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There are several different variations of "Gas Block" steel. 4140 chrome molly, carbon steel, stress proof steel, etc. Does it matter?
There are several different variations of "Gas Block" steel. 4140 chrome molly, carbon steel, stress proof steel, etc. Does it matter?
Yes, it can.
Heat treat matters as much as well.
I think I’ve seen 17-4PH (stainless steel) used as well.
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What type of steel is the Mil-Spec FSB made of?
I guess theres not a USGI TDP for LPGB's since they're not mil-spec to begin with.
Terms like "stress proof steel" are not descriptive. IMHO quality trumps material, though I would use stainless with stainless barrels and carbon with carbon barrels because it pleases me.
Andy
Cross Machine Tool description;
The Just A Gasblock -.750" I.D. Is a Low profile style AR15/10 gasblock compatible with all CMT UHPR™series rails along with many other rail systems.
* Includes 2 each U.S.A.made set screws for attaching to barrel, not soft imported screws commonly found on lessor gasblocks.
* U.S.A. made Gas tube roll pin included
* Manufactured from U.S.A. Stressproof steel
* Black Nitride finished for superior wear & corrosion protection
* Weight- 1.3 oz.
* Everything is Made in the USA!
SOLGW says 4140 Chrome Molly
ALG says carbon steel
BCM doesn't say
Centurion says carbon steel
As long as its similar to the barrel steel (4140 for example), i cant see it matter at all.
Its not a wear part.
...Its not a wear part.
It is if it's aluminum!
I would want the gas block to be the same or at least similar to the barrel steel so that the 2 metals don't expand at different rates. Different metals have different heat capacities and other thermodynamic properties. Never thought about gas block material until now tbh.
The gas block is a really low stress item. You almost could make one from aluminum, if that aluminum was 7075, almost.
The front sight for the M16/M4 is made from 1137 carbon steel. It has a yield strength of 80 to 90 KSI, and hardened to RHc 26-32.
It is not anywhere near barrel steel, and it doesn't have to be. It sees the same pressure the little stainless steel gas tube sees but is this huge chunk of steel. The act of torquing the gas block on the barrel by set screws, or the act of clamping it on probably puts more stress in it that actually firing the gun.
I would want the gas block to be the same or at least similar to the barrel steel so that the 2 metals don't expand at different rates. Different metals have different heat capacities and other thermodynamic properties. Never thought about gas block material until now tbh.
All steel has the same coefficient of expansion, at least to the practical level.
The gas block is a really low stress item. You almost could make one from aluminum, if that aluminum was 7075, almost.
The front sight for the M16/M4 is made from 1137 carbon steel. It has a yield strength of 80 to 90 KSI, and hardened to RHc 26-32.
It is not anywhere near barrel steel, and it doesn't have to be. It sees the same pressure the little stainless steel gas tube sees but is this huge chunk of steel. The act of torquing the gas block on the barrel by set screws, or the act of clamping it on probably puts more stress in it that actually firing the gun.
Thanks for sharing your expertise and knowledge. Much appreciated!
~Snip
* Manufactured from U.S.A. Stressproof steel
~ Snip
If what I said seemed like a slight, I assure you it was not. I assumed that you were repeating a description from a vendor.
The 5 you named (CMT, SOLGW, ALG, BCM, Centurion) are all quality and between them, I would pick the least expensive GB with the features I am looking for.
I am glad you started this thread - I did not know stainless and carbon steel had nearly identical expansion characteristics.
Andy
It is if it's aluminum!
Lol, yes. Like I said... similar to barrel steel. Al is a no go for a few reasons... wear, thermal expansion, there may be more Im not thinking of right now.
What about titanium?
From V7 Weapon Systems website : CONSTRUCTED FROM GRADE 5 TITANIUM
THREE SET SCREW DESIGN
SOCKET SET SCREWS INCLUDED. FEATURING A KNURLED TIP DESIGN FOR A MORE SECURE HOLD.
AVAILABLE IN SATIN TITANIUM FINISH OR DLC BLACK
CORROSION RESISTANT
APPROX. 45% LIGHTER THAN A STANDARD LO-PRO GAS BLOCK
LIFETIME WARRANTY
NOTE: TITANIUM'S THERMAL EXPANSION COEFFICIENT IS ABOUT HALF THAT OF STEEL.
THIS GIVES THE ADDED ADVANTAGE OF A TIGHTER SEAL AND MORE SECURE FIT AS THE TEMPERATURE RISES.
The gas block is a really low stress item. You almost could make one from aluminum, if that aluminum was 7075, almost.
The front sight for the M16/M4 is made from 1137 carbon steel. It has a yield strength of 80 to 90 KSI, and hardened to RHc 26-32.
It is not anywhere near barrel steel, and it doesn't have to be. It sees the same pressure the little stainless steel gas tube sees but is this huge chunk of steel. The act of torquing the gas block on the barrel by set screws, or the act of clamping it on probably puts more stress in it that actually firing the gun.
Does this mean its unnecessary to pin low profile gas blocks if properly installed (dimple barrel and use the correct loctite) since they are a low stress part?
Does this mean its unnecessary to pin low profile gas blocks if properly installed (dimple barrel and use the correct loctite) since they are a low stress part?
Ask yourself - other than recoil, what is trying to move your gas block around?
If properly torqued and setscrew staked, the gas block isn't going anywhere.
The clamp-on type has no easy way to ensure the screws don't move.
Ask yourself - other than recoil, what is trying to move your gas block around?
If properly torqued and setscrew staked, the gas block isn't going anywhere.
The clamp-on type has no easy way to ensure the screws don't move.
What is the proper torque for gas block set screws?
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