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]

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

[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.

[airgunnut]

There is a common complaint of dieseling spoiling accuracy and reported poor showing from the MPL leagues suggesting similar problems.

My compression calcs etc revealed that the gun hits a flash point threshold very easily.

The key is to clean it out completely and run it totally dry.

I found that lubed pellets have the same effect, the air as noted is at the flash point of some pellet lubes, but to run the gun dry? I would look into better lubes (for the gun) with a higher flash point

[tinbum]

Can you not use slip washers due to the spring binding! If so, has anyone tried tophats, spring guides, slip washers with a coil or two less spring?

If it were possible I think a smoother 45 running 4-5fpe would be the wasps-nipples!

[clarky]

Can you not use slip washers due to the spring binding! If so, has anyone tried tophats, spring guides, slip washers with a coil or two less spring?

If it were possible I think a smoother 45 running 4-5fpe would be the wasps-nipples!

First whatever you do don't use Silicone oil/grease externally on any gun. The emollient acids in silicone will ruin any finish, even bluing. Don't do it.
Yes obviously you could use a top hat but would need to remove the same amount of material from the main guide to allow the mainspring to cock.
Essentially, Beeman set the spring design so that it was almost fully spring bound with the std parts. Its a true statement that virtually nothing can be done to improve the 45.
The main argument lies with which way round you have the guide but personally I found a reasonable improvement in accuracy for a negligible loss (to me) in velocity with it fitting in the traditional manner. A Delrin guide will reduce guide rod friction on the mainspring for a small gain but the std item is already a perfect fit....so no gain in vibration damping was noticed by myself, except with it fitted forwards.
I would recommend you don't remove coils as its often fraught with problems. Introduction of heat into the spring ends. Getting the end square etc.

[clarky]

First whatever you do don't use Silicone oil/grease externally on any gun. The emollient acids in silicone will ruin any finish, even bluing. Don't do it.
Yes obviously you could use a top hat but would need to remove the same amount of material from the main guide to allow the mainspring to cock.
Essentially, Beeman set the spring design so that it was almost fully spring bound with the std parts. Its a true statement that virtually nothing can be done to improve the 45.
The main argument lies with which way round you have the guide but personally I found a reasonable improvement in accuracy for a negligible loss (to me) in velocity with it fitting in the traditional manner. A Delrin guide will reduce guide rod friction on the mainspring for a small gain but the std item is already a perfect fit....so no gain in vibration damping was noticed by myself, except with it fitted forwards.
I would recommend you don't remove coils as its often fraught with problems. Introduction of heat into the spring ends. Getting the end square etc.

Results
After turning up a replica solid Nylon guide (self lube Nylon 66) with 2mm removed from the base of the guide to allow a 2mm slip ring down inside the piston. (Guide fitted conventional muzzle end) I got no noticeable reduction in vibration, or increase in smoothness that i could detect. Over the Chrony i did get 9fps avg (13fps high) but i do not really view this as being worthwhile if you do not have the means to perform the machine work.
Conclusions..
Your HW45 must be run virtually dry with just a meniscus over the piston and guide rod. Even then you might still get the odd flash but Weblube rubbed into the metal well but wiped back off should leave some of the lube behind in the surface structure of the metal.... i got no dieseling and group size responded accordingly. Your guide rod can go down inside the piston for 30 fps jump in velocity as it increases the inertia due to mass increase but responds with approx 10mm extra on your group size .177 cal (.22 not tested) My Nylon guide gave me 10fps back....so i will stand the 20fps drop and take the better accuracy of the guide conventionally fitted.
Well thumbed Hobby gave the best accuracy/velocity combo.
The gun is already near perfect but too hot for lubes.

[TonyL]

Yep,
Both the .177 that I had years ago (should never have let it go!) and the .22 that I currently own love Hobbies.

As regards lubrication, a couple of thoughts:-

If it's better to run dry or very nearly dry, how about burnishing some moly into the cylinder walls / piston? This could take the form of either dry moly powder, used sparingly, and worked in, or the Dri-Slide type lubes.

On quite a few springer rifle threads, many have used Krytox. Now, if I remember correctly from those threads, it's very expensive, but you only use very tiny amounts and its flashpoint is far higher than other lubes ????? I also seem to remember that it's PTFE based and that all surfaces should be scrupulously clean (obvious anyway!) and that, if switching away from Krytox, it's the devil itself to remove all the tiny traces that have to be removed.

There has often also been talk (more so in the US) of the effectiveness and suitability of the Tungsten Disulphide based lubes.