Modding BSA Lightning XL trigger

[Hangtight]

Lumps of metal have been ordered and friend with the lathe has been warned! I'll get Solidworks fired up tonight and model up the parts so I should have accurate dimensions for the spring in the next couple of days. Knowledgeable people should expect a barrage of questions on clearances and O ring groove sizes

[bigtoe01]

Lumps of metal have been ordered and friend with the lathe has been warned! I'll get Solidworks fired up tonight and model up the parts so I should have accurate dimensions for the spring in the next couple of days. Knowledgeable people should expect a barrage of questions on clearances and O ring groove sizes

Im leaving my PM box full LOL

O rings grooves...for 25mm pistons i found 3mm CS O rings good BUT 2.5mm are better...BUT in 3mm CS you have more sizes available.

in 3mm CS you can get 19mm ID, 19.2 and 19.5 so you can play with crush

for the 19mm ID the groove needs to be 3.05mm wide, 19.15mm dia, then just buy the other 2 sizes as well and you can play with the crush incase the smaller O ring is not seeing to well. I used to leave 1mm from the groove to the face of the piston, I now leave 1.5mm...its stronger

The piston cap needs to be as tight tolerance as it can be but still slide nice.

[Hangtight]

I wasn't looking forward to finding all the little odds and sods needed for a project like this, but EvilBay is your friend! Tube, lump of phosphor bronze, Acetal, grub screws and O rings all on the way. But being tight I wasn't going to buy a big lump of Acetal just for the rear bearing, so if anyone has a little bit of 30mm dia stuff going spare...

[Hangtight]

A quick question. Is there any need for an Acetal bearing at the compression end of the piston if you're using a phosphor bronze piston nose with nice tight clearances?

[Hangtight]

Just a quick plug for a couple of EvilBay shops with great service. http://stores..com/maccmodelengineerssuppliesltd. Ordered a lump of phosphor bronze Thursday night, turned up this morning. Like wise http://stores..com/gwrfasteners for all sorts of grub screws and the like.
I'm nothing to do with the above firms, I was just impressed with their quick and accurate service

[bigtoe01]

A quick question. Is there any need for an Acetal bearing at the compression end of the piston if you're using a phosphor bronze piston nose with nice tight clearances?

well yes and no... I add one as it takes 10mins and takes some strain off the piston head as the gun is cocked

[Hangtight]

Had a bit of a chat to Bigtoe this evening. He mentioned checking the barrel by pushing a pellet down it, do i gave it s try. Moderate amount of effort required for the first 3/4", then you can push the pellet through most of the barrel with very little resistance until the last inch or so which requires more force than the breech. Is this the dreaded 'shit barrel syndrome'?

[Hangtight]

My lovely shiny new Charlie Da Tuna trigger has showed up. Unfortunately the rifle is back at BSA to hopefully have the barrel sorted out

Nice though innit!

http://i1211.photobucket.com/albums/...l/IMAG0593.jpg

[bigtoe01]

My lovely shiny new Charlie Da Tuna trigger has showed up. Unfortunately the rifle is back at BSA to hopefully have the barrel sorted out

Nice though innit!

http://i1211.photobucket.com/albums/...l/IMAG0593.jpg

so they took it back..interesting!

[Hangtight]

They took it back, but whether it gets sorted or not, time will tell. Spoke to one of the guys in the tech department at BSA who was very helpful, but I just wonder if it'll get sent back because "They're all like that sir."
Other people have got good things to say about BSA resolving issues, and I'd like to be included in their number! Fingers crossed

[bufo]

I was curious about this so I tried the pushing a pellet through the barrel thing in my GRT lightning today. It takes fairly even pressure all the way from the breech to the muzzle with me, then its tight for the last inch or so. Choked barrel? It has left nice neat, even rifling marks on the head and skirt of the FTT pellet I used. Does this mean I have a good one?

[bigtoe01]

I was curious about this so I tried the pushing a pellet through the barrel thing in my GRT lightning today. It takes fairly even pressure all the way from the breech to the muzzle with me, then its tight for the last inch or so. Choked barrel? It has left nice neat, even rifling marks on the head and skirt of the FTT pellet I used. Does this mean I have a good one?

yeah yours is ok..

A bad one will be tight at the breech for an inch or so, then slack in the middle as the breech tightness will have sized the pellet down, then tighter at the muzzle where the choke is.

[Hangtight]

I received my Lightning back from BSA today. It would appear that all they have done is chrono it, and fire a test group which apparently was 1/2" at 25 yards. Neither of my concerns regarding the tightness at the breech or the natural of the internal lubrication have been addressed. After speaking to BSA, I don't believe the rifle was disassembled and checked internally in any way.
While I'm disappointed, I'm not surprised. I've subsequently contacted BSA via email, the body of which is below. I hope for a positive response and I'll let you know how I get on!

Dear Sir,

I recently purchased a BSA Lightning XL SE GRT from Protek Supplies in Bognor Regis who have been most helpful in helping me resolve some issues I have with the rifle.
During routine maintenance (simply removing the action from the stock to clean and protect the underside of the action after use outside), I noticed two points that I wish to raise with you. The rifle has already been returned to yourselves with a covering note outlining my concerns. The rifle was tested, found to fall within your criteria and returned with no remedial action taken.

My first concern is with the barrel. My particular example exhibits a tightness at the breech for approximately 20-25mm, after which the pellet can be pushed down the bore with minimal pressure before reaching the choke. This is far more noticeable with pellets that have a larger head, for example Wembley Accupell or Powerpell at 5.51mm, than with something like AA Diabolo Field at 5.50mm. Various sources, including staff at Sandwell Field Sports have confirmed that this apparent restriction at the breech should not be the case, and can have a detrimental effect on accuracy and the nature of the shot cycle.
The note on your repair form (#6206) stated, "Our barrels have a tighter muzzle as they are hammer swaged." but made no mention of the tightness at the breech.
Having examined a friends Lightning XL Tactical in the same calibre, it doesn't exhibit the same tightness at the breech and is consistently more accurate with a range of pellets in a back to back test with my example, although being a conventional spring rather than a gas strut may have a bearing in this. It would however be disappointing if the more expensive GRT was inherently less accurate for whatever reason.

The second concern is with the nature of the internal lubrication as supplied. I completely understand that the gas spring is capable of long and trouble free service with the absolute minimum of a light lubricating oil. But the same can not be said for other bearing surfaces within the cylinder, for example the rear of the piston skirt to the inside of the cylinder during the high, off axis force associated with the cocking stroke. There is no evidence of any lubrication in this area other than a thin application of light oil. A swab of this area taken through the cocking slot revealed small particles of metal which would suggest that wear is taking place, even after only a few hundred cycles. As someone with an engineering background, I would be concerned that a steel to steel bearing face lubricated with just a static film of light oil would be subject to levels of wear that could render the components not fit for purpose within the warranty period. This concern was outlined in the covering note and was addressed with a brief note stating, "A dry system of operation. The only part that is oiled is the piston seal and cylinder."
The use of just oil in this area would seem to be at odds with accepted good practise regarding the internal lubrication of spring/ gas ram air guns. While I am quite happy and equipped to remedy this myself, to do so would involve the dismantling of the rifle thus invalidating the warranty. To not do so will cause considerable problems with worn components that will considerably curtail my enjoyment and the longevity of my purchase.

I bought this rifle because it's combination of performance, appearance, weight and dimensions made it really stand out in is what quite a crowded market. At the moment I am somewhat disappointed, and I sincerely hope that these issues can be resolved so that I can recommend your product to anyone and everyone else.

Best regards,

[bigtoe01]

Hangtight

I have something here with your name on it

https://dl.dropbox.com/u/920660/hang...l/IMG_4547.JPG

let me know if you want it?

[Hangtight]

Cheers Tony! Let's see what BSA have to say for themselves first, but I've got a feeling I might be learning about how to fit one barrel inside another! I presume the easiest/ best way to do it is to bore the BSA barrel to an ID that matches the OD of the breech seal, and turn the breech seal recess on the OD of the insert before they're pressed together? And how do you accurately bore a 10" barrel?