I'm in the process of building my first ar. I was wondering what would be the best twist rate for shooting a 55gr bullet. The barrel will be a 24" bull . The choices I have are 1n8, 1n9 or 1n14. The rifle will be used for ground hogs and coyotes. Any advise will be greatly apperciated.

I suggest the fastest, 1:8. It will shoot the longest/heaviest along with the lighter/shorter. This gives you the most versatility down the road with no draw backs. All of mine are 1:7 and shoot
45gr-80gr with no problems.

Perry

You're going to need enough freebore to shoot the longer bullets. A 1:8" will give you enough speed for 500yd shots.

Forget 1:14 as that will make it a 250 yd gun as it most likely won't shoot 55's.

Get 1:7,8, or 9 and plan on shooting 69 or 77gn Sierra Matchkings or equivalent weight game bullets. This is an honest 600 yard capable combination. The heavier bullets slice through the wind better.

Using a fast twist such as 1:7 will not preclude the use of 52 gn offerings. My and many other's 1:7 shoot 52 gn Sierra Matchkings into pencil eraser size 10 shot groups @ 100 yards.

Very lightly constructed varmint type bullets under 50 gns will self destruct in the faster twists at high velocities.

While we are at it is the M223nikon scope a good match for the rifle.

quote:

Originally posted by mdvjrp93:
While we are at it is the M223nikon scope a good match for the rifle.

Not on a 24" rifle used for GH & coyote. I like a little more than 12x for GH. I'd want at least 16x and would look at 24x too.

less twist = less stress on the bullet.
If you don't plan to shoot the heavy stuff go with the 1 in 9.
1 in 9 will stabalize up to a 69gr HP

All my 5.56's are 1:7 and I have never ripped a bullet apart in mid air. The 1:7-8 will allow you to shoot the heavier/longer TSX's and mhp's with no negative aspects on the lighter varmint bullets.

Faster twist=more versatility.

Perry

As typical on a question like this 99% of the dingel-berries don't read the whole question and what you asked. Lilja barrels says 1 in 12" for 55gr bullets and I think they know more about barrels than this bunch.

Hey Fat Albert appararently you are the top of the dingle berry class because that was not the question. 1:12 was not listed as an option.

I pointed out that there are far better options than 55 gn pills, especially with faster twists.

Also I have personally witnessed 40 gn varmint bullets spattering on a target at 100 yards fired from a 1:7 Colt Ar-15. They did not spatter on impact; they speckeled the target because the disintegrated in flight. Super lightly constructed varmint bullets below 50 gns can disintegrate in fast twist barrels at high velocities.

quote:

Originally posted by airgun1:
Hey Fat Albert appararently you are the top of the dingle berry class because that was not the question. 1:12 was not listed as an option.

I pointed out that there are far better options than 55 gn pills, especially with faster twists.

Also I have personally witnessed 40 gn varmint bullets spattering on a target at 100 yards fired from a 1:7 Colt Ar-15. They did not spatter on impact; they speckeled the target because the disintegrated in flight. Super lightly constructed varmint bullets below 50 gns can disintegrate in fast twist barrels at high velocities.

Me too. You just have to know which 40 gr bullets have enough jacket to hold up. MOST will work, some won't. The ratio of will to won't can depend on the depth of the rifling, too. The problem with optimizing barrel twist for 55 gr (1:9) is that sooner or later you're going to want to try the heavies and you've locked yourself out.

IMO: A 1:9 will do just about all of it and very decently .

I own a couple of Lija barrels on bolt rifles and absolutely respect their products as well as knowledge .

However Bushmaster must know something about AR'S and Twist rates as well !. I also had people tell me chrome lined bores didn't shoot worth a chit either ,so much for that BS to !!!.

Here's a target of mine using Bulk Bullets ( yep Bulk 55Gr with cannelures ) # 15 for count under the dime compared too #5 Winchester stock rounds left upper quadrant of target,an the first round fouler
of a different powder and bullet weight ,left lower quadrant . Not to shabby off sand bag at 200 yd !.

It does a might better with 68-77 gr but you need calipers to see it . Sierra & Hornady 68-69 produces the very best of accuracy from my AR'S W/1:9 twist . 52-53Gr.match open too nickel size groups ,an I've never shot anything lighter nor heavier out of them . Note my finer target stock !, a friend had a huge party over 8 years ago and we're still using the paper plates as targets . I think I'm down too 600-800 hundred now !!!?.

Doc:
Thats some GREAT shooting.
Mind if I ask what exact Bushmaster upper you are using?

I would go with the 9" twist. Also a 24" bull barrel is going to be HEAVY!! I would go with a mid weight contour in 18" or 20" if you must. ARs tend to be a bit on the heavy side anyway. PH

Since you are wanting to use 55 gr bullets and the barrel is 24' go with the 14" twist. It will nice stabilize .224 bullets up through all of the 55gr bullets without over stabilizing them. With equivelent loads you'll also have slightly milder pressures. The original twist for the .223 cartridge was 14" and it did fine except for the sub zero temps in Alaska. With the 24" barrel you'll over come the velocity problem.

My favorite bullet for ARs with 12 and 14" twists is the Speer 52 gr HP. Loaded to 3200 - 3350 fps (20 - 24" barrels) it is very deadly on coyotes, rock chucks and other assorted varmints. The faster twist ARs have a lot of trouble with the thinner jacketed varmint bullets spinning apart from the increased RPM of the faster twists.

Larry Gibson

Not at all Antelope Sniper ; All of it's Pre 2K XM15 E2S 20" Target , I purchased a few of these and also some barrels .
20" Bushmaster National Match Heavy Barrel Assembly
Chrome lined in both Bore and Chamber, 1 x 9" Button Rifling and heavy profile, this complete assembly includes Bayonet lug, Threaded Muzzle, Flash Suppressor, Handguards; Gas Tube; Delta Ring Kit, and Front Sight.

Options: Assembly w/ Lug, Assembly w/o Lug, Barrel w/Lug, Barrel w/o Lug



http://www.bushmaster.com/catalog_xm15_BCWA2S20.asp

http://www.bushmaster.com/products.asp?cat=7

An truthfully my best shooter wears an inexpensive Simmons Atecc 2.8-10X44 either purchased Pre2K or shortly after afterward .

I have much higher quality scopes on nearly everything else I own , Leupold ,Nikon, Zeiss and one Swaarovski .
I'm simply afraid of touching anything on it as it's a tack driver and that Simmons has never failed or even come close to failing .

FYI ; Out of all my optics I prefer my Zeiss's .Swaarovski is also top notch .As for Leupold's and Nikon's they're a push especially newer stuff ,IMO .

My .338's WM's an Lapua wear Nikon an Zeiss ,7mm Rem Mags wear Leopold and Nikon . Ive killed more game with a single Mauser 3K LH 7 RM than ALL my other rifles combined .My first scope was 3X9 something or another Bushnell ( Crap at best ) .
After saving my $'s I stepped up and purchased a Balvar Bausch & Lomb, 2X8 36 or 40mm maybe around 1964-65 just before my 2 plus year Asian Vacation with Uncle Sammy . I had that scope a LONG time and wish I still had it !. I then purchased a Vari X Leupold and it now wears a VariX111 2.5-10X50mm made mid 80's ?.

An thanks too " Woods " it also shoots respectively once again !. An that's nearly a miracle as it's had more rounds down it then I could count 1963- present , on 5 continents game an vermin !.

I also neglected to mention POA was same on all those shots , note the heavier fouler shot was a different powder (an I don't remember which powder , it's why I used them for fouling label fell off box ) May have been 77 match king definitely WRONG POWDER . Winchester were high stringing wide left , so I switched over too my 55 grain bulk bullet loaded with 25.5 Gr. BLC-2 BINGO it liked it an H335 , Varget .

1:14 twist was used in AR-15's for about 6 months.

Here is lilja's AR barrel link. They recommend 1:8 http://www.riflebarrels.com/products/ar.htm

Over stabilization is a whore house rumour.

Any bullet strong enough for a coyote ain't gonna disentegrate in a 1:7 223.

I have shot 10's of thousands of 223's, mainly from AR's and have seen millions of rounds shot.

I can't believe the inaccuracy's in this post.

No such thing as "over" stabilizing a bullet.

I should have prefaced my varmint bullet comment with this. The older bullets can be torn apart in flight but the 1980's to present NBT, Vmax, etc are good to go. Circa 1970 Hornady and Sierra lead tipped, cup and core's can rip apart if pushed fast enough BUT it is usually a hot hand load that does it.

1:8 will keep you from having to buy a new upper in a couple of years when you decide you want to shoot 70gr TSX's or 75-80gr heavy match.

Perry

Airgun1 and Perry

Oh but there is such a thing as "over stabilization" of a bullet. Measure the actual BC of a given bullet out of 7, 8, 9, 10, 12 and 14" twist .223s and you will know. I have, have you.....I thought not. Ask any ballisticion who studies external ballistics and he will tell you the same. Also check and see if the bench rest boys use fast twist or minimal twists in their BR barrels, you might find a clue there also. Load 50 gr SXs or Blitzes to 3200 fps and shoot them out of a 7" twist and see how many make it to 100 yards. The RPM of a bullet at 3200 fps out of a 7" twist barrel is 307,200. The RPM out of a 14" twist at 3200 fps is 164,571. Big difference of almost twice as much RPM and the attendant increase in centrafugal force. More than enough to spin some bullets apart. Read the cautions in several loading manuals against loading such bullets above 2700 or so fps in the faster twist .223s because they will spin apart. No "whore house" rumor, it is fact.

The 14" twist in the AR lasted a lot longer than 6 months. That twist lasted through the ones initially made for the Air Force and the initial run of XM16s made for the Army. They had green stocks on them and we called them "green guns". When tested at the Cold Weather Test Center at Fort Wainwright it was found in the sub zero temps the velocity dropped to a degree that the bullets were not stabilized. Since the Army wanted a "go anywhere" rifle the twist was increased to 12" to solve the sub zero stabilization problem. Numerous green guns were in the 173rd when we deployed from Okinawa in May, '65. I used one. Some SF advisors also had them back then. At the temps in RVN the 14" twist worked fine.

Hell, I was there and have shot the damned things since '64 in the Army and hunting with them (coyotes and rock chucks about which the OP asked). I don't get my info off the internet or out of gun rags I get it from experience and testing. One should be aware of facts before starting "whore house rumors".

The fact remains the .222 and .222 Rem Mag are extremely accurate cartridges with 14" twists using 55 gr and lighter bullets. That is what the OP wanted to know. The .223 with a 14" twist (I own one and have used it extensively...have you?....thought not) is also very accurate, particularly with the thin skinned varmint bullets suitable for coyotes and 'chucks. What twist is needed for 62 gr and heavier bullets is another story and a moot point to this thread because that is not what the OP wanted to know. Obviously you got that fact wrong also? Perhaps you should spend less time in a whore house.

Larry Gibson

quote:

No such thing as "over" stabilizing a bullet.

Well, Airgun1, I'll have to say there IS such a thing as "over stabilizing" but not to the degree that Larry Gibson states.

You have to go pretty "hog wild" in twist rate to get bullets to shed their jackets and do "the crazy chicken". I think 1:7" is "hog wild".

I've had bullets shed their jackets in my 1:7" Colt HBAR A-2. But this was when pushing 52 gr. Sierra MKs to the limit.

If you loaded down with these bullets and this twist, you would probably have no problems. But what's the point of loading down when you want the maximum performance the cartridge can deliver?

But, I also don't buy Larry's story about 1:9" twists having jacket shedding problems. I currently have 3 rifles with this twist and have never had a problem with any bullets shedding jackets (including lightweight bullets with very light jackets).

If given a choice, I would also not own a .223 with a 1:14" twist. However I do, and I realize it's limitations. It's limited to 55gr. bullets and under. And it's even marginal with the longer 55 gr. BT bullets unless you drive them pretty hard.

But don't take MY word for it. Call the ballistics technicians of the various bullet manufacturers and ask THEIR opinions. Then please report back with the results.

Well Larry I was in C/2-503 but a few years after you.

Ar-15 and M16/601/XM16 are different animals. Colt made darn few Colt Ar-15 SP1's in 1:14

"While the standard 1/14 .224 barrel twist was quite successful in commercial firearms it did not serve the AR-15 well. M193 ammunition utilizes a boat tail projectile rather then the more common flat base. Boat tail bullets have less bearing surface to engage the rifling of the bore then flat base bullets of the same weight. The result was that the 55 grain FMJBT bullets were on the edge of stability when fired from the AR-15. Accuracy testing conducted by the US Army, US Air Force, and the NRA showed unacceptable accuracy with the 1/14 twist. Because of these factors a twist change to 1/12 was approved on July 26th, 1963".



The world doesn't revolve around benchrest. I've owned/built 1:7,8,9,14 223 bolt guns.
Real world experience shows 1:7's not over stabilizing 52 gn SMK's in my Colt. Pencil eraser size 10 shot groups @ 100 yards. There is more to life than 100 yards with a 223. You won't get many coyotes if you are limited with a 1:14 and 55 gn, and not all of them will stabilize with that, and again that is real world shooting.

Overstabilization is not disentegration. I have seen the super lightly constructed varmint bullets not make it to 100 yards. Overstabilization with small calibers is a myth. I'll smoke 52 gn SMK's though a 1:7 and they are flying just fine.

quote:

Originally posted by airgun1:
Overstabilization is not disentegration. I have seen the super lightly constructed varmint bullets not make it to 100 yards. Overstabilization with small calibers is a myth. I'll smoke 52 gn SMK's though a 1:7 and they are flying just fine.

I disagree. From personal experience.

I've smoked 52 gr. Sierra MKs through the 1:7 and got VERY TIGHT GROUPS until the barrel heated up! 200m as I recall. Then the bullets shedded jackets. I had a good spotter and he told me it looked like a couple hit the ground about 50m in front of the target. Sure enough.... four shots in about .75" and six totally missing the entire target.

So it does happen.

But BC of a projectile being altered by the barrel twist? What absolute horse sheet!

Opinions vary!

Here are four groups shot earlier today out of a 223 AI, 8 twist. Four different loads and four bullets between 36 gr. and 53 gr.
Pearland shooting club, off bench and rest, 100 yds. Wind +/- 10 mph., temp =/- 70 degrees F.
GWB









I'm not a ballistician, but would a 1:7 twist 52 grainer be spinning faster at 3,000 fps out of a 223, or at 3800 fps out of a 1:14 twist 220 swift.

The Barnes varmint grenades at 3,600 fps out of my 1:8 twist seem to do fine.

I've yet to have a modern varmint round come apart at 223 velocities.

Just sayin"

GWB

I understand that is starts with heat from the powder combustion and friction from the bore of the rifle, coupled with the heat created from the friction of flying through the air, the core can become quite soft and the bullet explodes from all the forces on it.

Let's take the 220 Swift which got a reputation for burning barrels and vaporizing bullets. Let's say it's shooting a 45 grain bullet at an even 4100 fps. That's 210857.14285 rpm. That's with a 14 twist. Now take an AR 15 with a 7 twist shooting a 55 grain bullet at 3100 fps. That's 318857.148257 rpm. I've never seen and AR 15 with a 7 twist smoke a bullet in flight. I even pulled 22 mag rimfire Winchester bullets (40hollow points) and loaded them in my AR 15 with 7 twist and way beyond 3100 fps and not only did they not smoke, they weren't too bad accuracy wise.

Nope not buying it's the twist that smokes the bullet.

quote:

Originally posted by Geedubya:
I've yet to have a modern varmint round come apart at 223 velocities.

GWB

Key word--

I have had bullets separate in .224 fast twist barrels at high velocity- (22Newton)

and .30 cal light bullets(100-110 gr) in 10 twist barrels at high velocity -.300WM-

BUT not recently,

in fact it has been several years.

IMO it is related to velocity, twist,

AND bullet construction.

The "modern" bullets of all major bullet producers seem to be better constructed these days.

It sounds to me like people are using the term over stabilization to describe bullets flying apart in mid air. That would mean over stabilization is a result of bullet construction not physics.
You can not OVER STABILIZE a bullet. You can push a under constructed bullet too fast as it pertains to rotational speed and too hot in friction and have it rip apart in mid air. BUT do not call it over stabilization.
if this does happen it will be the SX or Blitz, older bullets designed for the .222 Rem. Blitz King, Ballistic Tip, V-Max, etc will not rip apart.

Perry

For the OP:

This is real world info, not theory.

1:7 with a 52 gn SMK is a one holer out of my Colt AR-15. But you better be aware of any wind. Definitely 250 yds or less power and drop.

1:7 with a 69 gn SMK yopu can pretty much ignore wind 15 mph or less @ 100 yds.

@ 200 yds I hold into a stiff wind a bit
@ 300 yds You have to pay attention to the wind much like a 52 gn @ 100 yds

600 yds is doable but you are looking at up to 36 inch hold into the wind.

You of course must know your come-ups with irons or scope from your zeroed range.

77 gn SMK's are even better but I don't use them. They are loaded to magazine length as are all of the lighter offerings(2.26" OAL).

Now my friend has an older Rem 700 laminated stock, heavy varminter with a 1:12 223. I let him try my 69 gn Service Rifle loads and he and that 700 loved them. I loaded him a case of those for target and crow/varmint shooting plus 100 65 gn Sierra GameKings for deer. He shoots deer with 223 but I don't recommend it personally. He used the 69 gn SMK's for one shot long range kills on three different deer. He just did not like the accuracy from the 65 gn SGK's. I called Sierra and told them that my friend's 700 with a 1:12 shot 69 gn SMK's just fine.

They were not surprized because it is not really the weight of the bullet that needs to match twist, but the length of the bearing surface. Bullets are sold by weight is why we refer to what weight bullets work or should work with what twist.

Fast twists work in 223 AR-15's. Go with 1:7 or 8 and try single loaded(longer than magazine length) 80 gn SMK's for the long stuff 600+ yds.

Amen to that. Over-stabilization occurs with something flying through the air with fins. Yaw is the issue, not disentegration.

quote:

Originally posted by perry:
It sounds to me like people are using the term over stabilization to describe bullets flying apart in mid air. That would mean over stabilization is a result of bullet construction not physics.
You can not OVER STABILIZE a bullet. You can push a under constructed bullet too fast as it pertains to rotational speed and too hot in friction and have it rip apart in mid air. BUT do not call it over stabilization.
if this does happen it will be the SX or Blitz, older bullets designed for the .222 Rem. Blitz King, Ballistic Tip, V-Max, etc will not rip apart.

Perry

If a bullet can be under stabilized it most certainly can be over stabilized. You guys need to read Greehill's work on twist. A bullet or artillery round can fly with either the nose up or the nose down. This is due to the rate of the twist. See Greenhill wrote his formula for artillery. An artillery round in the early days had a nose fuse and that nose had to hit first. That's where twist played an important role.

You guys are showing and talking about bullets that do work, haven't seen any of those groups with a Hornady SX or Spear TNT out of a 7" twist at 3050+ fps yet? Come on guys, lets see 'em. Point is I said that some bullets, particularly the thin jacketed varmint bullets, don't do well in 7 - 9" twists. That is still a fact regardless of how many groups you shoot with MKs.

Airgun1

I have killed hundreds of coyotes (Oregon, Nevada and idaho) with 12 and 14" twist .223s out to 400 - 500 yards. Also have killed god knows how many rock chucks out to those same distances. I've been hunting and shooting them with the .223 in 12 and 14" twist barrels since '69. Seems to me that's what the OP wants to do also.

There is "over stabilization of bullets". That is not to say they don't shoot well at close range or even moderate range. However, if you measure the BC you will find that out. The BC measures a bullets efficiency in the air. The higher the BC the more efficient. A given bullet at a given velocity witha a higher BC is better stabilized than with a lower BC. Measuring BC of the same bullets at the same velocities through 7, 8, 9, 12 and 14" twists you will find that with 55 gr or less bullets the higher BCs always come with the slower 12 and 14" twists. With 62 - 70 gr bullets the higher BCs come with the 9" twist. With the 75 - 90 gr bullets the higher BC come from the 7 - 8" twists. With the exception of the 90 gr MKs the 8" twists proves to give the highest BCs with 75 and 80 gr MKs which is why it is the twist of choice with those bullets.

A 100 gr bullet in a 10" twist '06 at 2700 fps will never be as accurate as a 165 - 180 gr bullet because the 100 gr bullet is over stabilized where as the 165 - 180 gr bullets are not. However, use a 14 or 16" twist and the 100 gr bullet then becomes just stabilized and the 165 -180s will be understabilized and won't shoot as well if at all.

The point is; for a given caliber, given bullet weight and velocity there is a twist rate that will give the best satbility to a bullet. With 55 gr bullets and under in the .223 at 3200 - 3400 fps that twist rate is 14". That's the facts.

Larry Gibson

If you care to do so, Montana Bullet Works web site has couplete spread sheets/charts which depict the most desired weight, bullet length, twist, etc. for a whole host of bullet diameters pertaining to stabilization.

It's certainly true under certain circumstances that bullets do come apart in flight especially the lightly constructed ones. I must have a super smooth bore in my Colt HBAR with 7 twist as I can't even destroy a 40 grain Winchester bullet pulled from the rimfire magnum ammo. I'm sure other barrels, especially with very sharp rifling or perhaps even deeper rifling might engrave a lightly constructed bullet in a manner that would greatly weaken it.

Anyways back to the OP's original question as which to get, 8, 9, or 14 twist I can say the very first original M16's had a 14 twist and it was found out right away that the 55 grains boat tail spitzers they were shooting weren't stabilizing correctly and they immediately changed over to a 12 twist. So with that said that is definitely out. An all around twist would be the 9, but as mentioned it may not stabilize the heavier bullets.

quote:

Originally posted by MFD:
If you care to do so, Montana Bullet Works web site has couplete spread sheets/charts which depict the most desired weight, bullet length, twist, etc. for a whole host of bullet diameters pertaining to stabilization.

As does Berger

http://bergerbullets.com/Produ...rmint%20Bullets.html

and so do many other bullet makers

quote:

Originally posted by Larry Gibson:
You guys are showing and talking about bullets that do work, haven't seen any of those groups with a Hornady SX or Spear TNT out of a 7" twist at 3050+ fps yet? Come on guys, lets see 'em. Point is I said that some bullets, particularly the thin jacketed varmint bullets, don't do well in 7 - 9" twists. That is still a fact regardless of how many groups you shoot with MKs.

Airgun1

I have killed hundreds of coyotes (Oregon, Nevada and idaho) with 12 and 14" twist .223s out to 400 - 500 yards. Also have killed god knows how many rock chucks out to those same distances. I've been hunting and shooting them with the .223 in 12 and 14" twist barrels since '69. Seems to me that's what the OP wants to do also.

There is "over stabilization of bullets". That is not to say they don't shoot well at close range or even moderate range. However, if you measure the BC you will find that out. The BC measures a bullets efficiency in the air. The higher the BC the more efficient. A given bullet at a given velocity witha a higher BC is better stabilized than with a lower BC. Measuring BC of the same bullets at the same velocities through 7, 8, 9, 12 and 14" twists you will find that with 55 gr or less bullets the higher BCs always come with the slower 12 and 14" twists. With 62 - 70 gr bullets the higher BCs come with the 9" twist. With the 75 - 90 gr bullets the higher BC come from the 7 - 8" twists. With the exception of the 90 gr MKs the 8" twists proves to give the highest BCs with 75 and 80 gr MKs which is why it is the twist of choice with those bullets.

A 100 gr bullet in a 10" twist '06 at 2700 fps will never be as accurate as a 165 - 180 gr bullet because the 100 gr bullet is over stabilized where as the 165 - 180 gr bullets are not. However, use a 14 or 16" twist and the 100 gr bullet then becomes just stabilized and the 165 -180s will be understabilized and won't shoot as well if at all.

The point is; for a given caliber, given bullet weight and velocity there is a twist rate that will give the best satbility to a bullet. With 55 gr bullets and under in the .223 at 3200 - 3400 fps that twist rate is 14". That's the facts.

Larry Gibson

Larry
I have shot the 50/55 gr SX's at 3000 fps out of my 1:7 bolt guns and AR's with out a problem. I do not remember my groups but they were not bad, 1" at 100 yds??? I opted for the Blitz King due to accuracy and velocity, 1/2" at 100 yds and 3250 fps.

P

I have a SW stripped lower. I just found a RRA A4 preator in 20 or 24 upper with 1n8 twist and bolt and carrier. I plan to drop in a RRA 2 stage trigger add a PRS stock. Possible mounting a 6-18 swift scope that I already have. Any thought on problems with this combo will be greatly apperciated.

With that large of a scope you more then likely will have to add a riser to the flat top and possibley an extended riser.

Perry

Yes I have pushed them to 3000 fps successfully a couple times too. However, push them to 3200 fps or how about to 3400 fps since the OP wants to use a 24" barrel and see what happens with those bullets out of a 7" twist. The point is; the OP wants to use 55 gr or lighter bullets to hunt coyotes and woodchucks with a 24" barreled AR. The 14" twist is the best twist for that because it will give optimum performance and accuracy with those bullets, particularly the thin jacketed type for varmints. Why should he limit himself to 300 fps and under with those bullets (the bullets he wants to use) when he can get 3400 fps with those bullets using a 14" twist? What match shooters do with heavy jacketed and heavier bullets punching holes in paper is not relative to the OPs wants. What you do with a 20" AR at 3000 fps is also not relavent as with the 24" barrel the OP will push 3400 fps. So shouldn't we keep our answers pertinant to the OPs question? Makes more sense to me than to go off on a tangent about what we do with heavier bullets in shorter barrels.

Larry Gibson.

quote:

Originally posted by mdvjrp93:
I have a SW stripped lower. I just found a RRA A4 preator in 20 or 24 upper with 1n8 twist and bolt and carrier. I plan to drop in a RRA 2 stage trigger add a PRS stock. Possible mounting a 6-18 swift scope that I already have. Any thought on problems with this combo will be greatly apperciated.

If that is what you decide on then just shy away from the "explosive" varmint bullets with thin jackets. There are suitable .224 bullets in the 55 - 64 gr bullet weights that will work fine in that twist at optimum velocity. Frankly, you'll be better off with the 14' twist given a 24" barrel and you use for hunting coyotes and wood chucks.

Larry Gibson

quote:

Originally posted by mdvjrp93:
I have a SW stripped lower. I just found a RRA A4 preator in 20 or 24 upper with 1n8 twist and bolt and carrier. I plan to drop in a RRA 2 stage trigger add a PRS stock. Possible mounting a 6-18 swift scope that I already have. Any thought on problems with this combo will be greatly apperciated.

Personally I would go with the 20" barrel. 20" is about the optimal length for the .223. You'll gain little FPS with longer barrels. The twist is perfect for your needs.

Terry

Don't worry about an 8 twist destroying your bullets, believe. I have the Colt HBAR with the 7 and I've shot the light weight varmint bullets with great results and as mentioned twice before I pulled 40 grain jackets bullets from the Winchester 22 magnum RIMFIRE and shot them exceedingly fast with no problems....and further I shoot cast bullets from my Colt quite fast with good results. You'll be just fine with what you bought.