The XM177E2 build continues

The customer had asked if they could come and watch key stages of the build and who am I to argue even if it is an unusual request. Luckily I know them very well.

Today was profile the barrel as per the previous exercise, carry out some basic assembly to confirm fit and modify the FSB (Front Sight base)

 

 

 

 

 

The original XM177E2 had the casting mark ground off on the rear of the base and the bayonet lug removed, so that is what I did. Note the tear drop forward assist on the main rifle picture, I am trying to get a look as close as possible to the original rifle.

The profiling went well although I did opt for a fine finish contrary to the original, I just could not live with the thought of building something that looked like it has been roughed out with a rasp on a Pole lathe…

I need the butt stock to arrive and we can then complete the assembly and run a couple of test rounds through it, then Cerakote and off to Proof. Oh, I also need to complete the muzzle device/sound moderator. I have decided to build it in three options:

1. Standard and 100% correct to the original Colt drawings.

2. Standard looking but for a spigoted barrel to give an 11.5″ overall look (XM177E2)

3. Standard looking but for a spigoted barrel to give an 10.0″ overall look (XM177)

I wonder how many people machined a barrel to the correct M177E2 profile today.

The picture shows the M177E2 11.5″ barrel look and the roll of hockey tape is there to hold the FSB up as it was just starting to rotate under its own weight which I think is a reasonable fit considering it will need painting.

Barrel profiling

There are probably a reasonable handful of people in this country who profile barrels in house and I do a modest number for ourselves and occasionally others RFD’s, however I always think it is rather special when I profile something out of the ordinary such as this one.

This is a dummy barrel to check the profile of a barrel destined for a Colt XM177E2 replica build, the only difference being the original barrel was 11.5″ in length and this one is 12″ to keep the build within the UK 12″/”4″ laws, or barrel length not less than 12″ and overall length not less than 24″

Why the test run? Well as much as I have confidence in my programming it is always nice to run the part in a soft metal first to confirm fit and this run exposed a tightness where the front sight base (FSB) fits which is annoying as I am good to the original drawing, albeit at the upper end so the FSB must be on the tight side and we have a stack up of tolerances. I will modify my program accordingly.

This was nice to machine as I did not need a steady due to the short length. Cycle time was a very steady 21 minutes and a few seconds and I will need to increase my feed speed on the finished article to leave some machining marks as the original would have had.

Chamber will be 5,56×45 NATO and it will be attached to an A1 upper and skinny hand guard.

Next job is machining the muzzle device which is a flash hider/sound moderator combination.

EDIT – In case you were wondering what an XM177E2 is I have attached an image from http://retroblackrifle.com/ who are my go to on-line reference for such things (Hope you don’t mind guys!)

Sound moderators

As well as designing and manufacturing our own sound moderators in house, we can supply and fit other makes when requested. Today was a Wildcat Predator 12 on a .308 Win Howa and as the Howa is pre threaded in 5/8″ UNEF it is just a matter of ordering it in and screwing it on, or nearly..

Firstly I like to correctly fit the rear bushing which means removing the bushing, screwing the moderator on, measuring the diameter of the barrel immediately behind the moderator and boring the bushing to suit.

People ask what the purpose of the bushing at the rear of a reflex moderator is and really, it serves a couple of purposes. Firstly it prevents excessive radial loads and damage to the moderator female thread where it is screwed on to the barrel and secondly, it allows the manufacturer to design a fairly generic back end to the moderator which can then be tidied up with the bushing.

I usually bore the moderator bushing with +0.25mm on the diameter of the barrel, or around 5 thou all round which is ample for expansion and general use. People ask why and there is an easy answer, it is my preference.

 

A Dremel is not the tool for opening the bushing and I seriously question why a person or shop would do this. It takes probably 25 minutes to measure, bore and fit the bushing, explain the safe use and maintenance of the sound moderator, fill in the table 1 of the new owners FAC and kick them out of the door and joking aside, I would always sooner spend 25 minutes explaining things and giving them a correctly fitted moderator, more to the point, we do not charge separately for this service.

I have read various views on bushing clearance and the implications of its lack of so I have added a picture of the moderator I run on my Accuracy International. It is a custom reflex with a stainless steel front and inner tube and an aluminium rear body, at the rear it is bushed with an internal O ring that contacts the barrel. Accuracy wise it works very well.

Once the bushing is bored and fitted I walk the customer through the do’s and don’ts of sound moderators. Never leave it on your rifle after you have been out shooting, regularly strip and clean the internals, keep an eye on any O’rings fitted and replace them if required and most importantly, lubricate the threads on the muzzle and the moderator with a wipe of copper grease or similar. WD40 will not do!

…and why am I telling you this? Because you need to know.

The Shooting Shed Støtteben F/TR bipod MkV – Another run.

I keep getting asked about our Støtteben bipod so it must be time to make another run of 25. For those of you who have not seen one, the Støtteben has a proven track record and is in use by multiple national teams and is well represented within the F Class league.

The SHED Støtteben bipod is manufactured from 6082 T6, A4 and 316 stainless with some Nylon washers thrown in for good measure so it is not going to rust!

This tried and tested super wide and super light F/TR bipod is the evolution of the original SHED ‘Plain’ bipod and is lighter, wider and sleeker, it has many new features such as the T Nut assembly and has a second fixing which is an M6 grub screw designed to screw into a dimple in the rail to give a second locking point and also act as a recoil lug, this means the bipod is always returned to the same position on the rifle when it is fitted. The elevation screw pitch has been reduced to give finer elevation control yet still with the left/right hand thread system so no more winding for 10 minutes to get the height you need. The feet are wider with added radiuses to give even tracking regardless of the width the bipod is set to.

Finish is vapour hone with hard anodising so a very flat black without any shiny bits to reflect light. The leg sections from the elevation fixings to the head are solid sided to give maximum rigidity and triangulation and this also gives somewhere to put the name of the bipod ‘Støtteben’ Which for those of you who do not read Danish means stabiliser. Støtteben are the stabiliser wheels children have fitted to their bicycles so now you know.

Vital Statistics:

Main bipod assembly: 6082 T6 aluminium.
Finish: Vapour honed and black anodised surfaces.
Screws: A4 Stainless Steel.
Elevations shaft: Stainless Steel
Elevation nuts: 316 stainless steel
Weight: Approximately 610 grams
Weight with optional toggle locks fitted: Approximately 674 grams
Weight of optional toggle lock 32 grams (1.15 Ozs)
Maximum recommended width: 785,0mm (31 Inches)
Maximum recommended height: 380,0mm (13.5 Inches)

Accompanying the bipod is a spares/options kit comprising of:

1x Elevation nut retaining clip.
1x Toggle lock and washer.

Price for the latest iteration MkV of the Støtteben will be £295.00 with the new version featuring some minor tweaks to improve tracking and aesthetics. Price for advance orders will be £265.00 and the bipods will be available Q4/2019

Another rail for a 400 yard rim-fire.

This is a BSA international scope rail fitted with a 75MOA rail instead of the normal 0MOA.

Now believe it or not, sourcing a low profile 75 minute rail is probably going to be a lost cause. In fact I did not even bother to look for one. Instead this was machined in the mill.

First job was to calculate the cut in millimetres because, despite my age, that is what I always work in given the chance. I have a spreadsheet that I use and just enter the ring separation and the required angle in minutes and voilà, it comes up with a number. I wrote the years ago as it is so much easier than getting a pencil and paper out and doing it the long way, plus I can easily add or subtract the minutes required to see the difference to the depth of cut. Most I have ever machined for a rail was 125 minutes. Yes, It converts to milliradians as well because that is what I was brought up with. (Reminds me of a comp I shot one day at Bisley, as I stood up someone asked me how much wind I was putting on, ‘About 18 mils was my reply’)

Then out with sine gauge and try and get the rail clamped in the Bridgeport courtesy of the new machine vice. Finally check the end heights just in case and put a few cuts across the underside of the rail, remembering to take the material from the front and not the back!

So here it is, a BSA inter bracket and rail ready for 400 yards .22LR competitions.