AR-15 what’s the logic?

[35 Whelen]

Decades ago I had thin jacketed JHP’s vaporize due to centrifugal force out of one of my 1-7 rifles. However, back then 1-14 and 1-12 were common twist rates for .223 rifles. Substantial RPM difference between them.

It took 17 posts to get to this fact, and typical of most facts presented in forums, it's ignored. I guess in this case it's probably because most people just shoot paper and don't understand the implications of a bullet that is rotating faster than it's was designed to.

FWIW, I have a 600 yd. range at my house and the 4H High Power team used to come practice on it prior to their annual trek to Camp Perry. Back then all their AR's had 1-9" barrels and they all completed with donated Hornady 75 gr. match ammunition. For the most part the 1-9" barrels stabilized the 75 gr. bullets out to 600 yds., albeit some better than others. The coaches and I surmised that perhaps some of the barrels were maybe 1-8.75" or some such twist while others were truly 1-9".

35W

 

[Varminterror]

It took 17 posts to get to this fact, and typical of most facts presented in forums, it's ignored. I guess in this case it's probably because most people just shoot paper and don't understand the implications of a bullet that is rotating faster than it's was designed to.

As counterpoint to what sounds like a rather damning anecdote here:

Paper is actually the easiest way to detect bullet failures - when one bullet makes multiple holes, it’s pretty obvious.

There ARE a handful of varmint bullets out there which will fail over 225-250krpm, especially in cut rifled barrels, but the slower speeds common to 16” carbine barrels, especially chrome lined and/or hammer forged barrels, and the FMJ’s most of their owners are shooting don’t typically present any issues. Most 50-55grn bullets do make it out of 16” 1:7” twist barrels with no complaints. I can’t imagine how many millions of rounds of 55grn M193 clone ammo has been fired from 1:7” entry level 16” carbines without any issue at all.

FWIW, I have a 600 yd. range at my house and the 4H High Power team used to come practice on it prior to their annual trek to Camp Perry. Back then all their AR's had 1-9" barrels and they all completed with donated Hornady 75 gr. match ammunition. For the most part the 1-9" barrels stabilized the 75 gr. bullets out to 600 yds., albeit some better than others. The coaches and I surmised that perhaps some of the barrels were maybe 1-8.75" or some such twist while others were truly 1-9".

35W

Also FWIW, if this anecdote was anything more than a handful of years ago, which I expect is a fair assumption, and remaining quite likely today, those Service Rifle barrels were most likely 20”, picking up 175-200fps over the 16” Carbines the OP is discussing, spinning bullets in a 1:9” twist around 16,000rpm faster than attainable in the shorter carbine.

Equally, the Hornady 75 BTHP which can be loaded to AR mag length for use in all stages of SR competition - as the 75 A-Max/ELDm cannot - is a stubby little bullet which is more easily stabilized than other bullets in its weight class. The Hornady 75 BTHP is only .981”, while the ELDm, as an example, is 1.120”, the Lapua Scenar 77 is 1.043, Berger 75 VLD is 1.063”.

Consequently, the BC on the Hornady 75 BTHP is relatively abysmal, at only .395G1. Comparatively, the 75 ELDm is .467G1, Berger 75 VLD is .424G1.

So the recurring anecdote of the Hornady 75 BTHP (or 77 Sierra MatchKing) stabilizing in 20-24” 1:9” barrels really doesn’t tell the whole story. It’s a short bullet which requires much less spin to stabilize and which offers considerably worse ballistics than others in its weight class. It shouldn’t be surprising that a bullet designed for use in a Service Rifle application actually works in a Service Rifle application… but we also have to acknowledge the pitfalls it brings with it BECAUSE of its design basis.

 

[redcon1]

Ain't that the truth. The ever-increasing urban population bias means that most gun owners will never even visit a range with greater than 100 yard targets. I know my local range doesn't have anything beyond that, and to get beyond 200 I have to drive over 50 miles away. The nearest in-state 1,000 yard range is almost 150 miles away.

I think most customers live in those urban areas where the ability to shoot at 1,000 yards is completely unavailable to them. My nearest 200 yard range is 80 miles away unless I want to shell out over $500 and then pay over $100 a year for membership to the closer range. It makes it real difficult to stay interested in rifle marksmanship and nigh impossible to develop long range marksmanship skills. What's really sad about it is that Camp Perry is only about 30 minutes away from me and that range will never be available to me. Add to that the anti-firearm friction being created by our..."opposition party", and I think it's a pretty safe bet that we will, for the most part, be the last generation of American men to give a darn about this sport with a few holdouts still hanging on I'm sure.

 

[dylan84]

Most people are shooting mil spec type offerings in bullets with their 7" twist barrels with a 16" or shorter barrel. These bullets have a thick jacket and won't explode unless spun ridiculous fast. I have seen more evidence that when a 223 is blowing, there is a manufacturing defect of some kind with either the bullet or the barrel. There was issues in the service rifle world with the first 90 grain sierras and they fixed the bullets. What stuck is the idea that they still blow up, which they don't!

 

[Varminterror]

I think most customers live in those urban areas where the ability to shoot at 1,000 yards is completely unavailable to them.

I spend a lot of my time connecting shooters around the country with local PRS and NRL clubs/ranges and I really hate that this sentiment is so permeating.

I will point out, first, that there is a failing by shooters to hold the expectation that 1,000yrd ranges should be as readily accessible as bowling alleys or skating rinks. Not every small community over 25,000 population will have a 1,000 yard public range within 30min drive. If folks compare 1,000 yard ranges to race tracks, Natural History Museums, or amusement parks, then the distribution becomes much more favorable.

If your definition of “completely unavailable” is “I’d have to drive over an hour and spend $100,” eh, you really can’t be helped, and most of the experiences in the modern world will evade you. 80 miles away is a round trip with a healthy volume of shooting attainable in an afternoon, which certainly doesn’t qualify as “completely unavailable.” It just takes more time and effort than you want to give.

 

[jmr40]

A 7 twist will shoot 55 gr pretty well, but not anything much lighter. I have both 7 and 8 twist barrels and find the 8 twist more versatile for what I do. I found some 50 gr factory ammo a few years ago that just plain shoots better than anything I've shot. And it was relatively cheap at the time so I stocked up. My 7 twist rifles won't shoot it, but my 8 twist barrels will.

I don't shoot anything heavier than 75 gr so either 7 or 8 twist handles it equally well.

 

[redcon1]

I spend a lot of my time connecting shooters around the country with local PRS and NRL clubs/ranges and I really hate that this sentiment is so permeating.

I will point out, first, that there is a failing by shooters to hold the expectation that 1,000yrd ranges should be as readily accessible as bowling alleys or skating rinks. Not every small community over 25,000 population will have a 1,000 yard public range within 30min drive. If folks compare 1,000 yard ranges to race tracks, Natural History Museums, or amusement parks, then the distribution becomes much more favorable.

If your definition of “completely unavailable” is “I’d have to drive over an hour and spend $100,” eh, you really can’t be helped, and most of the experiences in the modern world will evade you. 80 miles away is a round trip with a healthy volume of shooting attainable in an afternoon, which certainly doesn’t qualify as “completely unavailable.” It just takes more time and effort than you want to give.

80 miles one way. That's a 160 mile drive for the pleasure of shooting a rifle at 200 yards which is perfectly capable of shooting 1,000 yards. 160 miles is about a tank of gas to me which is bad enough but then I get to that range and find out that it's closed for some reason or another or there's other shooters occupying the only bench available or they don't want "city folk" on their range. It's too much friction. And you can gas light me all you want but, the fact is, it's not my fault. And as far as the closer range, that's a $500 dollar one time fee on top of a $25 background check fee and on top of a $100 per year membership and there's a waiting list and, what amounts to, a job application that needs to be filled out complete with references and the background check. So that's basically an elitist country club which increasingly describes this sport as far as I'm concerned. For the average 2A enthusiast living in the city, shooting their AR15 or whatever other rifles they own is increasingly prohibitively difficult and your gaslighting isn't going to change that. there are probably half a dozen ranges for handgun enthusiasts within 20 miles of me however and, so, that helps a little but bolt action rifles? AR15s? AR10s? Mind you, I have made that 160 mile drive many times but it's pretty laughable to think that a lot of other people would be willing to go through the trouble. The only people I ever see at these ranges are locals in fact.

 

[derek45]

Quality 55gr bullets will shoot sub-MOA 100 yard groups.

55gr VMAX, for example, shoots dime sized 100 yard groups, even with surplus BLC2 powder. It's also a great coyote bullet.

crappy russian, or bulk 55gr FMJ is NOT match grade ammo.

Here are some brand new, in the package, Winchester 55gr FMJ's I bought with a cabelas gift card years ago.



imagine these crooked turds spinning towards your target !
.
.
.

Here are Hornady, much better, but not match grade...

 

[lysanderxiii]

A 1:7 twist is not going to shoot 55 grn bullets very well, no matter how much money is spent on the rifle. The 1:9 barrel is best for stabilizing lighter and mid-weight bullets between 40 and 62 grains, which is what most people shoot in their AR. 1:7 twist is used by the military to stabilize 70-90 grn bullets.

I built a precision bolt rifle to shoot 55 and 62 grn bullets. I chose a 1:9 twist barrel.

I think the 1:7 twist barrel came about from the military M4 pattern. It's what the military uses.

Some people will disagree with that statement.

 

[General Geoff]

For the average 2A enthusiast living in the city, shooting their AR15 or whatever other rifles they own is increasingly prohibitively difficult and your gaslighting isn't going to change that.

A difference in opinion of what constitutes "Completely unavailable" is hardly gaslighting.

Long distance recreational shooting is an expensive and time consuming hobby, one which cannot reasonably be pursued without the dedication to go where you can practice. I lament this high barrier to entry for us city folk but shooting is more popular in rural areas with large, privately owned swaths of land for a reason.

 

[Varminterror]

160 miles is about a tank of gas to me

Do you ride a motorcycle? Even driving my F-350 which only got 8mpg, a tank of gas gets a hell of a lot farther than 160 miles.

Let’s be honest with each other here: Your entire post is self-justifying excuses. Driving 160 miles isn’t “completely unavailable.” There are thousands of folks out there shooting PRS matches every month with a reported average travel of 3-4 hours one way for their respective clubs/ranges when polled, and most folks at 2 day Pro series matches are traveling in excess of 6 hours. There’s a monthly ELR match about an hour from where I live which draws shooters from Texas, Nevada, New Mexico, Tennessee, etc every month. When I was shooting Service Rifle, Benchrest, or F-class games, I was driving 2-4 hours for practice matches, and a lot farther for any leg match. Shooting 3 gun and CAS/SASS, for a long time, that meant 2-3 hour drives for me as well.

For most of the members around the country which I connect with nearby PRS clubs and ranges, there are only a few states (South Carolina) where I just don’t have a solution for any range within 3-4 hours. MOST geographies offer something within that ballpark. Yes, there are fees associated with it, and rightfully so, as owning that much land, especially in populous markets and especially positioned such long range shooting can be done safely, is not cheap and removing it from potential revenue opportunity of agricultural use means there is an opportunity cost to bear as well.

No gaslighting going on here - cute pop culture buzzword though - you’re just not sufficiently interested or motivated to do what everyone else in the country doing it is willing to do. And that’s ok for you - but don’t pretend your subjective limitations apply, and that 1,000yrd shooting is “completely unavailable” to most people.

 

[redcon1]

A difference in opinion of what constitutes "Completely unavailable" is hardly gaslighting.

I think I described it as "increasingly prohibitively difficult" actually. That would be the case for me. For others, it may very well be "completely unavailable". I think for most others it is, in fact, so prohibitively difficult that for all intents and purposes, it's unavailable. And beyond that difficulty, there's also the cost which has always been an issue but more so of late than at any other time in recent memory. And the biggest problem with that is that the bulk of potential firearm purchasers are located in these cities, not in the boondocks. And so why on earth would someone who lives in a city spend a bunch of hard earned money to play a game that they can not readily participate in? And then they try to get into the game and the feds pass some new rule that turns them into a criminal. And why should they put themselves in a that kind of a position just so they can have a tool to play a game which is really beyond their means to fully participate in anyways. Why?

Long distance recreational shooting is an expensive and time consuming hobby, one which cannot reasonably be pursued without the dedication to go where you can practice.

All hunting, shooting and fishing is prohibitively expensive and that has always been the case. these are rich man's games. And it is made all the more expensive and difficult by the dearth of public rifle ranges proximal to urban environments as well as by the friction created by our own government. For my part, I'm just wondering why I even care at this point. Why should I care? More to the point, why should I get myself on the government's naughty list to defend a game that is, in increasingly, not something I can participate in? I think I'd be a hell of a lot smarter to sell it all and wash my hands of the game after 30 years of playing it and I am quite sure I am not alone in these sentiments.

 

[Varminterror]

I think for most others it is, in fact, so prohibitively difficult that for all intents and purposes, it's unavailable.

I’ve provided evidence quite to the opposite above, for multiple long range shooting sports. Any of us doing it are traveling farther than you are willing to travel.

It’s available to you, you’re just not interested.

What are you gaining (by apparently trying to gaslight the rest of us) by trying to convince shooters something relatively simple and broadly available is “completely unavailable”? Why are you so committed to convincing others that long range shooting is “completely unavailable” to them or others? What can you possible benefit by spreading that misinformation?

 

[redcon1]

No gaslighting going on here - cute pop culture buzzword though - you’re just not sufficiently interested or motivated to do what everyone else in the country doing it is willing to do. And that’s ok for you - but don’t pretend your subjective limitations apply, and that 1,000yrd shooting is “completely unavailable” to most people.

First off, you are totally gaslighting me. If it's a cute popular buzzword these days, it's because such a common tactic. You're blaming everyone else for not being interested in a sport that is not readily accessible to them. That's gaslighting. I'm not going to drive 3-4 hours to shoot a rifle. I shouldn't have to and, when I was younger, I didn't have to in fact. But over the decades, the game has changed and now I'm expected to. well screw that. if the rifle manufacturers want me to be interested in any of their products, maybe they should invest some of their profits into constructing shooting ranges near the large cities so that city folk can actually use the rifles they want us to purchase rather than trying to convince us that driving 3-4 hours to shoot is normal and expected. I'm not saying I'm done with it all right now, but it's clearly coming.

 

[redcon1]

I’ve provided evidence quite to the opposite above, for multiple long range shooting sports. Any of us doing it are traveling farther than you are willing to travel.

It’s available to you, you’re just not interested.

What are you gaining (by apparently trying to gaslight the rest of us) by trying to convince shooters something relatively simple and broadly available is “completely unavailable”? Why are you so committed to convincing others that long range shooting is “completely unavailable” to them or others? What can you possible benefit by spreading that misinformation?

It is laughable that you think this sport broadly available. It is not.

 

[Varminterror]

It is laughable that you think this sport broadly available. It is not.

It’s apt that Bryan Litz posted this last month:



It’s available to anyone in CONUS who is willing to travel 3-6 hours to spend a day shooting, because they’d rather shoot than make excuses. It’s not cheap, and shooters can’t expect to find ranges 2/3 of a mile long connected to every minor metro area, but long range shooting is irrefutably broadly available.

I help run a couple groups on Facebook and through PM’s, I connect shooters every month, some times multiple per week from all over the country, and that’s just for PRS shooting. The network of shooters all over the country in other disciplines of shooting sport or just casual, non-competitive long range shooters is even broader still than the sport of PRS. I’ve yet to find a state where there truly isn’t access for a shooter who WANTS to shoot 1000 yards to be able to do so.

I do find a lot of folks like yourself who reach out, and upon finding out that which is AVAILABLE to them takes longer than going to Starbucks for coffee will decide it’s not worth it to them, but I have never failed to find some resource within a 4-6hr drive where shooters could make a day or a weekend of going to shoot 1,000yrds.

Admittedly, I’m blessed here in Kansas, and own enough acres where I can shoot on multiple properties out to 875 and 1200 yards only driving a few minutes from home, and I have access to 5 ranges within 3 hours where I can shoot 1000+ or even 4000+, having memberships at 3 of them. I also keep an annual membership at an indoor 100yrd range which is a hair over a hour away. Yes, I pay for that access, and yes, I’m driving a 45miles, 70 miles, 90 miles, and 95 miles to the 4 ranges I member with, and yes, I’m driving 2-3 hours to matches at those 3 other ranges on any given month, and I’m paying a decent amount for that access. And as I admitted above, there are a few states where nothing exists (SC, for example), but luckily, most of those states remain small enough such guys can travel that same 4-6hrs to find ranges and matches.

“There are more things on Heaven and Earth, Horatio, than which are dreamt of in your philosophy”. - Wild Bill Shakespeare

 

[halfmoonclip]

Just bear in mind; heavy bullets in slow twist don't work.
With 62 grainers, in Viet Nam era 1:12 barrels, you'll be hard pressed to hit a barn from the inside.
Moon

 

[CoalTrain49]

Some people will disagree with that statement.

I'm just parroting what a custom barrel builder told me. Not the part about the clones, the part about the twist rate. I guess he could be wrong.

 

[lysanderxiii]

Just bear in mind; heavy bullets in slow twist don't work.
With 62 grainers, in Viet Nam era 1:12 barrels, you'll be hard pressed to hit a barn from the inside.
Moon

Not really . . . .

These two sixx round groups were fired at a distance of 100 yards by an expert firer from a supported position, using the same M16A1 rifle. The three inch group on the left was fired with current ammunition (M193) and the twelve inch group on the right was fired with the ammunition developed for the M16A2 and SAW (M855).

 

[d2wing]

I found a 600 yard range an hour away. But it was not only costly but you needed a referral from a present member. Ok. Then I found out that there is a long waiting list to get on that waiting list, lol. So I can sympathize. Not impossible but difficult. I lost interest. It is one thing to go to a match, another to find a place to practice, develop load data, and dope charts. To the more casual shooter like most of us it is a high hurtle. But to others they will find a way. Just like many other things.

 

[tark]

The M855 bullet will stabilize just fine with a 1:9 twist. It is the longer 64grain M856 tracer bullet that will not. The M856 being longer needs the 1:7 test to properly stabilize and also have the same trajectory as the M855.

Don't tell that to my AR which has a 1:9 twist, so marked on the barrel. I have shot a lot of M-856 tracer ammo in it. Haven't seen a one keyhole.

A 1:7 twist is not going to shoot 55 grn bullets very well, no matter how much money is spent on the rifle.

I had a dead stock H-bar years ago with a 1:7 twist. It would put 55 gr. M-193 bullets into one hole at a hundred. Were they overstabilized?? Who cares!! Can't argue with the results!

 

[12Bravo20]

Don't tell that to my AR which has a 1:9 twist, so marked on the barrel. I have shot a lot of M-856 tracer ammo in it. Haven't seen a one keyhole.

I had a dead stock H-bar years ago with a 1:7 twist. It would put 55 gr. M-193 bullets into one hole at a hundred. Were they overstabilized?? Who cares!! Can't argue with the results!

Each barrel will be different in how it shoots. And who is to say that YOUR barrel is actually a true 1-9 twist. We have all seen that what the barrel is marked does not always match how the barrel was machined when it comes to the twist rate.

And the whole reason for the 1-7 twist to stabilize the M856 tracer round was thoroughly tested at Aberdeen Proving Grounds, MD in the early 1980' when the M16A2 was being developed. And the Marine Lt Col. who was in charge of the A2 program has stated such. He is a member here on this forum but I always forget his username here. The Lt Col goes by Cold Blue on ARFCOM. And he has forgotten more than the rest of us think we know about the M16A2 and its development.

 

[1911 guy]

I like 1:9 for varmint guns and 1:7 for everything else. Admittedly most people with 1:7 barrels capable of stabilizing heavier bullets over longer ranges aren't going to do it. I don't drive my car at 140mph, either. But it has the capability, even if I don't have the skill.

Most shooters will spend all day at the 100 yard line and call it a day. And sometimes that's fun. But there's something satisfying about taking a homebuilt AR out to a quarter mile.

 

[lysanderxiii]

There seems to be some misconceptions on how an unstable bullet behaves. People seem to think that all unstable bullets go sideways and tumble immediately after leaving the muzzle . . . not so.

The definition of an unstable bullet is one where the over-turning moment is larger than the gyroscopic righting moment, nowhere in there is the mention of how fast it over turns, just that it will. So, if the over-turning moment is 0.0001 mm-N, and the gyroscopic righting moment is 0.000099 mm-N, it is going to take a while for the bullet to go sideways and start tumbling. M855 is still lethal to 150-175 yards from a 1-12 barrel, and probably capable of hitting a man-sized target eight out of ten times.

 

[Varminterror]

A 1:7 twist is not going to shoot 55 grn bullets very well, no matter how much money is spent on the rifle.

This isn’t true.

It’s often true to say that 55grn ball surplus ammo won’t shoot very well - because it’s junk ammo - but applying that blanket statement to all 55grn bullets and especially blaming it on the 1:7” twist is about as far from reality as it gets.