GPR Lock Improvement

[petew]

I have had several Investarm locks and all of them were /are very reliable and fast. The best improvement I found was using a liner with a larger hole and coned on the inside.  1 Lock had a frizzen that was a poor sparker, and I replaced that, and it is fine now.
 Where the frizzen pivots on the bottom can be filed/polished gently if it is rough , to speed the lock up a bit.

I tried the L&R RPL and it is no faster, and required a lot of inletting to make it fit. It also had the sear to long and was hanging up on the stock.I had to trim about 3/16" from the end of the sear. If your GPR lock isn't broken, don't fix it .

It seems to be fashionable today to "TUNE" every lock made. In reality I think this tuning is more of a fashion statement than anything usefull.  If it is working good any mating surfaces inside the lock will smooth themselves out rather quickly. Often after being tuned I have found the 2 little screws on the cover plate over the lock's working parts were tightened to much causing problems that were instantly fixed by backing out the screws a tiny bit.

Far to often I hear these Investarm locks are no good, however this is almost always by someone that knows a friend of a friend who is an "expert" that says they are no good. Good flints, a clean vent hole will make them reliable and fast.

For cleaning the vent hole I use a tip cleaner for Oxy / Acetelene torch tips.Pick a file from the pack that goes in easily , 1 push in and out cleans all the build up in the hole. I know these are files, and could enlarge the hole if it is a tight fit, and used excessively, but common sense use will never wear the hole with a file that is smaller than the hole. The roughness of the file grabs any buildup far better than a smooth pick will. 1 time in and out is all that is needed.

[rollingb]

Here is the touch hole on my GPR. I've heard others say their GPR had the same problem.

You can't move the barrel and tang forewards without creating a problem, and you can't move the lock rear-ward without creating another problem,... so if it was mine, I'd remove the touch hole liner, plug the hole with a metric bolt (be sure it is flush with the inside bore wall), cut the bolt off and file smooth,.... then mark the barrel in the proper location for a new touch hole, and re-drill and re-tap a new touch hole further forewards (using a standard thread for the liner instead of metric).

[Rob DiStefano]

what rollingb just typed is the way to go, but only IF that touch hole is THE culprit for pan flashes, and not some other reason, such as ... are you pricking the touch hole after loading the tube and before powdering the pan?

[Muley]

I have had several Investarm locks and all of them were /are very reliable and fast. The best improvement I found was using a liner with a larger hole and coned on the inside.  1 Lock had a frizzen that was a poor sparker, and I replaced that, and it is fine now.
 Where the frizzen pivots on the bottom can be filed/polished gently if it is rough , to speed the lock up a bit.

I tried the L&R RPL and it is no faster, and required a lot of inletting to make it fit. It also had the sear to long and was hanging up on the stock.I had to trim about 3/16" from the end of the sear. If your GPR lock isn't broken, don't fix it .

It seems to be fashionable today to "TUNE" every lock made. In reality I think this tuning is more of a fashion statement than anything usefull.  If it is working good any mating surfaces inside the lock will smooth themselves out rather quickly. Often after being tuned I have found the 2 little screws on the cover plate over the lock's working parts were tightened to much causing problems that were instantly fixed by backing out the screws a tiny bit.

Far to often I hear these Investarm locks are no good, however this is almost always by someone that knows a friend of a friend who is an "expert" that says they are no good. Good flints, a clean vent hole will make them reliable and fast.

For cleaning the vent hole I use a tip cleaner for Oxy / Acetelene torch tips.Pick a file from the pack that goes in easily , 1 push in and out cleans all the build up in the hole. I know these are files, and could enlarge the hole if it is a tight fit, and used excessively, but common sense use will never wear the hole with a file that is smaller than the hole. The roughness of the file grabs any buildup far better than a smooth pick will. 1 time in and out is all that is needed.

What did you use for a vent liner with a larger hole? What frizzen did you use?

[JStanley]

what rollingb just typed is the way to go, but only IF that touch hole is THE culprit for pan flashes, and not some other reason, such as ... are you pricking the touch hole after loading the tube and before powdering the pan?

I use a vent pick that is lightly ribbed after each shot and before priming the next.  I try not to cram it in there too far after the tube is loaded though.......  One thing I noticed one day after acquiring a color video borescope device from Milwaukee ( :idea

What do y'all think?

[Rob DiStefano]

having heard all the good stuff you've been doing, plugging that vent hole and drilling for a new line appears to be the correct task at hand.  my guess is that a coned vent liner won't make a difference as the problem is that the touch hole will still be located aft and up from the bottom of the pan.

[Muley]

I bought an RMC vent liner. Do I need to drill it out bigger or is it ok as is?

[Rob DiStefano]

I bought an RMC vent liner. Do I need to drill it out bigger or is it ok as is?

i'd let the gun tell you what to do.  if you feel the ignition is lagging, and you've done everything "right" - the vent hole is properly located, the hard hammer steel and pan and sharp flint have all been cleaned good, the vent has been picked good after loading, using a proper pan powder, pan powder properly located, etc - and yer either having pan flashes or too many kaaaa-boooms instead of kaboooms, then some folks like opening touch holes to .060" or so.  however, the more open the vent, the more it might suffer the "volcano effect".  it's all a matter of compromise ... like most things in life, eh?  

[Muley]

Yeah, there sure are a lot of compromises in life.

The last GPR flint I had I used 4F in the pan and 2F in the tube. I wasn't happy with that combination. I had a hard time keeping the 4F in the pan when hunting and it seemed to suck up moisture pretty easily. The 2F in the tube was ok, but my thought is 3F will ignite easier and maybe flow into the vent liner easier. Plus, I can use less for the same power as 2f for less fouling.

So, I ordered some Goex 3F and plan to use it in the tube and pan. Good plan or not?

[Rob DiStefano]

pete, that's what i do, and my success tells me it's a good thing - 3f in both the tube and pan.  you've probably seen my recent videos with my flinters, the .50 hawken and .62 smoothie, and can attest to the good ignition i'm getting with only one horn of swiss 3f.  so, ya sure can't hurt to try just 3f.  as i mentioned before, with muzzleloaders, particularly flinters, it's a combination of good things that make for consistent ignition (not to mention, consistent good accuracy), not just the tube and pan powder.  gotta have it all right, and if not, then a door is left open that could make way for some kinda failure.  in wet, or extra cold, or extra hot weather, that door gets cracked open a tad wider, too.  it is all about compromise - but only as dictated through the experience of trying (aka "trialling" and "testing").  go for it and good luck!  

[Muley]

Thanks Rob. I haven't seen your videos. Point me to them.

[Rob DiStefano]

[Muley]

Pretty cool Rob. I'm glad to see someone else blowing down the barrel. I catch flak for that sometimes.

[Rob DiStefano]

yeah, so do i.  ditto's for bouncing the rod.  

[Hanshi]

Cool video.  I also blow down the barrel but one or two quick puffs does it for me.  I'm not a rr bouncer but I do usually give it three or so taps.  Generally, thumb wiping of the flint/pan/frizzen is all I do.