Author Topic: FWB 300S, lost power (Read 9150 times))

indyducati · « **on:** May 21, 2015, 07:34:05 PM »

Hi guys,

I think I've a problem with a new-to-me rifle.
I got a nice FWB 300S a few weeks ago. It's been
a really enjoyable back yard hunting tool.
It shoots JSB Straton 8.3s REALLY well.

Today, three targets have flown away

I might blame my marksmanship on one, but
not all three. Prior to today, it's been deadly.

I don't have a chronograph. I'm not sure how
to troubleshoot my problem . I'll do some bench
shooting later on my 13M range, to confirm
accuracy. If velocity is down, maybe I'll see
some pellet drop ?

The cocking side-lever feels the same as ever.
The 'report' sounds the same

I'm wondering if the springs are fine, and I've lost
a ring ?

I guess I'll break it down and investigate this weekend.
Any advice or shared experience will be appreciated !

Steve

grauhanen · « **Reply #1 on:** May 21, 2015, 09:02:54 PM »

Just a note of caution if you open up your rifle as the FWB300S is a complex gun. If you haven't seen this already, it's worth a look: and http://www.pilkguns.com/tenp/spfwb300.htm
You may find the best accuracy from round nosed pellets such as the JSB Exact or Express. (Try the 4.50 or 4.51mm head size.) Pointed pellets like the Straton are not known for longer distance accuracy.

Meann-Machine · « **Reply #2 on:** May 21, 2015, 09:41:42 PM »

Steve,
What were your 3 targets? The 300s doesn't have enough power to take out a crow, for example, through the wing. A shot to the wing can prevent the pellet from reaching a vital area. You need to make an open breast shot, although a head shot is preferable.

Craig

indyducati · « **Reply #3 on:** May 21, 2015, 09:55:55 PM »

Thanks guys,

I appreciate the links. I've studied them long before I ever owned this rifle.

I've journeyman status in two mechanical trades. I'm now a field service engineer
of medical equipment. I can adjust the desmodromic valves on a Ducati motorcycle.
I've even rebuilt a Crosman 760

I haven't opened an FWB before, but am not
afraid to try. I'm also not afraid to send it to a pro if I foul up...

This rifle has a blue breach seal. I believe that might mean it's been resealed at
least once ?

It's funny, of the 5 different pellets I've tested, the Stratons are the most accurate.
That includes three different round nose JSBs.

My targets today were English Sparrows. I feel good about my shot placement.
They were within 40' from me.

In hindsight, I wish I had some sort of energy baseline from this rifle.

Steve

Meann-Machine · « **Reply #4 on:** May 21, 2015, 11:22:14 PM »

Sometimes when you don't have a chrony you can get a rough idea of power by shooting into a wet (soaked) phone book and checking the penetration. If you have, or can borrow what you believe to be a similarly powered air rifle shoot them both into the phonebook and compare.

Regulatori · « **Reply #5 on:** May 22, 2015, 01:03:41 AM »

Just because it has a newer breech seal, don't assume the previous owner also replaced the piston seal. A breech seal is an easy swap while the piston seal takes a little work. If you pull the cocking handle back a little, you can shine a flashlight into the slot and check the condition of your piston seal.

It's an easy gun to take apart. I've messed around with regular firearms but the 300S was the first air rifle I stripped down/reassembled. The whole process took 15-20 min.

The biggest pain is pulling the two front sledge pins...I used bent nose needlenose pliers and they came out easy. Just make sure to bag your parts and mark where that part came from. You don't even need a spring compressor for a 300S because the spring is so short. When it was time to remove the spring I rested the gun against a wood block (barrel up) and the spring came out with no issues. When installing you just use the block as leverage.

grauhanen · « **Reply #6 on:** May 22, 2015, 08:51:41 AM »

For parts, see http://www.ebay.ca/itm/Feinwerkbau-Mod-150-300-300S-Crank-lever-Air-rifle-Seals-Service-kit-/371327734065?pt=LH_DefaultDomain_2&hash=item5674db9131

dtdtdtdt · « **Reply #7 on:** May 22, 2015, 12:34:36 PM »

The FWB300 is a super accurate air rifle in general. If all else seems normal and you have a scope on the rifle, try shooting a series of targets covering 5 yds to 30 yds to the same point of aim with the same pellet. This will manually generate a ballistic arc table for your exact conditions. Remember the FWB300 is designed to shoot wadcutters at 10m into the same hole all the time. (It will too!)

Depending on what range you have the scope zeroed at, how high it sits above the bore, you may hit as much as 1.5" low at very short ranges and at the longer ranges too.

If you haven't taken a look at it, download and install the Hawke ChairGun Pro software. With velocity and weight, it will calculate the ballistic arc for virtually any pellet. The program has a host of other stuff in it too. Well worth the time.

As for velocities with an 8.3gr pellet I would guess a velocity with the FWB around 525-550f/s. Mine shoots H&N 8.18gr pellets at 565f/s all day. A bit heavier pellet will probably shoot just a bit slower.

Below are some results with mine at 50'

Ken T · « **Reply #8 on:** May 22, 2015, 05:47:48 PM »

I would try it for accuracy on paper targets using something like JSB 7.33 grain pellets or 7.87 grain.Domed pellets are generally more accurate beyond 10 meters.
The FWB 300 has a piston ring made of steel instead of a piston seal.There is a buffer on the end of the piston that can fail.The piston ring has a very long life.The buffer simply prevents damage to the piston.

yellow boy · « **Reply #9 on:** May 24, 2015, 05:23:28 PM »

My 300S has a piston ring in addition to a conventional piston seal. When I got it it shot JBS 7.3's @ 580 fps an8.4's @ 530 fps. When I disassembled my gun the first time the piston ring broke in two. I ordered new seals, a new piston ring and a new one piece Maccarri spring. The gun now pushes JBS 7.3's @ 680 and 8.4's @ 640 fps. I was told that the piston ring has a life of some several thousands pellets but I can't confirm that. Its a real kick shooting a gun that is over 40 years old ans is as close to dead accurate as I can make it. Enjoy your CLASSIC!
SKY

grauhanen · « **Reply #10 on:** May 24, 2015, 06:51:46 PM »

Congratulations! Good to hear you've got it fixed up.

Quote from: yellow boy on May 24, 2015, 05:23:28 PM

My 300S has a piston ring in addition to a conventional piston seal. ... When I disassembled my gun the first time the piston ring broke in two. ... I was told that the piston ring has a life of some several thousands pellets but I can't confirm that.

The piston ring should be good for a few hundred thousand pellets.

chuckinohio · « **Reply #11 on:** May 24, 2015, 07:44:24 PM »

Quote from: grauhanen on May 24, 2015, 06:51:46 PM

Congratulations! Good to hear you've got it fixed up.

Quote from: yellow boy on May 24, 2015, 05:23:28 PM
My 300S has a piston ring in addition to a conventional piston seal. ... When I disassembled my gun the first time the piston ring broke in two. ... I was told that the piston ring has a life of some several thousands pellets but I can't confirm that.
The piston ring should be good for a few hundred thousand pellets.

You are correct, depending of course on the state of the rifles maintenance, and barring the odd part that gives up the ghost prematurely.
Some diligent searching will turn up a measurement for the installed rings OD. There is a range, which is rather small, that will serve as a Go/NoGo measurement for the serviceability of a FWB 300 piston ring.

Edit- it's not the OD of the ring , it's the thickness of the ring itself measured when it is dismounted from the piston body-
http://www.network54.com/Forum/79537/thread/1364746744/FWB+150-300+Piston+ring+replacement.

mafatone · « **Reply #12 on:** May 26, 2015, 01:36:21 PM »

I own two of these bad boys. Chances are your springs are weak or broken. If your 300S is really super easy to cock, you need springs. Just curious, did it come from California?

indyducati · « **Reply #13 on:** May 26, 2015, 11:07:16 PM »

Yes, I had a very pleasant sale from a seller in California.

I haven't had time to do anything with this rifle yet.
The side lever feels the same today, as it did a month ago.
I've no experience with another FWB to tell if mine is different.

I've got a set of factory seals, springs and ring ordered.
We'll know in a few weeks, if anything is broken .

I appreciate your interest.
Steve

yellow boy · « **Reply #14 on:** May 31, 2015, 05:11:33 PM »

I just bought a second 300S and am looking at enlarging the loading aperture to allow for easier pellet loading. Has anyone done this? I am taking it to a machine shop tomorrow to see if they can mill or grind the outboard wall (ON THE SAME SIDE AS THE COCKING LEVER) of the loading gate. My RWS 54 has this configuration and it is much easier to load with a scope in place.
interested to hear any thoughts.
yb

dtdtdtdt · « **Reply #15 on:** May 31, 2015, 05:59:18 PM »

I have a 300SU. I solved the loading problem by using a shorter scope that leaves clear access to the loading port. Clearidge Ultra RM 3-9x32 AO. It is only 11.5" long, sits low on the rifle, and leaves the loading port perfectly clear and available. It meets all my scope needs for the 300 quite well.

My concern would be that you don't take so much material out of the loading port area to cause the action to flex enough to be a problem.

Before I took the risk of damaging my investment, I would try the scope approach.

yellow boy · « **Reply #16 on:** May 31, 2015, 07:12:44 PM »

I had a 4x12 Bushnell which measures 11 7/8" mounted last and it was still difficult to get the pellets inserted. If you look at your RWS54 you will see that the loading aperture is significantly wider than that of the 300S. Looking at the structure of the loading gate and how the cylinder and and piston fill the void I don't see any reason that the removal of a small amount of material would cause any significant weakness in the structure; but thank you for your thoughts. I am proceeding slowly with this whole idea and I am going to mount the scope on a riser fixture to see if that will get the job done.
yb

dtdtdtdt · « **Reply #17 on:** June 01, 2015, 04:40:38 PM »

Here is a picture of the action and scope arrangement on my FWB300SU. I set the scope back as far as practical while maintaining proper eye relief and have little trouble getting pellets into the chamber.

My method is to stand the butt on my leg, point the rifle straight up, cock the action, insert the pellet using my right hand, press it into the chamber until flush, close the action, and put to my shoulder and fire.

I found it very difficult until I got the shorter, smaller diameter scope. I had a larger diameter scope that wouldn't set back as far as this one does. Hence, the replacement.

As always, each of us finds our own solution. Good luck.

Doing it upside makes it a bit more challenging.

dtdtdtdt · « **Reply #18 on:** June 01, 2015, 04:43:56 PM »

This might be easier to see unless you are good at standing on your head!!!

You might also take a look at your mounts and how they interact with your objective bell. That may be keeping you from moving the scope back far enough to free up the chamber area. I set the rings as far back as I can to give the most flexibility. I tried several different mounts until I found this really cheap set that are very simple and small! Chinese made under $15 have "Sniper" engraved on them. I have seen them on the Internet since I bought mine at a gun show. Available in both 1" and 30mm tube sizes.

My preference is to keep the scope axis as close to the bore axis as possible to minimize the effects of droop and parallax. At 15' the pellets hit about 1.25" below the aiming point with a zero at 50.' This allows me more flexibility on very close shots like chipmunks at 20' or so. I shoot out my kitchen window (after opening

) to deal with the pesky little varmints.

Good luck.

grauhanen · « **Reply #19 on:** June 01, 2015, 10:44:32 PM »

Quote from: yellow boy on May 31, 2015, 05:11:33 PM

I just bought a second 300S and am looking at enlarging the loading aperture to allow for easier pellet loading. Has anyone done this? I am taking it to a machine shop tomorrow to see if they can mill or grind the outboard wall (ON THE SAME SIDE AS THE COCKING LEVER) of the loading gate. My RWS 54 has this configuration and it is much easier to load with a scope in place.
interested to hear any thoughts.
yb

bubba

From firearms culture, to improvise a solution or modify a firearm using limited skills and/or bad taste, so that although the owner of the firearm may be satisfied with the results, the firearm's resale value, and sometimes aesthetic appearance, has been decreased or reduced.

I went to a gun show and saw this rifle that was badly bubba'd with a hacksaw and some spare parts.

Thank you to our advertisers!

FWB 300S, lost power

Author Topic: FWB 300S, lost power (Read 9150 times))