Tungsten bolt in Max31a

Gaujo

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I would absolutely heed Mr. Lage's warnings regarding his products, as well as general knowledge of the MAC platform, as he has more than proven his expertise.

I wanted to extrapolate on coil cutting; do not do this. Coil cutting does not alter the spring's poundage, but rather shortens the overall length and weakens the integrity of the spring as a whole. It is a dangerous practice that should not be done in any firearm, let alone straight blowback or API operating systems.

Even if you did this on a stock MAC you would increase the bolt thrust by reducing the bolt's dwell time against positive spring pressure; this can lead to a runaway gun or hammer the rear of the receiver to the point of cracking. Reducing spring weight can be achieved by using smaller coils, or in the more practical case, removing material from the outside of the existing spring using something like a belt sander.

I've seen more than a few firearms ( mostly 1911's and Hi-Power camming systems) damaged or cracked due to users cutting coils

Coil cutting is widely considered the primary tuning method for cyclic rate for these guns. Sanding a spring does not seem like a reliable way to reduce it's overall strength as you would not be removing material uniformly from the round wire. It would seem acid would be best, but in both cases it would be very hard to do that just right. Less coils actually seems the most reliable way to reduce spring strength as long as you have sufficient spring compression distance left not to be close to bottoming out.
 

brenbuilds

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The big issue with coil cutting is the over all length, which then alters the springs preload when installed. It certainly can be done, but it's easier to get carried away. Sanding springs can be done by inserting a rod or dowel through and sanding a few light flats; at least two sides. You can check and feel the difference quite easily. It might be a slightly slower method, but you maintain your O.A.L.

On over sized, or rather intentionally lengthy springs, that some manufacturers sell, cutting coils is actually recommended in order to tailor it to your firearm.


I do agree the heavier W bolt will have less kinetic energy by virtue of it's weight in general, but depending how much the spring is reduced it could cause a boost in initial recoil velocity before the spring can load enough positive spring tension to defeat the now heavier object in motion. That could hammer the gun.

All in all just be careful; weird things can happen sometimes when messing with springs.
 

SecondAmend

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As an alternative to cutting spring coils to reduce overall spring force, sometimes coils are "torched", i.e., heated with an oxy-acetylene torch to reduce the spring rate while keeping the overall spring length and coil dimensions the same. Like cutting and grinding coils, "torching" is generally not recommended. Preferably, a spring having the proper length, internal and external sizing, and spring rate is designed and implemented for the particular application.
Best of luck.
MHO, YMMV, etc. Be well.
 

root

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Well Mr. Lage
If you have projects you just throw out can I have permission to dumpster dive the shop trash?

( gotta ask)

Best bet would be to wind a spring on a lathe with smaller wire dia.

Might take a few tries to get the poundage needed but it is also the most reliable and consistent way to do it.

Lage says not to do it I'd not do it.
Those WCF bolts are rather expensive and as of now not easily replaced.
 

Gaujo

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If you're going to do it, you use the m11/9 recoil rod / spring that VegasSMG sold for the 11/9 CFW a configurations.
 

CoffeeFreak

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Yes, if you choose to pursue this project, it would be better to re-profile the area on the CFW bolt that the sear would be catching on. Just copy the profile on the MAX-31 bolt. You could carefully do it with a Dremel and a diamond coated bit. After firing, you will need to keep an eye on any wear of the newly cut sear notch. The CFW bolt is shorter than the MAX-31 which gives it more rearward travel causing it to hit the sear harder on its return forward. You will also need to be careful about what ammo you use. You may tune it to work with a certain ammo and then switch to another ammo that may runaway due to velocity, bullet weight, etc.

Yes, I have tried this configuration and observed the CFW bolt/ sear problem and promptly disassembled it and shelved it. No I do not know what spring length I used. Keep in mind, by modifying your CFW bolt, you may be devaluing it if you sell it in the future.

Sorry for the longwinded reply.
I'm going to agree with you on the sear angle and position because you designed that angle. I also agree with the devaluation you might do to the modified CF-W bolt becuse they are becoming valuble, but not the wear of any impact from the increased rearward travel due to the reduced forward velocity of the heavier bolt. Energy increases with the square of velocity, and only in linear proportion to mass. So a bolt twice as heavy moving at half the speed should have about the same energy impact on the sear as a bolt with half the weight of the heavy bolt moving twice as fast.

That reduced momentum comes at a cost with that design. Reliability. That slow an ROF could be less reliable causing stripping and feeding issuies, light primer strikes and ejection problems like in the videos.
 

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