there is something seriously wrong with this weapon and carrier tilt is the least of the problems
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there is something seriously wrong with this weapon and carrier tilt is the least of the problems
You know, I don't dispute the folly of converting a DI gun to piston with as little as adding a piston and a solid surface in place of the gas key. But mechanically I think there is more going on in some guns than others when you have failures like this part of the time, and then no problems at all in just as many if not more others with equivalent usag.
I think there are contributing factors in extreme cases like this, but I don't know what they are.
isn't this what the seth harness buffer was made for?
The nature of the tilt is usually no big deal but I have found an upper that it is a problem with. It removed the entire opening of the mouth on the extension tube and was just intermittent with problems. It would wierdly do 149 round dumps repeatedly. Then it just got worse.
*To see if you could be having a tilt issue, take your upper only, push up on the area near the bolt like the magazine does, pull down on the rear of the carrier and cycle the carrier, if you feel it is hard to unlock compared to normally cycling the carrier you may benefit from this mod.
The TDP for the AR calls for a high tolerance near the chamber and it can be pretty far out near the rear of the receiver. Manufacturers have tightened the tolerances between carrier and bore so the tilt isn't as bad. The mass production of the TDP for the DI system makes it difficult, I think, for an all our replacement piston upper that has the added meat on the bottom rear of the carrier because it will cause a bind in certain limits of the tdp in the extension tube.
So I have really liked the looks of those anti tilt buffers. So I made one and it seems to have really helped out my situation I had with the tilting badly upper.
Here is what you need.
buffer, I used a H2
.201 drill bit
1/4-20 tap
.188 thick piece of aluminum about 5/8" square or round
1/4-20 button head cap screw
a milling machine-i know this makes it right out of the DIY but there are a few ways this could be done I just chose to mill it.
Step 1.take apart the H2 buffer,
Step 2. Make the round slug that fits very snugly into the rear of your carrier, should be about .62” in diameter but it may vary and you want a very good fit, in the step you are making the round you also put a .260 hole through the center, you can make this larger as this is for clearance and not a locator, it just needs to be larger than the o.d. of the threads and any offsets incurred. Once you have a piece with a hole in the center and a good fit with the carrier you are ready to move to the buffer head modifications.
Step 2. Find center of the buffer head,
Step 3 drill with .201 drill through the buffer head, you need to have the tapped hole as close to center as you can get it but it is not as important as the cylinder location the slug you made will go inside.
Step 4. You will need to mill a .04” deep round hole into the head of the buffer about the exact size of the slug. This needs to be concentric with the buffer as best as possible. If you do this in the same operation of the tapped hole, check for concentricity after the pilot, make the shift, then do the milling.
(This could be done differently, for example no need for milling if you get a shouldered screw, like a ¼-20 screw with a .25 shoulder on it, then you would nail your drilling and tapping on the buffer, and the hole through the slug should be roughly .251 to have a tight fit with the shouldered screw. )
Sneak up on your targets, the slug can be converted from its slug to its ideal shape very easily by holding it with a 1/4-20 screw, chucking the screw in a drill, turning it on and using a file as a turning tool to make the additional geometry. The taper on the slug really helps with installing the upper.
Look at the print and see if you can make the angled geometry to the slug, do not alter the diameter near the base, (I had to edge break the base to get a good snug fit into the buffer pocket)
Step 4. tap through the buffer head now.
Step 5. After making sure all the fits are good, screw the cap screw through the slug into the buffer. Look into the buffer and see how much is protruding. Keep taking apart and sanding the screw thread end until it is flush with the inside surface on the buffer. Take the cap screw and take a pair of pliars to screw the theads up just a little bit(this is assuming it is very easy to thread in and out after tapping) and apply red anti-seize to the theads. Now clean all the buffer internals, coat with a dry film lube if you have it(fine graphite), oils work as well.
Step 6. Install and check the action, the upper and won’t come apart with just removing the rear pin but that is nothing to complain about. When installing, rock the rear into the buffer while the front pin holes get aligned. Then install both pins and cycle. I can install and uninstall my upper whose pins are pretty free in just seconds. Any complaints about the upper-lower disassembly are overcome when you see how easy it is.
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Excellent post!!!! Many who are willing would benefit.
Very interesting.
I have an AA rifle (I actually have a few).
I don't have 10k through it yet. I think I have around 3000-3500 and I literally don't see anything at all near the buffer tube area. Unless something changes I wouldn't expect to experience the extreme carrier tilt shown in the pictures.
Not plugging our product, just want to participate and contribute to the discussion. We put 4,844 rounds (so far) through our piston operated Huldra Mark IV 5.45 carbine; Not a scratch on the receiver extension. It actually surprised me a little. With my DI guns there usually is a little cosmetic wear at that point. With our Adams Arms system, we haven’t seen any of the fabled carrier tilt that exist on other piston guns.
Stewart Mills
Huldra Arms
PS: We are shooting the 5.45 to keep expenses down. When rapid firing and doing drills for the sake of round count it is hard to waste good ammo. We figure it makes our testing more strenuous, using corrosive Russian mil surp ammo, if it can hold up to that, 5.56 isn’t a problem. Also, after 4,844 rounds I have upgraded respect for the 5.45 round. It’s the real deal, for not a lot of money. Our 5.45s are selling, especially the uppers.
Attachment 9508
no offense but you haven't solved anything its just that your upper is lining up well with your lower. The whole reason why you see it here and there and not everywhere is because of the TDP. The location of the bore near the barrel extension is quite critical while allowing a cone like location of the rear.
You have to be doing large numbers in all kinds of conditions, hot ammo/ suppressed/ oversized old ports to even see it sometimes. I have the same mfg uppers and an a common lower and the difference is amazing. Not to mention if I switched lowers into the mix.
Do you not have a system that takes an op-rod and hits the top of the carrer while a round is in the chamber and if you were pivoting over the top lugs your moment arm would be about a 1/4 of an inch. What do you have that is cancelling this moment? Moment=oprod force X moment arm. A nice fit between carrier and id of receiver is a receiver bore that doesn't allow that moment to creat much of a downward movement(nice fit, or even a drill walking in the upward direction instead of the downward) of the rear of the carrier and into the tube it goes.
If I were a piston mfg I would work on just having a kit with a antitilt buffer solution incorporated and......
Why doesn't anyone set up a broach operation so the piston carriers have the full guide rails like the DI system. When you do get in the situation of looking at the full TDP you will see some piston guns that really seem to break through the anodizing early and the full contact rails on the carrier would really help. Hell you could just take it after the lather operation when you have this huge damn ring on the carrier, stand it on the end and edm in the profile without even making a broach. Slow I know but all that 4 axis milling on the carrier isn't exactly fast.
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