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  #16  
Old 11-16-2008, 05:29 PM
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Biathlon Basic: Adjust Trigger Pull



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Biathlon Rifle Trigger Pull

The following threads will get you started:
BI 7-2 Trigger Modification & Stage 3 - Trigger Mechanism Adjustments and Modifications
BB Trigger Stop Anybody & Trigger Adjustment
Biathlon Basic Trigger Adjustments ... Trigger Modifications for Unadjustable Triggers
improvements modifications to the BB mechanics
Biathlon Basic trigger adjustment.
Can it be done and how do I do it?


Quote:
Yes the trigger pull weight can be adjusted heavier or lighter.



If you have the trigger group out you have to unhook spring #1
then you have to turn the bottom spring eye in to make the trigger pull
lighter, if you turn the eye out the trigger pull will be heavier.
Its all about spring tension Or friction. The fun part is hooking the spring
back up.

The pull weight is fine, but there is allot of take up.

True because its a two stage trigger. The 1st stage is the take up.
If you want to take away the 1st stag you have to drill the trigger bridge
& install a set screw 4-40 or 6-32.



Thats how I adjust the trigger on my BB.


Biathlon Basic Trigger Adjustment

This is from the factory manual - hope it helps.
While EAA was importing the Biathlon Basic,
some rifles were outfitted with an optional trigger.

The trigger the RAA rifles are fitted with
is different and is not externally adjustable.

The manufacturer states the trigger pull is set at the factory
and recommends the pull is not adjustable.

Optional Safety Biathlon 7-3 & 7-4

EAA Manual: Biathlon Bolt Action Rifle - Page 14



If Fuzzy ever finished this article in Fuzzy's Projects
it would be exactly what you're looking for - I think.
Izhmash Biathlon Basic Modifications
__________________
W. Edwards Deming ... Quality: It is not enough to do-your-best;
you must know what-to-do, and ... then ... do-your-best.
Ever-Onward ... Through the Fog ---- Fort Stockton TX 79735
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  #17  
Old 11-16-2008, 07:56 PM
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Trigger Over-Travel Adjustment.

Trigger over travel adjustment.- midwest swiss
Quote:








There thats all my trigger tricks I have done to my BB.
__________________
W. Edwards Deming ... Quality: It is not enough to do-your-best;
you must know what-to-do, and ... then ... do-your-best.
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  #18  
Old 11-16-2008, 08:15 PM
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BI-7-2 Trigger Retaining Pin, Hammer & Bolt

Trigger Retaining Pin - midwest swiss


Quote:
I will post a pic. of which pin to take out
& the trigger group will come out as an assembly.

Quote:
When you have the trigger group out you can
also adjust the trigger pull weight.

You just have to unhook the sear spring ,
turn the sear spring eye out to add more pull
or in to have a lighter pull.

I turned mine in 3 full turns to have a trigger pull of 14 oz.


Trigger Left-Hand Side - FuzzyLimy


Trigger Right-Hand Side - FuzzyLimy


Trigger Components - FuzzyLimy


Cocked Hammer


Bolt Assembly from the Underside

Quote:
... polishing should make are BB's operate
like a Swiss clock ..... Midwest Swiss
Biathlon Bolt Disassemby (Exerpted from Sobol Owners Manual)
__________________
W. Edwards Deming ... Quality: It is not enough to do-your-best;
you must know what-to-do, and ... then ... do-your-best.
Ever-Onward ... Through the Fog ---- Fort Stockton TX 79735

Last edited by aom22; 11-17-2008 at 01:37 PM. Reason: Add Link(s) & Images
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  #19  
Old 11-16-2008, 08:40 PM
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Bullet Feed and Bullet Shaving Problems

improvements/ modifications to the BB mechanics
Quote:
.... I am having to "drive" the rounds in with what seems to be too much effort...
BB mags ... Polymer Magazine Feed Problem: Bolt Shaving Bullet
Quote:
was indoor off the bench today and took time to note the angle of insertion
of the bullet into the breech and noted that the angle is too sharp.

The mag needs to be squeezed a bit to make the insertion angle shallower.

I could feel the top of the bullet being shaved with a slow bolt closure.
... Fuzzy Limey that explaines ... - midwest swiss
Quote:
Its not your magazines.

The bolt needs some fine tuning.

The BB in not a push feed system... its a controlled feed system.
Excerpted from Biathlon-7-3 & 7-4 Service Manual


... FuzzyLimy mentions a repair for this ... - Charlotte
Quote:
If you put a shell in a magazine, push down on the shell case
to get a feel for how hard the spring pushes back.

That is a "guide" for how much effort you should have to exert
to push a (spent) shell case into the pocket on the bolt face.

The outside claw/extractor is the primary thing you want to work on.

With my BB the primary issue was the claw reached inward
to the point that it was scoring or engraving the case.

I used a combination of a needle file
and either 400 or 600 grit wet dry sandpaper.

I relieved the sharp edge with a slight angle
which opened up the throat into the bolt face pocket
giving the shell an easier initial entrance into the pocket.

I had to relieve the underside of the claw only very little.

Anyway, it is a "file a little and check, file a little and check" procedure.

The more you sit and push a spent shell case in and out of that pocket,
the more you will understand what is going on and where you need to file.

The extractor on the other side should need less or no attention.
Stage 2 - Checking the Action for Smoothness - FuzzyLimy

Quote:
Referring back to the "possible quality considerations"
how smoothly does each round feed from the magazine to the chamber,
when actuating the toggle bolt,
as compared to the smoothness when actuating the bolt
without any rounds in the magazine?

From first-hand examination and trial of several examples of the BB action,
it has been observed that there can be a distinct "end-of-travel"
hang-up in the feeding operation.

If this is observed,
take a closer look at the way the incoming round is gripped
by the face of the advancing bolt,
particularly with regard to it "sliding freely"
into the bolt face pocket,
and under the claws of the two extractors.

If the extractor claws exhibit insufficient clearance from the bolt pocket face,
then the round does not fully enter the pocket
and tends to hit the chamber entrance at too steep an angle.


There is a tendency for the extractor claws to show
a little skewness in their pockets,
and to have rather sharp, burry edges.


To remedy this problem start by removing the bolt . . .
Depress the pawl at the rear and after lifting out the rear toggle pin,
slide the complete bolt block
and toggle linkage out to the rear of the receiver.

Now take a round of ammo,
and test insert it into the bolt face pocket by lightly sliding it upwards
as if it were being fed from the magazine.

In all probability it will only go about
1/2 to 2/3 of the way in before becoming "tight".

The remedy is to examine the extractor claws for skewness and/or burrs
. . . if found a LIGHT filing or stoning is recommended
. . . keep those under-surfaces of the claws basically parallel to the bolt face,
with just a slight relief on the lower leading edges.

Remove just enough material to remedy the problem . . . NO MORE !
. . . and keep testing with the re-assembled rifle/bolt
and a round of ammo as you go.

I'd suggest using an old style ignition point file, or better yet,
one of the "el cheapo" diamond-coated Chinese ones now available,
for the operation, which can then be done
without removing the extractors from the bolt.

Clean the bolt and toggles thoroughly after this adjustment
and re-lube the complete assembly with a suitable product
. . . I have used either Shooters Choice High-Tech grease,
or Primis Lube Gel with good results.
__________________
W. Edwards Deming ... Quality: It is not enough to do-your-best;
you must know what-to-do, and ... then ... do-your-best.
Ever-Onward ... Through the Fog ---- Fort Stockton TX 79735

Last edited by aom22; 11-17-2008 at 11:54 AM. Reason: Add Links and Text
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  #20  
Old 08-09-2010, 08:02 PM
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aom22
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Remainder of Fuzzy Limey Project ... Izhmash Biathlon Basic Modifications

Quote:
Originally Posted by aom22 View Post
BI 7-2 Trigger Modification
& Stage 3 - Trigger Mechanism Adjustments and Modifications ...

If Fuzzy ever finished this article in Fuzzy's Projects
it would be exactly what you're looking for - I think.
Izhmash Biathlon Basic Modifications
Here is very brief description of the remainder of the project.
Quote:
Originally Posted by Fuzzy Limey View Post
... To be as brief as possible, for this post, basically two things need doing
... slightly trim back and smooth one jagged end
of the double-ended hooked spring - (L.H. Bottom in my illustration).
This will make it a little easier to slip back into place when re-assembling the trigger unit.

Secondly, the trigger pull weight can be adjusted "up" or "down"
by screwing in/out the threaded rod
with the transverse hole in one end that fits
in the "sear actuator bar", (R.H. Center in my illustration).
Final adjustment of creep can be done with the small screw in
that same actuator bar .... it's trial and error here.
Don't get the threaded rod screwed out too far to reduce spring tension
or it'll just flop around.
My suggestion if this is not light enough is to hunt up
or make a new spring using thinner gauge wire.
In my case I needed to heavy up the pull to 3# for CMP competition.

Regards,
Bryan - The Fuzzy Limey

PS: A very small pair of fine needle-nose pliers comes in handy
in manipulating the spring hooks into place
... also an assortment of finish nails and fine watchmakers screwdrivers help as "third"
- (and "fourth") - hands when re-assembling the complete unit.

PPS: If by any chance you intend to use this BB for CMP shooting,
be aware that it is extremely easy to inadvertently touch
and move the safety lever back slightly in Rapid Fire antics.

I suggest drilling a small in the blade of the lever in front of the trigger guard
and inserting a small diameter roll-pin to temporarily disable the safety feature
... this is NOT a recommendation for a permanent installation !!!
__________________
W. Edwards Deming ... Quality: It is not enough to do-your-best;
you must know what-to-do, and ... then ... do-your-best.
Ever-Onward ... Through the Fog ---- Fort Stockton TX 79735
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