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Thread: 6.5 Grendel Group Buy Bolt 1/ Barrel Extension 0

  1. #21
    Warrior Kswhitetails's Avatar
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    Silicone RTV?

  2. #22
    Warrior Sticks's Avatar
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    Getting a good release agent on the bolt, chamber and extension might get a good mold, but then you would be doing very light manual measurements which will increase your +/- accuracy.

    I would do Paraffin wax before RTV
    Sticks

  3. #23
    Warrior Sticks's Avatar
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    Cut a case at the 1/3 mark or so, drill out the flash hole to the same bore as the firing pin, get a screw that will fit and affix the cut case to the ejector free bolt, then do your 90% casting and re-heat to flow back into the cut case.

    What are we measuring again?
    Sticks

  4. #24
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    When you lap the outer edge of the upper extension, the upper should be secured vertically ( LR..52 had an excellent discussion relating to this ). When doing this horizontally, the weight of the shaft of the tool causes some droop which then takes the griding face of the tool away from a plane perpendicular to the line of travel of the bolt. Looking at the pictures of the lugs on the bolt, there are marks on the near lugs from contact with the extension but none ( visible ) on the far lugs. This puts all the lock-up strain on a reduces number of lugs - and something has to give.
    I have been using the Wheeler tool on many builds. It is a simple, rotating tool and works quite well in this application. Any rotating tool will work equally well in this kind of application - you could even use suction cups as long as they are turrning at a reasonably fast rate and get the same results. The key is to keep the center of rotation and angle of rotation in-line with the travel of the bolt and perpendicular to that travel.

  5. #25
    Warrior The Profit Joseph Sith's Avatar
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    Im using hitechalloy's http://hitechalloys.com/hitechalloys_002.htm cerro safe they say to only use a light oil "non detergent" and that will fine for release. The cerro safe which ive used in the past shrink .0005" after cast and in hour is the exact same size. Only prob with that is grows after the hour.
    Im going to give cerro cast another try this weekend. It shrink .0001" and stays the same size throughout its life.

    So far i take a little PFTE tape and roll it around a dowel to the I.D. of the lugs in the extension and seat it all the way against the stub to create a wall to keep it out from under the lugs they might scrape a hair when removing but they come out just fine. Its great for throat, lands, neck and shoulder measurements. But id still like to take a full headspaced cast from the bolt back.

    I just realized... Silly putty!
    Last edited by The Profit Joseph Sith; 01-11-2018 at 03:41 PM.

  6. #26
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    Quote Originally Posted by just_john View Post
    When you lap the outer edge of the upper extension, the upper should be secured vertically ( LR..52 had an excellent discussion relating to this ). When doing this horizontally, the weight of the shaft of the tool causes some droop which then takes the griding face of the tool away from a plane perpendicular to the line of travel of the bolt. Looking at the pictures of the lugs on the bolt, there are marks on the near lugs from contact with the extension but none ( visible ) on the far lugs. This puts all the lock-up strain on a reduces number of lugs - and something has to give.
    I have been using the Wheeler tool on many builds. It is a simple, rotating tool and works quite well in this application. Any rotating tool will work equally well in this kind of application - you could even use suction cups as long as they are turrning at a reasonably fast rate and get the same results. The key is to keep the center of rotation and angle of rotation in-line with the travel of the bolt and perpendicular to that travel.
    Hind sight is so clear.....of course that makes total sense to mount vertically!!! Use gravity (KISS Method, keep-it-simple-stupid) I do recall when lapping the finish for the receiver face working off on certain areas more then others first. I thought to myself "I sure am glad I lapped this receiver" Now.....maybe not so much. Operator error? My only reservation about assigning causality to receiver face being out of true from poor lapping is the manor in which the first bolt lug sheared. Following the "drooping" theory, wouldn't you expect more pressure at the top of barrel extension/bolt with those bolt lugs shearing first? If I recall my lug lower to the extractor went...Same goes for when extension went off??

  7. #27
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    Quote Originally Posted by brut28481 View Post
    Aren't 6.5 Grr & Creed interchangeable? It was hard to load but I just kept mashing the forward assist with a hammer......
    Uhhhhhh..... wut?

    There being 2 events, it may be hard to determine the true cause.

    Could have been the original bolt was somehow out of spec, leading to uneven wear on the bolt, on the extension's lug surfaces,... Amazing how fast replacing worn parts can trigger a system failure.

  8. #28
    Warrior The Profit Joseph Sith's Avatar
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    I check my uppers with a .0015" feeler gauge and the lapping tool to see if it was square before lapping i didn't want to mess with them if they were good. I tested 7 uppers in one sitting. Both AP slick sixe uppers were slightly out. Two of the four generic Brownells M4 uppers were spot on two were slightly out. (Side note) ALL six ejection port door rod holes were unfinished.. Couldn't believe it.. What are the odds? Luckily i have extended .1250" pilot bits.
    Hopefully my M4E1 uppers i just got yesterday are better. Although im slightly skeptical of the method it SHOULD result in trueness. Its relatively the same process as used in thousands of rebuilt engines. I DEFINITELY which i had a bed with bearings and a dial indicator to check the lapping tools squareness or run out before i used it.
    I really dont think its critical at all that the interface between the two is "perfect" although it wont hurt. There is some slop inherently or they would be to tight to function correctly. And a well made barrel has ALOT more to fo with accuracy results than a slight cant.
    Eager to find out any word on this.
    Just my $.02..

  9. #29
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    Spoke to Lilja yesterday, they still haven't had a chance to look at it.....

  10. #30
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    Like all great love stories the Ballad of the Lilja barrel extension explosion must come to an end. Lilja has decided to replace the barrel without commenting on the causality of the barrel extension destruction. At this juncture it is probably difficult to determine what the true root cause was. Operator error? Poor Gunsmithing? Hot loads? Like all great Mysteries, we shall never know. I'd like to comment on Lilja's response, they quickly reviewed the situation and without question replaced the barrel. They stand by their products and I think they're a great company! The only one true question remains, should I lap my new Mega upper?

  11. #31
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    Good to hear.
    And good on Lilja for not quibbling and making the quick decision to put the customer first.

  12. #32
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    On a side note, I just got the 130 rdf in and ladders loaded for the Creed. I sure hope this new lilja barrel like these 130s because these are some beauties!

  13. #33
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    Quote Originally Posted by brut28481 View Post
    On a side note, I just got the 130 rdf in and ladders loaded for the Creed. I sure hope this new lilja barrel like these 130s because these are some beauties!
    Going further off topic...Can you seat one in a grendel case at 2.260" and post the pic in the reloading forum? Curious to see where the ogive is at that length.

    Back on topic, I had a 24" Lilja .260 on a set of mega upper/lowers I built up years ago. That was one of the best shooting guns I had the pleasure of running. The lilja barrel was fantastic. Sold it shortly after the obama inauguration but wish I would have kept it. Couldn't say no to the offer though.

  14. #34
    Warrior StoneHendge's Avatar
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    Quote Originally Posted by brut28481 View Post
    On a side note, I just got the 130 rdf in and ladders loaded for the Creed. I sure hope this new lilja barrel like these 130s because these are some beauties!
    I be drooling. I've got too many projects to be sure I finish before I get to play with the 130 RDFs. Need to finish 6x45 upper and find a load so I have a bucketful for April P-Doggin. Need to find a 223 load also and make a bucket for a course in April.

    What sort of COAL do you have to the lands in the Creed?
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  15. #35
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    Quote Originally Posted by koden View Post
    Going further off topic...Can you seat one in a grendel case at 2.260" and post the pic in the reloading forum? Curious to see where the ogive is at that length.

    Back on topic, I had a 24" Lilja .260 on a set of mega upper/lowers I built up years ago. That was one of the best shooting guns I had the pleasure of running. The lilja barrel was fantastic. Sold it shortly after the obama inauguration but wish I would have kept it. Couldn't say no to the offer though.
    Did you lap the mega upper? Requested granted. Look at the 130 RDF thread

  16. #36
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    Quote Originally Posted by StoneHendge View Post
    I be drooling. I've got too many projects to be sure I finish before I get to play with the 130 RDFs. Need to finish 6x45 upper and find a load so I have a bucketful for April P-Doggin. Need to find a 223 load also and make a bucket for a course in April.

    What sort of COAL do you have to the lands in the Creed?
    My criterion barrel @ 0.04" off lands gives me COAL of 2.860. B-Ogive of 2.226. Running a ladder of 43.1 down to 41.9 H4350 tomorrow. Pics of the 130 RDF vs. the 130 Norma Golden Target. I also run the 105 RDF in my dasher.....
    Last edited by brut28481; 01-18-2018 at 01:16 AM.

  17. #37
    Chieftain Klem's Avatar
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    brut,

    I have a Mega upper with 65Gr Lilja barrel. I haven't tried to improve it because it doesn't need it. It fits and shoots perfectly.

    Mega Arms is a subsidiary of Mega Machine, based in Tumwater WA. They service the aerospace industry located around Seattle which is why their firearm products are so precise.

    You could always fit it and see how it shoots, then if not lap it. The idea of lapping every upper regardless just doesn't make sense to me.

  18. #38
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    Klem, it only takes a few moments to lap one, it takes weeks and a lot of ammo to realize that it needed it and then the better part of an hour to break an upper down to lap it. And then you have a whole new set of unknowns - the fit of all parts is never the same as before. I do this for the same reason I carry a spare tire in my truck - hope I never need it but having it and not needing it is always better than sitting on the side of the road wishing that I did have it.

  19. #39
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    Quote Originally Posted by brut28481 View Post
    Did you lap the mega upper?
    I bought the nickle boron coated ambidextrous matched upper/lower. Nothing I do to it would make it better than what their CNC machines did. I have a cheap upper that I should probably lap but nothing from Mega gets touched.

  20. #40
    Mega Machine was purchased by Zev and is no longer Mega.

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