even if you don't use any accessories that contact the handguard, it is still advisable to get free floating handguards / tube since any heat flex that occurs in the barrel or in the handguards will translate to different pressures at the contact point of the handguard / gas block area in various conditions. This will affect accuracy. You want to eliminate this.

How much will it affect accuracy by? Are we talking 1MOA, more, less?

[ocabj]

How much will it affect accuracy by? Are we talking 1MOA, more, less?

I don't have a reference that can quantify the accuracy gains.

I can tell you that no serious High Power Rifle competitor with the AR platform uses a rifle without a free float tube.

[randy]

3 gun guys shoot 30 to 40 rounds in under 2 minutes. Hitting 10" to 16" targetsout to 400 yards, using light to medium contour barrels.

[maxicon]

How much will it affect accuracy by? Are we talking 1MOA, more, less?

The shift in accuracy depends on the barrel, the pressure applied to it, and how far out the pressure point is. More pressure and/or a thinner barrel gives more deflection.

A heavy barrel will flex less for a given amount of pressure, while a light one will flex more. Barrels with unrelieved stresses or a slightly non-concentric bore will flex unevenly as they heat up and cool down.

This is why competition barrels are expensive - they're carefully made on precision equipment from high-grade blanks by experienced gunsmiths. A good blank costs more than a mass-market finished barrel.

I can tell you that no serious High Power Rifle competitor with the AR platform uses a rifle without a free float tube.

High power shooters generally use slings, and they're cinched up tight to provide stability, which would deflect the barrel if it weren't free-floated. Anything where you're shooting for precision and putting pressure on the handguard (sling or bipod), accuracy will suffer if you don't use a free-float handguard.

The SU16A is a good example - it's got a thin barrel and a bipod attached directly to the barrel. Mine will shift 4-6 MOA when the bipod is used, and the shift isn't repeatable - you get vertical stringing. Shooting it offhand, with no sling, and just holding the handguard, will also shift it, but in my experience, it's not enough to notice.

3 gun guys shoot 30 to 40 rounds in under 2 minutes. Hitting 10" to 16" targetsout to 400 yards, using light to medium contour barrels.

They're not looking for MOA accuracy, though, right? I'm not that familiar with 3 gun. Do they use basic starter uppers, or do they use better-quality barrels? 16" is roughly 4 MOA at 400 yards, and you won't get that much shift from a decent quality barrel from heat. A good quality AR barrel should be able to hold to under 2 MOA shift under conditions like that, I'd imagine.

[randy]

Uppers run from the mil spec 16" to $1900 top of the line. No we don't shoot for moa. We just need to move steel at distance and hose paper up close.

Would I use my uppers for varmit guns or High Power? Yes.