D54 sled testing

[mcoulter]

The new OEM "adjustment pads" (rubber washers used in the mounting screws) came in and are a little more firm than what was on the gun.  I suspect what was on the gun were OEM, but had been affected by the liberal use of grease in that whole sled (or is it sledge?) area.  Unfortunately there was not any huge improvement swapping them out.  But making this change did encourage me to clean up that grease and really focus on what seems to be happening with the sled mechanism, it's adjustment, and how tight (or loose) the stock is set to be.

Here is where I think I have settled with these variables:

Sled adjustment & rear stock screw:  The sled adjustment screw is backed off as much as it can be while still allowing the stock screw to have adequate depth screw in and hold the stock to the action snugly.   

Front sled and front stock screw: As I cleaned the grease from the front sled it became clear that this is where the majority of resistance is coming from once the rear sled is free from the ball detente.  Moving the front sled by hand shows that it simply has more friction than the rear and requires probably 2x as much pressure  to move along its action.  I found that the front stock screw truly has a very small adjustment range before it becomes tight enough to adversely affect the action of the sled.  (basically I can turn it into a D48 with about 1/2 extra turn on that front screw).  I do have a torque wrench that measure in inch-pounds, but I gave up on that in favor of a bump test where I moved the action forward and while holding the gun vertically (and uncocked) let it fall 1/4 t0 1/2 inch or so down  and let the butt hit my table.  With the sled forward this would dislodge it allow the action to slide fully to the rear position.

** Sorry if this is super basic stuff and has been covered 100+ times, but it's helpful for me to write this down to see what makes sense and what I am probably doing incorrectly! **

So I can say the gun is a little better.  I can most definitely feel when the sled is free enough to take the recoil.   

Question:  As loose has I seem to have the action, after a shot it's clear while cocking the gun that the action has not fully moved rearward.  Is this normal for a 54?  It might have moved 1/2 of its full range during the shot.  Again, I suspect that if anything is causing this behavior, it's the drag from the front sled.

I should also mention that after cleaning up the grease, I DID apply a tiny amount of moly-based grease to the areas on the sled where the small roller balls make contact and also on the guide rods. The sled motion just felt "grabby" without *some* grease in these areas.

While the rear sled is super-smooth, I did notice some fore/aft play in the guide rods.  Would the gun benefit from adding some small shim material under the C-clip to prevent these rods from moving?



I got out early this morning to do some shooting.  I ended up shooting 3 targets of 25 shots (5-shot groups) at 55-yards.  I was making small changes to the stock, sled, my hold, and rest position hoping something might be an "AH-HA!" moment.  There were some making of decent groups but I don't feel like I'm "there" yet...  And the POI is changing all around due to the small changes I'm making.

[Mossonarock]

Would the gun benefit from adding some small shim material under the C-clip to prevent these rods from moving?

I've been curious about that too. My D56 has significant play in one of the rods on the rear sled. Just pulling the trigger is enough to rock the action laterally. Once I get that issue licked on this gun though...Oh boy!

[mcoulter]

Yeah, I think I'll have to sacrifice (snip off and drill a hole through) a tab from my feeler gauge set and see how it works.   Sounds like a 10-minute project  :-)

[DevilsLuck]

Following...

I haven’t tinkered with my 54 since getting it, except to add globe, and peep sights. I haven’t worked up the nerve to open her up yet. Fortunately she’s running like a Swiss watch straight out of the box. So far...

[dtdtdtdt]

Yeah, I think I'll have to sacrifice (snip off and drill a hole through) a tab from my feeler gauge set and see how it works.   Sounds like a 10-minute project  :-)

Regarding sacrificing your feeler gauge set. If you have a good one - don't.  Take a trip to Harbor Freight -or your nearest auto supply store and buy one or two of their POS feeler gauge sets for under $5 each and have all the shim material you will ever need. 

I don't think back and forth slippage in the rods is significant..Before doing anything drastic there continue working on your sled system.  It still sounds to me like there is some dirt in there somewhere!!!  A bit of lubricant on the rods and detent ball should be helpful. As far as I am concerned lubrication of the moving bits is OK but not in the barrel or piston. Side-to-side movement could be troubling. I would check all the attachment screws to ensure that things are snug there.  With the rifle apart and the action clamped in a padded vise, wiggle the parts side-to-side to see if there is any play. 

As for movement on firing.  Both of mine freely move to their full displacement back and forth.  The displacement is about 1cm or 1/2".

Also, the rubber washers would have to have been soaked in a chlorinated or other very aggressive solvent to swell them that much.  While interesting, it isn't worth more investigation since you now have the right ones.   

I think a very careful examination of the the metal works on both the stock and action is in order. look for any blemishes in the bluing or marks on the metal that indicate binding.  Then look over the wood for scuffs and areas where binding might be occurring.  Just for grins, try putting extra thin washers adjacent to the OEM washers to raise the action a bit.  If things free up, you have a bind somewhere. 

Your comment about the front screw causing binding and friction when tightened is very suspicious.  It is possible that something is funny there.   As said before by Hector and me, UseThey your torque wrench to set both to 20inlb and see if they are free moving.  If they aren't already there, I would check to see if washers can be installed between the stock screws and the wood of the stock.  The stock might be compressing a bit giving inconsistent binding. 

Also remove the action from the stock, clamp in a padded vice upside down and try moving the brass connectors back and forth to see if you can free up any tension there.   

Ig you have a very precise straight edge you might verify that the front sled and the back sled are in precise alignment. If the front one is angled even a little from the back it could be causing the binding. 

[Fate]

Dave, you, like some others on here, have helped me without knowing it. And you did it again with your feeler gauge shim idea... for my trigger side play. Nothing I had was thin enough so I let it slide.

Now I'll have to take it apart again and do it "your way." Didn't want to do that because of the difficulty I had putting retaining rings on the pivot pins, but I'll do it to eliminate the trigger side play... and add the 1st stage limiter at the same time. The limiter I could have lived without as I'm used to a long 1st stage in my 35, but the side play is nothing to be lived with if I can eliminate it. Now I can.

I'll reiterate what I've said elsewhere about my D48's stock inletting... the registration was off in the forward section on the right side by .5mm causing binding between my barrel shroud retaining band and the stock. It caused frustrating horizontal stringing even after my work on the barrel had made it shoot 1/2" groups... that were a half inch of individual holes. Relieving the stock there with some scraping and sanding, it didn't take much, has my clearances around the entire action even and clear now. So another good suggestion that'll probably help the poster you replied to.

That's why I read all the posts. One never knows what gems the gurus are going to pass along.

[mcoulter]

Devilsluck, I'm glad you're enjoying your 54!  I suppose it'll be easy to get used to NOT having that springer punch you in the shoulder, huh?   

Dave, No I don't think my feeler gauge set is anything good.   In fact there's a good chance that's where I got them from...  I think the "root cause" of the force needed to move the front sled is the pressure of the two small balls under the sled.  This fit seems more snug than the single ball on the rear sled.   Perhaps there's some debris in there causing the extra pressure?  (Seems unlikely given the close tolerances I guess...) Anyway, I probably will pull that off again and try to degrease these them a bit  better and see if that affects the pressure they're exerting.  I don't recall any side-to-side movement on these parts. 

It seems like the pressure to move the action when everything is assembled is pretty much the same as moving the front sled when it's disassembled.   I did look for gouging or wear marks in the stock but (so far) I don't see any.  But adding that extra washer you mentioned is a pretty easy thing to test too. 

Jeff, you're absolutely right about all the gems that are here for the finding.  I have such a long list of bookmarks I found myself going back and doing some targeted googling to find the things I *thought* I remembered being here!   

[dtdtdtdt]

Regarding the two front detent balls.  I have never touched them on either of my rifles.  For what ever reason, I haven't seen any need to do so.  I find that the rear detent ball is the one that controls the lock up of the action on cocking in my OEM 54 for sure. An experiment before doing anything major.  Remove the tensioning screws and put a couple drops of lubricant in the holes.  Tighten them just enough to keep tension on the spring.  Reassemble and check binding and return to the "cocked" position.  If too easy and the action won't stay in the forward position tighten them a quarter turn and try again.  It might be useful to do this on both the front and rear detents.  If the front ones are really tight that might be the "binding" problem. 

the motion on the Rods that I didn't think need to be concerned with is front to back.  Any free motion sideways could have serious impacts on accuracy and consistency. 

The comment regarding side-motion on the trigger blade is one I haven't worried about.  I just checked both my OEM 54 and my Hector Special .20.  Both have side-to-side motion of the blade when uncocked and much less when cocked.  It either case, I haven't attributed inaccuracy or horizontal changes in the groups.  I HAVE detected some horizontal changes when I accidentally put side motion on the trigger when shooting.  NOT much but detectable. 

I doubt that putting washers in place to reduce that movement would be necessary and may even cause additional drag on the trigger that may have more impact.  I know that Hector changes the t06 trigger pins when he tunes them. The Hector special does have somewhat less uncocked side-to-side trigger motion. 

I put the lighter springs in both mine so the trigger pull is less than 1pound in both cases.  Perhaps that compensates.

[Fate]

I agree with your assessment on the trigger "side play" Dave. When I had mine apart yesterday to install the 1st stage limiter I looked at it closely and came to the same conclusion. Your confirmation puts that non-issue to rest.

I also agree that trigger movement, either sideways, uneven, or anything but consistently smooth... and in fact the whole hand and finger use and hold is still a work in progress for me, as it plays a major factor in the size of my groups. Do it a minutely bit different and there goes my tiny hole back into a half inch one. That pellet should leave the barrel immediately and stop hanging around!

There is a new and growing deep appreciation for the skill level of those who successfully compete in field competition, like Hector for example. Perhaps even more awe comes from their enduring smiles and happy faces when the competition is over, regardless of how well, or how not-so-well they did! That part will probably always elude me. But I have standards now in both to aspire me to do better.

Which springs did you change, and how if I may ask?

[dtdtdtdt]

I agree with your assessment on the trigger "side play" Dave. When I had mine apart yesterday to install the 1st stage limiter I looked at it closely and came to the same conclusion. Your confirmation puts that non-issue to rest.

I also agree that trigger movement, either sideways, uneven, or anything but consistently smooth... and in fact the whole hand and finger use and hold is still a work in progress for me, as it plays a major factor in the size of my groups. Do it a minutely bit different and there goes my tiny hole back into a half inch one. That pellet should leave the barrel immediately and stop hanging around!

There is a new and growing deep appreciation for the skill level of those who successfully compete in field competition, like Hector for example. Perhaps even more awe comes from their enduring smiles and happy faces when the competition is over, regardless of how well, or how not-so-well they did! That part will probably always elude me. But I have standards now in both to aspire me to do better.

Which springs did you change, and how if I may ask?

At what range are you getting the groups you are talking about?  One hole groups are rare for any rifle below the 10m rifle class.  Half inch at 20-50 yds is quite good. 

To consistently get much better than that you will have to start weighing and measuring your pellets to get consistent weights and head diameters.  I tinkered with that idea for a while and decided it was more trouble than it was worth.  Even I'm not that anal!!! 1/4minute of chipmunk head is all I need. 

A TANGENT THAT ISN'T RELEVANT HERE BUT YOU MIGHT LIKE TO KNOW FOR PELLET SELECTION

A conventional powder scale or balance isn't good enough. They claim 0.1gr accuracy but aren't really that good.  About 0.2gr is the best you can trust .  I found a range of 0.5 to as high as 1.0gr in a single tin of pellets using a gem scale that can detect differences of 0.02gr consistently. That is 0.001gm.  I figured out that there were two populations of pellets in the same tin that were mixed at the factory.  That means they came out of different manufacturing machines with slightly different die sizes.  This is why many serious shooters by bulk packs of pellets certified to have come from the same press to minimize weight and size variations.

I calibrated my scale with balance weights that were originally traceable to National Bureau of Standards Calibration.  The result showed that the conventional gun scales that I have lose linearity at about 0.1-0.2gr.  I actually considered buying a used Mettler analytical balance to give me 0.0001gm or .002gr but as noted above even I'm not that anal!!!!!!

I sorted several hundred pellets into 0.02gr "buckets" and found that over the extremes of 1.0gr from the tin I got vertical stringing of about 0.5" at 50ft. 

If you want to play with that idea and have a gun powder scale,  I suggest that you individually weigh 10 pellets noting the weights and totaling them together.  Then remix the pellets are weigh all 10 at once.  If the gross mass of the 10 pellets is different from the total of the individual pellets the very low end of the scale is suspect.  (and it will be.)

The spring changed was the trigger spring that applies pressure on the trigger blade.  It is on the back end of the trigger mechanism.  Hector Medina provided me two light springs that got the trigger down to 12oz safely!!  I don't know of another source.  I'm sure he could give you a suggestion or sell you the spring. 

The reason I put the limit screw on the first stage was the light springs made the trigger blade flop around and were more difficult to control with no significant 1st stage control.  The long trigger pull was disconcerting to me with short stubby fingers. 

HAVE FUN

[Fate]

Thanks Dave, all things I will save and consider. So far the trigger is pretty good, and will be better once I get it to my liking. Although a slightly less heavy spring would be nice, I'm not sure I'm consistent enough in a number of things to deal with that light a trigger. I get the occasional surprise as it is.

My only scale now is a little one from Harbor Freight. I got a precision 500 gm weight to check it's accuracy and it was right. But I don't trust its accuracy with single pellets although it "measures" them. I tried sorting pellets some time back with my .177 35 and did single as well as 10 at a time... and found I too am not that anal. With the D48 I'm expecting much more than the 10m targeting I've been doing. My .177 does fine until around 25 yds on starlings, but I want more from the 48. Not sure, however, I will go into sorting, weighing, measuring, cleaning and lubing pellets though. I just want to buy pellets I can rely on and shoot.

Interesting how you seem to answer unasked questions. Your input here addresses such. All my shooting so far has been into a pellet trap inside at 10m, where I have put 15 into a 1/4" group, that grew to 1/2" with 40 or more in it as I constantly adjusted my trigger and scope. I have yet to settle down and just shoot this thing... so much to learn. To me, based on my .177, if I can get tiny groups precisely in the center at 10m, longer shots have been successful if I'm careful about judging distance and wind. That's why I'm beating my trap and pages of targets with the D48 for the same... precisely in the center, given the range's lower POI due to scope height and trajectory as defined by Chairgun. Later I'll verify that with a large distance marked target for real-world facts.

A question I WILL ask: I've never felt the need for a crony until now... the expense was an indulgence that would have made no real difference. With power, ballistics, and range now magnified it is probably time. I don'd need the best, just good enough, but have no firm idea on which crony to get. Suggestions sought and appreciated.

[dtdtdtdt]

A question I WILL ask: I've never felt the need for a crony until now... the expense was an indulgence that would have made no real difference. With power, ballistics, and range now magnified it is probably time. I don't need the best, just good enough, but have no firm idea on which crony to get. Suggestions sought and appreciated.t

A chronograph is helpful but not really necessary.  I haven't had mine out for at least a year now.  For comparison testing an inexpensive one is just fine.  The brand "Chrony" has one that is just above $100 list price.  It has the same internals, just not the add ons.  To get really good estimates of your pellet's velocity in your rifle without investment.  Go to straight shooters.com website.  Look up your rifle and their sales information.  On the screen is usually a tab named OUR TAKE.  It gives you their assessment of the rifle and information on velocities for a host of different pellets out of a new OEM rifle.  That will get you very close.  I checked some from my crony and d54 .177 against their information and found them to within 10-20f/s of what I got.  I think that is good enough for most of us. 

Regarding the scales... The cheap ones that are sold into the reloading industry are generally fairly good in the middle of their range.  it is just at the very ends that they fall down.   I am a Physical Chemist and spent a lot of time running an analytical organization where accurate weights are essential and being me I researched how they work. 

The most common ones have a load cell (a piezoelectric crystal that deforms on addition of weight) that gives off an electric voltage proportional to the weight added to it.  They are quite linear in response over most of their deformation range.  However, at both ends of the curve response suffers.  Decent ones come with one or sometimes two calibration weights to calibrate the response.  The cheap ones are "calibrated" at the factory and sent off never to be checked again!!!  The earliest one I got was WAY off  as much as 5 grains at 50 grains.  I bought it from MTM.  I used it to load a bunch of 30/06 rounds before I figured it out.  Fortunately it was off hight.  That is it read 50 gr with a load of 45 on the pan.  I ended up with some funky light loads but not a blown rifle!!!  I call the MTM and complained.  The guy said "ha ha.  about 5% of that batch weren't correctly calibrated."  I advised him of his liability and stupidity....

The unfortunate thing about even the decent ones is that the calibration weight and associated software are generally somewhere near the middle of the scale's range.  Example:  0-1000gr range may come with a 500gr calibration weight.  That assumes that the crystal response is linear and equally sensitive over the whole range.  A fair assumption in the midrange area - not so good at either end.  Most gunpowder loads are less than 100gr of powder down to 3-5gr.  Pellets are typically less than 20gr.  The calibration is supposed to put the 0 point through the zero point of the weight scale and the calibration point through the appropriate place on the scale. Visually a teeter-totter with one end on the ground and the other end in the air.  Calibration is essentially moving the fulcrum back or forth to match the calibration weight.  A better scale with two calibration weights put both weights through the appropriate part of the curve and let the ends float.  It may or may not pass through zero exactly. 

Anyway, the calibration weight I now use have as low as O.5gr weights and I know where my scales go. 

The old Lyman Ohaus balances are much more accurate and true weight.  They are frequently a bit wonky at the less than 1gr range as it takes them a long time to settle to their true weight.  That's why most people choose the electronic ones. 

[Fate]

Dave, I understand and agree with everything you said. I also come from a background in precise measurements, in electronics, where I spent the bulk of my professional life.

I gave my RCBS balance scale away three weeks ago. So that's not an option anymore although I have used it for this application in the past with good results. However, for my use I just "play" with the subject. There are no enduring results relative to my use. So what I have now, that Hf one, is good nuf for my occasional curiosity.

I've decided to just order a bunch more of the JSB Jumbos and Hades, which are expensive to play with. Throw in some new ones to fill out a couple pay for 3 get the 4th one free orders with some others to try. I'm not going to get anal with this. I just want to shoot. I'm a ways away from that level with this gun. It's being a challenge and I need a lot more time behind the wheel to get a handle on it.

I've made machines do what I wanted all my life... mechanical or electrical. My precision PB guns the same. But this 48 has made me aware it's not what I want, It's what IT requires. Makes me mad.