Heavier Buffer Question AR9

[Moondog1]

Clipping the spring will negate the heavier buffer. Yes it would decrease the return force. With the extra power spring you could spare a little, mabey!!!You might try calling KVP and see if they have heard of this happening and recommendation. It's possible the head of the buffer where the spring rests was made too long. They make it longer on purpose to get rid of overtravel, possibly got rid of too much overtravel.

I think you are right. i think it's really designed for an ar9 without LRBHO, the head is a good bit longer. No one has said any of these parts will work on the FX-9 I'm just experimenting. Thanks again though. I'm going to mess with some combinations when I get home and see what happens.

 

[Moondog1]

I've had very good luck with Freedom Munitions 147 gr subsonic. Light load 950 fps Works great in 6 different guns and four different suppressors

That's what I typically shoot until I run out. Then I go back on the Tula diet until the next order...

 

[Spikey]

I've also had decent results with North Georgia Reloading's 9mm subs . Cheap also ! Plus local guys if you call almost Chattanooga local .

 

[HfdSARG]

With that extra power spring it will be difficult but the bumper of the buffer should protrude. This is a spikes H3 buffer with spikes 9mm buffer sping.

 

[Spikey]

View attachment 1472793 With that extra power spring it will be difficult but the bumper of the buffer should protrude. This is a spikes H3 buffer with spikes 9mm buffer sping.[/QUOTE

I used this set up in a 16" barrel with a JP bolt with no issues. I wanna say I used it on a SBR build with a 5" barrel suppressed and unsuppressed without issue. But it's been awhile .

 

[Moondog1]

I have an update for anyone that cares!

So the kvp 7.5 ounce would not clear the LRBHO with any combination of springs. It would shoot and cycle fine, very smooth and less gas it seemed, with the spring I got with it.

When I manually cycled the bolt, I could look at the end of the buffer tube from the outside and see the plastic bumper on the buffer hitting the end of the buffer tube. There's a hole on the kak pistol buffer tube. So I decided to make the kvp bolt shorter.

I cut off about the width of the distance it was missing to clear the lrbho, then squared it up as best I could with the belt sander. Then I drilled out (no weights in this kvp 7.5 ounce buffer, i think its a solid peice of milled steel) enough to smash the plastic bumper back in and I drilled two new holes for the roll pin that holds the plastic bumper in. It's not perfect and I know it's no longer 7.5 ounces lol. But it works. So far it locks the bolt back on the last round out of 7 or 8 tries.
I haven't tested it unsuppressed, I have a feeling it will short stroke. Thanks for all the knowledge everyone. I also hope yall aren't too offended by me hacking up parts.

 

[Spikey]

I'm not offended. I enjoy the tinkering. If someone makes a fix or a screw up it's bound to help someone else !