Lets talk springs and buffers, I'm a little confused.

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[ARCHIVED THREAD] - Lets talk springs and buffers, I'm a little confused.

Posted: 5/29/2020 6:01:31 PM EDT

So I'm setting up my 11.5 midlength to go shooting tomorrow. It has an adjustable gas block but it should be under gassed just due to the design since I won't be using a suppressor. With that being said my BCM lower came with an H buffer and some spring from BCM, not sure what it is. From Damage industries I got their "normal" Music wire spring and a Enhanced spring. Comparing them to the BCM one how do you determine which ones are going to be stiffer? Measure the size of the spring metal and compare that to the length maybe? Here is a pic of what I'm working with.

I plan to run a carbine buffer and one of these springs...

Posted: 5/29/2020 6:27:10 PM EDT

[#1]

Don’t over-think it.

Every build starts with standard carbine buffer ~3.0 ounces, and standard carbine spring.

If it runs, you can just leave it alone.

If it seems kind of violent, go with a heavier buffer and/or heavier spring. But be ready for it to malfunction when it gets really dirty if you arrest the cycling to the point that anything with a 16” barrel or less doesn’t beat-up brass or bend cotter pins.

Posted: 5/29/2020 6:54:54 PM EDT

[#2]

With that barrel set-up and adjustable gas I would start with a regular carbine buffer.

Posted: 5/29/2020 7:20:54 PM EDT

[#3]

There are spring rate calculators online. Easy to put in the correct information and compare springs.

Posted: 5/29/2020 8:14:38 PM EDT

[#4]

You are definitely overthinking this one. If you cant tell the difference in spring rate by charging the rifle a few times and comparing the springs then there isn't enough difference in spring rate to have any real impact on bolt unlock time, cambering force, or cyclic rate.

I ran the Faxon 11.5 middy unsuppressed with a regular gas block, full mass carrier, carbine spring, and carbine buffer. It shot soft, locked back on empty, and had nice groups.

Have fun!

Posted: 5/29/2020 8:32:03 PM EDT

[#5]

Given you have an Adj. GB on it... you might be overthinking it.

Do you happen to know the gas port size ? ... or brand of barrel might be as GTG.

Did you buy a known smaller sized gas port 11.5" barrel ?

Posted: 5/29/2020 8:48:24 PM EDT

[#6]

------.

Posted: 5/29/2020 8:48:43 PM EDT

[#7]

BCM lower came with a good mil-spec spring.

Use it.

Try the buffer that came with it. Probably runs fine.

Posted: 5/29/2020 9:24:02 PM EDT

[#8]

Quote History

Quoted:
Given you have an Adj. GB on it... you might be overthinking it.

Do you happen to know the gas port size ? ... or brand of barrel might be as GTG.

Did you buy a known smaller sized gas port 11.5" barrel ?

View Quote

.625 gas port on the barrel and the gas block is also .625

Posted: 5/29/2020 9:27:40 PM EDT

[#9]

Try them all, why not.
Insert a magazine with 1 round in it to verify bolt hold open on last round. Be well lubed.

Posted: 5/29/2020 9:51:35 PM EDT

[#10]

An adjustable gas block negates the need to mess with springs and buffers.

Use the standard buffer and spring.

Posted: 5/29/2020 11:42:43 PM EDT

[#11]

Quote History

Quoted:

.625 gas port on the barrel and the gas block is also .625

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Given you have an Adj. GB on it... you might be overthinking it.

Do you happen to know the gas port size ? ... or brand of barrel might be as GTG.

Did you buy a known smaller sized gas port 11.5" barrel ?

.625 gas port on the barrel and the gas block is also .625

No no

That's the journal at the gas block, meaning the diameter of the barrel where the gas block is installed.

Gas port sizes range (typically) from .065 all the way to .0935 on some old 20" rifles. I'd assume based on the fact it's an 11.5" middy, you're probably sitting around .081 - .089 (ish). If it were set up for suppressed use only, probably more like .075 - .081 if my memory serves me correctly.

Posted: 5/30/2020 1:11:40 AM EDT

[#12]

Put whatever spring and carbine buffer you want in it. Shut off the gas with your adj gb and go one click at a time until the rifle is running how youd like. Thats the big advantage to a adj gb you can control it.