FWB Sport: gracious a loose screw never tightened!

[fwbsport]

So the squirrels were dancing around this morning and I was using the hw30 .177 with Crow Magnums getting pretty nice groups offhand.  So one squirrel was a stationary target long enough for me to aim and fire and hit the branch beneath him to send sputters of pine bard into his face and then they sort of disappeared.  While they were out of the picture I thought again about a rifle that would at least shoot enough like a laser to HIT the target or enough in or on the target to at least "get hit" to the point it either dies or struggles while other squirrels either eat or support the "wounded." 

Well that brought me back to reality here asking the question don't rats eat wounded rats? Do squirrels eat wounded squirrels?  So the thinking was getting off track from the mission which was to get those squirrels out of here!

I went back to the gun cabinet and took out the FWB with the Bushnell Trophy and did firing checks on the 1.5" diameter steel paddles to slam them exactly dead center--which didn't surprise me--using Crossman Premier 10.5 gr pellets from one of the 1250 per box thing--and then I decided to get to the bottom of an old problem I had with the FWB; something wasn't right with the stock holding the machine and even though the screws were tight I kept feeling a small movement after cocking the rifle. 

At first I kept suspecting the stock must be cracked around one of those side screws but every time I looked the stock was fine and so were the screws.  So I decided to tighten down some more on the left side screw which had resistance, as though it was all the way down, but then I got more aggressive in the torque on the torque screw wrench and all of a sudden there was enough space to turn the screw half or more around to the "real" snug point!

Well now I had to recheck zero!  And guess what?  It is still shooting to the same point of impact! But without the annoying loose or cracked stock syndrome!

I had expected POI to change SOMEWHERE after turning the left side stock screw tighter into it's real home, but not having done that it tells me the rifle was able to shoot to the same point of impact with one loose side screw!  Now that tells you something about Engineering.....

[dtdtdtdt]

Sounds like the wood fibers in the stock were compressed over time and the shooting acted like a little hammer aiding the squeeze. 

Wood compression led to the use of very hard dense woods like walnut for stocks.  Most air rifles seem to use beech that is apparently softer and more easily compressed.  In the past 70 years, glass bedding and recently the development of metal pillar bedding techniques to improve accuracy and stability was intended to deal with wood compression and screw loosening. Later tightening back to the same level of original torque requires more turn on the screw.

I suggest reading some of NCED's work that he has just reiterated for the shooting public on avoiding wood compression and dealing with it.  He essentially has developed pillar bedding for air rifles.  The most recent discussion from NCED on his work is a few posts back in this forum  in a question about screw head slot sizes.  Take a look at it and look back at NCED's posts for a few years when he detailed his methods even more!

He is certainly not the only one who does things like this but is the one who writes clearly about what he did and why!

https://www.gatewaytoairguns.org/GTA/index.php?topic=168179.msg155887353#msg155887353

It might help you out!!

[fwbsport]

Sounds like the wood fibers in the stock were compressed over time and the shooting acted like a little hammer aiding the squeeze. 

Wood compression led to the use of very hard dense woods like walnut for stocks.  Most air rifles seem to use beech that is apparently softer and more easily compressed.  In the past 70 years, glass bedding and recently the development of metal pillar bedding techniques to improve accuracy and stability was intended to deal with wood compression and screw loosening. Later tightening back to the same level of original torque requires more turn on the screw.

I suggest reading some of NCED's work that he has just reiterated for the shooting public on avoiding wood compression and dealing with it.  He essentially has developed pillar bedding for air rifles.  The most recent discussion from NCED on his work is a few posts back in this forum  in a question about screw head slot sizes.  Take a look at it and look back at NCED's posts for a few years when he detailed his methods even more!

He is certainly not the only one who does things like this but is the one who writes clearly about what he did and why!

https://www.gatewaytoairguns.org/GTA/index.php?topic=168179.msg155887353#msg155887353

It might help you out!!

Tx Dt!

I have been keeping up with this wood talk and even said awhile ago that Walnut was better for two reasons (I have Walnut on my two 35Es):

a) it's harder and less subject to change in form
b) it makes the rifle shoot smoother to have walnut than beech, because there is less compression in the wood and a harder more elastic response to the firing of the pellet.

I could add it doesn't scratch and all you need is a hand rubbing finish as simple as linseed oil to reboot the stock's beauty.

[SteveP-52]

I've posted before about the fact that I use Mac1 screw cups on my HW95 (and been largely ignored) for just that reason and also have a set on my Beeman R9. A simple and inexpensive tricked learned from lots of reading on GTA and bought because I don't have the shop equipment like Ed does to make my own.

http://www.mac1airgunshop.com/mac1-forearm-cup-kit-p/mcupkit.htm

[Yogi]

I've posted before about the fact that I use Mac1 screw cups on my HW95 (and been largely ignored) for just that reason and also have a set on my Beeman R9. A simple and inexpensive tricked learned from lots of reading on GTA and bought because I don't have the shop equipment like Ed does to make my own.

http://www.mac1airgunshop.com/mac1-forearm-cup-kit-p/mcupkit.htm

yeah, but they have been out of stock for forever......

-Y

[Jason_Garvin]

I had several of the new model.  I ended up shimming between the metal and the stock.  The close clearance between the stock and the breech ended up touching and making marks on the aluminum as it was cocked.  The shims added spacing on those front two screws and allowed better torque.

Jason

[Chouchin66]

Both my R7 & 50s have been epoxy/glass bedded @ front stock screw - screw cup, just like I do w/ my P.B. rifles... Seems to work well @ tightening my groups( maybe it's just me) , but believe it helps with consultancy/ harmonics.

[Yogi]

I have been keeping up with this wood talk and even said awhile ago that Walnut was better for two reasons (I have Walnut on my two 35Es):

a) it's harder and less subject to change in form
b) it makes the rifle shoot smoother to have walnut than beech, because there is less compression in the wood and a harder more elastic response to the firing of the pellet.

I could add it doesn't scratch and all you need is a hand rubbing finish as simple as linseed oil to reboot the stock's beauty.

John,

Wrong again!  At least you are consistent!   Walnut is rated at 1010 on the Janka hardness scale.  Beech is 1300.  Beech is also denser.  Laminated stocks are usefull because they are very dense.  Sure Walnut looks nicer, but it is NOT a better material for making gun stocks.

-Y

[fwbsport]

I have been keeping up with this wood talk and even said awhile ago that Walnut was better for two reasons (I have Walnut on my two 35Es):

a) it's harder and less subject to change in form
b) it makes the rifle shoot smoother to have walnut than beech, because there is less compression in the wood and a harder more elastic response to the firing of the pellet.

I could add it doesn't scratch and all you need is a hand rubbing finish as simple as linseed oil to reboot the stock's beauty.

John,

Wrong again!  At least you are consistent!   Walnut is rated at 1010 on the Janka hardness scale.  Beech is 1300.  Beech is also denser.  Laminated stocks are usefull because they are very dense.  Sure Walnut looks nicer, but it is NOT a better material for making gun stocks.

-Y

Yes I heard that point of view with a certain type of wood scale but for some reason what happens to screws torqued in my Walnut stocks compared to the Beech stocks in air rifles proves otherwise.

There are hardness scales of different things under different overall standards.  The beech is spongier here in Illinois than walnut.

[dtdtdtdt]

I have been keeping up with this wood talk and even said awhile ago that Walnut was better for two reasons (I have Walnut on my two 35Es):

a) it's harder and less subject to change in form
b) it makes the rifle shoot smoother to have walnut than beech, because there is less compression in the wood and a harder more elastic response to the firing of the pellet.

I could add it doesn't scratch and all you need is a hand rubbing finish as simple as linseed oil to reboot the stock's beauty.

John,

Wrong again!  At least you are consistent!   Walnut is rated at 1010 on the Janka hardness scale.  Beech is 1300.  Beech is also denser.  Laminated stocks are usefull because they are very dense.  Sure Walnut looks nicer, but it is NOT a better material for making gun stocks.

-Y

!!!

As usually the MIGHTY INTERNET has more information that anyone should ever want - some of it even true!

Here is a reference to wood strength for more species than I have ever heard of!!!

Short answer:  Beech and Walnut seem to be very similar in compressive strength.  But I have never seen a beech stock that I would show to a friend as a thing of natural beauty! Beech is used a lot because it is cheaper.  Zillions of military rifles around the world.....

On looking at the properties, the two that might be important for the question being discussed (compression around screws) both compressive strength and hardness might be useful.

Bubinga , Indian,  or Brazilian rosewood stock anyone???  Might be fun???


http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/3_Wood_Strength/3_Wood_Strength.htm

[fwbsport]

I have Brazilian Rosewood on two of my classical guitars!
It is used in the most expensive guitars and has been outlawed to use since 1980 something.  Now Indian Rosewood is used to replace rarer Brazilian.

I have some really nice looking Beech stocks on all my HW80s and don't mind them at all over Walnut.  But there is more resistance to the Walnut wood on both HW35Es.