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Brocock Concept Lite accuracy issues; need input/tuning advice

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bad_lighting

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Apr 8, 2020
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KY
I've been shooting spring piston airguns for 30+ years and this is my first PCP so I don't have much in the way of first hand experience with what should be acceptable performance or not. It's in .177 and I've tried a variety of pellets and it shoots JSB Monster "Redesigned" 13.43gr the best but it's only holding about an inch for 10 rounds at 50 yards. Frankly I was expecting better than that. Others that I've tried are Barracuda FT 9.57gr, Barracuda Match 10.65gr, Crow Magnum 8.8gr, RWS Basic 7.0gr and H&N Field Target Trophy 8.64gr. All of those are shooting from bad to ridiculously horrible- 3-5" at 50 yards. All of these pellets shoot well in my various other airguns.

Further, the JSB Monster v2s shoot most accurately with the power setting on medium vs. high or low. On low power the accuracy is extremely bad at 2-3" at 20 yards and high power produces groups about 1.5" at 50 yards or about a 50% increase in group size over medium power.

Now I'm well aware of barrel harmonics and handload for all of my centerfire rifles etc. so I figure that the pellets are operating at a particular velocity that the barrel likes. (also note that I've installed a DonnieFL suppressor which doesn't affect accuracy, it's the same with/without it) I'm wondering if it's possible to tune the gun via the hammer spring tension and improve accuracy by jumping up to a higher harmonic node and/or if I just have a sub par gun and need to send it back to the factory. I really don't want to send it back as my experience with BroCock thus far has been terrible with respect to customer service and parts availability.

I tried it out at 90 yards this afternoon and while there was a bit of wind around 10 mph the pellets were all over the place and it would barely keep 10 rounds on an 8"x11" target. The factory barrel/shroud seems quite flexible to me compared to anything else I've experienced barrel-wise. All of my other air rifles have solid steel barrels instead of shrouds/jackets and have basically zero flex. The barrel on the Concept Lite is flexible enough that I can deflect it with my fingers quite easily. Is this normal? It seems pretty suspect to me.

Other info: I've triple checked all screws, optic, mounts, barrel screws etc. for correct torque and used thread locker on everything. Gun is operating at correct pressure and has low ES/SD in the 2-4 FPS range. No complaints there and the shot strings seem to be stable. It's really odd to me that it's so finicky with the pellets and the power settings. In all my previous experience there is usually small variation in accuracy between pellet types with a few standouts but with this rifle the Monster v2s shoot okay to decent (excellent in my book is 1/2" or better at 50 yards) with all the rest being terrible to unbelievably bad.

EDIT: I've put about 1200 rounds through the gun thus far so it's broken in and I've cleaned the barrel/seasoned it multiple times.

As I am completely new to this brand/type of air rifle I'm hoping to get some expert advice or at least some general input regarding PCPs in the hope of improving the performance and accuracy. Other than that I like the rifle overall. The trigger could be better but in general I'm really happy with the rest of the rifle. Thanks in advance for any help anyone might be able to provide. I'm looking forward to the community's input.



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Is this a regulated PCP? 90 yards in a 10 mph wind with a .177 and expecting to group well is asking a lot. But as far as your other accuracy issues. Brococks tend to be very, very accurate shooters. So something is definitely off. You say that the pellets doing badly in the Concept, shoot “well” in your other guns. Do you mean they group better at the same 50 yards? I’ve found that it takes very little wind to move my .22 JSB 18s even at 40 yards, stretch it out to 90 or 100 yards and you can miss an entire sheet of 8x11 as that pellet can easily be blown 4” in either direction depending on wind speed. A 1”, 10 shot group at 50 yards is a good start, halving that could be a goal, but it wouldn’t be the norm, especially with any sort of noticeable wind.
 
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I think if you single load you should get acceptable accuracy. Agree with dairyboy 10.34gr JSB Exact and 10.34gr Air Arms also try Crosman 10.5gr Premiers Ultra Magnum. Often times the magazine would be the culprit. I have 2 of the Hilites and recently got a Sniper HR in 177. I'm surprised yours didn't like the 10.65gr Barracudas so it must be your magazine. YO!
 
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Is this a regulated PCP? 90 yards in a 10 mph wind with a .177 and expecting to group well is asking a lot. But as far as your other accuracy issues. Brococks tend to be very, very accurate shooters. So something is definitely off. You say that the pellets doing badly in the Concept, shoot “well” in your other guns. Do you mean they group better at the same 50 yards? I’ve found that it takes very little wind to move my .22 JSB 18s even at 40 yards, stretch it out to 90 or 100 yards and you can miss an entire sheet of 8x11 as that pellet can easily be blown 4” in either direction depending on wind speed. A 1”, 10 shot group at 50 yards is a good start, halving that could be a goal, but it wouldn’t be the norm, especially with any sort of noticeable wind.
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Yes, it has an internal regulator, Huma I think. It doesn't have an external regulator gauge though. With respect to other pellets shooting well, both the Barracuda FT and Match shoot 1" or less with my Beeman R7 (which is 30 years old now) at 50 yards but they shoot 2"+ with the Concept Lite. Literally the same tin of pellets so I know it's not a lot issue or quality control issue.

I'm getting plenty of vertical spread as well as horizontal. I'll see if I can't get out to the range when there's less wind and I'll post some group pics. I appreciate all the input as I really don't know what to expect accuracy standard-wise from Brococks or PCPs in general.
 
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If it doesn't work out even by single loading then if you have a return option I suggest getting something else such as a 177 Daystate Renegade HR (Huma Regulated) theres a very big difference in quality and accuracy. I have both so I can give you this opinion. The electronic trigger on the Daystate is to die for! Pellet friendly with a lot of different pellets too including a variety of cheap Grossman Wal-Mart pellets. It's more consistent over the crony than my 177 Daystate Redwolf and Pulsar and gets 80-100 shots depending on fill pressure. Easily sub 3/8" groups at 50 yards. YO!
 
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I think if you single load you should get acceptable accuracy. Agree with dairyboy 10.34gr JSB Exact and 10.34gr Air Arms also try Crosman 10.5gr Premiers Ultra Magnum. Often times the magazine would be the culprit. I have 2 of the Hilites and recently got a Sniper HR in 177. I'm surprised yours didn't like the 10.65gr Barracudas so it must be your magazine. YO!
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I'll order up some of the JSB Exact Heavies and try single loading to rule out the magazine. Frankly from what I've seen of the magazine it's a good design and doesn't unlock/produce side force until the bolt has the pellet completely seated in the barrel. Not sure why the magazine would be causing accuracy issues unless maybe the pellet is being presented to the bore off axis? I appreciate everyone's input.
 
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Problem is alot of airguns usually are pellet picky. Meaning you need to try alot to shoot good in it. Just cause they shoot good in another gun doesn't mean anything. You need to find THE pellet for every gun. For .177 usually JSB/AA 8.4gr and 10.34gr are usually good bets. For .22 JSB/AA 16gr and 18gr are also good bets. Now of course not all guns will like them and then you need to try others. I just don't think you've found THE pellet yet.
 
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The most important thing I read from your questions is the gun shot 1" groups at 50 yards when you got it but is doing much worse now. That means something has changed and you need to figure that out. Also 1" isn't bad for a .177 if there was a little wind.

Regarding the trigger how could it be better? Brococks have excellent, highly adjustable triggers. The only issue I had with mine was the previous owner had adjusted it much too light. It was all the way down to a couple ounces and sometimes didn't reset. Have you tried adjusting yours?

Regarding your comment on the barrel stiffness, if the shroud is similar to the other Brococks, which it looks to be from the photo, the shroud should be quite stiff. I can pick my Commander up by the barrel shroud and not even feel it flex nor get poi shifts Is it screwed in tight?

How do you clean the barrel? What tools do you use?

Regarding the magazine, is it getting seated properly? That can cause misalignment of the pellets with the bore and damage them. It is always a good idea to try single loading when tracking down an accuracy issue to insure it isn't related to the magazine. 
 
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Do you have a chronograph? It's hard to know what to expect if you don't know the velocity. This is almost mandatory equipment for powerful PCP's. If any given pellet is flying out at 1,000 fps the groups will be poor. 1" groups at 50 yards with .177 outdoors should probably be considered quite good.
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The most important thing I read from your questions is the gun shot 1" groups at 50 yards when you got it but is doing much worse now. That means something has changed and you need to figure that out. Also 1" isn't bad for a .177 if there was a little wind.

Regarding the trigger how could it be better? Brococks have excellent, highly adjustable triggers. The only issue I had with mine was the previous owner had adjusted it much too light. It was all the way down to a couple ounces and sometimes didn't reset. Have you tried adjusting yours?

Regarding your comment on the barrel stiffness, if the shroud is similar to the other Brococks, which it looks to be from the photo, the shroud should be quite stiff. I can pick my Commander up by the barrel shroud and not even feel it flex nor get poi shifts Is it screwed in tight?

How do you clean the barrel? What tools do you use?

Regarding the magazine, is it getting seated properly? That can cause misalignment of the pellets with the bore and damage them. It is always a good idea to try single loading when tracking down an accuracy issue to insure it isn't related to the magazine.
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For clarification: it shoots 1" with the ammo it most prefers and everything else is a far second. Nothing has changed with respect to sudden accuracy loss or similar. The first thing I did was dissasemble the trigger and see just how far it could be adjusted etc. I have it down to 1lb take up and 2.5lb break with the factory trigger and springs. It has a *lot* of overtravel. Probably 1/4" or more. My centerfire rifles usually have two stage triggers with 1lb take up and 1lb break with effectively zero over travel so the Brocock trigger isn't very good by my standards.

I think the Brocock Commander has a much larger diameter shroud than my Concept Lite has. I think that would account for the rigidity. With mine you can easily deflect it with a single fingertip at the muzzle. I took the shroud completely apart and re-tightened everything from the ground up when I first bought the rifle and then checked it again after 1000 rounds. Everything is still tight and correct.

Cleaning the barrel I use a draw-through line with patches and Simple Green for a cleaning agent. Pretty straight forward.

With respect to the magazine, it seats firmly and positively. Frankly I've been pretty impressed with the precision and reliability of the magazine thus far as I don't think it's caused me any issues, but I'll revisit it and double check just in case. I'm going to try single loading with the tray today and see what that does, if anything.
 
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Do you have a chronograph? It's hard to know what to expect if you don't know the velocity. This is almost mandatory equipment for powerful PCP's. If any given pellet is flying out at 1,000 fps the groups will be poor. 1" groups at 50 yards with .177 outdoors should probably be considered quite good.
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Yes, I have a chronograph. The JSB Monster redesigns are the slowest at just under 780 FPS, which jives with the factory listed 18ft/lb maximum rating. The lightest pellets are running about 910 or so. Way below subsonic and far enough below 1K fps that I don't think I'm seeing overspin issues etc.
 
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A Pull through and patches has a hard time removing built up lead in the choke. Matter of fact, it wouldn't. Had a daystate (same barrel I believe) that needed a bronze brush to get it clean. I wouldn't be afraid to make a few passes with with a brush and pull a few more patches to see if you end up with silver flakes on the patch. After a good polishing with JB bore paste, a brush was no longer needed. 
 
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A Pull through and patches has a hard time removing built up lead in the choke. Matter of fact, it wouldn't. Had a daystate (same barrel I believe) that needed a bronze brush to get it clean. I wouldn't be afraid to make a few passes with with a brush and pull a few more patches to see if you end up with silver flakes on the patch. After a good polishing with JB bore paste, a brush was no longer needed.
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Interesting point and something I hadn't considered. I guess I can pull the barrel off and run a brush through it properly and find out.
 
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