I could use some ideas

DanB

DanB

New member
Howdy all. I'm having difficulty maintaining a consistent velocity from my Independence and it's costing me points. The gun shoots at the 35 fpe level fine but put the power in the 20 fpe range and your talking 30+ fps spread with unsorted pellets and about a 20 fps spread with sorted. I've tried shooting at different pressures, 70-200 bar, different weight hammers, three different exhaust valve seats, many different lubes, different transfer port sizes, and many different pellets without positive results. When testing I usually tether the gun with a high precision Aqua Environment regulator, the pressure is very consistent. I also use an Oehler 35 and Pact mod 1 chronographs.
I would consider a spread less than 10fps, with pellets sorted to withing .04 grains, acceptable. If you can think of something else I could try I would appreciate it.

I would love to ditch the indy and build a rapid based on either a Smith or Dawson receiver but I don't think I could get it done in time.
Thanks,
Dan
_DPB8345.jpg
 
Seems the more you learn, the worse it gets? I have seen some barrels that need higher speeds to deliver consistency ... maybe this is what you have? In one case where I got one like this to work, it took shortening it about five inches to increase the blast required for that desired energy window.
 
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Gee Dan, you never mentioned you had an Indoor Range. When's the first match scheduled for?

I can't believe you're having that problem after seeing the scores you've been posting, plus after having doing most of the scoring on your targets and seeing them all up close and personal. My opinion is that you should definitely go back to the .177 as then you can crank your speed back up closer to what your gun is looking for. But, then again, what do I know?

Good luck this weekend shooting FT, and see you in a week.

Dave
 
therealld said:
Seems the more you learn, the worse it gets? I have seen some barrels that need higher speeds to deliver consistency ... maybe this is what you have? In one case where I got one like this to work, it took shortening it about five inches to increase the blast required for that desired energy window.
Click to expand...

Agreed, the more I learn the dummer I get. It seems about 95% of what I try makes things worse.
The barrel shoots well at full power so I won't cut it yet. I made some new thimbles for my smooth twist and BSA barrel tonight, I'll give them a try tomorrow. The ST is quite short at around 18".
Dan
 
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Dave Shattuck said:
Gee Dan, you never mentioned you had an Indoor Range. When's the first match scheduled for?

I can't believe you're having that problem after seeing the scores you've been posting, plus after having doing most of the scoring on your targets and seeing them all up close and personal. My opinion is that you should definitely go back to the .177 as then you can crank your speed back up closer to what your gun is looking for. But, then again, what do I know?

Good luck this weekend shooting FT, and see you in a week.

Dave
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I'm sure my parents wouldn't mind if we had a match in their basement;) My mom would probably make us cookies. The problem is it is only about 50'.
I've been thinking along the same lines as you, put the .177 barrel back on. It is frustrating since I can hook my kid's maruader up to the regulator and get single digit spreads at under 20 fpe but my damn fx puts out 30fps. The only fundamental difference that I can think of between my fx and most pcps is the exhaust valve. The end of the valve opposite the hammer is exposed to the ambient atmosphere. So what happens is that there is a tug of war going on with the valve. When closed the large end applies about 76 pounds (at 200 bar) of force to close the valve and the opposite end wants to open the valve by about 16 pounds of force. The reason behind this, I believe, is to reduce hammer bounce and less hammer force is required for a given output.
The arrangement adds extra friction to the exhaust valve opening. I may build a part that would eliminate the ambient pressure side of the exhaust valve as an experiment to see if it helps my at the lower outputs.
Dan
 
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Trying things that make it worse is the surest way to learning new stuff! When I am trying to solve a problem, I often make a fairly large change that I THINK will exaggerate the original problem. Sometimes it does, and sometimes it makes it better, or does nothing.

If it does nothing, I've learned the issue isn't sensitive in that direction.

If it gets worse, I try to do "the opposite".

If it gets better, well then I learn't again!

Anyhow, my experiences with accuracy and lowered power are in a way similar to yours, though not usually due to wider velocity spreads ... just worse accuracy. I've been having some luck by retuning to use closer to original pressure and slightly shorter barrels, though my experience isn't all THAT positive. Of course technically, as velocity is reduced, spreads need to get smaller to maintain the same percentage, but in the man, I have never noticed the setup with the very smallest spread to usually give the best accuracy.
 
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Well I determined the source of the excessive spread.......My BM barrel. I tried my original smooth twist barrel and a bsa barrel for comparison. The ST barrel for 50 shots of unsorted, lubed pellets averaged 764 fps, had an extreme spread of 14 fps and a standard deviation of 2. My bsa barrel for 45 shots averaged 737 fps, extreme spread of 13 fps, and a standard deviation of 2. Before I tested these barrels I ran 10 shots through the BM barrel. It had a 17 fps spread for just ten shots. The 26" bm barrel was about 40 fps slower than the bsa and 25fps slower than the 19" ST.
I found out something interesting too related to the testing procedure for the worlds. The benchmark barrel shoots kodiaks a good 2 fpe lower lower than 15.9g jsbs. My bsa barrel shoots kodiaks about .5 fpe higher than 15g jsbs. So if you have a BM barrel you can shoot the jsbs as high 21.5 to maybe 22 fpe. If you have a bsa or st no luck, you will be handicapped by about .5 fpe.
I don't know why my BM barrel is so slow and has such poor deviation at the lower powers. Joe's BM barrel definitely doesn't seem to have a consistency problem per his previous post.
Dan
 
sounds like your useing the wrong lube...it shows all the bite marks of bad lube..if your useing some lube that Roger L is useing -thats it.good luck in your quest.H.B.
 
deliterman said:
sounds like your useing the wrong lube...it shows all the bite marks of bad lube..if your useing some lube that Roger L is useing -thats it.good luck in your quest.H.B.
Click to expand...

Here is what I've tried so far for lube;
krytec
finish line ptfe chain lube
dry graphite
dry slide moly graphite
pledge
napier
dry silicone
dry ptfe
hbn
hornady case lube
royal purple
and no lube
If you have suggestions for lubes that I haven't tried I'd love to hear them.
Interestingly the pellets without lube produced the highest velocities and best consistency, only problem is the accuracy suffered.
Dan
 
Lube suggestion - Lanolin, Very fine powdererd carnuba wax, Lard, Lee Alox. Old school sometimes is a better choice
 
Dan,

I know this may be a dumb question, but have you tried Lube 1? I'll bring a can, or 2, along next Saturday if you haven't. I've got plenty!

Dave
 
Dave Shattuck said:
Dan,

I know this may be a dumb question, but have you tried Lube 1? I'll bring a can, or 2, along next Saturday if you haven't. I've got plenty!

Dave
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Slick 50 one lube? I have some, I've had it for about 20+ years, not empty yet, I haven't tried it yet on pellets. Thanks for the offer.
Dan
 
One Allan Zasadny's recommendation when we bought our Rapids. That's where Paul and I started. Haven't gone back to recheck yet, but probably should!
Dave
 
Dan,

That was chronograghed with only 5 shots, although I've chronographed 125 shots with an ES of 17 and SD of 6, there were better numbers with different pellets but these seem to be better with target results. That's a lot of different lubes you have tested, it makes me wonder if you got most of that out of the barrel when switching lubes. If you had pellets coated with HBN, it takes a lot of washing to get that off those pellets. When I slug my barrel there is a very light engraving on the head. Your BM (Benchmark) barrel will have a tighter bore then what we are using, head sizes will vary somewhat. Your particular barrel could have some small inconsistencies through out the bore.

When Jim mounted this BM barrel we kept it as long as possible 28 1/4" long the barrel is now 25 1/4" long, there was 0 change in velocity. I don't have any other barrels to compare the BM to. I did test a Broughton but the bore demensions were to big.

I always season the barrel with whatever lube I'm using after it's cleaned, it doesn't take anymore than 4-8 pellets to have it shooting. I don't clean as often as I should, sometimes I'll shoot a whole tin before I clean, but what I'm noticing is a change in POI in relation to the conditions, when running that many pellets through without cleaning. Brian shooting his .177 LW barrel uses a lot of lube where I don't, but you have 2 different barrels.
My experience is limited with these air rifles, there still a whole lot to learn and test.

Regards,
Joe
 
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Joe Friedrich said:
Dan,

That was chronograghed with only 5 shots, although I've chronographed 125 shots with an ES of 17 and SD of 6, there were better numbers with different pellets but these seem to be better with target results. That's a lot of different lubes you have tested, it makes me wonder if you got most of that out of the barrel when switching lubes. If you had pellets coated with HBN, it takes a lot of washing to get that off those pellets. When I slug my barrel there is a very light engraving on the head. Your BM (Benchmark) barrel will have a tighter bore then what we are using, head sizes will vary somewhat. Your particular barrel could have some small inconsistencies through out the bore.

When Jim mounted this BM barrel we kept it as long as possible 28 1/4" long the barrel is now 25 1/4" long, there was 0 change in velocity. I don't have any other barrels to compare the BM to. I did test a Broughton but the bore demensions were to big.

I always season the barrel with whatever lube I'm using after it's cleaned, it doesn't take anymore than 4-8 pellets to have it shooting. I don't clean as often as I should, sometimes I'll shoot a whole tin before I clean, but what I'm noticing is a change in POI in relation to the conditions, when running that many pellets through without cleaning. Brian shooting his .177 LW barrel uses a lot of lube where I don't, but you have 2 different barrels.
My experience is limited with these air rifles, there still a whole lot to learn and test.

Regards,
Joe
Click to expand...

A little while ago I tested some lubes and charted the results. My procedure was to first thouroughly clean the bore and then season it with the lube used on the pellets. I did one control group with no lube on the pellets, they were washed. What I found was that all of the four lubes tested at the time were markedly slower than pellets with no lube.
Here is a chart of the unlubed string,
no_lube.jpg

Here is the chart of pellets lubed with krytec,
krytec.jpg

What I found interesting was that the unlubed pellets velocity stabilized the soonest. They started slow and gradually increased fps until they started to plataeu about 35 shots in.
The krytec string started out very fast with the first shot, plummeted and then gradually began to increase fps. I think 75 shots was not enough for krytec to plataeu.
Most lubes started the string slow and increased speed.
It was an interesting experiment and shows that some barrels need some time to season after a cleaning.
Dan

edit, I should note that the pellets tested were unsorted.
 
blades said:
Lube suggestion - Lanolin, Very fine powdererd carnuba wax, Lard, Lee Alox. Old school sometimes is a better choice
Click to expand...

Thanks for the suggestions. I've ordered some lanolin, where do you get powdered carnuba wax and how is it applied?
Dan
 
Used as mold release, Plastic industry suppliers is a good bet. It is available in a solvent based spray or just use the powder mixed in with clean corn cob tumbling media and tumble the pellets in that for about 10 min. The Vibratory tumblers work well as they cause a swirling flow rather than a drum spilling and bouncing off the paddle/s in side. Another method is to heat the wax to a liquid state and roll the pellets in it ( same way Lee's liquid alox is used), I do not like that way as it is not that even and just need a dusting in our case. Not like cast bullets filling the lube grooves
 
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