GAS BLOCK

[rkfulgor1]

Im looking to remove my A frame front sight post and put a low profile gas block...Which have you used, prefer?
What are the pros\cons to the setscrew style opposed to the pinch style..I have a 5.56 SW SPORT

[nisils14]

What would be your purpose in replacing the front sight base? Both have are equal in terms of reliability if done correctly in their repspective manners. Clamp ons are easier for average joe to install. Whatever you decide to get, don't get a gas block that made in aluminum. If you're looking to install a longer free float handguard, I would look into having the FSB shaved. A pinned gas block shouldn't ever fail or cause problems.

[rkfulgor1]

Sorry should have clarified..I am putting a free float forend on...I will still have to remove it to change the barrel nut out..I guess I could leave it pinned and remove block and tube together..

[BPTactical]

Some will be dictated by your choice in FF.
For absolute rock solid reliability bob the factory FSB. I do them all the time and when it is re parked it looks factory and is the lightest.
Set screw type is the next choice as long as it is correctly installed.
Clamp type is the last choice. They are heavier and bulkier than either of the above. They are also the most failure prone.
Stay away from aluminum gasblocks.

[MarkCO]

I'll agree with Bert on the Aluminum, but a properly designed clamp gas block is the best. Less leakage and actually more secure than a set screw.

If you go watch the TheBelly's video on gasblocks, he explains why the CarbonArms gasblock is what he prefers. It was the only one of 6 systems that made it through a trial for a new weapon system that puts a lot more stress on the gasblock. And hey, it is made in Colorado.

[Lurch]

Why are aluminum gas blocks so bad?

[Hoser]

Why are aluminum gas blocks so bad?

They expand and contract at different rates than steel ones. Then they leak when they get hot.

[Lurch]

They expand and contract at different rates than steel ones. Then they leak when they get hot.

That makes sense.

[BPTactical]

I'll agree with Bert on the Aluminum, but a properly designed clamp gas block is the best. Less leakage and actually more secure than a set screw.

The failures I have seen with a clamp style are: A-(most common) over torqued clamp screws.
B- the bands stretch (from over torqued fasteners)
I am not familiar with your gasblock design Mark.

A PROPERLY installed set screw gasblock will work fine. I have built a fair number of high end rifles for a particular customer that runs them VERY hard, all with set screw blocks and not a one has failed.
What is critical is the particular set screw used. A lot of the manufacturers use a plain flat point set screw which will fail. I make sure that a cup point serrated set screw is used. They are capable of holding a tremendous load if properly installed, I fall back on my machinery repair experience and I worked on some shafts that had very substantial loads imposed on them and the only mechanism holding the pulley/gear was set screws. They worked fine.
Some guys insist on spot facing the barrel where the set screw contacts it. I don't feel it really makes a difference if a cup point serrated screw is used, it will dig into the barrel well and on a non spot faced barrel it "bites" into the barrel a bit better because the contact surface is not flat.
If the barrel is hard coated such as Melonited it must be spot faced to get through the hard surface so the set screw can bite into the softer barrel steel.

Aluminum expands and contracts at 3X the rate of steel. That differential will cause the block to work loose.
Not to mention with enough rounds the gas impulse will do the same thing a plasma cutter will do. I had a gent bring me a ultra lightweight carbine he had built that was short stroking. He had used an aluminum gasblock and after about 2K rounds the hot gas impulse had blown out the gas block to the point the forend had aluminum spatter on the inside of it. Uhmmmmm, yeah, that will make it short stroke.

This is also a very good argument for making sure you use a steel base and rings on a rifle. You want everything to expand and contract at the same rate.

[ray1970]

Here's one Bert chopped down for me. It turned out very nice. We cut it down to have a mid-gas system on a "dissipator" style upper.