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"That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892
"The body cannot go where the mind has not already been."
Based on my experience with springs in general and after watching Tubbs video I think the Tubbs flat wire spring is an improvement for rifles that are not subject to harsh environments. Tubbs is correct that eliminating the resonance does reduce or eliminate bolt bounce. The only problem I have with the Tubbs spring is IMO it is too stiff. If it was a couple of pounds lighter I would use it without hesitation. I spoke with Tubbs about this several years ago and his point was the spring was designed for high power shooters who usually shoot pretty hot loads.
CS if processed and heat treated properly does make a good, high endurance spring if the application is within the limits of the material. Many gun springs are significantly overloaded in their applications given the materials used. The main benefit of CS is higher temperature tolerance than music wire. Tubbs and Sprinco springs are higher quality than the average replacement part and the material is harder meaning it can take a higher load. IMO a Tubbs spring made from the correct SS alloy would be an even better spring but would be much more expensive. CS is not very corrosion resistant. Surface defects caused by even mild corrosion can lead to spring failure.
UPDATE:
I just spoke with the tech at Tubbs. He told me that all recent production flat wire springs are now made from 17-7 stainless steel wire. This change removes one of my main reservations about this spring. I ordered a couple to test. It looks like if your gun will run with this weight of spring it would be the first choice.
That's interesting. I spoke with Tubb himself on Thursday when I ordered mine and he stated that they do not make any SS springs. The reason I asked was because his site states that they are 17-7 SS. He said he would look into that. Mine came with an insert in the pkg that stated they were CS.
"An opinion solicited does not equal one freely voiced," Al Swearengen, Deadwood 1877.
I too will be interested to see what I get. The tech claimed they changed to SS about a year ago. He said he had worked at Tubbs for six years. Maybe the tech is confusing the coating they are using now with a material change. I have two of his original springs (unused) that I got about five years ago. When I tested my older spring in an A5 extension I got forces that were about 2# greater than his video shows. If they did in fact reduce the OD of the spring that would mean the wire is narrower that could account for the lower forces he shows.
When I get the new springs I will compare old to new and report back. The plot thickens.
As to telling the difference between SS and CS the only quick and dirty test that comes to mind would be to scape off a bit of the coating maybe at the end of the spring wire and apply a drop of salt water. If it is CS it will almost rust while you watch it. If 17-7 nothing should happen.
Last edited by DBR; 05-13-14 at 16:46.
Last edited by BufordTJustice; 05-13-14 at 16:55.
"That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892
"The body cannot go where the mind has not already been."
My old ones are not coated.
Just spoke with customer service at Tubb's. Said they switched to SS about 4-5 months ago. They have been dipping their springs for about a year, as a rust preventative and permanent lubricant, and that is continuing with the SS spring. Would think its safe to assume anything purchased at least in last 4 months, possibly 12, is SS. Not sure about the SS in these springs, but many SS alloys are less attracted to a magnet than non SS ferrous alloys, so maybe that is a way to test. BTJ, since you have a known CS spring, why not compare its response to magnet with the new one?
This is all in all a facinating discussion.
I would submit that IG is pretty dead on as the the root causes. I would also venture to add the following;
Issues to consider; gas port location on the barrel has an enormous effect on the actual port pressure, to wit; in measurements taken with M193 & M855, the port pressure of a carbine & a full sized rifle were virtually double. 26,000 (carbine) psi vs 13,000 psi. (rifle)
Basically a 5.5" change in port location doubled the port pressure.
Port pressure - just like chamber pressure / bore pressure that drives our little copper pills, albeit in a bit more roundabout route, drives the carrier. Doubling the port pressure is going to absolutely & significantly increase the carrier velocity in the extraction cycle.
Can you imagine the effect on bullet velocity if we doubled the chamber pressure?
The high speed movement of the carrier & bolt are the root causes of so many extraction failures. The carriers rearward movement cams the bolt to rotate & unlock. The high speed rotation can / will cause the extractor to open early from centrifugal type force. In addition, because the rifle is trying to extract the case earlier (than a rifle), the case has less time to transfer heat to the chamber wall and shrink away from it. (The shrinkage allows effortless extraction - see a bolt gun). Basically the cases are stuck to the chamber walls. Compounding the rotation/centrifugal failure of the extractor (spring/buffer/o-ring cured) is the tendency for the extractor to override the rim - deforming the case and failing to extract the case at all.
All of this mess has occured before the bolts lugs have even cleared the barrel extension.
The other component of this and where IG is correctly focusing, is the gas port SIZE. The size or diameter of the gas port is not going to change the port pressure. It will control the VOLUME of gas that is sent down the gas tube to the carrier key. The volume of this gas is actually measurable in pressure over time. Bigger port = longer pulse. Think of the gas pulse this way, it is a block of energy that travels down the tube to initiate and follow through with the carriers rearward movement. Pressure = speed and the length of the pulse (from port size) is the "oomph" to complete the task.
The fact that we have so much success in getting these rifles to operate at all lies in the beauty of the design. The carrier receives the gas pulse and by and large self regulates - once the bolt unlocks and the bolt moves outward from the carrier, the chamber that is in front of the gas rings is effectively moved to vent the pressure out of the port holes in the side of the carrier. Modifications have severely taxed the design however and we have further complicated the issue by changing bullets & powder.
Going back to the velocity issue (port location) and the length of the pulse (port diameter) - we can create some significant carrier speed with a lot of momentum. There is absolutely no doubt in my mind that this issue generates a significant rebound effect that is evidenced by the carrier propelling forward (at times) fast enough to out-cycle the mag spring that results in a failure to chamber a new round / closing on an empty chamber or creating a partial bolt override.
Momentum = mass x velocity. It works both ways, both in the extraction cycle and the chambering cycle. A carrier that impacts the barrel extension will bounce. That is almost a certainty. The various carriers, buffers and springs create a seemingly endless number of combinations.
Interestingly enough - one of the worst culprits for port size, pulse length and pressure are 16" rifles with carbine length gas systems. The bullet acts as a cork after it passes the gas port and keeps the barrel (and gas tube) pressurized far longer than a rifle or carbine. Conversely, a rifle like the MK12 uses a rifle length gas system, but the barrel length in front of the port has been reduced by 2", thus bringing the pressure down earlier, resulting in one of the softest, sweetest shooting AR platforms out there.
Given paramters for carrier weights - (I use mil spec USGI M16 carriers in all my rifles) the various buffer weights and spring weights - a balance can easily be found that prevents bolt bounce, ensures reliable chambering, extraction, lock back and doesn't beat the rifle or operator up. I truly do not understand the reasoning some folks use these highspeed "lightweight" carriers.
I subscribe to the view that a properly selected buffer (weight) will basically eliminate any of the carrier bounce issues. Proper spring selection will mitigate the carrier speed problems - and they play off one another.
An earlier post noted that the bbls were ported incorrectly - too large a port and you are already way behind in the solution race. It may come down to R&R the bbl or install a bushing to reduce port diameter - or an adjustable gas block - which will not reduce pressure - is changed port size which changes the volume.
I honestly think if it were not for the myriad of ammo / bullet combos, the "solution" to the carrier/buffer/spring/ puzzle would be ridiculously easy. As usual - we make it hard on ourselves. The truly one seriously frustrating aspect are the mfr's that use huge ports and pass a serious problem on to mostly unsuspecting buyers.
JM2C
ETA - in reference to David Tubbs comments about dip - the context of that is really focused on Hi Power / Competition. A lot of that generated out of his efforts to get the SR25 to shoot - he succeeded (won the Nationsals with it and gave it up immediately after) It is a very odd feeling and mostly screws with the shooters head. It doesn't help position either. I experienced it when I built an AR10 in 6mmx22-250 for HP competition. When the carrier moves forward, the entire rifle wants to either dip or pitch forward - very disconcerting when you're under the clock and trying to shoot X's.
Same goes with hs discussion on the buffer spring ocillation or wiggling - however he referenced it. That movement causes the classic "sprong" noise that drives some shooters nuts. I always coat my buffer springs w/ Wolfshead bearing grease - slicker than snail snot and no more noises - clean and fresh glob once a season and I'm good.
Last edited by opsoff1; 05-14-14 at 16:06.
opsoff
"I'd rather go down the river with seven studs than with a hundred shitheads"- Colonel Charlie Beckwith
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