First I would like to mention that I am not out to sell a product. Only give a good report where one is due. I say this because I get the BS every time I mention or rather praise RRA for their fine products, that I either work for them or whatever someone concocts to discredit my posts.

Okay, to the threads topic, "the myths of button rifled barrel twist rates". Keep in mind that all button rifled barrel's twist rates are not created equal! None are true to the manufactures specs as you would find in cut rifling from Kreiger etc.

How many times have you heard that a 1 in 9 twist barrel will not shoot 80 gr. SMK's or even 77 grainers of either Nosler or Sierra. Sure, in a true 1 in 9" twist, they probably won't but in the case of button rifled barrels, you should give them a try.

Over the years I have owned at least two Wilson chrome molly steel barrels said to be 1 in 9 twist that stabilized and shot the Sierra 80 gr. MK even out to 600 yards. I have won several medals in the NRA championships, Master class held at Camp Perry to prove otherwise.

Here is another example. Range report of a slightly used Savage Model 10 Cal. 223 Remington with that "sweet" accu-trigger. 26" heavy chrome molly steel barrel 1 in 9" twist. I bought this fine rifle yesterday as part of an estate sale. I knew the original owner and his family so when I was told that the rifle shot well, I knew this rifle would blend in perfectly with the others in the gun safe. What I didn't know was what bullet or load was told to me shot well. So early this morning, I packed up several different loads that shot very well in my RRA's and headed for the local club's 100 yd. range.

Arrived at Roscoe Sportsman's Club, SW. Pa. at 1005. The temperature was 52 F and the wind was dead calm with sunny skies. Scope set on 16x. Eye looking through it has a "ripe" enough to remove cataract. The rifle resting on a Hoppe's front rest and a sand filled,moulded rear rifle rest bag.

I'll list the bullets and groups. As for the loads, I have listed them here many times as they are my standard AR 15 loadings with one exception. The 80 SMK's were bumping the rifling. All groups were 3 shots. The loads listed using two different primers, the Federal 205M performed better than the Remington 7 1/2 BR.

Group #1   57 gr. Swaged Corbin Rim Fire bullets = 1 3/8"  Still experimenting with these!

Group #2  69 gr. Sierra = 5/8"

Group #3  60 gr. Sierra HP (my favorite short line bullet)  = 1/2"

Group #4  69 Sierra's again = 1/4" or 1 hole!

Group #5 77 gr. Sierra MK  =  3/4"

Group #6  77 gr. Sierra MK  (same load as group #5 different primer)  = 1/2"

Group #7  80 gr. Sierra MK  = 1/2" (remember, 80's won't group out of a 1 in 9)

Group #8  80 gr. Sierra MK (different primer)  = 1/4" one hole! (this particular 1 in 9 is probably closer to a 1 in 8 twist)

Group #9  75 gr. Hornady HPBT "match"???  =  1 1/2"

Group #10  75 gr. Hornady HPBT (tried again) = 1 1/4"

Group #11  60 gr. Hornady V-Max  = 3/4"

Group # 12  57 gr. swaged Corbin's again  =  1 1/2"

Well there you have it. Savage has really got themselves a very fine rifle and for the money, I'll bet I will make some folks with those fancy/expensive rigs cry next time we meet on the 500 yd. F-class range!

Besides the rifle's accuracy, the GREEN box bullets beat the RED box 'again"!!!!! Ha! For that matter, my home made rim fire jacked bullets did almost as well as the 75 gr. RED box "match" !

Note: You may have or may buy a Savage Model 10 with the 1 in 9 twist but if it were rifled on a different machine than the one that rifled mine, you may not get the same results with the 80's. So goes the truth about button rifled barrels! Have a 1 in 9 twist? You have to run some 80's through it and see for yourself if they will stabilize!

Dave McGrath

Dave, I have a Savage LRPV in 223 1-7" twist that absolutely hammers with the Hornady 75 hpbt.  I have shot my best five shot group ever @200 yards (0.559).  It is funny how sometimes a rifle will just flat out disslike a specific bullet.  I use the 75 exclusively because it has shot so consistently for me in this rifle.  I have yet to try this load at length with my service rifles (not enough time to tinker).  I got the 1-7" so that my HP ammo could be used without any concern about stabilization.  

Do you think the longer tube with the increased velocity may aid in stablilization?  My service rifle loads will do about 100 fps faster out of my Savage's 26" tube.

Dave,  How far out to the lands in that Savage?  My friend had a newer varmint weight 1:9 with the accutrigger with .052" freebore; I and a lot of other people had both older model 16 sporter and varmint weight 1:9 with .362" freebore, and that is not a misprint or miscalculation.  They all shot very well with 69 SMK; we never tried 80's as they were 1:9.  The heavies could be set back far enough to get a respectable freebore, but the light ones could only be set halfway back due to the taper.  I don't know why Savage put 3/8" of freebore in some of the early 1:9 guns?

Mike;

This Savage is a SAAMI spec chamber. Example O.A. L. of 2.430" with a Sierra 80 gr. MK seated to just touch the rifling.

Tight line;
I did not chronograph loads yesterday. The loads I tested were from my loaded AR match ammo and I would expect them to be moving about 100 fps faster out of the 26" barrel than they would out of my service rifle (20") barrels. The 80's should be going about 2800-2825 fps.
Who's barrel are you using on your Savage with that 1 in 7 twist?

Another thing I would like to mention about the Savage. You can buy your barrels already to install for about the same prices that you would buy a AR barrel. Simply put, no more difficult or expensive to rebarrel a Savage Mod. 10 or 16 or 110 than it would be to rebarrel your AR class rifles. Ha, fewer tools and time required too!

Dave McGrath

Wrangler, the barrel is the stock one from the factory.  These rifles have a single shot receiver and extra heavy bull barrel that is 1" at the muzzle

The throat is quite long:

80 SMK @ the lands 2.522

77 SMK @ the lands 2.397

75 HOR HPBT @ the lands 2.321

As you can see from the above data the 75 Hornady HPBT has to be seated much deeper than the 77 SMK.  In fact if I loaded both bullets to magazine length in my AR with  Wylde chamber the 75 would only be 0.015 off the lands wereas the 77 would be 0.098 off.  I have never come across a mag length bullet that was so close to the rifling.

Tight Line

I was unaware that Savage had marketed the rifle that you have. I think I would have sent it back and asked for a barrel with some throat in it! The SAAMI chamber is all you will ever need or want in a rifle like that. Unless you want to change barrels every 2000 rounds.

The 75's and 77's are meant to be bullets seated to AR magazine length. High power competition rules the day in sales of these bullets. They were not nor will they ever be sold for "F-class competition rifles. Now, in the case of Hornady, if they want to get their name into the winners circle at the Nationals etc., they need to come up with products designed around the Sierra or Nosler line. For now the only real name Hornady has in the high power game is "A Flier In Every Box" or rather, Cracker Jack Bullets"!  Another lesson to be learned in the sport of High Power is "A Lesson Learned Hard Is A Lesson Learned Well!" Buy your competition bullets from Sierra! If unavailable, go with Nosler. A little more money but a lot more points, less miles to get leg points..............I could go on and on but I think you get my point.

Dave McGrath

Tight-Line
Something's not right.
Just measured a SMK 77 and a Hornady 75 gr, the difference from the base of the bullet to the ogive is only .010 difference
Something is giving you false readings or your not measuring right. How are you measuring to the lands?
'Borg

ETA you are talking about the HPBT, and not the A-Max, right?
Re ETA, your you sure your not talking COAL?

I know what has been said about Hornady 75s but I have yet to see it myself.  Like I said before my Savage is a legitimate 1/2 moa rifle with the Hornady 75 hpbt.  Black Hills loads the 75 in their match ammo so they too must have seen acceptable accuracy.

I shot Noslers all last season and they shot very well for me, I would not hesitate to go to them again.  This year I am going back to the 77 SMKs but I do want to give the Hor 75 a try someday.  

Whith all the price increases and availabuility problems with components I think we all are much more willing to give new things a try.

I am using a Sinclair tool.  You use a fired case from your rifle and a bullet that you want to use.  The problem that I have found using comparators is that the guns that we are loading for do not have a .224 hole that we are trying to set our bullets to.  A bullet will always stop short of its ogive when placed by itself into the bore.  The lead going into the rifling has a contour that is specific to the chambering and at the same time each bullet has its on contour on its way to its ogive.  Where the two meet will determine a true maximum COL.  My comparator will never give me an accurate COL because its not a rifles throat, its just a .224 hole in a piece of steel.  After I got the Sinclair tool I have little use for my comparator.  

On a side note the I have found the 69 SMK and 77 SMK to have identical nose cone profiles and will give me data indicating the same max COL.

I guess what I'm trying to say is that the COAL doesn't have anything to do with the rifling, it's the ogive that you have to measure.
Like I said, there's only .010 difference between the two bullets in the ogive department.
I seat all long ammo with the ogive checker, and both bullets the same measurment to the ogive,, the throat doesn't change, so I jump .010. on both. The length from the case head to the ogive will be the same length, which is what you will seat all long bullets that you single feed on an AR.
I just measured the two again, the SMK is .990, the hornady is .988, .002 difference in length.
On the base to ogive, the SMK is .533, the the Hor is .540, .007 difference, so your seating should be within .007, if not, you have measured somthing wrong.
'Borg

Using my comparator is like measuring in feet and the Sinclair seating depth tool is like measuring in inches.  There are two shapes hear, the lead in the barrel and the profile of the bullet.  They sometimes match up in ways that my comparator will not show.  The ogive does not contact the rifling untill the bullet is fired down the barrel.

Wrangler,  sorry for highjacking your thread!

Okay, I had this Savage Model 12 out for a true test on Sunday. The range SAG in SW Pa. Distance 500 yards. Targets are the F class and a bit tougher than the standard NRA high power target. Well so I am told as I only dabble in the sport of F-Class but will tell those that haven't as yet tried it, it's a ton of fun! Hey, just the ticket for we old guys!

Weather conditions this entire week were very unsettled with heavy rains, high winds and reports of even tornadoes touching down in some locals. Sunday, the day of the match, we got the tail end of the weather system. All said, not the kind of day to test loads at long range but rather a test of a shooters wind reading skills.

The barrel on this Model 12 shows very little fouling which is uncommon to the only other Savage I own, which is a Model 11 in cal. 243 win. Believe me, It's a copper mine!

Like I said in my original post, the model 12 Savage I have in cal 223 Rem. is cataloged as being a one in nine twist. I tried several bullets including the SMK 80's and 77's and all shot very well! Fluke on the 80's and 77's? Decide for yourselves.

My first match score of the day was 199-10X fired with SMK 80 gr. The second match was in the early afternoon. The conditions were rough. I fired a 193-8X with SMK 77 gr.

I let my rifle down. My scores should have been cleans with higher X counts! To top it off, I used a cheap scope. A Simmons 4x16. The dual X cross hairs completely wiped out the X ring and touched the 10 ring on the target. I'll be buying a better scope but guess what, I don't need a better rifle!

I shot with a Harris bi-pod on the front and installed a Black Hawk tactical cheek rest on the Savage's black synthetic stock. Lowered the Accu-Trigger to it's lowest setting. This rifle is a hummer! Can't afford one of those big expensive rigs you have read about or seen on the F class sites, well don't stay home. Instead, try one of these new Savage model 12's!

End of story but remember, button rifled barrels are only in the ball park figures by the manufactures. If you have a barrel listed as a one in nine, you must try 80's and 77's to see if your barrel can stabilize them! Some do and some will not.

Dave McGrath

Great report Dave.  But with respect to button rifled barrels, can't one just measure the twist with a cleaning rod and ruler?  By the way, tell RRA we need more barrels ASAP! just kidding Dave.  Acutally I am looking for a spare SR flat top RRA "NM" upper.

I think the real myth here is what twist is required to stabilize a given bullet more than great discrepencies in advertised twist rates.  Compute twist requirements using the Greenhill formula and you will be amazed.  Now the Greenhill formula was originally developed for soft lead projectiles but it still gives you an indication.  There are other formulas out there that really get into the physics, adding in drag, velocity etc.

A big contributor to the myths is the NATO SS109 62 gn FMJSCBT projectile.  The design of this bullet required the US Army to adopt 1:7 twist, as 1:9 was marginal,  so people automatically jump to the conclusion that heavier bullets than it demand fast twist as well.

Many Remington 700 rifles with 1:12 twist barrels shoot 69 gn Sierra Matchkings very well.  My friend has one and we double checked the twist with the old tight patched brush on a cleaning rod and it came out 1:12 everytime.  I contacted Sierra about it personally and they said they were not surprized due to the design of the 69 gn SMK.  They designed that bullet to be shot at magazine length loadings, and a by-product is it flys well from slower twist barrels than one would think.  The 77 gn was designed the same way but I have zero experience with it as I load 69 gn SMK and 80 gn SMK, and have a good supply of each.  I am not in the flavor of the month club.

The bullet manufacturers and reloading component manufacturers in general all build a certain amount of fudge in their numbers to minimize complaints.  I think that is the case here with a 1:9 barrel shooting 80 gn SMK's well.  Some 9's probably will and some may not, or some may not at a specific  velocity.  There are tolerances; there are fast 9's and slow 9's, but they are both sold as 9's.  Label the bullet as requiring an 8 and much fewer complaints.

I was always under the impression that it was the M856 tracer that required the 1/7 twist. M855 ball shoots nicely out of 1/9 twist barrels.

B

No razzle dazzle with words here! Just factual experiences that can be backed up with scores. Besides, my posts are geared for the common, average competitor. In other words, I am out to keep the shooting sports alive!

I will reiterate as to what I originally posted and the reason for this topic. If a barrel maker that "cuts" his rifling, example would be Kreiger, he can guarantee you what the exact twist. For example his world class 223 caliber barrels for AR type rifles will be a true, dead nuts 7.7 twist. The manufacturers of button rifled barrels can not state the true barrels twist. If they call it a 1 in 9 it could very well be a 8.5 or a 9.5 and anywhere between and so on. I rest my case simply by stating what I created this post for. Have a one in nine twist barrel?  Try 80's or 77's before you write it off as it won't stabilize them!

My opinion on the point of bullet manufactures having built in allowances for twist rates, I would stick with Sierra for true test results as most of their barrels are "test barrels" (probably made by Kreiger) on universal receivers and I would wonder what Hornady's excuse is !

As for testing your twist rates by the use of cleaning rods and tight fitting patches etc. I won't go there because the average shooter does not own high quality cleaning rods with good ball bearing handles. He runs the risk of possibility ruining a good barrel in his attempt and get false readings or even different readings per attempt. We are talking small dimensional differences. Best said, accuracy testing and working up loads for his "button rifled" barrel.

On the military 62 gr. well, seems they are not known for accuracy in any twist. The AP tip in most is off center. Also, the military barrels are button rifled.

Had a model 70 Winchester heavy barreled Varmint about 12 years ago. Bought it new. It had the pillar bedded black composite stock with blued receiver. The stainless barrel on it was cataloged as being one in nine twist. The SMK 69's were very marginal, and the 77's and 80's were all over the place. Shot 60 gr. hp Sierras in one hole groups repeatedly! A real hog killer but not a rifle for across the course or F class. Truly a one in what? One in 9 3/4" ???


Dave McGrath

I will back up what wrangler said about twist rates. I bought the winchester HBV he talked about from him with every intent to use it acorss the course. It didn't do well with 69 Sierra's. I tried the 75 grain A Max, and the Sierra 80's. Off a solid rest with a 20x Leupold at  Reade range on a day with as little wind as you ever get at that range, it would hardly hold the 8 ring.  I sold it right away and never looked back.

Last Sundays F-class match at SAG. With the Savage!

First match. 200 -14X with 77 gr. Sierra's

Second match  198-10X with Sierra 80's

The nut behind the butt dropped the two points. Not the rifle!

Dave McGrath

I'm not sure if there's a newer post about twist rates and Wylde chambers, but just to let you guys know not all Wylde chambers are the same either. I measured my Wylde chamber throat length and get 2.012" from case base to lands on a 80 gr. SMK. That would make the OAL 2.514" as measure on several bullets from my box (new from Sinclair few weeks ago). I used a Hornady OAL gage and their ogive insert and a digital caliper for the measurements. Also went back and did it again, got same exact measurement a week later, on a clean barrel. The barrel is a 1:8 (Wilson I believe) from WOA (standard Service Rifle NM upper), John Holliger says to load these to 2.485" max on his website. I would need to load them to 2.5" minimum to get the same jump that he recommends as max. I have not done an exact measurment on headspace, but it seems right, no probs with pressure or jammed bullets. This barrel has about 800 rds. max through it, very mild loads, can't imagine any wear that would ammount to 0.027".

Here is a handy writeup someone did calling out the specs on various AR chambers, it lists two different "Wylde" chambers, one called the ".223 Holliger". I'll bet mine is the latter (mine=2.514", listed here=2.53").

http://www.whiteoakprecision.com/info-reloading.htm

My question is how should I taylor my load to compensate for the longer lead? Should I add powder? Leave the same .015- .020 jump? The Sierra Manual lists the 80 gr. MK at 2.55, I wonder why they would list it so long, when most chambers are 2.47"??  Any ideas service rifle reloaders?

Stop measuring chambers and go shoot. You're better off loading to the max length than to try to reach a particular jump distance. Adjusting jump on the Sierra 80MK is overrated. Use the suggested OAL and go win matches.

Thanks for the reply but wouldnt loading to max jam the bullet into the rifling and push back into the case?

[quote/]Stop measuring chambers and go shoot. You're better off loading to the max length than to try to reach a particular jump distance. Adjusting jump on the Sierra 80MK is overrated. Use the suggested OAL and go win matches.[/quote]


I agree with this statement to the point that when my Krieger on my current XTC rifle was new I found the sweet spot for my 80s and left the jump there (almost 4,000 rounds on it now).

I have not "chased" the chamber at all and shot a 193 at 600 during the NTI last week and legged out.