My test of BCG/Buffer weights and springs

[EnderZen]

Ok, I have been scratching my head about BCG weight, buffer weight, and springs for the longest time so I thought I would do an experiment to see what would work best for me. I figured since I have been asking questions here and taking a lot of good info from this forum, I thought I would share my results.

My test platform is a Liberty Leonidas built with Seekins upper and lower.

I tested the following 2 systems.

HEAVY-Full weight RCA BCG with adjustable gas key and POF cam pin and Gen 2 JP Captured Spring with all Tungsten weights and white (lightest) spring. Total reciprocating weight - 1.1 lbs.

vs

LIGHT-RCA Titanium BCG with adjustable gas key and POF cam pin, Gen 2 JP Captured Spring with all weights removed and with white spring. Total reciprocating weight - 8 oz.

I would shoot one shot at a time using Remington UMC 220 grain subs till i had the gas key set for reliable bolt lock back and ejection pattern for each "system". Then I took 10 shots with each and even used a chronometer just to see if there would be any difference.

MY RESULTS/OPINION
If you ask which one is softer, I would say the heavier because the impulse was noticeably longer and smoother BUT if you asked which one I liked, I would say the lighter as it was quicker and easier to manage.

Now I did notice bolt bounce with the LIGHT system so when at home I kept testing and taking slow mo videos with my iPhone (closing the bolt on a round in a loaded magazine) to look for bolt bounce. I tried the Gen 2 JP Captured Spring with no weights but the heaviest spring and I still got bolt bounce. I tried Taccom's ultralight buffer and light spring, standard spring and tubs "heavy" spring and still got bolt bounce with all the different springs. So I came to the conclusion for my system that I need to add a little bit of weight back in. The Gen 2 JP Captured Spring with the steel weights and the titanium BCG with adjustable gas key and POF cam pin are what work best for what I want (lightest system without bolt bounce). Just as a side note, just doing straight averages over 10 rounds the LIGHT system was 10 FPS faster than the HEAVY according to the chronograph but I dont think that is meaningful.

MORE TESTS
JP Captured Spring
vs
Armaspec SRS

I have been using the JP Captured Springs in a couple of rifles for a while and thought I would see if the Armaspec is any better. So since the JP with steel weights is almost the same reciprocating weight as the Armaspec carbine version, I compared those 2 systems. I know we are splitting hairs here with this comparison but if I had to say what I felt better to me, I would say the Armaspec. My opinion is that when closing the bolt, it feels slightly softer and quieter. Yes, splitting hairs, yes, this is my opinion.

MORE TAKEAWAYS
My opinion is weight = reliability across different possibilities. Let me explain, I only shoot Reminton UMC out of my Leonidas so I can fine tune it to work with the lighter weight BCG and Buffer. No bolt bounce, perfect ejection pattern. BUT if I shoot any other ammo, I know there is a very good chance I will have a FTF or some other gas related malfunction. So for my SBR where I sometimes shoot with or without a can and also shoot different types of ammo, I know I need to have more weight in the system. For example, during my testing, I got my Leonidas with the titanium BCG and JP Captured Spring with just steel weights/white spring shooting perfectly with the Remington 220 UMC (good lock back and ejection pattern) and then loaded a 30 round magazine with 5 different types of subsonic ammo (SilencerCo, Sig Sauer, Atomic...). I had 3 malfunctions. Then I did the same thing with my SBR with a can on it with and full weight BCG and JP Captured Spring with just Steel weights/white spring. I used Remington 220 UMC to adjust the gas block to get good lock back and ejection pattern and loaded a 30 round magazine with the same 5 different types of ammo and I had no malfunctions. So, in conclusion, I was able to tune my gun to one type of ammo by going lighter but it would become prone to malfunctions if I changed the ammo. Whereas, I can make it more reliable across different ammo and scenarios (can on or off) by keeping the weight reasonable (standard weight BCG and buffer).

Someone may say that i could have saved myself some time and just watch JPs video but I wanted to go through the test to see what works best for me and not just take someone's word for it. https://www.youtube.com/watch?v=M5liUH3CawE

This is my opinion/experience with my gun so other people may have different experiences but I put so much time and effort into this I hope someone finds this helpful.

[2manyToys]

Nice review.

Out of curiosity, how much smaller in diameter (if any) is the Armaspec spring guide rod compared to the JP rod? I'd like to use a Law Folder on my Leonidas once it's out of jail, but the JP rod is too big to fit through a bored out Law carrier extension.

[Kadonny]

Wow, this is great info.

I had problems with my Leonidas running right out of the box. I built a Mega lower with a standard cabine spring and buffer and was getting failures to lock open with 220 grain subs. Supers ran fine. I tried a lighter BCG and a Tubbs .300blk spring, still had issues. I put back in the stock BCG (came with my Leonidas) with the Tubbs spring and got the same thing. I then tried some different ammo to see if it didn't like the 220gr stuff and I was getting failure to pick up the next round on the Hornady 208gr subs I had bought.

Long story short, I ended up trying a Nemo .300blk spring for giggles and it seems all my issues went away. The Nemo spring ran with a standard carbine buffer and my stock OE BCG on all subs. It even ran with supers. My issue is I am worried about bolt bounce and rifle longevity with the softer Nemo spring.....is it too soft? Is it too soft to run supers? But now you have me thinking about the BCG with adjustable key to be able to dial up/down the pressures as needed for whatever loads I am running. I never knew until I read your thread that they even made an adjustable BCG key just for these purposes, thanks for the info!

So, how adjustable is the key both up and down pressures? The RCA web page specifically states that the adjustable key is to "soften" overgassing, not neccesarily deal with undergassing.

Great info though, lots of stuff to ponder!

[EnderZen]

It was a fun process but I have come to the conclusion that every gun is different and no tuning answer is good for all guns.

I had JP Customer Service telling me that i was going to destroy my gun by going so light and I would constantly have slam fires even with the adjustable gas key. I never had 1.. not 1 out of different lightweight systems and in the end I have run easily 1000 rounds with the titanium BCG. They recommend standard weight BCG with 2 of the 3 weights being tungsten.

Another take away I had is that a heavier spring never helped for my system. It seemed like lighter springs always made things work better. So a light spring with the standard carbine buffer and standard weight BCG. My guess is that you are fine. Check to see where you gun is throwing the brass (ejection pattern) to see if you are still under gassed. I also doubt you are experiencing bolt bounce with that much weight. I only had bolt bounce when there was not enough reciprocating weight (light buffer and BCG). Bolt bounce did not occur when I changed to a softer spring.

Anyway, about your questions, I only have the adjustment screw backed out one turn from fully shut off. You can back it out quite a few turns more. But I really dont know how this would help an under gassed system.

My guess is that you should be running fine now. But if you check your ejection pattern and you still are under gassed for the subs, then I would try one of the following 2 options. 1 - try putting the lightweight BCG you mentioned earlier into it and check again. or 2 - I would suggest you look into the bootleg or gemtech adjustable BCGs. The RCA you have to take out each time you want to adjust it. I think you can leave the bootleg and gemtech in the gun and just turn a "screw" to adjust the gas from use with suppers to use with subs.

[Kadonny]

Great info, thank you very much. I'm going to keep monitoring it, but last time I had her out she ran with all loads and all mags with the Nemo perfectly (knock on wood). My one hang up is I keep,reading if you have to change springs, you are not effectively treating the problem just masking it.

Again thanks, awesome info. By the way, how damn quiet is the Leonidas with subs. Insane.

[dellet]

When you start changing buffer weights, springs, gas flow or anything else you need to have a reason. If that reason is simply to get function, it's probably mis-directed.

Something that is a specialty build like a Leonidas, was designed to function in a certain way. If you set it up that way and it doesn't function, it's worth trouble shooting first, then modify to fit your needs.

To take that to an extreme, you could spend a a lot of time and money to get a barrel with a .310 bore to cycle subs without a suppressor.

There's always more than one way to solve a problem. Take for example Zender's bolt bounce. The easiest way to eliminate it is to go with a powder filled buffer, but he loses the captured spring. Now you have to make a choice.

The problem in my mind with the adjustable carriers is that they are not cutting off the gas flow at the source. They are simply redirecting the that excess someplace else. That means more crud where you don't want it, and less gas pushing the bullet out the barrel. Again it's a choice.

For what it's worth I don't really like the idea of the NEMO spring, partly because it's so weak that in a dirty chamber you find out what the forward assist is for and with supers you take a nice soft shooting rifle and install recoil when the buffer slams the back of the tube. But again it's a choice.

Installing parts designed to fine tune the way a piece of machinery runs, simply to get it to operate is a backasswards way of going about things. Or at least that's my opinion of it.

[EnderZen]

Kadonmy could send his Leonidas back to Liberty. They do have great customer service and turn around. I sent mine in to get the upgraded titanium core and had it back within 10 days.

[Kadonny]

I thought about sending it back, still might. In the meantime I'm going to keep testing it. Mine is "fairly" new with probably 300-400 rounds down the pipe, so I'm not rushed to send it back to them if it needs more breakin time. I can swap spring pretty easily, so I can keep testing the carbine spring to see if it irons out.