I just got a Tubbs 308 ar buffer spring last nite and tried it out today , it cycled all the rounds I put though it ,no FTE with all the brass landing at about one o'clock , I still have a H3 (5.4 oz) buffer coming maybe thursday .
I don't really have any experience with 7.62 and 300BLK ARs, so this is just in answer to your question regarding the 5.56 ones. The short answer is probably yes. Especially regarding the 20''. The 20'' was likely drilled at the gas port for a rifle buffer, which I believe is 6.2oz, so it's probably way, way overgassed with a 3oz. The 3oz buffer was designed for a 14.5'' carbine length system.
Most ARs are overgassed to begin with, so that they work with most ammunition even under adverse conditions. For example, most ARs will run weak .223 even when dirty, so you're going to get less than ideal results when using hotter ammo. So most people upgrade the factory buffer with something a little heavier. For example, most 16'' ARs will work just fine with a 4oz buffer, even with .223 whatever ammo.
Long story short, with the 20'', definitely upgrade to at least a 5oz buffer. With the 16'', you would probably be okay sticking with the 3oz, but a 4oz may make it shoot smoother with 5.56.
Most ARs are overgassed to begin with, so that they work with most ammunition even under adverse conditions. For example, most ARs will run weak .223 even when dirty, so you're going to get less than ideal results when using hotter ammo. So most people upgrade the factory buffer with something a little heavier. For example, most 16'' ARs will work just fine with a 4oz buffer, even with .223 whatever ammo.
Long story short, with the 20'', definitely upgrade to at least a 5oz buffer. With the 16'', you would probably be okay sticking with the 3oz, but a 4oz may make it shoot smoother with 5.56.
Uncle Money Bags is right on with his post.
Typically, if everything is in "spec," My typical defaults are as follows:
16" Mid length gas: H2, standard power spring. H buffer if shooting very weak ammo in high volumes with no cleaning (training class)
16" carbine length gas: H2, standard power spring. H3 buffer if it's an early 90's gun with oversized gas ports that are not in spec.
14.5" Mid length gas: H buffer, standard power spring. Carbine buffer if shooting very weak ammo in high volumes.
14.5" Carbine length gas: H2, standard power spring. H buffer if shooting very weak ammo in high volumes.
11.5" Carbine length gas: H2, standard power spring. H3 buffer if shooting suppressed or if gas port is eroded
10.5 - 10.3" Carbine length gas: H2/H3, standard power spring. H3 exclusively if shooting suppressed or if gas port is eroded
Daniel Defense MK18 upper: H3 or possibly H4 due to DD's oversized gas port size.
10.5" 300 blackout with pistol length gas: Carbine buffer to shoot subsonics and supersonics reliably. If shooting suppressed, will use H or H2.
Typically, if everything is in "spec," My typical defaults are as follows:
16" Mid length gas: H2, standard power spring. H buffer if shooting very weak ammo in high volumes with no cleaning (training class)
16" carbine length gas: H2, standard power spring. H3 buffer if it's an early 90's gun with oversized gas ports that are not in spec.
14.5" Mid length gas: H buffer, standard power spring. Carbine buffer if shooting very weak ammo in high volumes.
14.5" Carbine length gas: H2, standard power spring. H buffer if shooting very weak ammo in high volumes.
11.5" Carbine length gas: H2, standard power spring. H3 buffer if shooting suppressed or if gas port is eroded
10.5 - 10.3" Carbine length gas: H2/H3, standard power spring. H3 exclusively if shooting suppressed or if gas port is eroded
Daniel Defense MK18 upper: H3 or possibly H4 due to DD's oversized gas port size.
10.5" 300 blackout with pistol length gas: Carbine buffer to shoot subsonics and supersonics reliably. If shooting suppressed, will use H or H2.
All 4 of my center fire Ar's(carbine gased 5.56, 300 blk 308 win ,223 rifle ) are running fine now plus the 22 lr carbine , I was asking if a H3 buffer would help the 308 and if a H2 could improve the others . I now have a H3 for the 308 with a tuned spring that I will be trying out in a few days . The 308 has improved with the spring and the H3 buffer should help things along .
New range report --today I ran the Ar 308 with the Tubbs Flat ar 10 spring(20.5") and the 5.4 oz buffer -50 rounds of reloads and MHE factory loads ,with no problems -the recoil was firm ,much milder than when I first shot it with the PSA stock buffer(4.0oz) and spring(11") which was more like a 7.62x 54mm (like being hit by a little man with a 5 lb hammervery good!
Ok, so I have an SBR with a 10.5 barrel. As far as I know I have a standard buffer spring (didn't know they made them in different weights). I want to use a variety of ammo. I have some XM-193 factory ammo and I have reloads. What is the best weight to use any ammo?
The one that cycles reiliably. Start with a carbine and work your way up from there.
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