A popular mod to Mini-14 ranch rifles is to shorten (stiffen) the barrel to prevent stringers - which the older series was known for. My understanding though is that the shorter barrel also lowers the effective velocity of the round and thus effective energy. A longer heavier barrel would be the way to go for distance (100/200+ yards) accuracy.

It's a lot more fun to let the zombies get closer. Say within 100 yards.

At 300 yards you can't even see parts fly off.

I agree Blue. The target I'm posting was at 500 yards, (have posted it on another thread also). Accuracy does not suffer from barrel length but ballistics certainly do. Barrel length, powder burns rates, bullet weights, etc. have to be matched to get good ballistics from any barrel length. My particular spoon, (I built it), doesn't care for .223 at all.
The accuracy isn't all that good on my target but it has nothing to do with the barrel length. I was aiming at the heart, maybe the shooter has something to do with it ;)

http://forums.pelicanparts.com/uploa...1389822695.jpg

http://forums.pelicanparts.com/uploa...1389822775.jpg

1-9 is correct, and I am happy with it, no need to change. I know what it likes, and what it can do. If I want to reach out and touch a target the AR is not going to be anywhere close to the top of the "grab list"

My7.5" barrel pistol is fine on irons or eotech at 100....I suspect it'd do quite well at 200 as well

John Noveske was known for his 300m+ shots from. 10.5"

Yep. Was really responding to your 300m comment.

I pray I never really need to reach out that far.

I hear ya. I like shooting for distance but I don't ever want to have to do it

Lots of rules of thumb are wrong. Longer equals more velocity, usually. Longer means longer sight radius with iron sights, which will most likely be easier to shoot accurately, but one won't be any more accurate than the other.

No, a "dissipator" was a model Bushmaster sold with a full length handguard and sights, but a 16" barrel. Think of a standard A2, but instead of having ~4" of barrel forward of the front sight, you don't.

http://www.megpro.com/ar/15/disspro/diss16in.jpg


1-9 twist is plenty for 62gr. You don't NEED 1-7 until you get to 85 grains or more. Nothing you would be able to shoot through a standard magazine (OAL too long). My 1-8 NM upper shoots 80gr just fine.

I love proving folks wrong who think gas guns aren't accurate.

This is 100 yards, 10 rounds, iron sights with my Armalite NM upper and 69gr SMK handloads.

http://forums.pelicanparts.com/uploa...1389838404.jpg

forgot to mention I had a 80mph crosswind and had recently been blinded in a terrible chemical spill when I shot the target I posted at 100yds.


and was being stalked by a tiger that had escaped from the local zoo.

back in the "real" world
 

I appreciate the input (sensible, comical and imaginary ;) ). I should have specified; while I will be shooting a lot of factory ammo initially to build up a cache of brass, my highest priority will be shooting reloads at prairie dogs and jack rabbits between 150 & 300 yards. I will not likely ever be involved in competition shooting of any kind. That's just not my cup-O-tea. However, I have several farm and ranch friends who are more than happy to let me do varmint control for them.

I started reloading in 1973, but I haven't loaded a rifle round in over 30 years. At that time I was into making my 30.06 as accurate as possible for 200 yard shots at prairie dogs. That said, as I study modern loading charts for the 5.56/.223, I am inclined to work up loads for hollow point, boat tail bullets in the 75 grain weight range as my main and most used cartridge for the varmints. Outside of that, the rest of my shooting will be just for fun on targets at various ranges with a variety of bullets just to see how each performs with different powders and charges.

Based on extensive reading both here and various gun sites over the past 6 weeks, I am leaning toward the AR with a 16" barrel in 1:7 twist unless I can find a 20" where the price is not totally outrageous.

Thanks for the feedback all. SmileWavy

Based on this I would be looking at a .22-250 or maybe a .204 Ruger bolt action.

An AR-15 is great for fast follow-up shots on multiple targets...but whenever I do prairie dog control I find that I rarely have more than one p-dog in my field of view.

Just a suggestion.

I was thinking about this, too. I was thinking 18" barrel with rifle-length gas system, 1:7 twist. I, too, won't be able see targets with iron sights at 300m, but thought that if SHTF, and I only have time to grab one rifle, I want to grab the one that can do the most stuff, even if it doesn't do everything well.

As I posted earlier about shorter barrels, I did not mention why shorter can mean less accuracy. In this case this rule of thumb taken on face value is pretty accurate as there are several things that cause this:
- smaller sight radius for iron sights unless you use a red dot sight and shoot with both eyes open.
- Less velocity due possible less powder burn means the bullet might become unstable.
- Less spin due to same as above.
- Bolt cycle problems possibly due to low gas pressure.
- Crud build up due to incomplete powder burn causing possible bolt cycle issues.

These can affect accuracy since the shooter will become nervous if the rifle fails to work well for them so hitting the target can become an issue.

When I was looking for thoughts about picking a barrel length for a muzzle loader 1000 yard black powder gun I am starting work on, I found the following write up by a college student and it has pretty good testing process. After all my looking, reading and talking to other LRML shooters I decided to just use the same length as everyone else does!!??

http://honors.usf.edu/documents/Thesis/U82488180.pdf

The difference in velocity between a 20" and 16" barrel is about 150 FPS really not enough to worry about. For varmint shooting, at the ranges you are talking about, I would forget about 75 gr bullets, there are none suitable for the AR platform. The only 75gr that are varmint bullets are the Hornady AMAX, and they are really a match bullet that just happens to work. They are also too long to load at an OAL short enough to feed through an AR magazine.

The heaviest Varmint bullets you will find are 55gr, there are hunting bullets that are heavier, but I don't think anything designed for thin skinned varmints. I have had good luck with the Sierra 55 Blitzking.

A 1:7 twist is more than you need, 1:12 will stabilize 55gr bullets, but you are more likely to find a 1:9 which should still be fine, and will work with bullets up to 75 gr.

An issue you may find is that ARs with 16" barrels are probably going to come with a collapsible stock, and 20" rifles will probably come with a solid A2 type stock. If you plan on shooting at varmints prone with a bipod, it is something to keep in mind, hard to get a decent cheek weld the way some of the collapsible stocks are made.

If it was me, I would buy a stripped lower and build the exact rifle you want.