P94s Accuracy mission

Discussion in 'Sako Rimfires and Small Action Rifles' started by Boris, Feb 14, 2016.

  1. Boris

    Boris Member

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    Hi Sako Lovers!

    As I said in my introduction on the New Members Forum, last year I bought a second hand P94s Hunter. I did this because I am partial to Sakos in general, and because I had read all sorts of good reports about the accuracy of the P94s and how they had been popular with Benchresters in the 90s. Guess I was thinking a bit retro. I had in mind using it for friendly club level sporter class Benchrest competition. The basic rules are: standard factory barrel, standard factory stock, max 6x scope, max weight 3.515kg ( 7 lbs 12 Oz). Based on all the good reports I thought it may have a chance of being competitive, but though it has shown glimmers of hope, so far it has not approached that level.

    As a baseline, with all shooting at 50m, so far I have tried:


    10 different types of ammo, mostly mid to high end target types.

    10 different rest positions on the fore-end.

    5 different action screw torque settings from 2 Nm to 3.4Nm.

    Average group size over 42 groups at the moment is 0.658" with a SD of 0.177.
    The best average group size with a single ammo type with more than 5 groups on record is 0.56” for R50SC which is unfortunately reported to be going out of availability.

    Now I am going to offer some somewhat random thought bubbles and observations and we shall see where that leads us.

    Observation 1

    I was looking at the crown through a loupe the other day as one of the prime suspects needing checking. It seemed OK. During the process I discovered a rather neat trick. If you put something white down the barrel just past the area you want to inspect, then light will be reflected back up toward you giving better contrast. In this case I put a cotton bud about 20mm down from the crown. On inspecting the bore I noticed 5 small bumps just down from the muzzle. See photo.
    20160126_091014b.jpg
    My initial thinking on this includes:
    • Given the rules require a factory barrel, I can’t cut and re-crown the barrel to remove them.
    • Lapping them out would enlarge the rest of the muzzle enough to be a challenge to accuracy.
    • I could try to buy a second hand factory barrel, but the chances of buying a really good one second hand would be low.
    I’d be very interested if some experienced hands could share their thoughts. How bad is this? What are the chances this barrel can be made to shoot with bumps intact?
    Observation 2 will be about the trigger and is coming next.

    Regards
    B.
     

  2. South Pender

    South Pender Well-Known Member

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    I don't know whether this will help, Boris, but a number of years ago, I worked on getting my P94S HB to shoot and did several things that made it an excellent shooter. (1) I pillar-bedded it; (2) I had a Jewell trigger installed, and (3) I had the barrel set back and a new match chamber (Win. 52D) cut. Now, maybe (2) and (3) or all three are out for you, given the rules, so I don't know whether this information is helpful. Installing the Jewell trigger was a fairly big job, but my gunsmith is an accomplished metalsmith and was able to get it done.

    The rifle, in its original condition, was only a fair shooter: .40"-.50" 5-shot 50-yard groups with its favorite ammunition (Lapua Midas+). After rechambering--albeit with the original barrel--it became a .30" shooter again with its favorite ammunition and a good scope.
     
  3. Boris

    Boris Member

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    Thanks for your encouragement South Pender. I’ll hope to make some noticeable improvements too. Sorry it has taken a while to get back. My ponderings will mostly be at weekends.

    I have been looking at the trigger. It needs to be lighter for Bench work.

    There does not seem to be much discussion on the P94s trigger relative to say the CZ 452. (Any suggested links appreciated.)

    I noticed that the set screw for the trigger spring was set up so that it hit the stock long before it could fall out and that while being fail safe, restricted the amount one could wind preload off the spring. One could of course relieve the stock, but I went to a bolt specialist and bought two shorter screws to give myself some options. See photo below
    20151212_070130screws.jpg
    I notice that even when the trigger spring was removed altogether there was considerable weight on the trigger. Looking at the geometry of the trigger group, I wonder if the weight of the trigger release is also inversely related to the strength of the sear spring. It seems to be countering the firing pin spring. Are there any trigger experts willing to chime in on that? I think finding a heavier sear spring may be quite difficult as it is rather small, having to fit in a 3mm dia hole.
    B.
     
  4. Boris

    Boris Member

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    Observation 3

    By chance when I dismantled the trigger I placed the components on a magnetic tray designed to reduce loss of small bits and pieces. The sear and trigger became magnetised with opposite poles and now hold on to each other. If you have felt the way magnets hold and release, you may appreciate how this has given an additional classic ‘glass rod breaking” feel to the trigger. This was all totally accidental and possibly not even reproducible. :) I would still like to achieve a lighter weight for the bench.
    B.
     
  5. Boris

    Boris Member

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    Observation 4

    I took the safety out of the trigger group to have a look and probably like most people who have tried that, ruined the sear spring in the process. Does anyone know of a source for the genuine springs? I read on a forum that I can no longer find – I think it was here – that someone had come up with the brilliant idea of placing a ball bearing on top of the sear spring so the safety lever could be withdrawn without damaging the spring. As I said, it sounded like a great idea, so I went to some trouble to find a 3mm ball bearing to suit the task. Well, several just in case. :)

    Try as I might, I could not find a way to install the spring and safety with the ball in place on top of the spring. The spring kept bending sideways and the ball popped out. How did you do it? Eventually I replaced the ball bearing with a short length of modified bullet head nail. See photo below.
    20151212_062610Nail.jpg
    The shaft held the spring straight and I got things back together. I haven’t tested it, but I think the safety lever will be able to be removed without further damage to the sear spring. You need to make sure the length of the nail will not inhibit the necessary compression range of the spring to below the shaft of the safety lever.

    There must be a trick to removing a installing the safety lever from the trigger group. I haven’t found it yet, so I have muddled through.


    Well, hope there is some food for thought and comment.

    Cheers

    B.
     
  6. dodgyrog

    dodgyrog Well-Known Member

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    I have found that the Tikka T3 trigger fits the P94 very well - I fitted a Gant one to my Range but had to cut the safety off. Not a problem for target shooting.
     
  7. Boris

    Boris Member

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    Thanks for the tip dodgyrog. I'll do some research on the possibilities that presents. There may be a few options.
    all the best.
    B.
     
  8. Amleto63

    Amleto63 Member

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    Boris,
    I grabbed as well a used Finnfire P94S Hunter, mint conditions, same purposes (BR22 Production category, @50 meters, front rest only, 6.5x max. magnification). My goal is getting a consistant minimum 245/250 score.
    Scope is a Nikon Monarch 3 6-24x50 Fine Crosshair

    First I replaced the factory trigger spring with a cheap pen lighter spring and put some lithium grease between sear and hammer engagement. Currently my trigger safety breaks @ around 300 grams. A friend of mine will do a complete trigger job later, adding a third leverage and removing the safety in order to break at 100 grams.

    Action screw are torqued @ 4.5Nm

    First test with Lapua Center-X was good (246/250) but I need to improve as the rifle is very light and difficult to hold and keep my position.

    I would like to add pillars and bedding it but difficult finding some DIY pictures on the web.
     
  9. Amleto63

    Amleto63 Member

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    Would you please post some more info/pictures on your pillar bedding job? Thanks
     

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