Weighing Pellets - Insane question

This project is already a couple years old, so don't expect miracles. I already have the lighter valve spring in the tool box, purchased by accident. Thought I was purchasing a lighter hammer spring. Sounds like I need the lighter hammer spring (shorter as you put it). I get the short enough to have play in it. I'll look at Hill's site to see what they've got.

That's all part of the education. I'd never taken the valve apart before. I tried the lighter valve spring so had to take the valve apart. Amazed at how simple it is. Gives me confidence to tear it apart yet again.

Just reset the regulator a few minutes ago. Perhaps tomorrow I'll get out and see how close it is to 1600 psi. Also looks like I scalped an o-ring putting it back together last time. Pressure was down to Zero. Oh, the joys of tinkering. Makes getting it all back together all that much sweeter.

Shoot straight!

Tom - Last night I had an epiphany. Remember the old 1950's Bugs Bunny cartoons when the antagonist imagines himself a jackass and how funny that is? Well, when you tinker, it's important to "Untinker" that last tinker to get back to a baseline. Well, I realized I forgot to untinker that last tinker before the regulator. (Insert Jackass clip here) So, for the past couple months, all testing I've done is invalid. Probably two years ago, I installed what I think people referred to it as the BStaley fix or something like that to try to stop double valve hits. I tried it. Didn't do much so didn't take it out immediately. Even re-installed it last time I took the gun apart.

That explains why no matter how high I put the Hammer Spring tension (1/4 inch hex key) the FPS doesn't move. I took it out last night and will return to testing perhaps this afternoon if I can get it all back together. As for O-Rings, I bought a supply from O-Rings and More a while back. Still have sufficient for another rebuild. That's the other thing I love about the Marauder, it's SIMPLE! The Marauder has something like less than 10 O-Rings of about 3 or 4 sizes. the Impact has something like 40 O-Rings of 15 or more sizes. (It's early in the morning and don't want to get too exact).

I'll look at the O-Ring tool. The inside of the Marauder tube is a bit sharp on the punch outs so looking for anything to help. I may yet polish the tube.

Have fun! 

Tom - Yup, polishing sounds like a good idea. The Dremel and cleaning swab sound like an excellent way to approach it. I'll put the swab on my drill so it goes a bit faster. As for final adjustments, I need to develop some data points. Right now, after "Untinkering" so the gun is adjustable again, the three data points I have are confusing. 

about 1900 PSI (If you can believe the gauge) HS and HT at zero, Transfer port 3 turns. 35 shots per fill at about 830fps. If the TP is at 4, about 855 fps.

about 1600 PSI (If you can believe the gauge) HS and HT at zero, Transfer port 4 turns. 29 shots per fill at about 830fps.

about 1450 PSI (If you can believe the gauge) HS at 1 and HT at zero, Transfer port 4 turns. 37 shots per fill at about 810fps.

The Audrius regulator that I have has no markings, but the instructions say to imagine the top of the regulator as a clock dial. Clockwise by 1 hour = 5 Bar. Not quite perfectly accurate, but provides a reasonable starting point. Supposedly it's set at 2200 PSI at 12. Next test should be at approximately 5 which should give me about 1300 PSI. My plan is to start there and work backwards to 12 until I find something that gives me 800 to 830 on average with the lightest hammer spring adjustment and as close to 40 shots per fill as I can get. I'll redo all of my testing in a more consistent fashion so I get decent results. Figure it'll take at least a week to complete the testing and figure out where it needs to be. Once I find the magic combination, I'll stop. Considering that the process to adjust the regulator takes me 20 minutes or so, one test per night might be a bit much to expect. So many other things going on.

Hard to believe this conversation started with a question about how variations in pellet weight impact FPS at the muzzle and evolved to a complete tuning exercise. 

Love this stuff.

As always, Many thanks,

Tom -

Tonight I decided to haul all of my tools out to the test area (unfortunately wife doesn't like shooting indoors). So, First, topped off my tanks. Only have 2 90 CI tanks, so they don't have lots of reserves. Thank heavens for a compressor! Wouldn't be able to do it without one.

Start Settings HS 0, HT 0 TP 5 (Set screw is in place). Unsorted, un-weighed pellets.

Started at 5 O clock position on the regulator. about 1300 PSI. 790 FPS, Tried increasing HS a couple turns, no change.

4 O Clock position - if you can believe the gauge a about 1400 / 1425 is PSI. 810 FPS, again tried increasing HS a couple turns, no change.

Stop, refill the tank I'm using. Only takes about 6 minutes.

3 O Clock position. in the 1550 - 1600 PSI range. first shot was 827 fps, so right on the nose for my desired speed. So, disconnected the bottle and fired magazines as fast as I could. 40 shots between 809 and 827 fps. Looked like #40 was the end of the regulator, so stopped there. That's a 2.2% variance in pellet speed, plenty close enough for me.

I'll validate the tests again later, but for now, I'm stopping the adjustments. This is close enough for my purposes. Validation will be done with weighed and sorted pellets. Looking to see how consistent this combination really is.

By the way, all parts, except the Audrius regulator are stock. No parts are modified or replaced. Gun is 6 or 7 years old, hasn't been shot much. I probably fired more pellets through the barrel on this exercise (close to 2 tins by the time it was over) than the prior two years. That should help break in the barrel a touch.

Provided the validation backs up the initial test, I'm where I want to be. I'll let you know how it shoots. I've beat it a bit during this experience, so I just hope it shoots straight. probably be able to test shoot in a couple days.

Many thanks for the support and direction. Invaluable! I'll keep you posted.

Tom - spent last night weighing pellets. I want to see how tight the regulator really works, so getting pellets at same weight to 1/100 gram. Using Crosman Premier 14.3 Hollow points. Mostly because they are cheap and I'm going through lots of pellets in this testing. Sorted to the tenth of a grain, then resorted the 14.40 to 14.49's to 1/100 because that's where the most pellets were in this tin, and double weighing showed a couple mistakes from the earlier weighing session.

In the next couple days, I'll fill the Marauder to 3000 PSI, and do a 50 shot string to see how exact it really is. This is more of a OCD thing now, as unsorted pellets did pretty well with a really tight string.

I did notice that the pellets in this tin ranged from 14.16 to 14.70 grains. That's over a 3.75% variance ((14.7-14.16)/14.3 = 0.0377622) If I made a math mistake, it was 5:30 AM when I did the calculation! 

Now that I have the range much tighter, we'll see how she flies

More to come

Understood. 

All of the info above is based on shooting the same pellets from the same gun with no changes to settings to eliminate as much variation as possible. Changing pellet brands, or even switching between the Premier Domes and Premier Hollows would negate the value of the tests. So far all of my testing is with the Premier Hollows. The Premier Domes do shot at the same speeds, but for the sake of accurate testing, it'll all be done with the same pellets. The 18 grain JSB's shoot about 70 fps slower, so I may pick up some of the 15 grain JSB's later and give them a try. for now, it'll be tuned with the Crosman's.

Sort of like Matt Dubber's new YouTube video on slugs and the FX barrels. Counter intuitive - a perfectly polished barrel will actually slow the slug down, which is why he recommends a lubricant for slugs. Even the method of choking the barrel had a major impact on the results. The slightest variation in the equation of air pressure, pellet weight, alloy, and a half dozen other things can significantly change the results. It's a weird world we live in!

I need to watch the rest of your sorting videos. So far, results were excellent, but a bit strange.

Good News - I started with one magazine filled wit h 14.49 grain pellets.10 rounds with an extreme spread of 4. (Dancing in the streets~!!!!!!!)

Next, tried a magazine of 14.41 grain (.08 grain difference). Extreme spread 4. More dancing in the streets!

Now for the weird. Last session, speeds ranged from 809 to 827 fps. Same brand of pellets, but different tin. Unweighed and unsorted. Still, 18fps spread isn't bad.

Tonight, the speeds immediately jumped 40 fps or so. The 14.49's were shooting 870 to 874, and the 14.41's were shooting at 874 to 878 fps. Just to make sure it wasn't the different tin of pellets, I loaded up 5 magazines from the same tin that gave me the 809 to 827 range last time. You guessed it, up at 870-ish.

I double checked the adjustments and nothing changed. HS and HT are at zero. All I can think of is that I scalped an O-Ring and the debris was caught in something and it finally blew through the gun.

It's also down to 30 shots per fill. Not all bad though. I may leave it this way as the JSB 18 grains should shoot about 800 fps on this setup. That'll give me two pellets to choose with acceptable power.

Now for the ugly - definitely has a leak, so I probably scalped an o-ring last time I put it back together. That means I'll be polishing the tube before I thought I would. I'll pick up a shotgun swab and start with that. I'll also Dremel the holes.

I'll try again this weekend and double check the results. Very perplexing to say the least, but also means if I tear it apart to polish the air tube, I can start the tuning process over again if I want. Then again, this seems like a good balance, once I figure out how accurate the gun is at 50 yards.

I can see my weekend will be spent on the work bench cleaning up the gun. Plus, as long as I'm spending all this time on it, I just ordered the Hill Transfer Port and the 255 and 262 springs. I already have the lighter valve spring. will install all parts as soon as they come in.

I'll also check all the components you recommended above. Seems odd that it was so sudden but whatever. I'll dig in and figure it out. 

I figured when I bought the Marauder, it was my learning platform. Since it was adjustable, and had so many out there, I thought eventually I could make some custom tuning modifications and there would be people that could help, and now, after 6 or 7 years, I'm finally getting around to doing the tuning and you are helping lots! It's been a good shooter, but the tinkering is fun too.

When I bought the Impact, I kept the Marauder as a project gun. At this point in my life, I need a little technical stimulus as I don't have access to my wood shop. Long story there. Father is 94 and requires constant care. I can work on the gun in the basement where I currently live. The last couple of weeks tuning and tinkering have been incredibly fun! I thank you for all the input. When it comes to tinkering, the Impact is just too easy! (My hat is off to FX for the Impact, I love the gun, but really, I want that setup to shoot at 75 and 100 yards, the Marauder is fun to play with!)

I'll pick up a shotgun cleaning swab and get ready to clean / polish the barrel. I have a rotary tool that can debur the tube and will tackle all that this weekend. Probably take the gun apart (again!) tonight. Wife is a bit concerned that I keep tinkering, but I keep telling her it keeps me out of trouble.

I'll keep you posted . . . . This is getting seriously fun.

I'll sing praises to the Marauder in one other area - Simplicity. I had to completely rebuild the Impact last winter. While the Marauder has something like a total of 8 O-Rings, the Impact has something like 15 different sizes, and multiple installs of each. Don't even ask about the regulator O-Ring, that one alone took me an hour to re-install. Ernst Rowe did a complete YouTube series on the Impact tear down and rebuild. If you want to see a complex gun, watch that. Over the weeks (yes, several weeks to tear down and rebuild), I gained a lot of confidence in working with airguns.

So, I decided to regulate the Marauder. Super Simple compared to the Impact. I can tear it down in a few minutes and get it back together in not much more. It is much more difficult to play with the regulator than the Impact, but for tinkering and making it your own gun, it's incredibly simple and straight forward. I'm so happy I kept it as a learning platform. Even before I bought the Impact, learning how the adjustments on the Marauder worked get me ready to understand the adjustments on the Impact as they are roughly the same, just managed a bit differently.

I just bought the Shotgun cleaning kit and will start polishing the tube this weekend. When sharpening wood working tools, I use the sandpaper system and it should work nicely here. I'll finish off with some abrasive compound on the bore mop.

The Marauder is an amazing, underrated platform. Crosman's difficulty with barrel quality in the early models was probably one major reason, but the quality today is really up with some of the best. Before regulating, I was shooting 2 inch groups at 75 yards. The groups were one magazine each, so that's 10 shots each. Not bad for a $400 gun pretty much out of the box! Best part is that if I set it up as a 50 yard gun, but want to go to 75 yards, it's easy.

Much tinkering this weekend to do, but hopefully I'll have results early next week. 

Tube polished, and I can feel the difference. I also polished the hammer a bit. Took the rough edges off and smoothed the machine marks. Checked the settings as you specified. The HS and HT were still at zero (I did wrap the Hammer adjustment with teflon tape so it is tighter.) Set screw was still set properly.

I do have a question about the hammer set screw. I don't see one. There's an unthreaded hole on the top of the hammer, in front of the Stud Bolt. I wonder if it's a defective part? I'll have to call Crosman on Monday. If that's the case, I'll order a Hill Hammer to solve the problem.

I looking at the schematic from Crosman and it shows an Acetal Pin in the front hole, which is missing in my hammer. I can see the hammer threads through the unthreaded hole. I can see where the missing screw is needed to keep the hammer screw from moving.

I installed the lighter spring in the valve, and am waiting for the lighter hammer spring before completely reassembling. Polishing seems to have taken care of the O-Ring scalping problem. Used a Dremel tool as suggested to ease the edges inside the tube. The tube and punch outs are absolutely smooth. Kinda cool!

Lighter hammer springs and larger transfer port should be here Monday evening. I'll reassemble and test as fast as possible, but minimum waiting a couple days.

I noticed that the hammer has a compound on it that makes it difficult to turn. The coumpound was only on the first half inch or so of the screw. I suspect it as an attempt to save $$ at Crosman. Probably worked OK in testing, but in reality, the set screw is needed. I'll call Crosman on Monday and ask. My goal is not to use it, so leave it at zero. We'll see if it'll work or I need to adjust the hammer. At $65 the hill hammer is a bit pricey, so I'll stick with the Crosman for a bit.

Can hardly wait for tomorrow when the springs arrive. I'll be able to put this back together and do a quick test. Topped off my tanks yesterday, so I've got air to work with