.750 vs. .875 gas block? Barrel Performance?

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  • BenL

    John Galt Speaking.
    I've been shooting Heavy Metal Division this year for 3 gun. The Current barrel is the 16" RECON barrel that came on the DPMS; it's OK... cold, it's ~2 MOA barrel, but as it heats up, the groups open up. It only becomes a problem when there are longer shots (250 yards+) at the end of a stage. I was thinking about upgrading the barrel to a Shilen barrel- they are available in .750 and .875 diameter at the gas block.

    My question is this: will there much difference between .750 and .875, performance-wise? I know one will heat up/cool down slightly slower, but will they perform about the same, otherwise? I have a TJC Titan comp that's .750, but if the .875 will perform better, I'll just replace the comp.
     

    photoracer

    Competition Shooter
    Oct 22, 2010
    3,318
    West Virginia
    Well one is going to weight more. Are you OK with the weight of your rifle as is? Is either of the barrels fluted? If the only difference between the comps is the esthetics of matching the barrel diameter just use the one you have as the threads should be the same. I would go with the heavier barrel if I could handle the extra weight at the end of a COF, but at my age I prefer lighter. Either barrel may likely be more accurate than your current one.
     

    501st

    Ultimate Member
    Jun 16, 2011
    1,627
    I've been shooting Heavy Metal Division this year for 3 gun. The Current barrel is the 16" RECON barrel that came on the DPMS; it's OK... cold, it's ~2 MOA barrel, but as it heats up, the groups open up. It only becomes a problem when there are longer shots (250 yards+) at the end of a stage. I was thinking about upgrading the barrel to a Shilen barrel- they are available in .750 and .875 diameter at the gas block.

    My question is this: will there much difference between .750 and .875, performance-wise? I know one will heat up/cool down slightly slower, but will they perform about the same, otherwise? I have a TJC Titan comp that's .750, but if the .875 will perform better, I'll just replace the comp.

    So you are comparing a chrome lined barrel to a high end stainless or carbon steel barrel? At this point diameter isn't going to matter unless you are doing mag dumps. (which would be stupid with a match barrel)

    Get the .750 diameter barrel. (or whichever is cheaper) Coming from a dpms barrel it is almost impossible that you will not be satisfied with either shilen.

    And fyi, making multiple threads in different sections is unnecessary at best and rather annoying at worst.
     

    BenL

    John Galt Speaking.
    I've been shooting Heavy Metal Division this year for 3 gun. The Current barrel is the 16" RECON barrel that came on the DPMS; it's OK... cold, it's ~2 MOA barrel, but as it heats up, the groups open up. It only becomes a problem when there are longer shots (250 yards+) at the end of a stage. I was thinking about upgrading the barrel to a Shilen barrel- they are available in .750 and .875 diameter at the gas block.

    My question is this: will there much difference between .750 and .875, performance-wise? I know one will heat up/cool down slightly slower, but will they perform about the same, otherwise? I have a TJC Titan comp that's .750, but if the .875 will perform better, I'll just replace the comp.

    ^ Read.
     

    BenL

    John Galt Speaking.
    Well one is going to weight more. Are you OK with the weight of your rifle as is? Is either of the barrels fluted? If the only difference between the comps is the esthetics of matching the barrel diameter just use the one you have as the threads should be the same. I would go with the heavier barrel if I could handle the extra weight at the end of a COF, but at my age I prefer lighter. Either barrel may likely be more accurate than your current one.

    Thanks PR. I'm sticking with 16" because it feels "faster". I would hope a Shilen barrel would be more accurate.

    I'm leaning toward the heavier barrel in hopes that it can handle the longer strings better.

    Sent from my SAMSUNG-SM-N910A using Tapatalk
     

    501st

    Ultimate Member
    Jun 16, 2011
    1,627

    Thanks PR. I'm sticking with 16" because it feels "faster". I would hope a Shilen barrel would be more accurate.

    I'm leaning toward the heavier barrel in hopes that it can handle the longer strings better.

    Sent from my SAMSUNG-SM-N910A using Tapatalk

    Yes, I read all the posts. If you can deal with the extra weight, get the .875. If not, then the .750.

    You not making things clearer by not stating the number of shots/time duration of your "strings".
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    The attachment method can also effect accuracy as well, so can the material of the gas block.

    Aluminum is a terrible material for gas blocks due to the very ing rates aluminum and steel heat and cool, it can lead to gas issues. Steel and titanium is the better material.

    As far as attachments methods go, the least amount of stress out on the gas block seat the better. Set screws and drilling and pinning can apply stress on the bore where a clamp on model won't if fit properly.

    I would also use about 20 ft# max and rocksett on the muzzle device, too much torque can apply stress on the last 1/2 of the rifling.

    IMO the thicker the barrel the better, but understand your limitations with maneuverability.
     

    BenL

    John Galt Speaking.
    The attachment method can also effect accuracy as well, so can the material of the gas block.

    Aluminum is a terrible material for gas blocks due to the very ing rates aluminum and steel heat and cool, it can lead to gas issues. Steel and titanium is the better material.

    As far as attachments methods go, the least amount of stress out on the gas block seat the better. Set screws and drilling and pinning can apply stress on the bore where a clamp on model won't if fit properly.

    I would also use about 20 ft# max and rocksett on the muzzle device, too much torque can apply stress on the last 1/2 of the rifling.

    IMO the thicker the barrel the better, but understand your limitations with maneuverability.

    OK. Thanks, Chad. I also think that clamp on GB is the way to go for this application (game gun.) Who's steel clamp on GB do you like?
     

    BenL

    John Galt Speaking.
    Buy a Krieger barrel, problem solved.

    Krieger, Shilen, Walther Lothar... all good barrel makers. Krieger's shortest barrel length is 20" for 308. For this application, I want a 16" barrel. Shilen's "ultra-match" grade (hand picked, best-of-the-best, tightest specs) is available in .750 and .875 in 16" without the wait.
     

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    OK. Thanks, Chad. I also think that clamp on GB is the way to go for this application (game gun.) Who's steel clamp on GB do you like?

    Any name brand unit will suffice. I prefer the clamp on SLR rifleworks adjustable models for an application like this. Tuning the gun will give you the lightest recoil impulse for the ammo you are using. Works almost as well as a brake.

    I also suggest you have a rail that covers the GB so when you do a barrel dump your GB isn't repeatedly struck.
     

    BenL

    John Galt Speaking.
    Any name brand unit will suffice. I prefer the clamp on SLR rifleworks adjustable models for an application like this. Tuning the gun will give you the lightest recoil impulse for the ammo you are using. Works almost as well as a brake.

    I also suggest you have a rail that covers the GB so when you do a barrel dump your GB isn't repeatedly struck.

    Thanks, I'll give them a look.

    The GB will be under cover :thumbsup: (I'm hard on guns. My Infinity is on it's 3rd front sight.)

    2015-06-20%2010.18.42_zpshrzfz1ul.jpg


    ETA:

    Winner.

    http://slrrifleworks.com/index.php?route=product/product&path=57&product_id=125
     
    Last edited:

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    Be forewarned, those adjustable SLR GBs are addictive and expensive. Before you k ow it ALL of your AR'S will have them.

    With the exception being the .50Beo. ;)

    Alexander Arms and their damned .906" gas block seat....
     

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    ...and don't forget the weird 49/64-20RH muzzle threading. :innocent0

    Thankfully mine wasn't threaded, bought the entry upper and just built it out to my preferences. :)

    Minus the gas-block, had to chop mine to sneak it in under the rail.
     

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