Nominal size of FFFF powder in thousands???

[Oil Derek]

It's a shame that Mad Monk isn't with us anymore.  Anyone know the nominal size of FFFF powder?  Sorry for my ineptness, but I can't get a bolster fitted closer than .006" from flash hole forward. Is this too much of a gap?

[JLayne]

I don’t know the answer regarding the size of powder granules. But if you post a picture of the gap in the gun building section, I expect there are several people who could offer good advice as to whether the gap is significant enough to cause concern, and if so, how to fix it.

Jay

[Oil Derek]

Thank you Jay. Not worth it, it’s not a plank build.

[EC121]

30 seconds on Google will tell you all you want to know about the various grain sizes.

[bluenoser]

Powder of any granulation also contains some fines.  I think you need to find the source of the problem and close the gap.  As a last resort, you could solder a brass shim to the bolster and taper it.

[rich pierce]

I cannot think of anything that could or would impede me from getting a tight fit between barrel and bolster.

[Oil Derek]

Thanks men.  All true remarks but some border on the arrogant!

AND EC121, in the 30 seconds it took you to respond you could have just stated the size! lol

AND Rich, maybe it's called experience ... which I don't have. Shame on me. lol

[TDM]

My own rule of thumb is if a strip of typing paper slides easily into the gap 4F powder will too.

[bluenoser]

An afterthought:
If it is fitting tightly from the touchhole to the rear, but leaving a gap forward of he touchhole, that would likely mean something is not flat.  Did you check both the barrel and bolster for flatness?  Is the touchhole liner standing a little bit proud?  Just food for thought.

EDIT
Brain f@#t
The liner has likely not been installed yet.

[Oil Derek]

Thank you TDM and bluenoser for constructive input. 

Putting a straight edge to barrel flat, bolster and inside of lock plate indicates they are flat(enough). Been using the paper trick too. Barrel and stock may not be parallel so I’ll shim the heel of the lock and see if front gap closes.

[rich pierce]

Thanks men.  All true remarks but some border on the arrogant!

AND EC121, in the 30 seconds it took you to respond you could have just stated the size! lol

AND Rich, maybe it's called experience ... which I don't have. Shame on me. lol

If the bolster is flat, I get the 2 flat surfaces to snug up by removing wood from the lock inlet. If there’s a gap at the rear, then something is impeding the lock from settling in at the back half. If s gap at the front, it’s the nose of the lock. Inletting black or soot will tell the tale.

[smylee grouch]

Years ago I used a used lock on a build that had a slight " dish " on the bolster about where the vent would be. I noticed it when the lock plate was fully inlet. I " tinned " that area on the bolster with soft solder and closed the gap. The current owner says its still there.

[Oil Derek]

Thanx guys.

The bolster seems ok Smylee.

Rich, yes I have been smoking and working the nose area of the lock mortise. I keep taking out wood on the bottom side but am not gaining anything. However, when I shim the back of the lock by .035" the gap reduces to .002" gap. One concern is how far before I inlet into the ramrod hole and eliminate the front panel flat.  Ran into the later on the Lyman GP project. 

[bluenoser]

Assuming both surfaces are dead flat, your problem pretty well has be wood contact toward the nose.  I would not tap in for color transfer in the middle of the plate because that can give a false reading toward the lower part of the inlet.  On a flintlock, I tend to tap in at, or immediately below, the pan for final fitting.  I suspect your problem area might be wood contact at the top and immediately ahead of the bolster.  I had a similar situation on my current build using a lock from a well-respected maker.  The bolster appeared to have been flattened on a belt sander and needed to be trued.  I hold their locks in high regard and don't consider that to be a manufacturing defect.  It is just one of those things that need to be checked and, sometimes, touched up.  I use a blank lathe bit with a thin film of transfer color (Prussian Blue) on it to find high and low spots.  Rubbing the blank on the barrel and bolster will show any high or low spots.  Once trued, removal of a little wood just ahead of the bolster allowed the lock to drop into place with full contact.  An overly deep inlet toward the rear is easily corrected.  Don't throw in the towel.  You are almost there.

If you could tap in for color and post a photo, folks could likely identify the problem.

[Oil Derek]

Do you mean tapping/striking the plate to make contact in the inlet?  The only thing on the lock plate is the frizzen and I've only used finger pressure to make contact in the mortise.  As it now stands, without any shim or inletting at the back of the lock I have it to .002" from pan forward. Apiece of paper pulls out with much effort but does not tear.  The fence area is only place making full contact with the barrel.  Between pitting of the barrel and a not absolutely "true bolster" I don't know if I can get the extra.  Nose of the plate is already 1/16" below panel flat.

[Oil Derek]

An observation.  Most of the black contact points have been the width of horse's mane/tail hair or the size of a pin's head.  Is this the normal expected showing?

[Dennis Glazener]

Is there a chance that the lock plate is canted toward the bottom i.e. the bottom of the lock striking the barrel before the top? Or maybe the main spring touching the barrel before the bolster?

I assume you tried the plate without the internals in place.
Dennis

[Dennis Glazener]

An observation.  Most of the black contact points have been the width of horse's mane/tail hair or the size of a pin's head.  Is this the normal expected showing?

No, ideally full contact showing solid or almost solid black contact.
Dennis

[Dennis Glazener]

Any chance rear lock bolt is too tight slightly pulling the plate on an angle frot to rear? Would not take much for a 2 thousandth gap at front lock bolt. Try looseing rear and tightening front lock bolt.
Dennis
ps all suggestions shots in the dark!

[Oil Derek]

Good points Dennis, thank you.

Yes fitting the plate without any internals including the main spring for now.  There is only one lock bolt and it is rear of center of the plate by about 1/2" and is itself a modular plate that holds the lock guts which bolts to the lock plate.  If that makes any sense to you.  I have NOT tried using the lock bolt to secure the plate yet.  That will require hogging out wood so that the plate will even sit in the mortise.  I thought the logical step was to get bolster fit right first.  You might be right though, could be tough to get the front of the bolster to make great contact with the barrel. Solid bolster contact is in the fence area only.  No evidence of it being canted or biased toward top or bottom edge of bolster. 

[galudwig]

Almost sounds like tightening the lock bolt is flexing the plate and creating a gap. T/C’s had one lock bolt centered and were notorious for binding the internals if you overtightened the lock screw. There could be a point that is pushing the plate when it is tightened down. Is it flush when the bolt is out or loose?

[bluenoser]

I am a rank amateur at this compared to many members here, and I ask that someone step in if I offer poor advice.

I mean tapping the plate to make solid contact in the inlet.  I don't believe finger pressure would be sufficient to give a good imprint.  I lightly tap with a light phenolic (plastic) tipped hammer and where I tap depends on where I am with the inletting.  When doing the final fitting of the bolster, I either tap directly on the pan or, with the aid if a thin piece of hardwood, directly under the pan while making sure the plate is not canted.  If it is, or might be, canted out at the bottom, I strike a little lower.  It is best if your plate is completely stripped while inletting to eliminate the possibility of some component interfering with the process.  Inlet one component at a time.

You mention pitting of the barrel.  Are you using an old barrel?  If so, I think it doubly important you true and smooth up the area that will make contact with the bolster.  You should also true up your bolster if it isn't already flat.
If your frizzen is still on the plate, is it possible the frizzen screw is protruding past the face of the bolster and interfering with your inletting?
If it looks like the rear of the inlet is too deep, install a shim or temporarily build up with masking tap before going further.  You don't need an overly deep rear inlet complicating things.

Dennis has made some good points.
I assume that, at this point, you have not drilled for the lock bolts.  That should only come after the lock is fully inlet.  Tightening the rear lock bolt could cause problems later on if the rear of the plate is inlet too deep and not corrected.
If the plate is canted toward the bottom, I would expect there to be a gap all across the top of the bolster.
The mainspring could cause the problem.  Leave it off until the plate is fully inlet.

A photo would sure help us better understand the problem.

[Oil Derek]

Ah, some clarification here guys.  To my knowledge, this is a 1970's era factory TC built flint gun.  Original stock and barrel and all hardware.  Just replacing the factory lock with a L&R replacement.  Junk TC lock as sear and sear return spring cup were broken.  I was told replacement parts weren't available ... and here we are.

I have NOT altered the factory inlet to be able to secure the L&R plate with the lock bolt. Thus no warping of the plate while trying to fit the bolster. (See above posts).

I have the bolster within .002".  However, I am very annoyed now as basically the front lock panel flat will completely go away when brought flush to the lock plate.  Major heroics ahead to maintain stock symmetry I suppose. More than I expected/wanted to do. Ugh!

[bluenoser]

Sounds as though you are dealing with a PITA.  Would thickening and perhaps tapering the bolster by soldering a shim to it help?  You would also have to shim out the frizzen and do some shimming of the inlet for the plate.  Beats having your lock panel disappear.  As I recall, TCs have a pretty thick forestock.  Might slimming it down help?

[Oil Derek]

@ bluenose perhaps.  I suppose there is extra wood on these guns but I don't know what original plains rifle stock architecture looks like.  Maybe others here have reworked the TC to look more period correct and will chime in.