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August 26, 2013, 01:55 PM | #26 |
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My ordnance friends at the Secret Service Armory in Beltsville (both deceased unfortunately) told me their internal test confirmed FL sized cases were more accurate than neck sized.
Machine rests can be interesting and depending on the system you are testing the mounting fixture can be somewhat orthodox. For instance at Aberdeen PG we had a machine rest for a M16 that was set up on a trailer. It would be towed down to Romney Creek Range and unhooked and then jacked up on steel legs that spread out and raised the trailer on a paved road. The legs went out at angles so basically there were two A frame type set ups which made for a very solid fixture mount. This mount clamped the barrel just behind the flash suppressor and also clamped the buttstock. I remember the first time I ever saw it used to test at 300 and 600 meters it was set up and roughly aimed at the target which was 32'x32' and covered with target cloth. Yes it looked like a drive in movie screen. We fired a group and went down for a looksee and pointed out the impact area so the guy on the hard mount could adjust L R U or d to get the group where we could check accuracy from the ground and not use a cherry picker bucket truck. We got it shooting where we wanted and the lead gunner loaded it up and reached up and grabbed the grip and just started jerking rounds off and I watched his technique and it reminded me of milking a cow. He was introducing stress off the bore center line with every pull. Then the senior guy said to let me shoot it and he never said a word. He was also a Master Class NRA shooter and he walked over and looked in the spotting scope (mine) I always took to the range and I noticed a hand gesture and we exchanged a "look" and I very gently reached up and very lightly touched the grip so as to not introduce any stress and to keep my trigger finger in constant position and I was ready. When he lowered his hand I started to fire and I watched his hand the whole time. When he saw the wind change he would change position of his hand to a braking type motion and I would hold up. When his hand went back down I started pulling the trigger again. We shot the whole series and my groups were about half the size of the professional gunner. We had this one supervisor gunner who in the real world would be called a alpha sierra sierra and he was always complaining why his gunners could not shoot accuracy. After all he had about seven million rounds experience on me. The Test Operation Procedures in place called for 3 NRA Master Class shooters to fire accuracy/dispersion testing. We had like four on the PG but did not have access to the others so at times the Marines had to send shooters in from the MC rifle team Quantico. At any rate we shot the 300 meter series and moved back to 600 and we "zeroed" the mount so it would hit where we wanted and quit for the evening and we were going to shoot Saturday. The next morning the fog off the Chesapeake came in and visibility was about 50 yards. The next morning I drew the complainer and his crew and we loaded up weapons, ammo etc and went to the range and went down and put up target and came back and proceeded to mount the rifle and I did the shooting. All three rifles tested printed about three feet apart max so the 6x6 paper captured all without moving the adjustments on the mounts. I shot the whole series at 600 meters with a 50 yard visibility onto a white target and we finished up the series and headed back to call it a day and finally the chief gunner couldn't stand it any longer and he just had to know how I could hit the target at 600 meters every time and couldn't see but 50 yards. I didn't answer him at first and he asked again and I said, "It comes from having a Master card." and there was nothing he could say. The Master Class shooters shot against the rests for years and the final opinion was the shooters could duplicate the rests for accuracy but for a long series of shots the machine rest would win because it did not fatigue. This I realize will not sound familiar but when you shoot 100,000 to 150,000 rounds a year and you do it several days a week you develope a confidence in your ability. Its kind of like a rifle in your shoulder is just as comfortable as driving. Rifle firing from a bench rest is not that hard but looking at the iron sights for long periods can be a eye strain and if you are not used to it things tend to go South fairly quickly. I remember on the 9MM pistol test we had a Master Class pistol shooter and he knew when it was time to quit and we never questioned him on it as we understood the problem. I never had time to get into NRA pistol so did not have a Master card at that time though now I do.
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August 26, 2013, 02:24 PM | #27 | |||
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Quote:
Quote:
√(3/4²+1/4²+1/2²) = 0.935 moa average combined group size. If the actual total size is 1½ moa, then the other contributing disturbances are actually larger than you thought. They’d have to combine without the 1/2 inch gun and ammo error to equal: √(1.5² - 1/2²) = 1.414 moa Quote:
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August 26, 2013, 04:04 PM | #28 |
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Hummer90,
You posted while I was composing. Interesting to hear your experience with the guns in machine rests vs. humans comports with Vaughn's and my own less extensive experience. When I still had current master cards in conventional pistol and air pistol I don't recall x-ray vision coming with either one, and neither was I able to zero my arm and come back to find it in the same position in the morning, though the way hydraulic exoskeleton development is going, that may change soon. My suspicion about the Lee Collet Die is that using it by itself improves accuracy over FL sized brass when the FL sizing operation is pulling necks off-axis, as demonstrated in the video I linked to earlier. So if someone sees improvement using neck sizing-only, neck pulling is the first thing I'd expect to find in their full length sizing operation. But if you full length size without pulling necks off axis, then you can beat neck sizing by adding self-centering into the mix. I think Bart prefers the use of bushing type FL dies to achieve the expander-free non-neck bending FL sizing configuration. I've had good luck doing two-operation sizing with the Lee Collet Dies and the Redding Body Dies just moving the shoulder back a thouandth or two, but I can appreciate that a poor quality or inadequately rigid press might have trouble maintaining coaxialilty with that approach. I also have one totally ordinary Redding FL sizing die in .30-06 that I got a carbide bead expander kit for long ago, and it doesn't pull necks off axis, either. The expander is a spherical bead, so it pulls with uniform force even when the case is slightly tipped. I use a dry neck lube with it, too, which reduces the drag still further. I've not had quite as good luck in other, shorter chamberings with this approach, and suspect the flexibility of the long decapping rod is part of the trick. (Hmmm. That gives me an idea for a floating decapper/expander die design…)
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August 26, 2013, 04:04 PM | #29 |
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Unclenick, I well understand the statistical probabilities of this you've mentioned. And the human errors may well be bigger than I think they are. It's my opinion that those human errors may well need to be adjusted in magnitude; upwards. But the holding area's are easily and accurately measured; just watch the size of the wobble area you have using a scope.
But the facts remain that none of the high power match rifle champs testing their stuff in machine rests could equal what they did shooting on paper from shoulder fired positions. Not even close. In mulling all of this over and over, I oft times think the biggest variable is how much the rifle's aiming axis moves off the holding area from recoil while the bullet's going through the barrel. It may well be a lot more than I've estimated. Human error in corrections for wind was not considered; it will open up groups horizontally. Their machine rests held the rifle like humans do; fore end clamped at the front part of the cradle and butt stock clamped at the back end. When fired, the cradle slides back on its 3-point suspension system so the rifle barrel whips and rises like it does in position shooting. Here's a link to the rest I'm most familiar with; David Tubb's as made by his dad, George. There's a dozen or more in existance made in the 1960's. http://www.flickr.com/photos/1278722...7594303093714/ The Tubb 2000 tube gun's shown, but conventional wood stocked rifles mount the same way. They've got escushions epoxied in place on a cross bolt at each side of the butt stock a couple inches in front of the recoil pad; the cradle's cross bolts' centering balls at the back end fit there. Fore end's clamped the same way as this tube gun's mounted. It recoils about 2 inches with a 13 pound .308 Win. rifle. Hummer, your comments on man versus machine are interesting. Not at all surprised that a muzzle-clamped rifle's machine rest accuracy equalled that of good marksmen shooting off their shoulder. I've no idea who designed that machine rest shown in the link. As I remember, the plans originally came from Hornady Bullets. Rifle case resizing dies..... I prefer standard full length sizing dies with their necks lapped out to the desired size. They better center sized case necks on case shoulders than bushing dies do. None of the bushing dies made by RCBS and Redding size fired case necks all the way to the shoulder; they stop about 1/20th inch short. Those Redding and RCBS dies are the best commercially available full length sizing ones made these days and do indeed produce excellent results. Both companies say that unsized portion of the fired case neck helps center the case neck in the chamber. Even though it doesn't touch the chamber neck in any way when the round's fired. Neither admit nor understand (to me, anyway) that rimless bottleneck cases center up front by their shoulders centering in the chamber shoulder by firing pin impact and the case necks float free untouched by the chamber neck. Last edited by Bart B.; August 26, 2013 at 08:19 PM. |
August 27, 2013, 07:25 AM | #30 |
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Bart,
I'm not disputing that people have a hard time matching a very accurate rifle's machine rest capabilities, but like Mark's findings, I've concluded the better shots can often keep up when the precision isn't quite that high. When my dad was still coaching the OSU pistol team, he said the rifle team coach got a Russian (IIRC) laser systems that gives you a plot of your hold to study and puts a marker where the shot breaks. It turned out the best shots actually shoot under their overall hold area. The main reason is they release shots both when the hold is best settled and subconsciously pick up releasing shots between heartbeats, so the heartbeat disturbance has to be excluded from their actual shot release hold area when calculating the hold area's contribution. For anyone in fair aerobic condition and not too excited, the beat disturbance is the smaller portion of elapsed time between beats, so, randomly, even a lesser shot does tend to have more shots off beat than on. It's one element that really doesn't obey the normal distribution.
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August 27, 2013, 07:43 AM | #31 |
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with all due respect, life is too short to put this much time and energy into getting one ragged hole with three shots
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August 27, 2013, 07:49 AM | #32 | |
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Unclenick says:
Quote:
Which is why the US Olympic Rifle Teams 'smith and ammo tester mentioned to me some years ago that good lots of rimfire match ammo would shoot about 1/3 to 1/2 MOA at 50 metres in their machine rested free rifles, but when shot prone in English matches, the best on target accuracy was about 1 MOA. Few international prone rimfire shooters make perfect scores on the 50 metre target's 10.4mm diameter 10-ring. And good marksmanship can enable shots to break inside ones holding area, too. Those holding 3/4 MOA can break shots inside 1/2 MOA most of the time. Last edited by Bart B.; August 27, 2013 at 09:43 AM. |
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August 27, 2013, 07:50 AM | #33 |
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GRIZZ... it's rocket science for the common man...
I get "almost" as much out of reloading, as I do from actual shooting... I like to think out of the box enough, that I rarely stumble on that one hole group, but when you develop a load that you can shoot in your rifle, that shoots amazing... it's definitely better than just going out & shooting "average, run of the mill" ammo
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August 28, 2013, 07:57 AM | #34 |
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Grizz, I am the common man. I posted a link, it disappeared.
http://www.gunauction.com/search/dis...temnum=7309186 I have a rifle holding/support devise, the devise has its origin in a B17, seems we needed pictures, to get the pictures we needed volunteers, problem! A one plane formation got a lot of attention when flying out of England to Germany and back, To reduce flying time the volunteer group striped the plane. Long story, they returned with the pictures, one survivor was a shooter/reloader, nothing on the trip into and out of Germany changed anything. He built the gun holding devise after the war, complete with shock/dampeners. The link that disappeared. The rifle was listed, as expected when the auction hit the Internet everyone went straight to the key board and in an effort to make themselves look good at someone else's expense etc., etc... I could not believe someone could build a rifle in that configuration without knowing what they were doing, I bid. I was involved with one of the most socially dysfunctional forum of the day, I ask members to hold it down until the auction was over, I was concerned the attention would drive the price up, if anyone else bid on the rifle they would not admit it. and no they did not ‘hold it down’. I won the bid, I loaded 12 different loads of 10 rounds each, 120 rounds, with different cases, powders, bullets and head stamps and went to the range. No patterns, just groups, none of the groups were larger than a quarter in diameter, some groups shared the same hole, I did not adjust the scope. The rifle had a Timney trigger. it did not cock on close, it had a short hook up. The action did not have a recoil lug, the magazine was made when the rifle was bedded, The rifle did not have a trigger guard that covered the bottom of the action, There was no floor plate. Had the rifle required a lot of tweaking I would have finished a 308 Norma mag with the parts. There was nothing I was willing to do to improve on the accuracy. The scope I added cost more than the rifle and I was able to match the height of the rear receiver ring with the front receiver ring with see through scope rings. The scope required the height because of the large bell. F. Guffey |
August 28, 2013, 09:02 PM | #35 |
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Not your average bedding job, but it sounds like it doesn't let things move around much. Pretty and functional are not always synonymous. Interesting tale.
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August 28, 2013, 09:38 PM | #36 |
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WOW!! Great subject. Tired, so I didn't read through all of the long postings. Not an expert by any means on the NeckSizeing part, but the 1 gun (Only gun I was loading at the time) I hated it..... I have no idea if I was doing something wrong or if the dies were bad or what. I have a Browning A Bolt 25-06. Lee collet dies with once fired factory brass (Mix and match batch). I think the first time I reloaded them they were fine.... Second time, I started running into prob.. They would NOT chamber in my gun. Bullet seated fine but I have no idea what I was doing wrong. The only thing I can think of was; in order to get a good bullet seat, I had to put a lot of pressure on the die to get the neck to squeeze shut, which inturn, made the body of the case expand beyond the called size...
Some times, The gun would chamber the round but wouldn't take it out unless I pulled the trigger. Sucked during deer season. Had to shoot many trees. An end to the story, I still have some of those rounds, but will not do anything with them. Bullet puller and resize the whole batch... Some people say that they resize after 2-3 shots. I say skip the whole idea and stick with FL dies. Not worth it for "Better accuracy" which I really didn't see. WILL NEVER BUY THEM AGAIN.... OH yea, My Lee single stage press broke using them too. Then again,,,, It might have been me putting too much pressure on it for the neck to size... Still don't quite understand them type of dies.. |
August 29, 2013, 02:26 PM | #37 |
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Loademwell,
Sounds like you had a problem. Since it worked the first time, you know it wasn't the dies doing it. The fact it worked once suggests to me the pressure was too high for the brass you were using (Federal is the worst about this; too soft) and most likely just needed to back the powder charge down 5%–10% for that brass in your gun. Awhile back a fellow on another board had a chamber that was off axis with the bore; that is, the chamber centerline was tilted a few thousandths off the bore centerline. So, after firing, his cases weren't quite straight at the neck and the caseheads weren't quite square with the case bodies. As a result, they would only go back into the chamber if he rotated the case until the headstamp had the exact same orientation it had when he first fired it. Any other orientation would see the out-of-square rim stick out enough to start wedging against the bolt face. But this happened at every firing, and the first firing was not immune. Firing reforms the case to the chamber, so of course these ill-fitting cases both extract OK after firing.
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August 29, 2013, 03:33 PM | #38 |
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I used to shoot matches with a guy who had the rifle barrel clamped in a square split sleeve about a foot long whose bottom half was epoxied firmly into the wood stock's fore end. The last back inch of the barrel as well as all of its front were clear of the wood. At least 1/8th inch clearance was all around the reciever and magazine. Shot very, very accurate, too. Guffey's rifle pictures reminded me of it.
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August 29, 2013, 03:46 PM | #39 |
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not in the same league... but I have a 10-22 that I've done some work on, including a laminated thumbhole stock, that is channeled for a heavy barrel, the gun came stock with a standard weight barrel... I started shooting it, before I added a heavy barrel, & the accuracy is so good, I've yet to try putting a heavy barrel on the gun... looks a little goofy, with the thin barrel & big channel, but if the rifle had shot that good with the original stock, I'd have never touched it...
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August 30, 2013, 08:55 AM | #40 |
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Two questions I often ask in the neck-only versus full-length fired case sizing controversy are. . . .
What's the difference between rimless bottleneck cases' fit in the barrel's chamber when they're fired when one's neck-only sized and the other full-length sized such that the fired case shoulders' set back one or two thousandths? What are the problems that arise from either one's fit in the chamber? It's my opinion that once the answers to these two questions are known, one can more easily discriminate between the sizing tools' and techniques' impact on the ammo's performance. |
August 30, 2013, 09:59 AM | #41 |
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So... now that we have been discussing common calibers with sharp shoulders, how about something a little less cut & dried ???
rimmed cartridges with long taper shoulders... like 22 Hornet & 30-30 ( just for example ) the Hornet I have in both Contender form, & in rifles that should be quite accurate... 30-30 I have in Contender format, & in a custom falling block single shot rifle, that should be capable of more accuracy now that I'm thinking about it, there are probably several others... 7-30 Waters ??? neck sizing more important as far as accuracy in these cases ???
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In life you either make dust or eat dust... Last edited by Magnum Wheel Man; August 30, 2013 at 10:10 AM. |
August 30, 2013, 11:50 AM | #42 |
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The .300 H&H Magnum's a good example of low angle (8.5 degree), long tapered (about .375") shoulders. It became "the" cartridge for long range matches starting in 1935 through the late 1950's. All the top ranked folks shooting it tried different versions of neck only and partial neck sizing of fired cases. But neither shot bullets as accurate as full length sized fired cases or brand new ones.
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