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Old September 3, 2013, 05:44 PM   #1
Jerry45
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What's up with Remington and 1/10 twist?

My 700 BDL 30-06 only likes 150 gr. bullets. I thought 1/10 was for heavy bullets.

I recenty purchased a Remmy. SPS Tactical AAC-SD... 1/10 twist. 900 rounds down the tube and I've yet to find a bullet powder combo that will shoot under 2 MOA at 100 yards. It hates 168 SMK and 180 SGK using either Varget or 4064. It will shoot 175 SMK and Hornady 165 InterLock SPBT to 2 MOA but at times it throws them hither and yand. It does so many strange things it would take fare to much typing to explain. Swopped scopes with my bench 308. It isn't the scope.

Took it to my smith. He says only thing he can come up with is somethings up with barrel. He checked it with a bore scope but diidn't see a pproblem. It's in a Bell & Carlson Tactica Metalist stock, which he checked out. I took out of the original stock becaues it's worthless. Comb is too low and if you put the slightest bit of pressure on the forearm it touches the barrel.

I'm taking it to the range again tomorrow. If it stll doesn't shoot sub MOA after the tweeks I've done I'll try some 150 gr. bullets next week. If that doesn't do it I'm ordering a 24 or 26" Krieger barrel 1/11.5 twist for it. I'm really disappoints in this rifle.

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Old September 3, 2013, 05:58 PM   #2
Jim Watson
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It isn't the twist.

You may have a lemon barrel or one that by chance favors lighter bullets.
You say it "only likes 150 grain bullets" but later that "I'll try some 150 gr bullets next week."

Well, which?
Does it shoot 150s accurately or do you just hope it will?

900 rounds of tinkering is a lot.

Maybe it DOES need a new barrel and will then shoot well m
But the difference between 10 and 11.5 twist won't be the reason why.
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Old September 3, 2013, 07:03 PM   #3
Jerry45
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I wrote that my 700 BDL 30-06 only likes 150s. I then started a new paregraph about the SPS Tactics AAC-SD 308. Both rifles have 1/10 twist barrels.

I agree 900 rounds is a lot of tinkering. I've tried it with and without a brake installef. I've worked up loads using 2 different powders with 4 different bulletd and seversl different OALs. Can't do that in 100 rounds. I really hate to give up on it... but it's close.

The 06 shoots 1/2 MOA with 150s MOA with 165s then + 2 MOA as bulet weight increases. Haven't found anything the SPS will shoot under + 2 MOA.
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Old September 3, 2013, 07:29 PM   #4
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Jerry,

Too bad that 'smith didn't measure the barrel's bore and groove diameters; bore scopes don't do that.

The most common cause of a .30-06 with a 1:10 twist barrel not shooting accurate is the groove diameter's too big. Winchester Model 70 30 barrels were notorious for this. One cure was both Winchester and Western Cartridge Company making their match bullets almost .3090" in diameter so those oversize barrels would shoot well.

A 1:10 twist for the .30-06 started back in 1903 with the .30-03's 220 grain long round nose bullets leaving at about 2600 fps needed it to stabilize them. In 1906, when the round was changed to 150-gr. bullets, the government kept the old twist. Commercial rifles also had a 1:10 twist 'cause that's what most customers though was best. It wasn't until the 1950's that the 7.62 NATO round shooting 150 grain bullets virtually as fast used a 1:12 twist barrel for best accuracy and bullet stabilization.

I noticed your comment that if you put the slightest bit of pressure on the forearm in the rifle's original stock, it touches the barrel. You're the first person in decades I've known to mention this. The old "dollar bill slipping between the barrel and stock" has been a myth for a long time. You're one of the few I know of who've noticed that accuracy robbing issue.

I'd take that rifle back to the 'smith and have him measure the barrel's groove diameter. He can slug it with a lead pill and also see if there's loose/tight spots in the diameters. Then measure the diameter of the pill. It needs to be no larger than .3080" if decent accuracy's the objective.
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Old September 3, 2013, 08:06 PM   #5
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Bart, it's the 308 that's giving me all the trouble. But it's possable the problem you post. As far as the original stock touching, the SPSs are noted for that. Flimsy plastic stock. Works fine as long as a bypod isn't used or the rifle is supportd well aft on a rest.

SPSs got good revies for accuricy. I was taken aback when it threw bullets all over the place. I've thought about selling it but I'd rather pay to re-barrel it than sell someone my lemon.

This is what the 06 does with 150s.

1/2" diamond.
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Old September 3, 2013, 08:43 PM   #6
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Curious - How are the action, the recoil lug, the chamber length of the barrel, and the remainder of the barrel bedded? I am not a bench rest expert but in my experience bedding can be critical to the accuracy of a rifle. I worked on and improved the accuracy of hunting rifles starting with action bedding, followed by recoil lug bedding, partial bedding forward of the case head, and, if necessary bedding, slightly forward of the case, followed by free floating the barrel. Bedding was always Acra Glass from Brownell's. I believe aluminum bedding blocks and pillar bedding have reduced the labor and time needed to achieve a rifle's potential.

PS. On 3 of my 4 synthetic stock rifles, the forend is flexible enough to require significant sanding to assure no contact with the barrel. One is a Remington 700 BDL .270 with a 22" barrel in a Brown Precision stock; the other two are Browning A-Bolt Stainless Stalker rifles (7mm and .300 Win Mag) with 26" barrels.
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Old September 3, 2013, 08:57 PM   #7
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Jerry, I've no idea why Remington uses 1:10 twists on most of their .308 Win. barrels. 200-gr. bullets shoot very accurate from one. But it's way too fast for good accuracy with 150-gr. bullets. That's one reason why the US Palma Team rejected Remington's offer to build 20 rifles for them at no cost as the Team could only use bullets no heavier than 155 grains in their .308's.

No part of the barrel should touch anything except for the receiver face it screws in against. Any bending of the fore end gets transferred through bedding between any point on the barrel and the fore end where there's epoxy. This is why the most accurate rifles have no bedding under the barrel; anywhere.
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Old September 3, 2013, 09:03 PM   #8
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Bart, you are probably right about the 220 grain bullets but the 1:10 twist goes back to the Krag, which fired the same bullet. No computers back then; Army ordnance arrived at the 1:10 mostly by trial and error.

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Old September 3, 2013, 09:11 PM   #9
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James, a bit of icing on your good information cake regarding slow, heavy 30 caliber bullets.

The prime reason the US Army wanted 1:10 twists in the .30-03 was the success of 200 to 220 grain bullets in the .30-40 Krag's used by the US Palma Team in winning long range competition a few years earlier. Even Harry Pope agreed that those blunt, heavy round nose bullets needed a 1:10 twist for the velocity they left at. Interesting fact was when the US Palma team was shooting lighter bullets in the .30-06, Harry Pope used 1:12 twists in the barrels he made for them.
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Old September 3, 2013, 09:12 PM   #10
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1:10 twists are pretty much the norm in most .30 cal rifles with most rifle makers, not just Remington. If you're putting together a rifle for a specific purpose there may be better options. But one of the selling points of most .30 cal hunting rifles from .308 up to the 300 mags is being versatile enough to shoot bullets from 125 gr up to 250 gr acceptably. The 1:10 seems to work well enough for what most people want. There are custom rifle and barrel makers for those wanting something specific.

I don't think the twist is your problem in this case.
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Old September 3, 2013, 09:15 PM   #11
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I bought a stainless Remington 308 VS from a guy that claimed he could not get it to shoot. First thing I noticed when I got it was that the stock was uneven, and touching the barrel on one side. Couple of minutes with a Dremel fixed that, and it really likes the 178 Amax and Varget. I had 2 Winchesters, a 30/06 and a 22/250 that would not shoot a darn with the factory stock, put a cheap Ramline on the 30/06 and groups went from 1.5-2 inches to 1/2 inch at 100 yards. The 22/250 would do about an inch which I consider horrible for a varmint rifle, put a Ramline on that as well and it became a one holer. Stocks have more of an effect than you might think.
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Old September 3, 2013, 09:15 PM   #12
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Question for Bart: Is free floating the entire barrel necessary for the best accuracy in any bolt action hunting rifle? (Please note this is an honest question and I respect your expertise.)
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Old September 3, 2013, 09:17 PM   #13
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Jmr40, I agree with your comments on 30 caliber barrels being 1:10 twist; for the most part. Virtually all .308 Win. factory barrels were/are 1:12 except for Remington and one other I now forget.

I've shot 180's from a .300 Win Mag's 1:13 twist barrel with excellent accuracy through 1000 yards. Those bullets were spun about perfect for best accuracy from that magnum size case.
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Old September 3, 2013, 09:54 PM   #14
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Lefteye, the Metalist stock has an Aluminum beding block that is integrated with a fill length skeliton running throughout the stock. Bedding surface and recoil lug checked. Action torqued to 55 in. pounds as per Bell & Carlson. The 30-06 is in an identical stock as the SPS.

Here's the 06.

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Old September 3, 2013, 10:00 PM   #15
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Remington 308s are 1/12. The "SPS Tactical AAC-SD" is a special beast. Even the regular SPS Tactical is 1/12.
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Old September 4, 2013, 12:52 AM   #16
Jim Watson
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Ah, OK, I missed the shift from BDL to the new alphabet soup model.

The point remains, there is something out of whack with that barrel not likely involving the nominal twist rate.
I am not a gunsmith but I have read of things like uneven bore/groove diameter with the muzzle being the large end, or an uneven twist rate with the muzzle being slower than the breech. Somebody once said that on the scale of barrel value, the factory job was about a $50 part vs a $300 Krieger.

It might be the stock. The B&C has the stylish bedding block, but they have been reported to benefit from glass bedding anyhow.

Historical examples, when H Pope actually made barrels for Krags, he used an 8 twist!

Then there was the batch of 1903s that checked out more accurate than usual in the spot check of service rifles and the targeting of all NMs, etc. Turns out, a machinist had set up a rifling machine wrong and they had 11 twist rifling instead of 10. Did the Army get smart and revise the spec? No, they reset the machine to 10. I think they rebarrelled all the odd ones, too.

My FLG was showing me his new rifle and its sight in target. The last five shots at 100 yards were the proverbial one ragged hole. But then it is a .50 cal so that is not as small a group as it sounds. But it is also a round ball muzzle loader with iron sights, too.
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Old September 4, 2013, 01:36 AM   #17
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I tend to agree with my smith that it's a barrel problem. Why? My 06 is in a B & C and yoy see how it shoot. I pulled the low shot. My benckrest 308 resides in s B & C and shoots 3/8" five shot groups. Could I hsve gotten a bad one for the SPS... sure. But neither I nor my smith believe thats the problem. We'll see what happens at the range today. If won't shoot I guess the only way to find out is to put a new barrel on it. The 06 and bench rifle are long actions so there won't be any stock swapping.
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Old September 4, 2013, 04:52 AM   #18
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Well, if the barrel doesn't like 168gr SMKs, then the first place I'd check is the crown.

Flat base bullets can beat boat tails in accuracy because there is less bearing surface on the tail for off center gasses to push against. I'm assuming that the 150 gr bullets are flat base, could be a bad assumption on my part.

I'd try recrowning first.

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Old September 4, 2013, 05:48 AM   #19
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Lefteye, yes, free floating the entire barrel is necessary for the best accuracy in any bolt action rifle. That's the only way to keep the stock's fore end from transferring its bending amounts in normal handling through the hard bedding material between it and the barrel to the barrel. When this happens, the barrel whips and wiggles differently from shot to shot instead of being the same fore every shot when totally free floated.

Poorly fit receivers in the stock's inletting for them sometimes need a pressure pad between the stock's fore end tip and the barrel for good accuracy when shot off ones shoulder with the fore end resting atop something on a bench. But when shot from field positions without that fairly repeatable artificial support, best accuracy goes to hell in a hand basket.

While the difference is often small, it is there. And the way most folks test their rifles to see the difference usually won't make it visible. Remington puts the following info in their web site: Only the Model 700 Tactical Target, SPS Tactical, VS SF II, Model 700 Sendero SF II and most Custom Shop rifles are factory free-floated. Other Model 700 models and Model Seven models, including the Model 700 VLS, feature a pressure point near the tip of the fore-end of the stock. Their free floating barrels' receivers are fit to a bedding block.

Jimro, Sierra's 30 caliber match bullets shoot much more accurate than any of their flat based 30 caliber bullets. None of their flat based ones have shot in the ones, but their boattail match bullets will. With 22 and 24 caliber bullets used in short range benchrest matches, the hand made ones do have a slight accuracy advantage up through 300 yards.

What are "off center gasses?" Never heard of such a thing. I do know that Sierra switched in the 1950's their match bullet designs to hollow point in stead of full metal jacket 'cause the heel dimensions were better controlled.
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Old September 4, 2013, 09:11 AM   #20
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Jimro, I asked the smith specifically about the crown. Not that there appeared to be anything wrong but because the rifle has a "flat" muzzle. There is no bevel. Why Remington did that I don't know but the rifle "supposedly" is designed specifically for use with a suppressor. I'm glad I didn't spend $$$$ on a suppressor for it. I've see videos of them being shot with and without suppressors and brakes, so I bought and tried a brake. It actually shot a little bit better with the brake but still inconsistent. I've actually tried 2 different brakes. No one can say I haven't given this rifle a fair shake. I've tried and done everything I can think of. That's why I posted. Sometimes someone comes up with something I didn't think of. At the rate I've been shooting and tinkering with it, it will need a new barrel in a couple of months anyway.

Heading out to the range now. Taking the wife and grandson so I'll be there all day. I'll post the latest on the BEAST tonight.
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Old September 4, 2013, 10:19 AM   #21
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Bart B. "off center gasses" might not be the shooting term, but basic gas chemistry and physics tells us that in an enclosed environment pressure is equal against all surfaces. If a crown is out of true, once the bullet (the only thing keeping the gas in) passes by the out of true portion and unseals the system that is where the gas will preferencially go instead of "pushing" against the bullet. Too much gas pressure on one side of the base of the bullet on exit from the muzzle is not good for accuracy, and boat tail bullets have a longer bearing surface for the gas to interact with over flat base bullets, which as you noted have an accuracy advantage at short range.

A lot of milsurp rifles have that "counterbored" muzzle because careless soldiers with steel cleaning rods made the muzzle not a true circle and accuracy suffered.

I'd still try a recrowning job, recess the muzzle 1/8 of an inch and machine an 11 degree target crown.

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Old September 4, 2013, 05:45 PM   #22
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Looks like a lost cause. 1/2" diamonds. One target shot with 175 SMK over 44.2 Varget. Other target 165 gr. Hornady InterLock SPBT over 45.0 Varget. 4 different bullets and 2 different powders yielded pretty much the same results in prier workups.

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Old September 4, 2013, 06:31 PM   #23
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Have your gunsmith take the barrel off and see if your rifle is one of those M700's in which the receiver threads were so poorly machined, that Remington poured glue around the barrel shank to keep it in place.
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Old September 4, 2013, 10:39 PM   #24
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Slamfire, thanks for the heads-up. First I've heard of that one. I'll find out when he installs the new barrel. Haven't ordered it yet so I don't know how long it'll be before I get it. Smith will be squaring up the action and cutting new threads so if it is a Remington patch-job it won't matter in the end.

I just finished taking the scope off and found a loose rail screw. Wasn't loose last time I checked it... trip before last. When I say loose it just took much less torque to brake it lose than the other three. Two front screws were tight tight. Forward rear took a little pressure to break loose (less than the front two.) but the one all the way in the back turned with very little pressure. Had maybe 5 in. # of torque on it. Threaded holes and screws were cleaned with mineral-spirits then Acetone then RED LockTited so I don't understand why the rear screw turned so easily. I pulled the action and found that the recoil lug isn't square in the action. Only the lower edge is making contact with the beading-block. That will also be taken care of when the new barrel is installed. Bedding block seems to be square. When cleaning I did notice a tight/rough spot in the bore about a third of the way forward of the breach. Felt like it cleaned up so it may have just been carbon/copper fouling. I had put about 125 rounds through it since the last cleaning. Barrel cleans/cleaned up pretty easily. Couldn't find anything else out of whack.
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Old September 6, 2013, 08:36 AM   #25
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Jimro, I agree that gas will escape first where the bullet's heel first clears the crown. That's easy to understand. But if it's minimized, it won't effect accuracy to any observable amount. Here's why.

I've worn out 4 barrels in 7.62 NATO chambered Garands and cleaned them every 30 to 60 shots with a solid steel rod that rubbed away the barrel steel back from the crown. The bore and groove diameters were worn away evidenced by the lack of copper fouling where the wear was. Copper fouling stopped about 1/8th inch back from the muzzle for every 1000 rounds. After a total cleaning removing all the copper wash, it would start building up again but never where the bore and groove diameters has been enlarged by the cleaning rod lapping away metal. And there was always more in one area (typically at 4 o'clock in the bore) from how I used the cleaning rod and it was twice as far back on one side opposite the other. When the barrels were replaced at about 5000 rounds, there was no copper wash for about 3/4ths inch back from the muzzle on one side and about half that much on the other.

This tells me the metal wore away more at one point that the place opposite it in the bore. As more metal wore away, more gas escaped at that point at the bullet's heel than the others. So there was some uneven gas ejecta around the base of all bullets fired starting with the first hundred or two fired.

Yet accuracy stayed the same from brand new to worn out barrels. With good commercial match ammo, 2/3 MOA at 600 yards was normal for about 3000 rounds. It opened up a tiny bit after that but still stayed under 1 MOA for another 2000 rounds. No discernable change in zeros for any range was observed.

Why? The only answer I can come up with is the gas ejecta at one place around the muzzle was very repeatable from shot to shot. As accuracy with rifles is typcally best defined as reducing all the variables to zero (or as close to zero as possible), the varable in this gas ejecta issue with bad crown is not a problem when it's not very much. But a horribly mutilated crown may well cause other issues as that will tip the bullets way too much upon their esxit from the muzzle. I've seen some crowns with a protruding burr that had to groove bullets as they exited.

For all the others, a "crown" is typically referred to as that few thousandths of an inch where the muzzle's angled away from the bore diameter out just past the groove diameter. The "face" is the muzzle shape from the crown's outside to the muzzle's outside diameter. The face can be flat, rounded or angled to some amount as counterbored back from the muzzle.
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