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+--- Thread: 6.5G & Gas Blockd (/showthread.php?tid=21248)
6.5G & Gas Blockd - bob4432 - 05-15-2020
Anybody have any repeatable data that shows any consistent accuracy issue that has occurred occur when using a adj gas block that it attached via set screws on the bottom of the barrel?
FWIW, the barrel will be a quality unit, depending on current availability so thinking 10.5" - 12.5" hoping for something like a Lilja but depending on stock, but would settle for BAHanson and I plan to do this on all the pistol calibers I build - thinking 3 off the start.
Also, since I would hopefully be hitting paper and steel and not people, that is my situation. They would obviously need to be of the utmost accuracy, followed by accuracy.
Last but by no means last at all, I plant to be running a ML LAT LaTue on all the builds, unless somebody can show me a better M-LOK rail in the areas of quality, strength of material and third - price per $. I don't mind spending extra $ if the extra $ translates to something of incredible value that basically is a no brainier.
Appreciate your time (I know the Lat has laser engraved M-LOCK & LOAD) which at that time I could request an "in the white" rail and have itself anodized and laser engraved with w,/ itself what is shows on the pic (or better yet, have LaTrue Tactical in the state of AZ, wonder how Mark would go for that, of course anything I did would of course have Mr. LaRue's sticker on it, wouldnt want to piss him off.
Again, appreciate your time,
Bob
6.5G & Gas Blockd - FRB6.5 - 05-15-2020
Love to see definitive "proof" of that as well. IMO it is largely an exaggeration of something that is possible with poor assembly practices, not a guaranteed outcome.
Properly dimple it (or buy a barrel pre-dimpled) and assemble with proper torque (using a inch pound torque wrench) and some Rocksett or a proper high-temp, low to medium strength threadlocker.
LaRue, KAC, Giesele, BCM, DD, Wilson Combat etc. All use set screw blocks. DD, Giesele, BA take it a step further and use a cross pin as well. JP is the only high end rifle I can think of off top of head with a clamp on gas block.
As to getting an in the white LaRue rail I doubt it. They are usually OK with customizing orders with parts they already offer, but they won't change manufacturing process for one item. Just mask off a window around it and hit it with several coats of paint or paint the whole rail if going for a different color. I do agree they should just put their logo and the length on it, the moniker is silly looking.
You will also have difficulty assembling a LaRue hand guard with anything other than a non adjustable micro gas block (BCM, BA, LaRue, Bootleg, Vltor I've used), anything larger width or height wise will not pass through the back. There is a video in another thread showing an adjustable set screw block being used and how fiddly it was to do. A clamp on will be even more difficult.
6.5G & Gas Blockd - lazyengineer - 05-15-2020
In my experience, it's an irrelevancy regarding impact on accuracy. For the grouping data I've scientifically gathered and cross-examined, gas-block; fixed or variable, had zero effect on group-sizes - for me at least. For good practice, I always offset it off the shoulder by the thickness of a dollar, so that it doesn't have variable force against the shoulder as things heat up, but I haven't actually seen that make a difference.
If you way over-torque the screws, I suppose it's possible for some force-balance or even deformation into the bore, but again, I doubt that actually applies in all but the most extreme cases.
That said, I did find it interesting that Alexander Arms in their earlier generation design barrel I bought during their quite-attractive sale a few months ago, uses an extra-thick barrel diameter under the gas block. No one else does this, and it does require their own non-standard sized gas-block, but the design concept was there's a lot more metal there to absorb any weird torque, etc. I like that. FWIW, that 1/9 twist 20" Grendel barrel is the only Grendel barrel I've been able to make really shoot well; as it's an older AA Barrel when Bill Alexander threw away all the conventional dimensions, and built a barrel with non-standard thread, non-standard gas-block, and non-standard twist rate; as he found that to be optimal for Grendel during his development. As it turns out, that barrel shoots like a dream. Most barrels now have drifted back to conventional faster 1/8 twist, 5/8" threads, and standard gas-blocks. I've never been able to make any of those sing as well as Alexander's.
Just my own experiences flavored with my own bias'. That said, you will find plenty of others with more experience than me, who've had great luck with other more standard barrels with more standard sized gas-blocks. And pretty much anything LRRPF52 (and others like KLEM and LR1955) says, take to the bank, as he sort of wrote the book and fired more rounds than anyone short of Bill Alexander himself I imagine.
But to your original question, no, in my experience gas-block has very little affect on accuracy. I suppose if it's variable, and you vary it, that might change something from different settings, but inherently when dialed in and locked down to any particular setting, I haven't found any difference. I also haven't found any need for it, either.
6.5G & Gas Blockd - bob4432 - 05-15-2020
What brought me to the table of thought was that Mark says many of his barrels will do 5 holes in ½ and so i kept reading (½MOA easily makes me the weak link regardless of anything's else, but this time I kept reading and noted the barrels are either dimpled or flat), thus the question, and I received a 16 BA "Hanson" barrel, that, as another has pointed out has the cross pin & I have an early SLR dimple jig (new ones have more option than the one I have
I think I only have .400 & .450", but a new jig is hardly a price to pay to get the system as close to mechanically accurate out to 600yds as I can, but I know the 6.5Grendel has another ~250- ~300yds in it @ my altiyude.
I don't want the rail "in the white" (I am not a machinist, so the nonencluture may be off, but the person that would be doing this for me has the necessary background and college degrees, & has done work for some of the other manf listed above) or have the LaRue Team do anything to create any additional work. I meant to say just remove it from the machine, remove any cutting fluid as I can get the piece "into the white" where it is prepped and ready for the anodizing process (don't even care about sharp edges, can take care of all of it), and I have access to a laser engraver to put Mark's appropriate grapghics back (putting the LaRue Tactical logo in a state of AZ outline was just a joke, unless Mr. LaRue wouldn't mind)?
Also noted how thick the ~11.5" Alexander Arms barrel is.
I would really like LaRue to put out a 6.5Grendel in ~10"-12.5. I would think Mark could beat Alexander Arms prices too boot? Maybe? Or if I am stepping on toes I will back off.
Appreciate the info all,
Bob. Maybe I will send LaRue Tactica a letter and see if somebody can put together a LAT w/ all the parts that come with the kit and the just grab a rail wherever it is technically finished being machined and I can get the rest taken care of (company I would be dealing with is up-to-date ISO & AS certified, so it is not like I am going to anodized this in a backyard anodize kit (while they do fit their purpose, I know I would be getting the same level of finish (no disrespect, this is science and the place I have access to keeps their anodize tanks to a very high standard as that is what the customer sees first as they usually do not have the equipment to measure to the accuracy that companies that do this for their life)
Again,
Appreciate the time,
Bob
6.5G & Gas Blockd - FRB6.5 - 05-15-2020
A 12" LaRue Grendel barrel has been requested for years on their forums. Hopefully someday he does it.
IMO I'd just use the BA provided gas block on the Hansen barrel, it will work fine with the LaRue guard. If the reason for adjustable gas is a suppressor you will likely be happier with a Bootleg adjustable carrier, much easier to access and adjust.