Author Topic: B28A .22 (Timmy'd and TurboTuned) Review  (Read 4352 times)

Offline onemountain

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B28A .22 (Timmy'd and TurboTuned) Review
« on: November 24, 2009, 03:06:44 PM »


First a bit about the gun pre-tune, in its stock form. For those who may not know, the B28A is a Chinese clone of the Diana 350 magnum, a powerful German breakbarrel rifle. I bought my B28 used and largely broken in with about 1500 pellets through it. In stock form it weighs 8.5 lbs and is a whopping 49" long. Definitely muzzle heavy. The fit and finish were surprisingly good; I think that's one area where the Chinese have been improving things quite a bit lately. The butt pad could be a little nicer- it's ventilated rubber, and does what it's supposed too, but is a bit smelly lol. The long barrel and long piston stroke make for a long lock time, and the gun is unsurprisingly rather hold sensitive, and takes a good bit of technique to shoot. The cocking effort wasn't very high given the gun's power; that's largely due to the long stroke and the long barrel acting as a long cocking lever and reducing the force needed. The cocking cycle was just a little bit gritty with a fair amount of spring noise. The firing cycle had a good backward kick and a minimal forward jolt, making a good solid THWOCK! I was pleasantly surprised that there wasn't really any noticeable torque during the firing cycle. Unlike the original, it has a metal trigger. Unfortunately, that's about all the good that can be said about the trigger. It's first stage is about a mile long, and the second stage isn't quite smooth and creeps a bit. The trigger also wiggles a bit in the guard. But all in all the B28A is a good springer for the price, and quite powerful, at ~24 fpe.

• • •

Well, this morning my B28A in .22 arrived via FedEx from Gene Curtis, better known as Gene_SC here at the GTA. It had three things done to it: first, it stopped off at Tim's (GTA screen name Timmyj1959@yahoo.com) for a chop and a new crown. The stock barrel on the B28A is 19.5." He chopped it back to 15" and gave it a perfect crown. The advantages of chopping the barrel back are twofold: it reduces the guns notoriously long lock time, and makes more compact, which is something a 49" gun could definitely use. It's kinda funny to call a 44.5" gun "compact" though isn't it lol. The downside is that since the barrel acts as the cocking lever, the cocking effort goes up if you shorten it. However, I am more than happy to make the tradeoff, and Tim did an excellent job. Thanks Tim!

Next it went off to Gene's place for a TurboTune and a muzzlebrake. The brakes he makes are of the cocking aid/crown protecting kind. I asked for and received a 7" brake (he makes from 4-7" and I decided why not go all out lol). The brake extends only .125" past the end of the barrel. So while it gives a good grip for cocking, the gun is still compact compared to the stock model. Some people hang the brake out further to maintain leverage for cocking, but I'm happy with keeping her shorter. The weight of the brake helps maintain the muzzle heaviness, which helps keep the gun stable. However, the gun does balance better; it's not quite as muzzle heavy as it was in the stock form, and I felt that it was too muzzle heavy then. I think it's just about right where it is now. I won't be able to tell for sure until I scope her up, and that probably won't be tonight.

I won't go into the details of what Gene does in his TurboTune, that'd take too long. You can read about it at his website here.

Here are the differences I've noticed post-tune. Please keep in mind that I've only been able to get a handful of shots through the gun. I haven't scoped it up yet, and I probably won't be able to shoot any groups to share until the weekend. Bear with me folks, I'll probably maybe get around to it sometime doing that if I remember to. On to what I've noticed so far:

Fit and finish: I guess I'm using the category name a bit loosely here. No, Tim and Gene didn't refinish it or reblue it or anything. The only difference is that the barrel's shorter and has a big ol' muzzlebrake on it. I think it's definitely an improvement aesthetically.

Weight and balance: the gun weighs 8 lbs even now. It also balances a bit better, and it no longer feels like I'm swinging a flagpole around trying to point at something. Shorter is definitely better for this gun.

Trigger: a bit smoother and lighter, and the second stage isn't too bad now, it breaks more crisply. It would take a dedicated trigger tune (or better yet, complete replacement) to truly sort this trigger out. I'm beginning to think I should adjust the first stage out entirely because most of the issues are with it.

Cocking cycle: Noticeably harder, but that's because of the shortened barrel. That said, it doesn't feel all that much worse. It's definitely smoother, and substantially quieter.

Firing cycle: a sharper feeling, dulled linear THUD. No torque. Very smooth. The discharge sounds vaguely like a whip cracking. Not a supersonic crack, just enough to come across as meaning business. The kick she has also tells you she means business. No way around recoil at this power level in a springer. The perceived noise of the gun firing is lower to me as the shooter. I don't know how it is now for a bystander as compared to before. I need to get someone to just stand nearby and listen to get any real definitive answer on the noise issue. One thing I do know is that this gun is NOT neighbor friendly. That's the price of power. You can't have your cake and eat it too. Well, at least not unless you spend a bunch of money and get a kick-a** shrouded PCP!

Hold sensitivity: I won't know how it is until I can get out and shoot some groups.

I'd like to add a little note here: During one of my pre-tune shooting sessions I thought I began to notice the gun's firing behavior mellow a bit. I wrote it off in my mind as it just really starting to break in. I also had trouble shooting it from that point out. Well, it hadn't broken in. It had just plain broken- the spring, that is. Gene sends the old springs and guides back with the gun, and lo and behold my spring comes back in two pieces. Sure helps explain why it suddenly got harder to shoot! I don't own a chrony so I didn't have that method of checking the gun's health. When the gun started shooting erratically I assumed it was me, and started moving the targets in closer. If I'd just taken a few longer shots not at a noisy target I probably should have noticed that the sound of the pellets going down range was different shot to shot, indicating wildly changing velocity, and providing a hint of the broken spring. So a lesson for all us airgunners without chronies: know how far your gun should penetrate a given material or what the pellets should sound like going down range when its healthy, and occasionally check to see that it is using these measures. If I'd done so I would've figured out what was going on. All that said, I guess it's good I sent it off to get tuned when I did…

Consistency: here's where things start getting really interesting. The pre-tune numbers are abysmal to the point of irrelevancy due to the broken spring. 70 fps standard deviation and 232 fps extreme spread abysmal.

Post-tune, using Gamo Hunters (15.3 gr), 10 shot string: Average: 847.9 fps. Low: 837 fps. High: 861 fps. Extreme Spread: 24.0 fps. Standard Deviation: 8.1 fps. These numbers are ok, but they don't do the tune justice. You need to see the string to see why:

848
843
837
839
842
846
851
853
859
861

Or better yet, the change shot to shot:

-5
-6
+2
+3
+4
+5
+2
+6
+2



The shot string drops at first then climbs steadily, as opposed to fluctuating around a central value. I don't think this gun has settled into its final average fps yet; apparently it's still climbing up toward it. I assume this is because of parts getting more flush or the piston seal seating itself better or something mechanical like that; perhaps a tuner can enlighten us as to why. Note that the velocity is stepping up in small increments, never more than 6 fps in this case. I take that to mean two things. First, it's not too far off its final average. And second, it's going to be very consistent around that average, much better than than the given 24 fps extreme spread and 8.1 fps standard deviation. It's a pity that I don't have a chrony; I may never know what power level it settles into. But again, I don't think it'll be much above what it's at now.



Power: How can anyone write a review of a magnum springer without mentioning power? Well, in all honesty it's the category listed above this one that's all important. Consistency is the name of the game. I'm used to hearing about guns receiving Maccari parts in a tune losing a little bit of power. I was expecting around 22-23 fpe post tune. Not exactly what happened. For the string above, the energy she's getting at the average velocity is 24.43 fpe. But given that the velocities are still climbing I think last shot in the string is the most representative of whatever energy she'll settle onto. And the energy of that shot is 25.20 fpe. Talk about exceeding expectations! That would correspond to 842 fps with predators…



So far I'm simply delighted with how this gun turned out. It's lighter, balances better, looks better, cocks smoother, cocks quieter, shoot smoother, shoots quieter, and shoots harder. What's not to like?



I'd like to end with a big thank you! to Gene and Tim. This is all their doing!



I'll add pics later, hopefully later tonight. Still got things to take care of..

Yea, though I walk through the garden in the shadows of pests,
I will fear no squirrel: For thou art with me;
thy scope and thy trigger, they comfort me.

()()                          
(O.o)      
o( ()()  ~In memory of Alu~

????? ?aß?!

Offline Jaymo

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Re: B28A .22 (Timmy'd and TurboTuned) Review
« Reply #1 on: November 24, 2009, 03:20:37 PM »
Sweet. I really should send my long-barreled R9 to them for a chop 'n tune.
15th Battalion, Mississippi Sharpshooters, CSA.

Il buono, il cattivo, ed il brutto.

\"Mmm, bacon.\"
\"Squirrel.\"
\"Mmm, squirrel.\"

Offline Gene_SC

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Re: B28A .22 (Timmy'd and TurboTuned) Review
« Reply #2 on: November 24, 2009, 04:55:01 PM »
Great objective and thorogh review Eric. I have to say that Timmy's work on the crown was beautiful. He has an exceptional eye using the proper grit stones. I think the b-28 is a very well ballanced shooter now that you have had a few inches taken off the barrel..:) But I am a bit bios towards carbines..:)

You will notice after a hundered or so shots that your accuracy will get mor consistant. The barel was completly stripped of all lead deposits. SO seasoning has to be worked back into it.

I also thought your B-28 with the nice wooden stock was just beautiful after it was all done and cleaned . Please show us some pictures of it.
THE ONES I SLEEP WITH: BSA Lightning XL, AA TX-200, AA ProSport, BSA Ultra, HW-97K, Crosman NPSS .177, FX Cyclone, HW-30 Nicle Plated, AA-S200, Crosman Marauder, CZ-634, R-9 DG, Webley/Scott UK Tomahawk, Benji Kantana, Benji Marauder, Benji Discovery.....
....

Gene\'s Tunz n Toyz
Springer Tunin

Offline onemountain

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putting off pics until tomorrow..
« Reply #3 on: November 24, 2009, 05:56:41 PM »
..because they came out awful with the lighting I have available tonight and my cruddy camera. Will try to get some daylight shots tomorrow.
Yea, though I walk through the garden in the shadows of pests,
I will fear no squirrel: For thou art with me;
thy scope and thy trigger, they comfort me.

()()                          
(O.o)      
o( ()()  ~In memory of Alu~

????? ?aß?!

Offline KK0605

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RE: B28A .22 (Timmy'd and TurboTuned) Review
« Reply #4 on: November 25, 2009, 02:20:08 AM »
Great review Eric! Can't wait to see the Carbine B28!
Kyler
*~K~*~K~*
My one and only air gun: TF89 .22!
http://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=23042&posts=11#M183344

Hunts:
http://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=23067&mid=183338#M183338

Everyone is a genius at least once a year. The real geniuses simply have their bright ideas closer together.
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Offline onemountain

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UPDATE: PICTURES!
« Reply #5 on: November 25, 2009, 06:58:31 AM »


most of the pics are pretty self explanatory, but a couple: the macro function on my camera was misbehaving and I couldn't get a proper picture of the crown. Sorry Tim Also, the last pic shows the cause of a delay in making the bed to take all these other pics






























Yea, though I walk through the garden in the shadows of pests,
I will fear no squirrel: For thou art with me;
thy scope and thy trigger, they comfort me.

()()                          
(O.o)      
o( ()()  ~In memory of Alu~

????? ?aß?!

Offline kp4att

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Re: B28A .22 (Timmy'd and TurboTuned) Review
« Reply #6 on: November 25, 2009, 08:21:34 AM »
ONEMOUNTAIN....NOW I KNOW WHY DO YOU KNOW SO MUCH ABOUT SHORTENED BARRELS.... HE HE HE.... GOOD BLESS YOU ///  GERALD
-------------------------------------------------------------
GERALD (KP4-ATT): PUERTO RICO ISLAND!!!
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(Feb 3, 2010)
SUMATRA 500cc .22 - mira: Centerpoint 6-24 x 50 mm

MARAUDER .177 - mira: Leapers 8-32 x 56 mm (30mm)

RWS 48 .177 -     mira: Leapers 4-16 x 50 mm

RWS 350 .22  -  mira Centerpoint 3-9 x 50 mm

GAMO WHISPER VH .177 - mira BSA Panther 2.5-10 x 44 mm

953 .177 (INDOOR) - mira Simmons 3-9 x 32 mm