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Thread: sound moderator bore vs calibre success

  1. #1

    sound moderator bore vs calibre success

    not sure if this is the best section but here goes.

    I have an overbarrel PES moderator that I purchased at vast expense some years ago for use on a Sako Quad on a variety of rimfire rounds from .17M2 to .22WMR. works like a charm

    As I am in the market for a .243 I had the idea in the back of my mind that when I bought it he said it would go up to .2xx calibre but couldn't remember the xx part and assuemed it would be 223/222/22-250 etc!

    Quick call to Steve Kershaw who sold it to me and it appears I am in possession of a 7mm (.2755) bored moderator! (quick check with a 7mm drill bit shows that it can be nothing else)
    Not only is he very confident that it will work on the .243 it may even work better than the 7.5 or 8mm bored(.30 cal) moderators often used due to the smaller bore!
    Apparently .83mm or .0325 clearance is perfectly fine (and have just read about a chap who used an 8mm bored mod with a .308......0.006" clearance!!! bit close for me!)

    I need a new delrin spacer for the over barrel part cut to the barrel diameter of 243 and to get it checked over for concentricity / 90 deg shoulders etc but that is pennies compared to a new mod!

    Think I have just saved myself 200+

    Now I started thinking.
    My FAC lists a "small bore" moderator when it appears I have a "full bore" moderator.
    apart from the ridiculous situation that allowed me to buy it in the first place I technically have something incorrect on my FAC.

    L&B FLO were very helpful and all I have to do is write in and explain what I have and what it should read.
    I also will have no restriction to using it solely on the 243 once swapped to FB status.

    One size it appears does fit all!!

  2. #2
    Had my wrist slapped recently because in 2007 i bought a .243 rifle and a full bore mod for said rifle. Only when i sold the riflee and mod this year did they tell me i had no rightt to possess a mod up to..30 cal as my ticket said ..243. After explaining that i could not buy a specific .243 mod they said they would let me off this time.

    Sorry for speeling and spaces on new touch screeen tablet thing.. lets just say wee dont get on thawt well

    Regards pj

  3. #3
    so....how exactly does one check if the moderator is
    a) fitted perfectly parallel to the bore
    b) large enough bore to accomodate 90gn of lead and copper at 3000+fps!?

    looking down the barrel is pretty tricky to clearly see if there is a less than 5 thousands of an inch obstruction!
    its fitted and looks fine to my eye when veiwed from the breech but part of me says there must be more to it than having a good look and putting a round "through" it!

    was thinking of having a metal rod of 243 calibre machined, something like brass. if enough was inserted into the muzzle and the rod was true (i.e. perfectly straight) then it would clear the moderator bore equally on all sides if mounted centrally.

    any thoughts?

  4. #4
    Quote Originally Posted by bewsher500 View Post
    so....how exactly does one check if the moderator is
    a) fitted perfectly parallel to the bore
    b) large enough bore to accomodate 90gn of lead and copper at 3000+fps!?

    looking down the barrel is pretty tricky to clearly see if there is a less than 5 thousands of an inch obstruction!
    its fitted and looks fine to my eye when veiwed from the breech but part of me says there must be more to it than having a good look and putting a round "through" it!

    was thinking of having a metal rod of 243 calibre machined, something like brass. if enough was inserted into the muzzle and the rod was true (i.e. perfectly straight) then it would clear the moderator bore equally on all sides if mounted centrally.

    any thoughts?
    Clean the bore then look down the barrel you will quickly see if there is a misalignment by a shadow at the muzzle end.

  5. #5
    I once acquired a .22LR with a moderator (small bore), but had no permission for the mod on the FAC,,nor did I realise I needed permission separately for a mod...RFD sold it no probs...only when it came to sell it again was the issue flagged up with the FLO, who to say the least, was NOT all that pleased. The RFD nearly lost their license...I was ok though, just a misunderstanding of the rules, but they were pretty tough of the RFD who let the mod go, and who didn't point out the rules to me at the point of sale. oops..

  6. #6
    Quote Originally Posted by pj1 View Post
    they said they would let me off this time.
    Police speak for "we don't want to pursue this issue because we aren't certain that you have done anything wrong"....

  7. #7
    Quote Originally Posted by j0e_bl0ggs View Post
    Clean the bore then look down the barrel you will quickly see if there is a misalignment by a shadow at the muzzle end.
    thats my problem, with a 20-22" barrel a wafer thin shadow is (almost) impossible to see but could still be an issue.

    I found a long allen key that fit the bore perfectly and follow the rifling and it is closer to one side of the mod bore than the other but then I am not convinced it is not sitting on the land on one side and the true bore on the other side making it squint.

  8. #8
    Why not insert the correct sized cleaning rod, if you have a short one pop it in through the end of the can.
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

  9. #9
    it would need to be the correct size of the bore from can muzzle all the way down into the bore to avoid any angles in the rod.

    I think I need a 243 sized rod in some material. Delrin would do I reckon

  10. #10
    Quote Originally Posted by bewsher500 View Post
    it would need to be the correct size of the bore from can muzzle all the way down into the bore to avoid any angles in the rod.

    I think I need a 243 sized rod in some material. Delrin would do I reckon
    delrin is too flexible
    as for the cleanig rod....jeeze!

    oh and if your barrel is 'choked'?
    Last edited by j0e_bl0ggs; 05-07-2011 at 20:12.

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