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Old May 15, 2013, 07:44 AM   #26
Bart B.
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Detachable magazine accuracy issues were first noticed in the mid 1960's by master class service rifle competitors using well rebuilt M14NM's in competition. When the US Army and Marine Corps shops finally worked out all the bugs with that rifle and using the best lots of M118 match ammo, commercial .308 Win. match ammo or handloads, they noticed a zero shift of 1/2 to 3/4 MOA at 200 and 300 yards depending on the magazine used. Any magazine that had the slightest slop in its fit would be given to the combat troops; only magazines that fit solidly were used in competition.

Clamped in an accuracy cradle used to test rifles and ammo for accuracy, tight-fitting magazines produced better accuracy than loose one. Not all that hard to figure out why when one realizes that all the parts of a semiauto rifle have to go back to exactly the same position with the same force for best accuracy to happen. With two tight fitting magazines, one would shoot just as accurate but the group center would be 1/2 MOA or more away from where another tight-fitting one would shoot. The rifles recoil was sufficient to dislodge a loose fitting magazine enough that one could see the shot string on target move around in impact. Magazines that fit really tight would stay in place from shot to shot. Sometimes a magazine would be "spread" out at its top end to make the sides bear harder against the receiver to keep it in place. Top level shots could tell the difference shooting the rifles in normal positions shoulder fired, too. All the parts in a rifle have to go back to exactly the same place after reloading the next round if best accuracy is the objective.

For slow fire matches where rounds were loaded one at a time into the attached magazine then the bolt tripped to chamber it, an extra tight fitting one would be used. As the M14 magazine was also used as a palm rest for standing position, it had to be a really tight fit with some extra force required to lock it in place. That also prevented it from being displaced in theprone position by accidental body and/or sling contact. The slow fire magazine was usually marked to indicate it was for slow fire with an "S" or "SF" for identification.

For rapid fire matches where 2 rounds in one magazine and 8 rounds in another would be used for 10-shot rapid fire matches, two magazines had to be used which both enabled the rifle to shoot to the same place. These magazines typically fit a tiny bit less tight so they could easily and quickly be removed and replaced in the reciver but still held immovable in place. One was marked "R1" and the other "R2" (or just "1" and "2") indicating one was for rapid fire and the first one holding 2 rounds, the other was the second one holding 8 rounds.

In a conversation with GySgt Frank Kruk, USMC, in the late '60's (1964 NRA Nat'l Service Rifle Champ) he told a bunch of us Swabbies that the Leathernecks on the USMC Rifle Team would almost fight over who got what magazine when a crate of new ones was opened for replacing their old ones. We jokingly suggested to him that the USMC team go back to M1 Garands and get them from the USN shop that built them as they had no issues with all sorts of 8-round clips and we didn't care how they fit. Garands had no accuracy issue with those clips. GySgt Kruk said that would be fine with him 'cause he knew the Navy Garands shot 7.62 NATO rounds just as accurate as their M14NM's and were much easier to maintain.

Regarding commercially available detachable mag's fit for standard factory bolt guns, I don't think they're any different. Put one in and if it has any noticeable slop in fit by moving it around, set it aside and try another one. Once you've got a couple of really tight fitting ones, test your rifle for accuracy shooting it as best you can. . .without a magazine. After putting 5 to 10 shots (whatever a magazine holds) in a downrange group, put in a magazine and shoot the same number of shots. See if both groups have the same center; last one's well centered on the first one. Note also if the rifle shoots to a different point of impact with different magazines. If you can shoot that rifle no worse than 1/3 MOA at 100 yards without a magazine in it, you should be able to see the differences. The less accurate the shooting system is, the harder it will be to see how magazines impact zeros and accuracy.

Those for high end tube guns are much better as well as more expensive. And bolt action match rifles with a 5-round clip guide in the receiver bridge never had any accuracy problems with them charging internal box magazines.
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Last edited by Bart B.; May 15, 2013 at 07:53 AM.
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Old May 15, 2013, 08:19 AM   #27
Bart B.
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Truckn14269 says:
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But also the longer the barrel... You loose accuracy due to the barrel resonating with greater length.
All those folks winning Palma matches with long, skinny 30 inch .308 Win barrels not nearly as stiff as a 22 inch featherweight hunting barrel getting 1/2 MOA average accuracy at 1000 yards will win any bet you choose to make about that.

It doesn't matter what frequency any barrel resonates, whips, wiggles, vibrates; each one does it exactly the same for each shot. They all are very repeatable in this regard.
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Old May 15, 2013, 02:45 PM   #28
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Thanks bart ,EDIT : would the tightness of the mag and accuracy issues have more to do with making the receiver and or complete platform more stable or ridged when using tight fitting mags and not so much how the mag is sitting in the well pre-say ? Could a tighter mag change the vibration of the barrel or whole rifle which intern would change POI per mag change .


EDIT : Truckn do you know what 1/2 MOA is @ 1k ? I would think world class shooters can do it all day long . I heard of a guy once shooting a 3.something inch 20 shot group at 600yds with irons .Just think what a guy could do if he had a scope . I could be wrong but this may be one of the biggest face plants I've ever seen here @ TFL

My edits were to remove some thing as well as add quite a bit .
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Last edited by Metal god; May 15, 2013 at 05:10 PM.
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Old May 15, 2013, 06:09 PM   #29
Truckn14269
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Yes.... 1/2" @ 1,000yds is 1/2" @ 1,000yds which isnt likely, but 1/2" @ 100yds translates to 5" @ 1,000yds which is very likely. Just like a 3" group at 600yds is Still 1/2" @ 100 yds which is Also Very possible
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Old May 15, 2013, 06:19 PM   #30
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Take a look at a Savage or Ruger in 25-06, should be everything you need and then some.
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Old May 15, 2013, 06:31 PM   #31
Truckn14269
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Metal god..
I agree about the face plant.... 1/2" MOA at 1,000 yds is just nonsense
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Old May 15, 2013, 06:40 PM   #32
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My Savage 10BA shoots .5 MOA from 100-400 yards on a good day. Just last weekend, my son put 3 through one hole at 100! Point being, it's darn accurate with a good load.

He did his 1st 1,000 yard F class in Feb. When I looked at his score on his best relay (he's 14 but does well for his age) I figured the group for 20 rounds was around 30". And that was with a 10 MPH wind end of the day.

My son was paired at the last match with a world class shooter and he was scoring (name withheld) and if I recall, they shot mostly 10's, 5 X's and one 9. This is a person that often shoots a perfect 200 score. That would be nowhere close to .5 MOA and this was literally a world class shooter.
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Old May 15, 2013, 06:56 PM   #33
Jim Watson
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Gee, Truckn, it has been a while since I shot LR, but I distinctly recall the Palma types, (also Match Rifle, and Any-any sling shooters) getting 1000 yd targets with 20" ten rings and 10" X rings, while I had to struggle to hit a 10" ten ring just because I had a bipod on my F-T/R.

Have they changed targets because it was getting too easy?


Rob, I recall zero target shooters with .25-06.
There is not the selection of high BC bullets for .25 that there is for 6mm, 6.5mm, 7mm, and .30 cal.
Also the case is over bore and barrel life would be short.
I think a .257 Roberts or .25 Souper would be about right with a heavy boat tail and enough twist.
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Old May 15, 2013, 09:06 PM   #34
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Jim,
I was just going off the OP's interest which sounded fairly casual, "targets and deer" in a 500 yard rifle, you would definitely be correct in stating that not many (if any) target shooters are using it.
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Old May 15, 2013, 09:19 PM   #35
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Sorry, I should have pointed out this was specifically a .308.
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Old May 15, 2013, 09:26 PM   #36
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That's awesome about your son!.... Keep him shooting
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Old May 15, 2013, 09:40 PM   #37
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Remington 700

I bought a Remington 700 SPS in .308 brand new, for $545 and after optic, bipod, scope rings and everything put on, I was at about $1200 before tax. Love the gun but I do need to bed the stock.
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Old May 15, 2013, 09:40 PM   #38
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Hi Truck,

I think you may be misunderstanding what is meant by 1/2 MOA. The phrase means 1/2 minute of angle. It does not mean 1/2 inch.

What the heck is minute of angle? well, a minute of angle is a measure of angle, just like degrees... 10 degree angle, 5 degree angle, 1 degree angle... 1 degree is getting pretty small. But the really really small angles are measured not in degrees, but in minutes of angle.

A minute of angle is 1/60th of a degree. Imagine a right triangle where the base of the triangle is 3600 inches (100 yards), the height is 1 inch, and the hypotenuse is 3600 inches. That very tiny angle is 1 minute of angle.

So it works out that at 100 yards, 1 MOA is pretty much 1 inch. But at 300 yards, 1 MOA is about 3.14 inch. At 1000 yards, 1 MOA is about 10.5 inch.

So when people talk about 1/2 MOA at 1000 yards, they are talking about shooting a group of about 5 inches. And this level of shooting does happen at major competitions. It is not a fantasy.
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Old May 16, 2013, 07:22 AM   #39
Bart B.
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Metal god asks:
Quote:
would the tightness of the mag and accuracy issues have more to do with making the receiver and or complete platform more stable or ridged when using tight fitting mags and not so much how the mag is sitting in the well pre-say ?
I think it has more to do with the magazine. The receiver's fixed in dimensions; magazines vary a few thousandths. So, to me, the big variable's the magazines.

Quote:
Could a tighter mag change the vibration of the barrel or whole rifle which intern would change POI per mag change.
I don't think a magazine will change the resonant frequency the barreled action vibrates at very much (it does add mass to the barreled action, though), but moreso how it fits will change the amplitude and axis those vibrations have. Just like an out of square case head slamming against an out of square bolt face when the round's fired; the barrel vibrates differently compared to when square case heads slam against square bolt faces. New cases have reasonably square case heads so their effect on accuracy is minimal as the bolt face issue remains constant; one reason semiauto M1 and M14/M1A rifles shoot new cases so darned accurate with their out of square bolt faces. A given metal shape has a given resonant frequency it vibrates at. So a barreled action without a DBM installed will have a different one with the DBM installed.

With M14's and M1A's, zero's shift up to about 3/4 to 1 MOA across a batch of magazines. I've no data on these modern bolt gun's accuracy issues except what happened not too long ago when the military was comparing internal box magazine .300 Win Mag sniper rifles to DBM .338 Lap Mag ones and the Win's out performed the Lap's at ranges from 1000 to 1500 yards for accuracy. But that may have been 'cause the Win Mag's easier to shoot accurately hand-held in prone off ones shoulder than the Lap Mag's are.
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Last edited by Bart B.; May 16, 2013 at 02:55 PM. Reason: Zero shift, not accuracy degrading
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Old May 16, 2013, 11:02 AM   #40
Bart B.
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Jim Watson, did you ever shoot long range on the old, original military C target with a 36" five ring and 20" V ring that dates back to the very early 1900's? When that finally went away in the early 1970's and was replaced with the NRA LR target wit 10 and X rings dimensions you mentioned, lots of old timers threw a fit. No longer could they shoot inside 36 inches all day long and never drop a point. But the new target sure made breaking tie scores easier but you've gotta shoot inside 20 inches now to never drop a point.
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Old May 16, 2013, 12:36 PM   #41
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Gotta feel sorry for Gumby. He opened with "Guys, I'm looking for a rifle to punch out to 500 yards. I plan on target shooting & possibly deer."

I hate to delete good knowledge and commentary, so let's get back to the subject of the thread, okay?
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Old May 16, 2013, 12:45 PM   #42
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Rem 700, Sako. 270win, 308win, 30-06, 243win. Awesome long range combos!
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Old May 16, 2013, 01:04 PM   #43
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A .260 Rem's gonna do fine for game up to deer as well as paper punchin up to 500 yards. Easier to shoot accurately than a .308 as it's got less recoil. And a host of great bullets across the weight spectrum's hard to beat.
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Old May 16, 2013, 01:28 PM   #44
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lol good call Art , I had to go back and read the OP to remember what this was about . I do not own either of these but I'm really becoming a big fan of the ballistics of the 270 and 7mm-08 . I have a 308 and they are more then capable for what you want .
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Old May 16, 2013, 05:46 PM   #45
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I own both calibers and for Gumby's intentions the .270 is a better choice. I drop deer all the time with my .270 long rifle and my .308 handgun. The .270 is every bit as efficient with less meat loss. As far as ballistics, it out performs the .308 at long range as well.

Quote:
.270 Swift Sirrocco 130gr, 1211ftlbs of energy, -38.2 (drop) at 500yds
.308 Swift Sirrocco 150gr, 1156ftlbs of energy, -46.0 (drop) at 500yds
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Old May 16, 2013, 06:03 PM   #46
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I've read good things about the ruger GSR and she is a looker for sure...

If you plan on hunting deer at 500 yards you might want to think about working on your hunting skills, closer is better and far more rewarding
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Old May 16, 2013, 07:22 PM   #47
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If you plan on hunting deer at 500 yards you might want to think about working on your hunting skills, closer is better and far more rewarding
Agreed, the skill factor in close quarters hunting has excellent allure. I think Gumby is referring to distance on paper.
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Old May 16, 2013, 07:56 PM   #48
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For all practical purposes, anything in the 7mm08 through '06 class can give good groups to 500 yards. Any of them are "don't bother to think; just point it and pull" for Bambi to 300 yards.

Seriously tight groups come from tweaking a rifle and tailoring a handload, plus mucho practice.

For hunting, as near as makes no nevermind, sight in for two inches high at 100; that's near dead-on at 200 and about six inches low at 300. Going out beyond 300 means really knowing the distance and judging the wind.

But it's claimed that 90% of all deer are killed inside of 200 yards. Based on what I've done and seen, well, yeah, I wouldn't argue with that.
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Old May 16, 2013, 09:22 PM   #49
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A-Bolt

I have a browning A-Bolt in a .300 Winchester magnum and love it. I'm sure you will be able to shoot out to 500 yards with it. I never had shoot that far with it Mainly because I do not have a deer field that big. there priced around 600 for standard once on the browning website, and you choice in many calibers, I got mine in stainless and camo stock with the Boss system. that ran me about 1000.
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Old May 18, 2013, 07:54 AM   #50
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I'd suggest a Reminton 700 AAC-SD in .308. It has a 1-10 twist so you can shoot heavier bullets for the longer range. Mine will do .6 to .5 MOA at will with hand loads. 180 Hornady SST over 44 grains of H380 will stack 'em. Bergers shoot well too. I paid $670 out the door for the rifle and have added a timney trigger and B&C medalist stock. Nikon M308 glass on top. Well pleased with it for a total package under $1500.
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