Military Issue M4 Question

[ryknoll3]

Also, 1:7 twist barrels will usually shoot 55gr just fine, though they often can be more accurate with heavier bullets.

 

[Principal Skinr]

Also, 1:7 twist barrels will usually shoot 55gr just fine, though they often can be more accurate with heavier bullets.

Thanks! I was having some uncertainty about the 1/7 since I have so much 55 grain ammo stocked up.

I guess the best thing to do is to try it out and see how it does.

Is 1 MOA too much to expect from a 1/7 shooting 55 grain bullets?

 

[abnk]

Thanks! I was having some uncertainty about the 1/7 since I have so much 55 grain ammo stocked up.

I guess the best thing to do is to try it out and see how it does.

Is 1 MOA too much to expect from a 1/7 shooting 55 grain bullets?

1MOA at what distance (spare me the lesson on angular vs. linear measurement)? If the ammo is decent and consistent and you do your part, 1' is not too much to expect. However, if you're going to shoot surplus steel-cased ammo at 300 yards with iron sights, 1' IS too much to expect. I'm sure you see that the answer is subjective to many more factors than just bullet weight and barrel twist.

 

[LPMan59]

1/7 will do just fine with 55 grain ammo.

here's my Colt 6920 using Brown Bear .223 and American Eagle .223 from a rest, standing and crouching. not bad for my usual crappy shooting

 

[Destro]

Wow. I thought 1/7 was more for 70+ grain bullets. I know my 1/9 rifles handle 62 grain bullets quite well, with excellent accuracy.

1/9 twist is almost as gross as a chrome moly bbl.

 

[223 Gunner]

I've owned several AR's over the years, my favorite is a Govt. profile bbl. with a 1/7 twist. I am a purist, this is what the military uses as a standard bbl. config. I've always had to order uppers to get this. Usually from Bushmaster, everyone will have their own opinion as to mfg. preference, I have always had good luck with Bushmaster and Armalite, these are who I stick with. And for the record I don't believe in shooting steel cased ammo out of your 1000.00 dollar rifles, this is why I rarely buy used AR's unless I know the person. I don't want to start the argument of steel vs. brass, everyone will have their own opinion on this as well. But if I ever have an AR for sale, you will know it has never seen a steel cased round.

 

[Principal Skinr]

1MOA at what distance (spare me the lesson on angular vs. linear measurement)? If the ammo is decent and consistent and you do your part, 1' is not too much to expect. However, if you're going to shoot surplus steel-cased ammo at 300 yards with iron sights, 1' IS too much to expect. I'm sure you see that the answer is subjective to many more factors than just bullet weight and barrel twist.

Sorry...100 yards. Isn't 1 MOA 1" at 100 yards, 3" at 300, and so forth? That's why I didn't say the yardage. Please correct me if I'm wrong.

Also the assumption is good ammo. This would also be with a good scope. I'm interested in the accuracy of the gun itself. I can easily get 1 MOA with my 1/9 ARs on factory ammo. (PMC, Remington, Black Hills). I can get close with Silver Bear steel case.

 

[Principal Skinr]

1/9 twist is almost as gross as a chrome moly bbl.

Don't make too much fun...My most accurate AR has a chrome moly match grade barrel with 1/9 twist and shoots 1/2" 5 round groups at 100 yards with PMC or Black Hills ammo, making more or less one hole. (It is even more impressive when you consider it is me shooting it!) It would only be gross if I hit a hog 5 times in the same 1/2" spot.

 

[abnk]

Sorry...100 yards. Isn't 1 MOA 1" at 100 yards, 3" at 300, and so forth? That's why I didn't say the yardage. Please correct me if I'm wrong.

It is the same, which is why I said spare me the lesson on angular vs. linear measurement. However, as the distance increases other factors' effect will also increase and it is not fair to blame the barrel for deterioration of accuracy.

Also the assumption is good ammo. This would also be with a good scope. I'm interested in the accuracy of the gun itself. I can easily get 1 MOA with my 1/9 ARs on factory ammo. (PMC, Remington, Black Hills). I can get close with Silver Bear steel case.

The only change to the above criteria being the 1:7 barrel twist, you should get 1'. If you don't get that, the culprit is likely not the barrel twist, but something else in the upper.

 

[kwood]

Here is a nice little read on AR history
Not to in depth but a good little read none the less
How To Keep Your AR Running, Part 1: AR History

 

[223 Gunner]

Thanks kwood, that was an interesting read. All stuff I knew, but had forgotten some of it. All the designations such as A1 and A1E1 I had forgotten what some of them meant.

 

[Principal Skinr]

It is the same, which is why I said spare me the lesson on angular vs. linear measurement. However, as the distance increases other factors' effect will also increase and it is not fair to blame the barrel for deterioration of accuracy.



The only change to the above criteria being the 1:7 barrel twist, you should get 1'. If you don't get that, the culprit is likely not the barrel twist, but something else in the upper.

Thanks abnk! Sorry it took awhile to get back to this. I've shot the rifle a few times since starting this thread and it is turning out to be a nice one. I've now got an Eotech Exps 3 with a 5x flip magnifier. It will have this setup for a hog hunt in Texas in about 10 days!

Thanks to everyone for lots of great information!