HW45 answers

[clarky]

For anyone interested in the 45 I have spent some of my xmas school holiday meddling with one.
There is a common complaint of dieseling spoiling accuracy and reported poor showing from the MPL leagues suggesting similar problems.
The mistake being made is tuning for power. It does not require it but it does require accurizing.
My compression calcs etc revealed that the gun hits a flash point threshold very easily. This thing produces too much heat for oils being introduced (either at the factory or later by home tuners)
The key is to clean it out completely and run it totally dry. I also noticed that with the steel guide inside the piston (as is often recommended for more power) it produces more inertia. It also removes weight from the muzzle end of the gun as the piston bottoms in the opposite end. De-stabilizing the weight and balance through the shot cycle. I.E weight at the muzzle end suddenly shifting to the rear.
I tried the guide rod/weight at both ends. While it does appear that you get over 30 fps from the extra inertia of it down inside the piston, it nonetheless makes the gun slightly more difficult to control.
Given that I would not be using oil, I turned up a fresh guide rod from self lubricating Nylon 66 at placed it in the traditional way around at the muzzle.
Initially the gun felt less thumpy and shot to shot consistency had gone into SSP territory.
Result....if you can tolerate the 45 running at 4.7ftlbs (still plenty high enough for me) instead of seeking 5.7ftlbs....running dry and with guide rod at the muzzle end, this thing will place .177 Hobby into 1 inch circles at 10 yds all day long off hand. Tune it with oil and guide rod inverted and you will double the group!

[TonyL]

Nice little write-up, sir.

I love my 45 to bits. Never had a look inside it, I really ought to, one day, but then it's one of those "If it ain't broke, don't fix it" scenarios, I suppose.

What are your views, by the way, on the 45 using the PTFE piston seal? There has been a recent thread in General Airgun on the general unsuitability of PTFE seals in rifles, and them only seemingly being fine if the cylinder is absolutely perfect.....With the lower pressures and stresses involved in a pistol and, I'm guessing an accurately made cylinder in the 45, has anyone ever reported any long term issues? Has anyone had a play with a 'O' ring or parachute seal conversion?

[slugger]

im getting a 45 in a few days and wondered if you guys could point me in the right direction for a strip-down guide ?
also is there anything [mods wise] recommended for the 45 ? better spring-guide/top-hat? better piston seal ? does the TP [or equivalent] need enlarging/polishing ?
the only pistol ive worked on [in the last few yrs I mean, as a gat gun in my youth probably doesn't count] lol ...... is my lads hw40.. that was very simple to take apart/clean/lube and re-assemble [I actually made a new breath-hole for the comp chamber so as to ease cocking effort for my lad] , anyways back to the 45.......what are the "must do" mods/lubes etc, thanks , seb

[TonyL]

Google up "Weihrauch HW45 Review" matey.
There you'll find a very detailed review of this pistol. I think it's Todd Cooper and reference something like tbay/tel or similar, with strip down guide and various recommendations.
Excellent reading, it is.
Hope that helps.

[slugger]

funny you should say..I had just found and read > http://my.tbaytel.net/coopers/HW45Review/review.html

[TonyL]

That's the one!

[clarky]

Nice little write-up, sir.

I love my 45 to bits. Never had a look inside it, I really ought to, one day, but then it's one of those "If it ain't broke, don't fix it" scenarios, I suppose.

What are your views, by the way, on the 45 using the PTFE piston seal? There has been a recent thread in General Airgun on the general unsuitability of PTFE seals in rifles, and them only seemingly being fine if the cylinder is absolutely perfect.....With the lower pressures and stresses involved in a pistol and, I'm guessing an accurately made cylinder in the 45, has anyone ever reported any long term issues? Has anyone had a play with a 'O' ring or parachute seal conversion?

IMO the PTFE piston head is fine in the 45. PTFE does have a tendency to permanently deform, which in a powerful air rifle is more likely to occur. In the shorter 45 cylinder however, this has not proven to be a problem in my exp, while 45 cylinders are superbly true, possibly owing to them being much shorter than the rifles. So if PTFE is going to be used, its probably best in the 45....I wouldn't mess.
The problem with the 45 is one of dieseling. My best advice is to use some Weblube on the cylinder wall and piston but wipe it off, leaving something like the oily feel you get when you have wiped over a spanner. It will prevent wear enough but will not diesel.
The darn things are built to last donkeys years regardless of correct lubes anyway.
However, I do disagree with the spring guide rod being fitted down inside the piston.
There can be benefits to doing this but they are outweighed in accuracy terms (ive proved this with a technical rig)
There is definitely more forward shunt and very slight flip due to weight exchange. It must hamper accuracy, especially off hand. I initially only lost 34 fps by switching the steel original guide to the rear end but got 12 fps back by machining a new one from Delrin.
The gun performs best with Hobbys or JSB match (Weihrauch own recommendation but also Bowkett mentioned flat heads as being best)
It does like a decent red dot sight mounted quite forward. It likes some weight toward the muzzle which the current guide rod view hampers.

[clarky]

im getting a 45 in a few days and wondered if you guys could point me in the right direction for a strip-down guide ?
also is there anything [mods wise] recommended for the 45 ? better spring-guide/top-hat? better piston seal ? does the TP [or equivalent] need enlarging/polishing ?
the only pistol ive worked on [in the last few yrs I mean, as a gat gun in my youth probably doesn't count] lol ...... is my lads hw40.. that was very simple to take apart/clean/lube and re-assemble [I actually made a new breath-hole for the comp chamber so as to ease cocking effort for my lad] , anyways back to the 45.......what are the "must do" mods/lubes etc, thanks , seb

Slug, there is a good strip down guide through TRRobb easy way guides but also at least one on the web if you do some HW45 searches.
Like I said in reg mods, you must try to run the gun as dry as possible. The fast compression ratio (spring power, stroke and TP) all contribute to a gun which will flash over any high flash point oil you care to put in it, regardless of the oils high FP claims. Just clean it out and leave a meniscus on the metal surfaces. In other words clean all the oil out with a rag but dont use de-grease agents and do the job too well. This should give you just enough slight friction/wear reduction but prevent dieseling which wrecks the guns accuracy.
Top hats/weights etc appear to have no noticeable effects, other than employing the relatively massive guide rod to this use inside the piston. It will increase inertia, benefitting velocity by 35fps but increase the jump.
I have proven that weights can help overcome secondary compression recoil in rifles but the barrel is too short in the pistol....thus just increases inertia.
I am currently experimenting with further Nylon/Delrin guides for it.

[Adam77K]

Interesting. Mine does 5.7 ft.lbs in .177 with light wadcutters like Geco or R10. Very smooth to shoot but smokes a little from time to time, especially when unused for a time. I don't use Hobbies simply because they are a (literal) pain to seat properly with your thumb, and if you don't seat them properly you risk chewing up the breech seal with the skirt.

[clarky]

Interesting. Mine does 5.7 ft.lbs in .177 with light wadcutters like Geco or R10. Very smooth to shoot but smokes a little from time to time, especially when unused for a time. I don't use Hobbies simply because they are a (literal) pain to seat properly with your thumb, and if you don't seat them properly you risk chewing up the breech seal with the skirt.

The Hobby has a quite heavy but soft skirt to it, where your seating problem is often mentioned as a problem but controlled tests have revealed one of the most accurate pellets for the money ever made. Its because the skirt merely seals the pellet but the head must not be deformed. The soft large size of the Hobby skirt may damage slightly due to tight skirt but does a wonderful job of sealing if you can trouble to thumb them in correctly, producing incredible gas tight consistency and high velocity.
Ive never been able to beat the pellet in HW barrels incl the 40 pistol, provided I take care when loading.
In recent tests with a FAS 604 and Steyr pistol they produced the second best group behind R10 out of 6 top choices but R10 are considerably more expensive.

The 45 should produce upto 5.7ftlbs regardless of the 4ftlbs nonsense sometimes quoted on here. Its fine for plinking set up like this but it will not win MPL matches no matter how hard we try, or who shoots it. However tuned down as I describe it has a real chance of getting into top 5 points

[slugger]

im not worried about power, my lads hw40 [which I de-tuned] only made 3 ft lbs max....and now after the mods about 2 ft lbs........and its still crazy accurate for plinking ranges..no, I'd rather end up with consistency and minimal recoil/muzzle flip.. I wont really comprehend this central guide/rod you guys are on about until ive got mine and pulled it to bits....... but im assuming I can make a piston sleeve [is there space?] to help keep lubes where they should be and not work their way infront of the piston seal ?

[clarky]

im not worried about power, my lads hw40 [which I de-tuned] only made 3 ft lbs max....and now after the mods about 2 ft lbs........and its still crazy accurate for plinking ranges..no, I'd rather end up with consistency and minimal recoil/muzzle flip.. I wont really comprehend this central guide/rod you guys are on about until ive got mine and pulled it to bits....... but im assuming I can make a piston sleeve [is there space?] to help keep lubes where they should be and not work their way infront of the piston seal ?

Slug, no you wont be able to use a piston sleeve. There isn't room to get one in, indeed the fits in the 45 are just about perfect. Its very hard to improve on except for the fact that HW and one other tuning houses decided it was a wise move to put the spring guide rod the other way around. This was 20 years ago when power was everything.
The guide rod is merely the length of bar with a top hat which passes through the mainspring to keep it straight when cocking and reduce vibration upon firing. It can add inertia to help over come secondary compression rebound in rifles when fitted inside the piston. This extra mass helps to drive the piston down hard to overcome piston rebound issues but only in guns with sufficient barrel length to create big enough secondary compression issues in the first place.
With the 45 there is only a negligible effect here (30fps) but it hates the extra thump down when trying to control it....at least according to the rig I built to test it.
Also if the guide is down inside the piston, the opposite end of the mainspring is not guided at all as the spring unwinds.
Im currently toying with a small top hat of Delrin inside the piston and a 3 parts as long guide at the usual end of Delrin. I will use self lubricating Delrin A/F.

[slugger]

I think ive got you... make sure to make 2 of the guides and tophats , ;0

[slugger]

clarky, ive just had a look at an exploded diagram..... I can see now exactly what you mean . it does indeed seem logical to have the guide at the muzzle-end so it stays stationary/les mass when firing, however, is 'some' of the guides job to keep the coils of the spring away from the cocking linkages ? I only ask because in the diagram they look to go through the comp-tube and piston [if this is correct then the tabs will be inside the piston and vulnerable to the spring rubbing on them] ?

[clarky]

clarky, ive just had a look at an exploded diagram..... I can see now exactly what you mean . it does indeed seem logical to have the guide at the muzzle-end so it stays stationary/les mass when firing, however, is 'some' of the guides job to keep the coils of the spring away from the cocking linkages ? I only ask because in the diagram they look to go through the comp-tube and piston [if this is correct then the tabs will be inside the piston and vulnerable to the spring rubbing on them] ?

No it just looks a bit like it might in the exploded view. HW even had the guide the regular way around when they first built it. I think they switched it around about 91.