788 barrel threads

Discussion in 'Advanced Gunsmithing & Engineering' started by okie, Jan 14, 2009.

  1. okie

    okie Gold $$ Contributor

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    Is a 788 barrel threaded the same as a 700? It looks as if the 788 has no real shoulder?? Reason being I've got a 788 that has a really bad bore and plenty of take off 700 bbls are easy to find. I know it would need to be headspaced properly ---would it require a lot of lathe work? I don't really want to put an expensive custom barrel on a 788. thanks in advance, marc
     
  2. Ackman

    Ackman

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    It works fine.....788 threads are the same as a 700 -16 per inch - only 1"dia. Just turn the 700 shank to 1.00" and recut the threads. The 788 action has a longer threaded portion and a thicker recoil lug, so the shoulder will be further forward. But that's it. My 788 has 700 sporter barrel and it shoots very well.
     
  3. GerryM

    GerryM

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    ackman are you sure about that?
    I don't have my thread gauges yet but i do have a take off barrel. The 788 threads look finer. I also noticed that the 788 is flat on the back . {no recess for the bolt like the 700}
     
  4. Ackman

    Ackman

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    Gerry, mine was done nearly 20yrs ago. But if memory serves, the thread pitch is the same. However, when you turn the shank to 1.00" they're either completely gone or almost completely gone anyway so it doesn't matter. And the 788 has no recess which will make things easier. It's a very practical solution to rebarrelling the 788.
     
  5. okie

    okie Gold $$ Contributor

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    thanks for the info guys
     
  6. Cheechako

    Cheechako

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    I believe the 788 has a tenon .995" major and 20 TPI. The 1" tenon diameter will probably work if the minor of the existing thread is not a lot less than .995" But not the 16 TPI of the M700. The bolt nose counter bore will also have to be removed which could mean a need to re-cut the chamber. An easy job for someone who knows what they're doing but necessarily one for a novice.

    Ray
     
  7. LHSmith

    LHSmith

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    I am not a machinist...but is it a good practice to set back a factory takeoff barrel,particularly a sporter weight). ....this usually results in a net bbl O.D. somewhere around .75" to .87" in the shoulder area...and depending on the size of a particular rounds chamber.....there's not too much steel there to contain the explosion. Just wondering ?
     
  8. Ackman

    Ackman

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    It's been a long time since I messed with this but yes, the 20TPI sounds right. Even so, people are making too big a deal out of this. I have a bunch of takeoff 700/722 barrels sitting around. Threads aren't all the same. Major thread dia. varies from 1.057"-1.064"....that's .007". Minor dia. is .993-.998". Thread depth isn't the same either....and the largest thread actually has the smallest minor dia. Go figure. Turn them down to 1.00" and even with that smallest minor dia, you'd have a non-concurrent groove only .0035" deep, which is very very shallow. Even if you take it down to where the whole thread is gone and cut new ones to the correct depth.....if the major dia. is 3-1/2 thousandths small - if the top of each thread has a very tiny flat - it's meaningless. You needn't get too carried away worrying about this stuff.

    That counterbore is just to enclose the Rem. bolt snout. Flush it off and a case extends out to where the extractor groove is exposed, same as any other non-counterbored barrel. Factory chambers are very generous and shortening the barrel enough to cut a new tighter one is a good idea. My barrel is a 700 sporter and the whole thread was cut off. Shoulder dia. in front of the lug is 1.095" and it's fine. The gun is a .223 with very minimal non-turned neck chamber.

    If you're wondering about barrel dia......the T/C Contender is chambered for .223 cased rounds. Also some larger, lower pressure cartridges. Those barrels are .815" dia. at the breech.

    I'd also strongly recommend buying your own reamer. Measure the brass and have it done to minimal spec's. With a decent barrel the gun will shoot very well.
     
  9. okie

    okie Gold $$ Contributor

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    thanks again---I'll have a professional rebarrel it.
     
  10. Cheechako

    Cheechako

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    okie

    You've made a good decision.

    I agree with Ackman that changing a 700 barrel to fit a 788 action is a fairly straightforward job, one that he or I could do in an afternoon. But it's not something that I would recommend for someone who has never done a barrel fitting and/or chambering job before. Knowing all of the little things that can lead to trouble takes experience to learn.

    Good luck with your project.

    Ray
     
  11. GerryM

    GerryM

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    I only stuck my nose in for 1 reason. Some people think you can just screw on one barrel from any other remington and it will fit. The 20 threads is the issue. Try running a 16tpi threaad into an action that needs 20 tpi and you have a mess
    You made a wise choice taking it to a smith.
     
  12. 1oldbullshooter

    1oldbullshooter

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    Every where I go I run into this guy named "Ackman".....:D
     
  13. JayIdaho

    JayIdaho

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    The 788 has a 1"-20 thread. The 700 family has a 1 1/16-16 thread.
    The correct way to measure a thread is to measure the PITCH DIAMETER. The theoretical major diameter of the thread is ALWAYS smaller than the stated diameter, if the thread is correct. The Machinery's Handbook has a very good section on threads and thread specifications.
    The best way for most of us to measure the pitch diameter of a male thread is with THREAD WIRES. They are about $10 for an Import set. Kind of tricky to learn to use but will give you accurate measurement. I also use thread micrometers but they are expensive,got mine on Ebay). They are especially handy for the extra-fine threads used on muzzle brakes.
    Frank deHass was probably the biggest butcher of thread specifications to ever have his misinformation in print. He simply measured the o.d. of a barrel thread and put that in his books. That was wrong but it is all history.
    Those with experience should strive to give good, accurate information to those that are below them in skill level.

    Jay, Idaho
     
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  14. William T Mullenberg

    William T Mullenberg

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    If the Savage barrel is 1" 20TPI how hard would it be to use it in a 788? Could the Barrel nut be retained?
     
  15. SBS

    SBS Gold $$ Contributor

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    Savage small shank barrels are 1 1/16-20. While you could alter it to 1-20 and use a barrel nut, I don't know of any barrel nuts on the market with that thread, maybe there are??
     
  16. Shawnba67

    Shawnba67 Silver $$ Contributor

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    The threaded portion of a 788 is 1.54" long. There would not be any meat left for the nut.
    Turning down a 700 barrel is a option, not ideal though
     
  17. Ggmac

    Ggmac

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    Da ! This post is 9 yrs old start a new one . Or not .
    If you have the experience and tooling you can use a Rem 700 turned down and threaded and chambered , NOT WORTH IT ! Unless it's just for giggles . Savages will PROBABLY not have enough meat on the barrel for a barrel nut , if you could find one or for a substantial shoulder .
    788s are great older actions , were once coveted for silhouette and BENCHREST . Quick lock time , rigid receiver etc . Have many and it would be worth your $ for installing a good barrel .
     
    Last edited: Jun 12, 2018
  18. William T Mullenberg

    William T Mullenberg

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    My son and cousin both have 22-250's with 6-18 Leopold scopes that were deadly for 15 years now they're 1.25" at 100yds . The local gun smith say why spend 350 bucks on 300 dollar gun and offered to sell me his old shot out 308 for $175. Now we have three.
     
  19. Ggmac

    Ggmac

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    Collectors are paying good $ for certain models . The 30-30 44 mag and 222 are some of the favorites. I personally like the 222 and 6mm .
    Definately a rifle worthy of a good rebarrel , even if e r shaw , for a varmits / hunting rig
     
  20. SBS

    SBS Gold $$ Contributor

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    I realize the point is moot since 1"-20 nuts are not available, But,,, a savage sporter small shank barrel rethreaded would work. At 1.555" from breech end, the barrel diameter is 1.040 -- larger than the 1" OD thread diameter needed for the 788.
     

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