openclassterror
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Posts posted by openclassterror
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That does sound promising! When I assemble a new build, I use a thin liquid lube on the carrier to receiver interface (rails), almost dripping wet. I also use shooters choice red gun grease on the cam pin, and cycle the bolt head up and down the cam track about 20 times to distribute it in the slot. Even with high quality parts it sometimes takes a little running to wear all the parts in together. One thing to keep in mind is that we are taking a bunch of mismatched finely tuned parts and expecting them to run with the reliability of an overgassed, minute of barn carbine. Sometimes it takes a little tuning. I have learned way more about how these things run from troubleshooting match guns than in 10 yrs of general gunsmithing repairs. You have to admit, you have a lot more knowledge about how the components interact now than if it had just run out of the box, eh?
Tom
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I have only one 18"/ rifle gas barrel in the shop at the moment, and it is a DPMS S.S. HBAR contour barrel (This is a misnomer, as Colt never made an HBAR with this barrel length and gas system. But I digress.....). Port size is .098. Keep in mind that the back (inside) jaws on most dial calipers have a small flat on the measuring face, and in a small round hole they usually read small by about .002 or so. Gage pins are the best way to measure, but most guys don't keep a set in their tool box. You can also use drill bit shanks as gages, although there are gaps in between sizes. Measure the actual drill shank, as they are typically a thou or two under flute size. The most common port size I have seen on rifle length gas systems is .096. That seems to be standard for DPMS 20s, and Kreiger uses .096 on their 20inch barrels. Derrick Martin of Accuracy Speaks was putting .110 ports in his service rifle barrels last I saw, and that is at the very big end of where they should be. Keep in mind service rifles are typically built as heavy as they can be, and usually use max heavy (M-16) carriers. These are most easily identified by the lower rear part of the bolt, behind the hammer slot. On a commercial AR carrier, there is about 1/2 inch of steel across the bottom of the carrier at the rear, on an M-16 carrier it is more than an inch long. When these carriers are used commercially they are typically called "Match" carriers to separate them from the full auto parts stigma. In and of themselves, they do not contribute to full auto usage other than the extended tail area is needed to trip the auto sear. However, many people think the added mass contributes to reliability in forcing the bolt closed on balky ammo. So you see them on a lot of semi-auto only rifles as well. This background info doesn't apply to your situation, as you are going the opposite direction (light carrier), but might be helpful to somebody. So in answer to your question, your port seems a little bit on the small side, especially since you have less barrel length under pressure beyond the port. I would have no qualms upping to .098 or so, especially since you already have an adjustable gas block.
Tom
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Another note on something that affects inertia guns- size/ mass of the shooter. I am 6'3" and about 250. My 11 yr old son is 5'2" and only about 120. He cannot get my inertia gun to cycle reliably at all, even with 1-1/4 hi base stuff. Many instances of empty chamber/ failure to load malf's. His stance is poor, as he has to lean back a ways to keep the 13 shot tube from tipping him over on his nose. He has no trouble with my short 1100 gas gun cycling, but he doesn't hafta play counterbalance either.
. So, there are some other factors that play into reliability experiences with this type of action. You can't prevent the gun from moving, but you can't let it move too much either. Might help explain why some loads work for some and not others.Tom
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One other thing touched on by another post, but not pursued, is the possibility of over-gassing. I don't think that is the case, as it should not have improved by removing buffer weights, but if the bolt is reciprocating too fast, the follower can't lift the cartridges fast enough to get in front of the bolt and pick them up. The other reason it doesn't seem to fit is that the bolt cycled better as it lost weight but still wouldn't lock back. The easiest (read laziest) way to diagnose the is to have someone stand to your right and watch the ejection cycle as you shoot. Have them wear safety glasses. Also, where is your brass going when it ejects?
Tom
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It is always a possibility to mess with the springs. My biggest worry about running non-standard components like that is that if the spring breaks in an out-of-state match and you need a funky spring, chances are that nobody has one you can swap in. If you have to go that route, I would advise making a duplicate spring for your range bag, and test it for function before you put it in as a spare. If you have to open up the barrel port, there really isn't a down side since you already have an adjustable gas block to throttle it back down. Just make sure that whoever does the work deburrs the bore. If you have to exceed .109 diameter, or if the hole is already over .105, I would look for other causes before drilling out the barrel. Keep in mind that a fixed gas block has a maximum hole diameter of .159, and most rifle length gas tubes have a .125 hole to admit the gas into the tube. So, going over .109 or so just moves the smallest restriction to another spot. I don't know what the smallest restriction is in whatever adjustable gas block you have, but some have mentioned before that occasionally you find one with a big burr or a hole not drilled completely thru the passage, and the gas block itself has a restriction. Worth a complete disassembly and cleaning to check if you run out of other ideas.
Your parts list looks good, I think its just a little tweak that's missing, not a major parts swap. I run a JP low mass bolt and buffer, standard spring, and fixed gas block, but with a hybrid gas system on a 16 inch Noveske barrel with mid gas port. I have had no cycling issues whatsoever, and only clean it maybe every thousand rounds or so.
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The reason it ran with the carbine buffer and not the rifle buffer is that the shoulder that the spring rests against on the rifle buffer is partway down the body, and the carbine buffer spring rests against the underside of the buffer head. Therefore with the rifle buffer installed, the spring at rest is already compressed about an inch and a half further, and therefore more highly tensioned to start with.
Tom
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Trigger pulls are universally poor, though that is the only thing they come into our shop for. Hammers do not always function with the JP trigger upgrade, so unless you buy a complete trigger group you may need a new hammer. Otherwise, the ones I have evaluated seem solid.
Tom
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As I recall, Criterion barrels tend to run toward the small end on gas port sizes in the barrel itself. Hate to overstate the obvious, but if the hole in the barrel is too small, you could run an adjustable gas block with a quarter inch hole and still not get enough gas. Many off the shelf ARs are over-gassed, just so they will function with crummy ammo. A quality barrel typically comes with a correctly sized port to prevent battering with full-pressure loads in a fixed gas block. What is the port size on your barrel? We did a bunch of prototyping on an adjustable piston system with settings for suppressed, normal, dirty, and "wolf".
What we found was that a standard carbine length gas system needed the port in the barrel increased to about .075 (.062 is about typical) to cycle reliably with low power ammo. We increased the piston port to almost 1/32 oversized before we realized that the barrel itself was the throttle. Typical rifle-length port size on a 20inch barrel runs .096 to .105, though I have seen ports as big as .110 from some manufacturers. 18 inch barrel should be similar, but nearer the big end. Keep in mind that an 18 inch barrel has 2inches less DURATION of gas pressure, therefore needs a little more gas than a 20. Your department likely is running carbines, which tap gas at higher pressure (closer to chamber), or recycled military rifles (20 inch barrel) which are more forgiving. UMC is known to be lower pressure than mil 5.56.
Tom
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Low Recoil-
Speer Lawman- 1oz at 1200
Remington Slugger- 1oz at 1200
Winchester Ranger- 1oz at 1200
Fiocchi Aero- 7/8 oz at 1300
Full power used-
Winchester Super X Max dr.eq. 1oz (no vel listed, OLD box!)
Remington Slugger- 1oz at 1560 (ow!)
Couple others of which I didn't keep info.
No Failures except 2 of 5 Aeros failed to load subsequent round. All 5 ejected successfully though.
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I haven't tried low velocity 1-1/8oz, but it cycles without fail at 1oz 1100fps loads. Even with the crappy Winchester hulls
Now, that's really strange—those are the same specs as the Fiocchi slugs you said, in the other thread, that your gun doesn't like. Odd...
As I said in the other thread, I have never been able to find the Fiocchi 1oz slugs. The low recoil Fiocchi's I tried are the 7/8 aero slugs at 1300fps. I have had only one FTF with ANY 1oz load of any kind, and that was my fault for not cleaning it thoroughly after I did some work on it. I know the manual says to use 1-1/8 or better, so I am not saying they all work with 1oz loads, but I am not seeing the oddness of my answer. Perhaps you misread my other post?
Edit- I must add that I have not done a definitive study on the Fiocchi 7/8oz slugs. I shot only 5, and at that point the shotgun had only about 100rds through it. So in order to make sure my remarks are not interpreted as a hard and fast rule, I am only relaying my personal experience in a very limited test. I know they theoretically produce more energy than the 1oz Aeros, but as I have not tried those in my gun I cannot say if they work better or not. The only low recoil slugs I have shot enough of to confidently say I trust are the Speer managed recoil Lawman slugs, which I was able to buy a quantity of. All the others I tried functioned with no failures, but I don't think I have shot more than maybe 25 of any other brand of low recoil slugs. As I stated, in our neck of the woods slugs have been in short supply for quite some time. I am not trying to present myself as a guru of the Stoeger platform, I am just trying to relay what experiences I have had with mine.
Tom
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Update- I talked with Tim on the phone, very knowledgeable guy. Had everything I wanted in stock, and planning on shipping it out tomorrow or Friday. My confidence level was upped quite a bit ordering from someone who is actually familiar with the product he sells. I will update when I get the upper put together and try it out!
Tom
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+1 on brownell's mags. Great warranty and customer service, good price. I buy 100 at a time and sell them for $12.50 each. If customers drop, ding, or break them I swap them out for a new one and send the bad ones back to Brownells. They have replaced all of them without question. I must say tho, half the ones brought back workerd fine in my rifles and I kept em instead of returning.
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Thanks- I've been poking around your website since the first reply, I might give you a call tomorrow if I don't get too many drop-ins at the shop.
Looks like most of the kits available throughout the market are some variation of the ciener kits, but with a barrel shank adapter instead of a chamber liner. Black dog magazines seem to be the new standard. Are these pretty correct assessments?
Tom
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Please forgive me if this has been broached already. I want to duplicate the ergonomics of my centerfire upper. Who makes a reliable .22lr upper conversion that does not come with a handguard, front sight, etc. I don't want to waste a bunch of money on parts that will come off 5 minutes after I open the box. Basically a barrel, bolt, stripped upper if it is not standard, and mags. And obviously whatever buffer conversion it uses. I want to install the same quadrail and charging handle as I use, gas block not even necessary. Any thoughts? I have no objections building a complete upper myself if someone has a matched-parts setup that works.
Tom
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Only tried the 7/8oz from Fiocchi, I have never actually seen their 1oz slugs. It has been hell finding a selection of slugs here for almost a year. I have run it successfully with low recoil from Remington, Speer Lawman, and Winchester, and std slug loads from Remington and Winchester. In one September match I had slugs from 3 different boxes in the magazine at once! Whatever I could scrounge before each match. The ONLY one I have tried that wouldn't cycle was the Fiocchi.
Tom
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I have a theory that the reason the Stoeger m3000 inertia gun is so forgiving load-wise is the carrier extends forward around the mag-tube because the recoil spring is there instead of inside the stock. This adds mass to the "bolt group" (for lack of a proper term), which resists movement more efficiently than the bolt by itself. Because the assembly weighs more, it stays put longer, which compresses the inertia spring further before "un-springing" for any given load. Mine runs flawlessly with loads that stall Benellis consistently. Not enough of an engineer to claim factual truth, but it seems like the most reasonable explanation to me. I run a 13-shot tube AND a ported barrel, and no cycling issues with light loads, even if I start with a 15 shell ghost load. I swear it loses HALF its weight by the time it is empty!
How light of loads are you talking? I can run 1145fps 1 1/8 oz in my M2. If love to be able to shoot some 980's in the shoot off.
I haven't tried low velocity 1-1/8oz, but it cycles without fail at 1oz 1100fps loads. Even with the crappy Winchester hulls
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My son shoots 20ga with no trouble, and his is only a 22inch youth barrel. Use mod choke as a minimum if steel is on the course. #7-1/2 takes down poppers and texas star plates no problem if you center your patterns.
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I started with an 1100 and it was a great place to start. I think I was consistently finishing top 3 in local matches and moved into open class before I felt the need to upgrade. Final straw was when the bolt carrier broke this summer during a match. But, it had many, MANY rounds through it by then. Make sure the interceptor latch doesn't have too much free play (Brownell's sells thicker retainers if it's loose), add a mag tube and speed latch, and shoot it til you can go faster than it can. In the meantime, shoot at matches and try out as many different shotguns as you can sweet-talk your way into. Most guys are proud of whatever they have settled on, and more than happy to let a new shooter try out their stuff, as long as you bring your own shells. Then, you won't be dropping coin 'til you have a better idea what suits you.
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I have a theory that the reason the Stoeger m3000 inertia gun is so forgiving load-wise is the carrier extends forward around the mag-tube because the recoil spring is there instead of inside the stock. This adds mass to the "bolt group" (for lack of a proper term), which resists movement more efficiently than the bolt by itself. Because the assembly weighs more, it stays put longer, which compresses the inertia spring further before "un-springing" for any given load. Mine runs flawlessly with loads that stall Benellis consistently. Not enough of an engineer to claim factual truth, but it seems like the most reasonable explanation to me. I run a 13-shot tube AND a ported barrel, and no cycling issues with light loads, even if I start with a 15 shell ghost load. I swear it loses HALF its weight by the time it is empty!
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On the subject that it runs on his lower, but not yours- I have about 15 different carbine length buffer springs at the shop right now from 4 different manufacturers. Free length varies by almost an inch, and number of coils varies by 3 full turns. All 4 makers claim "mil-spec" for their buffer components. I GUARANTEE you that if you were running on the ragged edge of cycling pressure some would function and others not. I don't ever guarantee functioning of rifle components unless customer brings me the whole rifle AND the ammo they intend to use. I comped an XDM 9mm for a customer, exact copy of the one I had been shooting. He told me he was shooting remanufactured 115gr 'factory spec' ammo. I test fired with factory ammo, and he trashed my work at the next pistol shoot because it wouldn't cycle. I found out from the guy he was buying the ammo from that he was shooting very light practice loads, as in like 950 fps range!?! Now I won't modify anything that effects cycling without the customer's ammo, and make it CLEAR that I can't guarantee function should he change the load.
On another note, I have noticed that the gas passages on some of the adjustable blocks (Syrac in particular) are somewhat of a maze for the gas even when full open. Larger than the barrel port hole, but more restrictive than the .159 straight hole of a fixed block. Seems like as long as it exceeds the smallest restriction in the system ( barrel hole) it shouldn't matter, but I still wonder.
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I'm in for Western! I hope the dirt around the targets is prepared to take a beating!!!!!!!!!
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The threads are nearly the same, and if you cut the tube end off, there are only about 3 full turns of thread engagement. That is why almost everyone says they will go most of the way on then tighten up. You are essentially re-forming the threads when you force it past that point. The correct fix is a properly threaded nut, but as has been said, grip it tight and it WILL go. If you remove it after and look inside the tube, the anodizing will be missing where the threads stretched. The reason I don't like this approach is that aluminum is more prone to brittle failure than mild steel (like the shotgun's factory tube), and 6061 doesn't handle cold-forming well. I can almost picture the tube launching itself and about 6 shells downrange right before the end of the fastest stage run of my life......... At least make sure you install the heavy-duty Nordic clamp if you use the "it ALMOST fits" method
Tom
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I have been using one HARD for the entire second half of this season, and only had trouble with it twice. (Both my fault!) First time was an FTF from a poor cleaning job after I opened the loading port and ported the barrel. Only once, but after the match I broke it down and thoroughly cleaned it instead of just blowing the crap out with an air nozzle
. Lotsa aluminum under the action bars, duh. The only other time I had a problem was after re-cutting the trigger hook to reduce engagement distance and sweeten up the pull, I took too much, and it doubled twice in a match. Both times I was shooting so fast the RO didn't notice, but I knew it happened 
. I advanced the disconnector timing to close the gap, and no issues since. I have several thousand through it now, and mostly the cheap Walmart Federal crap, with no malfs. Only thing I have found so far it won't cycle are the Fiocchi low recoil slugs. Ejects the empty, but next shell stays on the carrier. No issue with any other low recoil slugs tried. I milled out the loading port like the pics Kelley posted in the clays forum (thank you sir!), works great. Nordic mag tube, Benelli Supernova threads opened up in the lathe. I am intending to make a nut to replace the Nordic as a drop-in part for this model if we can ever get the AR guys to quit ordering parts and let us catch up! Nice thing about the modular Nordic tube is that only the attachment nut needs to be manufactured, the tube itself is interchangeable. Somebody here asked if we were going to put the nuts into production, Sorry I didn't reply before I forgot who asked. All I can say is I hope someday we aren't buried. If we do, I will announce it by buying in as a vendor, as I don't want to take advantage of the nice folks who pay their dues to keep this forum going. I appreciate the genuinely good people on this forum and I think that following the rules is important for all of us, so I desire be part of what makes this forum special.Tom
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Noveske fluted stainless match, 16 inch with mid-length hybrid gas system. Soft, controllable, consistent 1 MOA, but still handles FAST!
. So, there are some other factors that play into reliability experiences with this type of action. You can't prevent the gun from moving, but you can't let it move too much either. Might help explain why some loads work for some and not others.
What we found was that a standard carbine length gas system needed the port in the barrel increased to about .075 (.062 is about typical) to cycle reliably with low power ammo. We increased the piston port to almost 1/32 oversized before we realized that the barrel itself was the throttle. 
. Lotsa aluminum under the action bars, duh. The only other time I had a problem was after re-cutting the trigger hook to reduce engagement distance and sweeten up the pull, I took too much, and it doubled twice in a match. Both times I was shooting so fast the RO didn't notice, but I knew it happened 
. I advanced the disconnector timing to close the gap, and no issues since. I have several thousand through it now, and mostly the cheap Walmart Federal crap, with no malfs. Only thing I have found so far it won't cycle are the Fiocchi low recoil slugs. Ejects the empty, but next shell stays on the carrier. No issue with any other low recoil slugs tried. I milled out the loading port like the pics Kelley posted in the clays forum (thank you sir!), works great. Nordic mag tube, Benelli Supernova threads opened up in the lathe. I am intending to make a nut to replace the Nordic as a drop-in part for this model if we can ever get the AR guys to quit ordering parts and let us catch up! Nice thing about the modular Nordic tube is that only the attachment nut needs to be manufactured, the tube itself is interchangeable. Somebody here asked if we were going to put the nuts into production, Sorry I didn't reply before I forgot who asked. All I can say is I hope someday we aren't buried. If we do, I will announce it by buying in as a vendor, as I don't want to take advantage of the nice folks who pay their dues to keep this forum going. I appreciate the genuinely good people on this forum and I think that following the rules is important for all of us, so I desire be part of what makes this forum special.
ACR lightened bolt review
in Rifle - Technical
Posted
What do the accuracy groups look like? I am not against the platform, but the ones I have seen in use have problems getting good hits on 300+ yard steels. Is yours more consistent? Soft and Fast are great, but in a match with 20sec FTNs on the long range stuff and a par time, a couple of no hits can take you right out of the match.