openclassterror
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Posts posted by openclassterror
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Two possible causes, (related) are most likely, but I will share a couple others as well.
1) Bolt is not fully closed. When viewed in slow motion, you can see that the bolt bounces when it closes. This is due to the inertia spring. When the bolt slams shut, it partially compresses the inertia spring, bounces back open about 3/8 to 1/2 inch, then slams shut. This occurs about 0.16 to 0.18 seconds after firing, and is a hallmark of all inertia operated guns (except the Ethos, which has a patented spring-plunger lock assist to prevent it). Most of us can't engage targets fast enough to shoot splits in this range, so we never experience a failure from this unless the gun is dirty. Fact is though, if the bolt isn't closed, the firing pin can't reach the primer. What happens when the bolt assembly is dirty is that when the bolt bounces, it doesn't fully re-seat. Under these circumstances, a great deal of the hammer's energy is expended slapping the carrier forward, resulting in a light strike on the primer.
2) Firing pin and/or spring are dirty, and bind in the channel. This requires much less explanation than the first. The solution in either case is a good cleaning and lubrication of the bolt and carrier assembly.
3) Lack of lubrication on carrier rails or outside of mag tube. Causes same affliction as 1), due to excess friction preventing the bolt from closing freely.
4) Hammer spring. We install a TTI Benelli hammer spring as part of our trigger work. It is weaker than the factory spring, but reduces trigger pull due to friction reduction between hammer and trigger. In our experience, it only lack sufficient force in case of 1), or 3). The factory hammer spring can mask these symptoms as it has enough force to push the bolt closed AND strike the primer until the bolt assembly is nasty dirty. If you are the kind of guy who cleans your guns once a decade whether they need it or not, it might be worth the increased trigger pull to go back to a factory spring. Of which I have probably over a hundred, so let me know if you want one
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A few weeks ago I had a customer in our reloading area buying primers/powder/projectiles that he couldn't get near him. He proceeded to tell me about his time as a sniper in the service and how he got to take his rifle home with him and that he is now reloading for his local sheriffs department (all their duty ammo) because he could load so well. He also told me about he was developing a load for the AMU guys for 308 that was outperforming the stuff they were loading in house and that he was keeping a 175 gr .30 cal supersonic past 1400yds without any signs of over pressuring. That one made my brain hurt.
That would require a starting velocity of 3150 fps for a 175gr matchking. Sounds legit
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Just got in a Benelli extractor and can't get the pin holding the original out. Grrrr.
The pin is in an offset hole. You can't drive it through from the side that is easy to see. Clean the bolt head thoroughly and use a light to look in the hole on the opposite side. You can see about half of the end of the pin, where the holes mismatch. Using a small punch, drift it out until the pin is sticking out a little on the top side, then use pliers to pull it out. They usually aren't very tight, but if it doesn't come out easily with the pliers pressing on the outside of the extractor against the tension of the extractor spring will usually free it up. Unless you pounded on the end that was easy to see, in which case the pin may be mushroomed and you will have to drift it completely out from the bottom with a very skinny punch. Or so I have heard......
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OP,
What was your final decision/outcome? I'm kind of in the same boat myself. No charge machine shop...18" Govt profile Bushmaster (cut from a 20") and thinking about fluting forward of the FSB. I haven't shot it yet, so no baseline on accuracy. I've got no other reason to do it, than just because I'm bored. Thoughts?
The barrel dia forward of the gas block is less than .750 (usually about .720). Bore dia is .224, leaving about 1/4" total wall thickness. Anything less than 6 flutes is almost a waste of time, as the short distance between a rifle-length gas system and the end of an 18" barrel doesn't leave room to remove much material. Let's say you do 1/4" flutes, 1/8" deep, and they end up with an effective length of 3". Therefore:
material removed = Pi (R^2) /2 x L (surface area of a circle with 1/8 rad, divided by two as the flute is a half circle, times length)
(3.14 x (.125x.125) / 2) x 3" long = .0736 cu in per flute, times 6 flutes = .4415 cu in. removed by fluting. This is assuming the flutes are full depth all the way to the ends, which they are not. They get gradually shallower at both ends due to the radius of the fluting cutter.
Weight of steel is approx. .29 lbs per cubic inch. Therefore, .4415 cu in x .29 lbs = .128lbs, or approx. 2oz. So, cutting 6 flutes 3" long ahead of the gas block will reduce total weight by less than 2oz.
It is a measurable amount, but not a significant amount. Again, it is also not a good idea on a hammer forged barrel, as residual stresses may be released during fluting that could cause the barrel to warp. Hammer forged blanks start out several inches shorter than final length, and stretch as they are forged to shape, creating an elongated grain structure. Cutting slots along this axis can make the barrel spring badly. Not always, but often enough to make most gunsmiths shy away from the job for fear of scrapping the barrel.
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We recently got an M3K in that is not already pre-sold, and we will give it a thorough evaluation in factory form before taking it to the extreme limit on port work. It will be a test-bed for an all-out pushing the envelope race gun. I will start a new thread to track our progress, as soon as we are back on track with our backlog of work. Can't jump into a new project when there are customer guns overdue..........
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The trigger spring is cheap, and as long as the rest of the trigger group is unmodified it is a definite improvement. If you order the hammer spring, might as well get both but keep the factory spring. PM me your phone number, as I am about 30 messages from caught up on the phone, and I don't know how far down the list you are
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Hey guys, thanks for being patient. We have been a bit behind, but now that my hand surgery is behind me and the doc has released me back to light duty we are catching up. Still way behind on phone calls, though. Remarks on the TTI springs-
We use the TTI hammer spring as part of our trigger work package, and in all competition builds. As long as the gun is clean, the only time we see light strikes with the TTI hammer spring is if the bolt is not fully closed. The heavy factory hammer spring will actually force the bolt closed and still retain enough energy to strike the primer, but the TTI will not. We do not use the TTI trigger return spring on our builds because we reduce the sear engagement. The weaker spring in combination with a short reset makes the trigger mushy, and increases the chance of the gun doubling under recoil. You have to choose between a lighter, mushier trigger (TTI) or a crisper, shorter trigger pull (mechanical trigger job). Combining the two is dangerous.
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Is this an extractor issue ? My gun is seems do this every 5 or 6 shells I tried 3 different loads federal bulk
AA and remington club all had the same issue I am going to order an m2 extractor tonight. Is there anything else I should look at?
image.jpgYes, the rim is slipping off the extractor as soon as the ejector makes contact. The Benelli extractor should fix the issue, but adding the slightly stronger Benelli extractor spring is also a good idea
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A +5 allows 9 in the tube. The +3 may allow 8 of some of the shorter 2-3/4 shells, but normally will only allow 7. A +4 will hold 8 in the tube, but may allow 9 with certain brands of slugs that have shorter hulls. Spring length can affect capacity. If your spring is 14" longer than the magazine it may allow one less shell than if it is cut to only 9" long.
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So it was an out patient type procedure? Glad it is working out for you.
Yes, entire operation was at the plastic surgeon's office, local anesthetic, 45 minutes from arrival to checkout. Have to go back in on Monday to have the sutures removed, then I am free to shoot again! I wasn't able to grip a pistol without pain for the first 5 days, but have been gradually increasing my dry-fire regimen since then.
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Yes, my strong hand. 20+ years of machining takes a toll on your hands, as well as playing Bass guitar since I was 13. Damage to my right hand was severe, left is moderate. I will wait on the left hand until I am not so far behind on work. Kind of had to do the right hand, as I was occasionally having my fingers lock up, or just randomly dropping things from what seemed like a secure grip. Doc said if I continued to tough it out eventually the nerves would die and I would lose the use of three of my fingers. If I had known how minor the surgery recovery would be I would have done it long ago.
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I had a checkup with the doc after carpal tunnel surgery on my right hand, and got cleared for light duty use. It has sucked not being able to shoot, but my grip strength is measurably improved versus pre-surgery less than two weeks ago. In addition, the 'pins and needles' sensation in my first three fingers went away within hours after the surgery. If you have Carpal Tunnel and have been avoiding the surgery, I highly recommend it. Actual surgery only took maybe 10 minutes and the benefits are immediately apparent. Now I am just waiting for the sutures to be removed so I can start live-fire practice again!
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Finally bought one of these for my 13yr-old son's rifle. He has struggled with trying to remember Mil- holds when under the pressure of the clock, so I thought a simpler reticle would help. He shot it in his second match this weekend, and had his best finish to date, 4th overall and 85% of the first-place score, top junior. Ran all the close shots at 1x, then dialed to 6x for the long prone shots. Hit the 312yd target on his second shot, 400 yard target on first shot. I will say it is not as clear as the glass on my Vortex Razor HD, but it isn't $1,400 either. Reticle is simple enough to use, zeroed at 200 for xm193s out of a 16" barrel. Use a chrono to check velocity out of YOUR barrel, then zero at the recommended distance for your bullet. Easily good enough for the 4moa +/- targets we shoot at in 3gun. Adjustments repeated well during zero procedure, grouped under 1moa at 200 yds without trouble. Definitely seems worth the price. I will recoup before the year is out just in ammo my son won't burn missing targets
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Normally the shell catch prevents the lifter from lifting until the shell depresses the tail of the shell catch as it pops back out of the magazine tube. What is likely happening is that the shell catch isn't holding the lifter down, and the lifter is slipping off and starting to move upward before the shell is all the way out of the magazine tube. This usually indicated a bent catch (over-tuned), or a rounded-over shelf on the shell catch where the lifter is supposed to stay until the shell pushes the catch aside. If you retract the bolt with the magazine empty after hitting the shell release button and then ease it forward, you can see the lifter just start to move upward when the bolt locks open. If you hit the bolt release button on the outside of the receiver, you are simply pivoting the tail of the shell catch out of the lifter's way ( which is what the shell would be doing if it just came out of the mag tube) allowing the lifter to move upward so the bolt can close. What you are describing is the lifter lifting before the shell hits the tail of the shell catch. A new shell catch is likely the solution here.
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My AR does that, not yours? HAHA!
So, here is one from MY OWN shop- A guy comes in, bragging about an AR kit he put together ( Basic Del-Ton M4-type, nothing special). Says that he has a bunch of Green tip for sale, $2 a round ( right after the ATF "ban" was announced). It is useless, he says, because it is horrible for accuracy. He has a Barska red-dot on the rifle, and in his words, "I can put a full mag of 55s through the same hole at 100 yards, but the 855s won't even hit the paper." Damn. I have a 1-6x on my competition rifle and keeping under 1MOA is a chore, even though the same match ammo consistently shoots 3/4 MOA or less with a 24x scope. I can't even imagine holding a 1/4MOA ("one hole") group with an 8 MOA dot sight. Let alone with a mil-spec plastic clamp-on handguard, and the front sight still in the way. He says it is because of some special "assembly tricks" he knows to tighten up the accuracy. As I recall, the upper was fully assembled when it arrived, all he had to do was put the parts kit in the lower. Wish I knew all these cool tricks!
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Well, better right now than in the first string AT the match........... Easier to come up with plan B now than between stages. BTDT.
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I would be willing to pay even more for an entry fee if it meant professional RO's and a consistent fair reset that I (and my shooting buddies) did not have to lift a finger to accomplish. Especially if those reseting where scantily clad ladies.
OOOh!!! I'm in!
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Often means the shell release bar is slightly bent, and is not fully clearing the shell rim. The opposite is also possible, with double feed the result. When it doesn't feed, is the shell hung up on the first or second catch? There are two, on opposite sides.
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Thanks for all the positive feedback guys! As some of you know, my health has been lagging for a while, and on the bad days I just want to hang it up and go on disability like my Doc says to. But reading about how much fun you guys are having, and getting to be part of making it happen keeps my spirits up when I am having a bad day (like today). Keep shooting, and I will keep making parts!
Tom
PS Adam, it was great fun squadding with you at Ironman, and watching your improvement just since last year. Good finish, even if you beat me by .02 percent at the match
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Sarcasm from you? I am shocked! Now I have to go back and look at all your other posts to date, to see if there were other sarcastic posts that I missed
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To note, I didn't say that he SHOULD throw his away, I said that I would, if it was mine. I am well aware that pretty much any method of tightening the gap is productive as long as the extension can't "squirm" in the receiver. BUT, I am anal-retentive about gun builds, and uppers are cheap. If I got one in for a customer's gun that fit so loose, it would go back to the maker. One advantage to using "mil-spec" parts is that if it is out of tolerance from the GI print, you can generally get the manufacturer to replace it. Ditto the names with reputations (like JP). One phone call is generally enough to get satisfaction on a bad part.
Kurt, I may have a bucket of parts (or more) that are serviceable, but not good enough for me to feel good about putting on a top-tier build. A different attitude is required when building a gun with my name all over it for a customer versus, say, a varmint gun that I use myself. Lemme know what cast-offs you need, and I can look through what I've got for ya
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TOO FAR. Which is usually the problem. Without any mechanical constraints, people go overboard. Just because you can doesn't mean you should
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1.010 receiver bore is ridiculous. .9975 on the extension is at the extreme limit of tolerance as well. Add them together and it is like throwing a hotdog down a hallway. You can bed them together with shims or epoxy, but I would toss the upper for sure. Even the $30 Anderson uppers are never that loose. Good uppers are too inexpensive (in the big picture) to try getting by with a poor one.
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Not at Ironman. An A5 broke in half on stage 7 during the OLHOT match. Same place they always do, where the mag tube meets the receiver.
"The Sweep" Target to Target Skill Builder
in Rifle & Shotgun - Technique
Posted
Dang. That looks like a great drill! Never thought of shooting stationary targets while swinging through like that