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barrel work

Barrel Work

I can supply new barrels in the usual airgun calibres .25, .22 and .177. I have some issues with the current quality of Walther airgun barrel blanks, so now exclusively use hammer forged BSA blanks. These are made by the traditional method of hammering the barrel blank with carbide hammers on precision carbide mandrels to create the internal barrel surface. BSA barrels have a unique style of rifling pattern, twist rate and choke, which has been tried, tested and refined for over a hundred years. They generally have better linearity and concentricity than their button rifled European counterparts, and it's also notable that they tolerate a wide range of different pellet types better than any other barrel make I know. These forged blanks are parallel ground and cold blued with a superb rich deep satin quality of blueing. I regularly machine these blanks to prepare replacement barrels for all manner of different airguns, by profiling or porting them to fit an existing action eg SKAN, Rapid, Stealth, Steyr, Alros, Crosman, Daystate etc.
Please note, I do not supply barrel blanks or barrels in .20 cal.

If you require a replacement barrel for your airgun and I've come across this make or model before, then you may not even need to send me your original to copy, as I can often supply a drop-in replacement made to exact specified length dimension etc. For unusual barrels, customers frequently send me their original to copy the threading, porting, breech lead-in, or various other dimensions. This is the best scenario, as when I have the original I can often improve on sloppy, loose, or out of spec dimensions on the commercially machined item, or of course provide for custom requirement.

Some of my replacement barrels are for the Gunpower / Airforce range of air guns, as yet another appeal of these guns is their versatility which allows easy interchange of barrels. This can give you a barrel length and/or calibre change conversion in literally minutes, and the swap over can even be done in the field.

To prepare this type of barrel, I firstly reduce a barrel blank to the required length (a Mr hacksaw job), taking care to retain the choke if present. After squaring the ends, the main portion of the barrel is profiled by reducing the barrel diameter to accomodate the breech slide. Sometimes the hammer slide area is additionally profiled to allow users to use the same hammer when swapping barrels. These profiled friction areas are generally left with a mirror polish. The breech is then crowned or slightly radiused both internally and externally, and pellet fit checked. The equivalent (much more complex) process with firearms, would be called chambering. I then prepare it for screw cutting at the muzzle by carefully reducing to diameter and provide a thread run-out groove. Taking care to retain concentricity with the bore, a ½" UNF x 20 thread is cut with a single point tool over many passes to give the finished thread for attachment of a standard sound moderator. A custom made thread protector ring is made and fitted at this point if required.

All my muzzle threads are lathe cut with carbide threadform tips precisely aligned in a special tool.
These tips are unique for every different threadform and pitch, and are made to very exacting manufacturing standards. They are essentially form tools, which inherently have all the threadform information for pitch geometry, thread crest and root radii. The threadcutting process is done at slow lathe speed around 50 rpm, taking as many as thirty separate passes of the tool to form the final thread, and when done with care, produces a beautifully formed polished thread to precise specification. Following this I crown the barrel at the muzzle with a special tool, usually providing a polished 11° target crown.

For barrels prepared for the Gunpower range of air guns, these also require custom made aluminium bushes to be made , fitted, and precisely aligned. If required, a frame end cap, through which the new longer barrel will protrude, is custom made at this point in a range of different materials to customer design preference.

If a barrel requires a transfer port to be cut, e.g. for a Rapid Seven, Daystate etc, this is an important stage as all barrels, even top quality match grade barrels have bends in them, but these generally aren't seen until revolved on a lathe. Some barrels like the Career which are pencil thin and made of very soft metal, always have bends. Walther barrels have more substantial diameter but usually have multiple bends in them, ie kinks, but BSA barrels are the truest of them all. These have virtually no visible run out on the lathe, however, even these barrels have slight bends, and it is important to identify where these are.

To do this the barrel is first run between centres on the lathe to prepare a short section at the breech which is parallel and concentric with the bore. This removes and prevents any concentricity error, ie. run-out, from interfering with the measurement. Then, holding by this part only, it is rotated very slowly in the lathe to observe the distant muzzle end which will be seen to transcribe a circle. This identifies very precisely where the linearity deviance is at the muzzle end, and I extrapolate this back to the breech, where it defines the circumference position for cutting of the transfer port, which is at 180° to this. This work is done so that the axis of the bend is in a vertical plane relative to the transfer port, which in turn ensures the ballistic curve and the optical sightline are in the same plane. If the port is cut at 90° or some other angle to this, the barrel will always be inaccurate, as although you will be able to zero for accuracy at a certain distance, ranges before or after that will be out of ballistic alignment. This is similar to the old gunsmith technique of "shooting the barrel round", but with modern PCPs, you only get one chance at this when machining porting, and it is very important to get it right.

I select only the finest barrel blanks available from BSA, and I do work of a guaranteed high standard. This often proves to be a winning combination, producing a major accuracy turnaround for many different types of airguns.
The accuracy of a barrel in any given action, is however affected by many different factors, and can therfore never be absolutely guaranteed.
Accuracy of my barrels is consequently never implicit, and no assurance of combined performance or accuracy is either stated or implied.


Advisory note for UK FAC holders.
 

If your air rifle is registered as a Section 1 firearm then you categorically do need a variation on your Firearm Certificate (FAC) to own a second barrel capable of being fitted to this gun, and all Police Authorities in the UK are unanimous in their requirement in this respect.

You would therefore be committing an offence if you attached an unlicensed barrel to your Section 1 firearm,  the same as if you attached a moderator which was not listed on your firearm certificate. 

The point at which the second barrel becomes an S1 firearm in law in its own right, is when your handling recipient RFD (Registered Firearms Dealer) transfers it over to you, and at this point it should be written into his firearms register, and your FAC variation permitting ownership filled in accordingly.  i.e. you need a variation slot available and it should be completed as soon as you attach the new barrel to your action.

If the weapon is an FAC gun, it doesn't matter whether or not it's air or powder, or if the configuration of the barrel has any effect on the power output.  Any barrel which can be fitted to the gun must be included on the certificate.

Therefore if it is your intention to fit a new barrel to a S.1 firearm, that barrel must be included on the FAC and the handling RFD should treat the transaction accordingly.

 
Gallery last updated 16th March 2010


.20 cal crown
.25cal barrel with oil blued jewelled sleeve and polished transfer port showing linearity mark and breech lead in
.25cal barrel with oil blued jewelled sleeve and polished transfer port showing linearity mark before porting
.25cal barrel with oil blued jewelled sleeve and polished transfer port
.25cal barrel with oil blued thread protector ring profile
.25cal barrel with oil blued thread protector ring showing UNF thread and crown
.25cal barrel with oil blued thread protector ring
.25cal barrel with oil blued TPR
.Oil blued sleeve with jewelled banding for Rapid action block 2
11 degree target crown .22cal
Alros muzzle convertion
Alros with original and new BSA barrel
Baikal Makarov with new .177 cal BSA barrel, and CO2 bulb screw
Baikal Makarov with new .177 cal BSA barrel, breech detail and polished replacement butt screw
Baikal Makarov with new .177 cal BSA barrel, breech detail closeup
Baikal Makarov with new .177 cal BSA barrel, crown closeup
Baikal Makarov with new .177 cal BSA barrel
Barrel after foresight removal, with thread and ring
Barrel blank, in the white, muzzle threaded
Barrel blank, in the white, profiled for Stealth
Barrel blank after crowning and muzzle threading, complete with thread protector ring
Barrel blank after crowning and muzzle threading complete with thread protector ring
Barrel blank after crowning and muzzle threading
Barrel crown, UNF thread and ring closeup

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