Anyone put a Lothar Walther barrel in .177 or .22 QB78?

[imadunatic]

I found Bob's .25 LW conversion and I'm going to borrow a couple ideas from that to nail down the stock barrel (I'm thinking the second top set screw as well as adding the 2 #6-32 set screws back on the sides near the pellet tray); but it got me wondering if anyone has upgraded the stock barrel on their QB to a LW barrel?

Currently hunting for some better long range accuracy (still haven't found the best pellet for this gun, at least not at long ranges) and I know this is the extreme answer, but it seems like installing a LW .177 barrel has got to help long range accuracy.

Any opinions? Just blush and eyeliner to go with the lipstick on a pig or is this a worthy upgrade?

For a little 10m 5 shot group porn, I shot this .190" group tonight (in terrible winds, but I was patient) with Crosman Premier Ultra Mags. If these would group under an inch at 50 meters I'd say I found my pellet, but they open up to .700" at 20m and go WAY wonky at 50 meters. All out of the JSB exacts, but should have some here Wednesday for more testing, I'm hoping the perfect pellet is near, for if I can't tighten this up at 50 meters I'm going to start considering more extreme measures.

[Gerard]

Well if you're after really long airgun distances, 50 metres and beyond, and if you're in a windy place... it seems you've answered your own question. Pretty close to zero long range bench rest types go with the smallest pellet. Most are getting into. 25" or .30" and some even bigger. .177" can manage out to 50 metres in dead calm but many find it challengingly wind-pushed even at 30 metres. But take that with a grain if salt as I'm far from expert in the longer stuff, most of my shooting being 45 metres and closer. I like the shortened .22" barrel on my QB78D as it groups nicely at those ranges. If I were considering a lot of 50 to 70 metre shooting I'd probably go to either my full length barrel (adds about 10% velocity with any given tune, over my 13.4" barrel) + hotter tune + .22" in heavier weights (25gr or heavier - currently loving the 18.13gr JSB), or to a .25" barrel.

[happymecanic]

I'm currently building a QB78D with a .177 LW barrel, but it'll be for 10 to 25 meters target shooting. Over that distance, I guess wind drift would be a major factor in accuracy. However, since I haven't tried it yet, I have no hard data to provide. My rifle will be fed by a 90 grams CO2 cartridge, with a modded valve and custom tank block. The barrel is 23 3/4'' in length, so there's potential for high velocity, but I don't know yet how it'll perform at long ranges. I guess a heavy pellet (10+ grains) shall help. I must add that I had good results at 40+ yards with a bone stock  .177 Umarex Surge at 40+ yards, with 7.9 gr. CP match pellets so maybe there's hope

[Ribbonstone]

Trajectory and windage is set by velocity and  pellet BC.  Better pellet BC's are normally with larger caliber, heavier weight pellets, generally with a roundnosed shape.

Short range shooting is great for weeding out the really bad shooting pellets. Doesn't really predict the best longer range choices. So far, the best at longer ranges have two things in common: round nosed shape, medium to heavy weight for the caliber.  Well...that pretty well goes back to a pellet's BC, as heavy round nosed pellets generally have higher BC's.

I've not had the best of luck with Crosman pellets in QB barrels. although other folks have....that luck just skipped me along the way.  Suspect you might find the same is true for you, I'd certainly not condem a barrel for not shooting well with this or that pellet (so long as it shot one pellet or another well).

Do have some still running on their issued QB barrels.  Have had some poor QB barrels, but mostly on the early ones.   Have rebarrled one years back with a 5mm HW blank and have a .25 LW barrled  upper half (not my rebarrel job...this one much nicer than I can do) on a PCP tube.

Worth rebarreling?

Don't know the cost of having one rebarreled by someone else (in today's market), but it's not going to be cheap.  Even if you've the tooling to do it yourself, LW blanks aren't cheap.

BTW: That .25 LW was originally on a co2 conversion (bulk fill). Really wasn't hard to get +30 foot pounds out of it (and suspect there was more to be had with valve mods).

[imadunatic]

Don't know the cost of having one rebarreled by someone else (in today's market), but it's not going to be cheap.  Even if you've the tooling to do it yourself, LW blanks aren't cheap.

BTW: That .25 LW was originally on a co2 conversion (bulk fill). Really wasn't hard to get +30 foot pounds out of it (and suspect there was more to be had with valve mods).

Wow... 30 FPE on CO2 is impressive!  This is currently being bottle fed CO2 though I'm thinking it's going to HPA this winter. I have the ability and equipment to fit the barrel myself and I didn't think the LW prices were too terrible (albeit more than I paid for the just the gun!); but what I'm really thinking is that if I want to consistently shoot long ranges I need to leave this .177 alone once I find the right pellet and then build a .22 or .25 just for long range shooting. I think half the fun of these guns is the tinkering.

Jason's thread got me thinking that these QB's are quite capable and if I could hold that ~.2" group at 25 yards I'd be tempted to call this a win for shorter ranges (and as everyone has said, move on to a larger caliber for really long ranges if I so desire). What I should probably do first is move over to HPA and get the velocity up a ways (currently running around 685 fps @ 75 degrees) and then see how it performs.

[Ribbonstone]

Actually, had that bulk-fill .25 made at Mountain Air quite about 9-10 years back, so the nice barrel work and bolt conversion isn't mine but Roy's.  Just a basic conversion.  Lost track of what that costs back then.  31gr, at 665fps isn't too shabby for co2.

Then that air tube got converted to a long-tubed HPA.  Mostly run on 850psi output, would do just a little better than co2 so far as energy.  Run on 1200psi output, would get into PCP energy levels.

Then all the "guts" and the .25 upper were used on a 3K PCP tube conversion (it's still being used that way).  Not a large air volume, but was looking for power at that time and wanted to make it to 60 foot pounds (have dialed it back down to a more sedate speeds now).


Point being, while a good custom QB barrel, well fitted to the breech, doesn't have to be a one-use item. Kind of like LEGOs, the parts interchange well and good parts tend to get used in ways you haven't thought of yet.

Have rebarreled a few air rifles from blanks, but the only QB I personally did was back when MAC1 offered some 5mm HW barrel blanks (think he was clearing out odds and ends).  That might have been 7-8 years ago.  Was a learning experience.  Think I got the breech end almost "right" a couple of times before deciding to cut it off and try again.  Got to where I was happy, the barrel ended up shorter than full length, but it's been a very good shooter.

That upper has also been on a couple of rifles.  Used for a long time as a HPA conversion, recently went back to being a simple looking 12gr. co2 rifle (mostly built from spare parts).  Kept tuning it and adjusting, until I managed +60 shots per fill at +11 foot pounds per shot. 

The other QB based rifles still use QB barrels.  Might have been shortened and massaged a bit, but at least one has had nothing done to it at all (except keeping it clean).  If I had the LW blanks in my hands, I'd not rebarrel them.

But you may be jumping the gun here.  Considering the $$$, would certainly test a lot of pellet types, keep it clean, look over the crown, take a really hard look at the breech area, etc. before condemning a QB barrel.

[Taso1000]

Guys,

Can the 21 grain .177 H&N Piledrivers be made to shoot at 100 yards and beyond?  It seems like they would be the ultimate long range .177 pellet but I haven't seen anyone test them this way.  What barrel twist would they need to be accurate?

Thanks,

Taso

[imadunatic]

But you may be jumping the gun here.  Considering the $$$, would certainly test a lot of pellet types, keep it clean, look over the crown, take a really hard look at the breech area, etc. before condemning a QB barrel.

I think you're right. I've re-crowned recently and I did notice a tight spot near the muzzle that I may need to look at closer if it persists (I've not had it apart lately since I deburred the crown). It's close enough to the end that I think I could just trim the length and start fresh if need be. My brass screw crown job ended up being huge because the stock crown was terrible. Not sure, but I'm thinking the giant crown might be too much.

I'm no expert, maybe someone else can chime in (this is about as good a picture as I could get) as to whether or not this is alright. I did notice a small burr that I subsequently removed and it did help the group a little, if I can't find a pellet it likes I'll probably trim it back and put a smaller, cleaner crown on it instead of this beast.

[nervoustrigger]

That looks quite good, as best I can tell on my phone's display.  But I strongly recommend pushing a couple of pellets through and make sure they do not hang up even in the slightest as the head emerges from the muzzle.   That is far and away the most certain way to confirm there is no burr.  Much better than the cotton swab test in my experience.

[Ribbonstone]

Odd as it seems, the ONLY barrel I got to shoot the 21gr piledivers from was one  cut-down QB barrel.  Out of 13 .177 rifles tested, from 6 foot pounds to 32 foot pounds, the only one that showed promise with those long pellets was a shortened QB barrel.

Give you an idea of size/length/shape:



WHY this barrel likes them and the other 12 didn't...I do not know.  Even other QB barrels didn't shoot them well, LW/CZ/BSA/and "who knows" barrels didn't shoot them well. Choked/unchoked and long/short didn't seem to matter.  All of about the same twist rate (measured). Velocity didn't seem to matter.  For some odd reason that one barrel "liked" them and the other 12 didn't.

And that barrel had some things working againt it. 
 Not uncommon for cut-down QB barresl to have the bore off center.  This one is, but as there are no heating issues as there are in powder-burners, can pretty well ignore that (although it can complicate an LDC addition).



Home-brew hand tool crown job (but not a bad one):



Pretty short barrel (where I'd have likely picked up speed with a longer one).  Did have a nice stock made for it, in an odd style, but one that works well in your hands (not so well from the bench):



 But it shoots well enough to be useful at least to 40-50 yards (remider: this is the best of 13 different rifles tested):



IF (and it seems from my tests to be about an 8%-10% chance) you do find them shooting well,  then the BC of the pellet seems to be an amazing .08 over the short range (lets say 0-40 yards) with some evidence of it being even better at longer ranges.  Thats about 2-3X better than the better .177 pellets, and really does make an improvment in windage/retained energy.

Also seem to get unstable  AFTER contacting a critter.  May not be a bad thing, but I'd not count on them for extra-deep penetration.
http://www.network54.com/Forum/79537/message/1473009275/Non-graphic-+no+%26quot%3Bnude%26quot%3B+chickens...21gr.+piledriver+tests

[Gerard]

Looks very uneven on my Note 3 phone screen. Blew it up and took a screenshot, then added a couple of notes in red;



The groove on the left looks perfect, very clean geometry. But the one on the right is barely there, and what remains looks smeared and more curved than flat. There seem to be a few of each type as I look around the crown. This sort of result is the reason I stopped trying the brass bolt and abrasive method, as it's in line with the circumference of the bore and as such tends to smear steel across the grooves instead of away from the bore axis. Instead I've gone to using first a grinding burr then a rubber abrasive burr in the Dremel with the barrel spinning in my small TAIG lathe. The burr spin is tangential to the crown's edge, pulling steel towards the outside of the barrel. I use light touches to begin with, very even pressure and softly, then as it gets closer to finished I lighten further and further until just barely touching the steel. My results give fairly neatly defined grooves. I only wish this barrel's grooves ran a bit deeper... but it's fairly accurate for my ranges.



You can see where I've just left the initial Dremel grinding burr marks away from the crown edge, no need to fuss there. The innermost edge is the only important element. And these marks serve here to show the direction of the tool's rotation, perpendicular to that critical edge. I could have gone finer, perhaps used a hard cotton burr with buffing rouge on it, but really didn't see the need beyond getting a fairly clean exit point.

[nervoustrigger]

Now that I'm back at my PC and can see it more clearly, I agree with Gerard.  There are a few places around the circumference that have questionable features.

Also, the method he describes which helps draw the burr out of the bore is a technique I also like to use.  At least I think we are talking about the same thing.  I would term it "radial polishing", meaning the abrasive action is from the center of the muzzle outward to the perimeter.  For a visualization:


However having said that, circular polishing like the brass screw technique can work equally well.  You just have to be careful, go slowly and let the abrasive do the work.  If you apply force in an attempt to speed things along, what happens is metal gets pushed into the bore.  If the abrasive works it down, eventually there will be a wire edge that will fall away and you'll be left with a crisp, burr-free transition from the bore to the crown.

[Gippeto]

Any opinions? Just blush and eyeliner to go with the lipstick on a pig or is this a worthy upgrade?

Not a 78, but a largely custom 79. IMHO...the LW barrel was a very worthwhile upgrade. Likes 10.3 JSB's (4.52mm head size) the best with Baracuda match a close second. Typically 3/8" groups at 50 yards.



5 shot 25 yrd groups...10.3 JSB's on the left, Baracuda match on the right.



Al

[Ribbonstone]

Looking for preeconcieved notions.  Scope always beats iron?  Crosmans can't shoot? QB's can't shoot? 12gr. co2 guns can't shoot? .177 always more accurate than .22?  Things that some folks hold to be true just as "common knowledge".

Targets: Benchrested, really good day, as close to dead calm as it gets,  great lighting, etc. About as nice a day as comes by when these were shot (all on same day) 5 shots each bullseye/20 yards.
#1


#2


#3


#4


#5



Rifles used. Notice, one is not scoped. One was a .22, but round nosed pellets and close clustering makes that hard to tell.  One runs on a 12gr. Co2 cartridge.



A = .22 cal AA s200
B = .177 AR2078
C=  Alfa Proj (a co2 rifle...kind of a lite-weight match gun) using apature sights
D =.177/2260 Crosman HiPac (rebarrled with a take off RWS 850 barrel).
E = .177 cal AA 200T

So if you want to play...then match the target to the rifle.  It's pretty much just going to be random guessing.

So list the LETTERS first (A, B,C, D..etc)  then the target number after each letter.
Like:
A 1
B 2
C 5
Etc.


Point being that it IS GUESSING.  Get to a certain point, the differences won't matter for most uses. Can certainly measure them with a caliper, or see the differences it would make in scoring a real bullseye, but for 99.9% of what we do...it doesn't make a rat'srump.

[imadunatic]

Thanks for the replies guys. Exactly the analysis and insight I was hoping for. I'm gonna break it down tomorrow night and chuck it up in the lathe to dress the crown. I thought it looked like a burr, but I wasn't sure the best way to deburr it without making it worse, carbide burr and buff makes perfect sense.

[Atomic Powered Gruds]

Such great info here, I have no clue when I will be able to do anything with my own rifle let alone when I can get a new/used one to tinker with. I have a 1322 and want a QB/Crosman and am trying to trade my Benjamin NP would like to trade into a good Co2 or at least get my moneys worth in parts/tools or a couple of clunker rifles. Really not worthy getting into a rut, I would love to tune the 1322 at least but am out of lube, only got the Crosman silicone springer stuff left right now. I babied the NP then found myself loving the 1322 that was bought for a cheep plinker .

 Ah well at least I can afford food and power so I can hang out with you guys. Seriously though you guys and all this information helps keep me from going insane ... more so than I already am.

[imadunatic]

Ok guys. Pulled apart the QB for a closer inspection on everything and right off the bat I noticed that my bolt O-ring is tearing AGAIN... I've replaced it a couple times, made sure the bolt wasn't bent, polished the lead and it still insists on tearing up o-rings.

Which leads to my next question, when polishing the leade, do you actually ease the sharp edges of the rifling? I think I'm going to use Timmy Mac's split dowel/wet dry paper and spin method to polish everything. Can I go too far with this?

Also, I have 2 tight spots in the barrel, for lack of a better way to quantify what I was feeling, I pushed my cleaning rod against a kitchen scale to measure force required to move the pellet. It takes 6 pounds of force to get the pellets to enter the barrel from the chamber (I assume the rifling is sizing the pellet as I can see tiny remnants of the rifling on the head and skirt), then it takes about 4 oz of pressure to move the pellet through the rest of the barrel and then the last half inch takes about 1 lb 4 oz (ish... this is tought to measure, but it's definitely tighter for the last half inch). I can't see any anomalies in the barrel through my optivisors and it's definitely not the front sight hole, so I'm thinking that last half inch just needs to go. Is this a fair analysis or are there other tricks to buffing this out (JB bore paste on a brass brush perhaps?).

I have confirmed there is a burr on the crown and the pellet in the picture is right where the barrel starts to tighten up (it provided a nice reflection for the flash so I left it for the picture and so you could see exactly how far from the end it starts to get tight.



Thanks in advance for any suggestions guys. You're teaching me something new every day.

[Gerard]

Sounds safe enough on the leade, just don't go crazy and open it out so much that you need a bigger pellet just to seat properly. I'd put 600 grit paper on a dowel but with a few layers of masking tape between and a long conical taper on the dowel. The tape, not too tightly applied, should cushion the paper and allow for feathering the sharp edge while working the spinning dowel in and out.

I had a slightly uneven, sticky feeling barrel for my 2260. I split out a long piece of spruce and whittled it small enough to easily pass through the bore, then pushed a wad of 0000 steel wool (very fine stuff, bought at Lee Valley - I use this stuff all the time for polishing ebony) through 90% of the barrel's length from the breech end. Used a bit of tape on the stick to mark where to stop. This is a 'smooth twist' imitation polishing method, can't remember who advocated it first, but either here or on the Yellow forum. Pushed that tightly rolled, about 3/4" long wad of steel wool back and forth 90 times, then for the last 10 times (total of 100 pushes in each direction) pushed it all the way through the crown. The result was that pellets pushed through it with silky smoothness, and my group sizes shrank.

Sounds to me like you've got a slight barrel choke right where it's supposed to be. Wouldn't complain about that. It's often a good thing. You can just wear the thing in by shooting it, or polish as described above, or do some other method.

As for the probe O-ring... I got sick of those getting tattered looking after just 1,000 shots or so, so I made one out of 95 durometer urethane rod. Fussy stuff to turn on the lathe, need freshly sharpened bits, but it'll probably last as long as the rifle. This urethane is phenomenally elastic and durable, so I made it just slightly over-sized. Seals perfectly, not the slightest trace of air blowing back when a feather is placed in the breech. Same for the transfer port seal I made from the same stuff, which is slightly squashed into place.

[imadunatic]

Thanks Gerard, if need be I'll give the steel wool a shot.

So I'm guessing the excess force required to get the pellet into the barrel is not right? It should be a nice even push all the way through (including the transition)? Do you power polish (like in a drill) with the tapered wooden dowel or is this more something you spin by hand for a few minutes until the pellet glides into the barrel?

I bought some A90 A70 poly o-rings , but they're a smidge too big (size 003) and they just get destroyed the first time the bolt is cycled. I thought I read somewhere about modifying the bolt to accept the 003 O-rings but I cannot for the life of me find it. I'm thinking I may just need to open up to groove to the correct size for that o-ring? Maybe someone else recalls exactly?

Do you have any pics of the bolt seal you made? I have lathes... and tooling... and ambition... and ability and I'm not afraid to use all of them if need be! 

I'm guessing the urethane is something like this: http://www.mcmaster.com/#8695k171/=1454yw1

[Taso1000]

The force at the breech end of the barrel is the lands of the rifling imprinting on the pellet.  This is normal.  You want the imprinting to be gradual and smooth. 

So the lands have a smooth and aerodynamic transition.  You don't want the initial land impression to be bigger or wider than the rest of the barrel rifling. 

Also a burr or flash here or around the barrel port will shave of lead and through your pellets out of balance.

I hope that's clear enough lol

Taso