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BSA R10 giving me fits trying to tune

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bchannell

Member
Nov 1, 2020
366
364
Parkersburg, WV USA
I just acquired an R10, and first shots at 30 yards show it to be a super accurate shooter. Chronograph results were, terrible to say the least. I got over 50fps ES on a 30 shot string, switched chronographs to make sure there wasn't an error and sure enough, it was true. Then the rifle developed a leak and I resealed it, and it was somewhat better. So, I started from scratch and am trying to tune it. I can get it down to roughly 30 shots with an ES of 17fps, and that's the best I've done so far. I turn the hammer spring tension up and it goes from 730ish to the 7teens, turn up hammer some more and it goes down again to low 700's. The funny thing is I'll get strings that are super consistent for around 10 or 15 shots, then the velocity begins to rise steadily. Today, I shot 705ish, then 715ish, then 720s, and steadily on up. I never have shot a complete bottle string, because I'm thinking it just isn't shooting right.
The last time I had a rifle that got lower velocity with increasing hst, was when my Brocock wasn't anywhere near heavy enough on hst and it was going crazy. Once I got it in the ballpark, wallla! everything started going fantastic immediately. But, I've got the R10 cranked, but maybe it needs more?
Also, I removed the reg and set it at minimum, put it back in the gun and it was so low, that no air was getting into the plenum, started raising it and it responded just as it should. Is this as good as the factory reg can do? It surprises me if that's true, as the HW100 has nearly the same design, and mine can do less that 10fps ES over it's entire cyl.
I'm just stumped on the R10 until I can find a direction. I'm thinking a Huma reg might help, and suggestions?
 
Sounds like your HS tension was not near the optimal percentage of 5% less than the max speed in correlation with the regulator setting. Once you go past the max HS setting that is optimal for your eg set point, the FPS drops. So whatever speed you are trying to reach starts with a reg set point, adjust HS fo find max speed then adjust accordingly. Sounds like you figured that out! Hope this helps and yes, the R10 platform has a small plenum so yeah, probably need to up reg pressure more than you might think 👍.
 
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OK, I'm with you. So, I cranked up the hammer several turns. I was actually trying to get it spring bound, but didn't get there is six or seven turn, so I went with it. Shot a 30 shot string. The velocities go steadily up from 700 to 732fps.
I'm going to crank the reg up a tiny amount and start with the hammer at it's lightest and move the hst up a little at a time and see if anything starts to make sense.
 
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Not an R10, but I had a BSA Ultra SE and Scorpion SE. Both had undesirable extreme spreads, but they were both unregulated. The hammer spring adjuster will bottom out before the spring will coil bind, but it doesn't stop turning, it stops in a threadless groove so it doesn't fall out into the action. At least the SE models I had were like this. Not sure if you have the older R10 that's based on the same action.
 
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Did you buy the R10 new or was it 2nd hand?
BSA regulators of old were not the best. Sounds like a regulator (if regulated) and/or valve issue, which can be maddening.
I changed out my BSA R10's (purchased new - 2015) OEM regulator to a Huma. I got about 70 shots (.177 cal.) per fill after going to this regulator.
I had also, made a blast tamer (hammer) bounce device which helped me gain about 10 shots per fill.


Can't remember what my ES is:unsure:.

In a Perfect World, when shooting at 50 yards, try to keep your ES at or below 1% if shooting at 700 fps. 700 fps x 1% = an acceptable ES of 7 :oops:.
If the gun shot at higher velocities, the acceptable ES can be higher.

The Best ES should be recorded when shooting at 95% of max velocity at any given reg. set-point.

Bob Sterne's article gives the details.
hardairmagazine.com

How Important Is Extreme Spread To Accuracy? - Hard Air Magazine

Extreme Spread is the difference between the fastest and slowest shots in a string. But how important is Extreme Spread to accuracy?
hardairmagazine.com hardairmagazine.com
 
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It's used and I really just did this tuning because of a leak, but it's not going well on the tune and I've never had this much trouble. I really don't think it's the firing valve, but it's possible. I've inspected every inch of the rifle and my take is, it's just a crappy regulator, but I can't say for sure. It is a newer Mk2, but I don't know what changes the reg went thru over the years. I'm thinking Huma, but don't want to spend the money if I'm not going to see a pretty decent improvement. I just need to shoot it more and see what's going on.
I did pull my Brocock Sniper out of the safe and shot two clips thru it just to see if my chrono was a problem. I knew I had stored it just above reg pressure, and it shot a 14 shot string with 11fps ES and it was just going off the reg on the last 4 shots, and that includes the first shot in several months, so I know on a regular string, the ES would have been lower. It's one of the most predictable guns I've ever owned. I've shot strings of 40 or 50 shots with an ES of 9fps at 900 fps. So the chrono is not the problem.
 
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I have been very fortunate for the last four years my Mk2 (.177) shooting lights out from the get-go. However, it recently developed a slow leak and after replacing all the orings and still having issues, I ordered a Huma reg.

The factory reg was set at about 110bar and I was getting 60 shots @ 850fps with H&N 10.65 Baracuda Match.

I installed the Huma reg visually set at 110bar without doing any hammer spring adjustment and it shot well below 850. I don’t recall exactly what it was. I turned in the hammer spring increasing the speed but started seeing a diminishing return.

Know that it took around 100 shots to get the reg to stabilize and provide an ES of 13 fps and an SD of 4 fps for 50 shots.
(Most tuners will tell you when increasing hammer spring tension does not increase speed, reduce tension and increase reg pressure)

I bumped up reg pressure without changing spring tension and was able to get the speed up to 910. This is right at the max speed and still keep it under the 20fpe rule for AAFTA FT. With a bit more tweaking of the reg and spring I am able to still get almost 60 shots on a fill.

I bought and highly recommend the reg tester for the R10 reg. They are on sale and worth every penny.

Right now, I've got my reg set right at 140bar. My goal is to find a reg/hammer spring setting that gives me at least 60 shots while keeping velocity in the 900-920fps range.
The saga to be continued…
 
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davecole said:
I have been very fortunate for the last four years my Mk2 (.177) shooting lights out from the get-go. However, it recently developed a slow leak and after replacing all the orings and still having issues, I ordered a Huma reg.

The factory reg was set at about 110bar and I was getting 60 shots @ 850fps with H&N 10.65 Baracuda Match.

I installed the Huma reg visually set at 110bar without doing any hammer spring adjustment and it shot well below 850. I don’t recall exactly what it was. I turned in the hammer spring increasing the speed but started seeing a diminishing return.

Know that it took around 100 shots to get the reg to stabilize and provide an ES of 13 fps and an SD of 4 fps for 50 shots.
(Most tuners will tell you when increasing hammer spring tension does not increase speed, reduce tension and increase reg pressure)

I bumped up reg pressure without changing spring tension and was able to get the speed up to 910. This is right at the max speed and still keep it under the 20fpe rule for AAFTA FT. With a bit more tweaking of the reg and spring I am able to still get almost 60 shots on a fill.

I bought and highly recommend the reg tester for the R10 reg. They are on sale and worth every penny.

Right now, I've got my reg set right at 140bar. My goal is to find a reg/hammer spring setting that gives me at least 60 shots while keeping velocity in the 900-920fps range.
The saga to be continued…
Click to expand...
Hey Dave,
You should be able to get 910/920 fps at 115 bar.
My R10, IIRC is set at 110 bar and got the above velocity using 10.34 gr. JSBs.

However, I did put in a lighter (aluminum) hammer and improved valve flow too - I did it so long ago .... I can't remember exactly:unsure:.
Motorhead, told me what to do to improve efficiency..... I may have installed a stronger hammer spring too.

Just got back into the gun after having it sit for 3+ year with a leak - that ended with the bottle breaking off the gun.
After my OEM bottle recently broke off the gun (moisture rot) I purchased a 280CC bottle w/SS connection, made a SSG and new LDC.

BSA R10 - 280cc Bottle - LDC.jpg


BSA R10 SSG1.jpg
 
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FINALLY, I made some progress! I changed everything, thinking, I wasn't getting any place as it was. I upped the reg a bit over a 1/4 turn. Lowered the hammer spring to about 3 turns in from where the cap would just fit. Changed pellets to AA 10.3gr domed.I got about 45 good shots. The first 3 or 4 were loopy as the gun was empty, obviously, when I made the changes, and every time I air up, it is flaky for a couple three shots. Then it settled in to 892fps avg, 11fps ES, 1.2% ES, 2.9fps stdev.. IF you take out a shot or two at the end, that may or may not be caused by going off the reg, then you get 35+ shots with 894fps avg, 7fps ES, .79% ES, 1.8fps stdev.
Now that's what I'm talking about. That wasn't a full fill either. It has a 200cc bottle IIRC and I filled it to 200bar. It has a 232 max fill, so I would expect a few more decent shots before going off reg.
I'm not sure what's up here, but these guns, (fac) don't like low reg pressure at all.
 
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Great to hear ;) - everyone goes through these issues with their guns to get their guns sorted out.

That said, the Huma regulator is the way to go on R10's if you really want to gain control over the shot cycle.
232 bar fill, 100/110 bar set-point and you should get 60+ good shots at the velocities quoted above.
The problem is - Huma's are pretty expensive. Just depends how much you like the gun because you'll likely only get some of your $$ back upon re-sale:whistle:.
 
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Well, update here, the next shot string was not as good. I was thinking the reg was not holding pressure but I don't have a test rig to see what the reg is set at. Sooooo, I ordered a Huma reg and installed it. First shot string 39 shots, 9fps ES, 1.0% ES, 907fps avg, These are the very first 39 shots from the new reg install. It came set at 110bar and I increased it to 130bar and installed it, pumped the gun up and shot two dry fires to get the reg filled with air properly and shot the next 39 over the chrony. Wow! what a difference! I still need to do a full string and see where the hammer is going to need to be set, but I'm pretty impressed with this. I have to say, I shot 19 shots, took a break and came back and shot 20 more, so pretty impressive I think.
Evidently, the factory reg was not working. I replaced the bellville washers and still no luck. I'm wondering if I had it just set way, way too low. I'll work on it at a later date, but for now, I'll shoot the Huma and let it settle in.

I would like to give a big shout out to HUMA. I ordered the reg on Jan 6 and it arrived today. Five days over the pond! Pretty impressive service indeed!!
 
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