After discussion with an F/TR shooter I ended up setting myself the task of building a bag rider for an Accuracy International but keeping it as light as possible. The thing is what is light in the bag rider stakes? The plate and tube as raw material were a tad under 200 grams so what could I really get such a thing down to and yet still keep it fit for function?
The bag rider started off as a piece of 10mm aluminium plate and a length of 20mm aluminium bar, loosing weight from the bar itself is easy enough, keep it at a sensible length and bore the middle out, give it a light skim and polish on the outside so it slides nicely in the bag and round the nose off so it does not catch.
Now cut the plate to size, and grind to size, it can be draw filed and then polished later, finally add an M8 screw to hold it all together. 168 grams…
Bore the bar out a bit more, and machine a relief in the middle of the plate and weigh, and repeat. At times like this I realise some targets are always going to be hard to beat, having a wife that plucks target weights out of the air does not help any and even when I had got down to 115 grams she was sure I could go lighter. Anyway here is the finished article. 100 grams on the nose, yes I could bore the bar out further but that means grinding a new boring bar and that will have to wait. Also machining out the centre of the plate was getting sketchy and I had removed the guard from the mill so I could get a finger on the workpiece to dampen out the vibration, never a good idea.
This one fits but is scruffy on the inside so I will build it again but next time build a dedicated fixture to keep things a bit more secure and less hairy.
I had been looking for an engineering project for a while, something different that would test my new milling machine and non existent milling skills and give me something worthwhile at the end. I know, why not design and build an annealing machine? Why not add interrupted motion and a rotating station when the case neck is heated and why not build it in the shed. So here it is, the Silver machine because it is self colour aluminium and there is a bit of a Hawkwind thing somewhere deep.
The interrupted drive is via a GenevaX drive principle with 12 stations, 10 load, one anneal and one eject. Motor is a 24vDC with separate speed control and a 10RPM gearbox
This post is a bit out of sequence so I will delete it later and maybe document the whole build as best I can from start to finish. Meanwhile courtesy of a new Blog plug-in here it is in action.
It is a comfort thing…
I picked up an old RCBS press from Spud (Of 1967Spud fame) the other day, it is going to be used purely for a Danish M1889 8x58R Krag-Jørgensen so I bolted it down at one end of the bench (Tip, always bolt your reloading press to a robust surface with some big bolts to stop it moving around) Once in I had a closer look, all OK apart from the spring that holds the case holder in place is missing, RCBS will probably mail me one out Free of Charge if I ask. What else? Urgh the handle is a piece of plastic and I like wood, so off to wood loft for something suitable, a piece of European Oak looked about right so I roughed it to near finished diameter, bored it to suit the existing handle, glued it on with epoxy and chucked the handle in the 4 jaw of my lathe. Odd how I never use a 3 jaw these days, even for round stock as I find it so quick to clock in the work piece with a 4 jaw chuck.
Anyways, a quick run down to bring it parallel and to finished size, a sand over and coat or two of sander sealer and a final application of wax and I now have a handle I will feel comfortable with.
Reloading is a huge subject in it’s own right and covered by countless books, articles, web sites and forums, put 5 shooters in a room and get onto the suject of shooting and you will come across 5 separate opinions.
Take the subject of OAL, COAL, OverAll Length (All the same thing in principle) This the maximum length of loaded round in a chamber, it is the length of round that when the bolt is closed just touches the lands. This may or may not be a meaningful number to you, if you are shooting .308 and your magazine will only feed 2.800″ OAL rounds what is the point in building to the extremities of the chamber at say 2.900″ if it means you have to hand feed.
In fact why bother determining the OAL? Well some rifle/bullet combinations shoot more accurately when they have a shorter jump (Distance the bullet has to travel) to the lands, some actually work better when jammed (The bullet is physically engaged into the lands when chambered, such as the Berger VLD’s
Now I could go into the merits of jam versus jump, pressure characteristics and so on but that is not the point of this article, probably because it is called OAL (OverAll length) Gauge. So back on track for a moment. How do you measure the OAL for your rifle assuming you want to? Well the old favourite was a couple of length-ways slits with a hacksaw in a case, stick a bullet in and chamber it, in theory it will slip in the neck because of the slits and give you your maximum OAL, actually it will give a longer OAL because the soft jacket of the bullet will deform slightly when pressed into the lands so you could end up .020″ over length (20 thousandths of an inch) “Woahhh! Twenty thousandths of an inch? That is slightly less than not a lot.” Yes but we are talking about accurate reloading here and that plus twenty could bump your chamber pressure up to an unacceptable/dangerous level. If you are going to laod your own better to know the exact distance.
Next way to measure OAL was a piece of pipe soldered to the end of the case, a bit of stiff wire inside and hey presto an improvised OAL gauge. I still have mine somewhere…
Stony Point/Hornady make an excellent OAL gauge however it is a bit short for my liking and apparently the ends snaps off if you are clumsy.So I make my own OAL gauges and here is one I made earlier.
This one utilises a 6mm aluminium inner and a robust outer tube. The construction is all aluminium apart from the stainless threaded lock screw, the thread on the nose that the case screws into is M8Fine because that is what I had available and the whole thing works rather well if I say so myself. I have made a few of these for mates in the past so this does mean they need to see me if they have a new case that needs tapping. I usually say cover the return postage and pop a couple of quid in the next H4H collection point or similar.
Occasionally I have to put a knurl on something, you know… that sort of chequered finish on things like thumbscrews and the likes. This knurling is to give a grippy finish when you have wet hands and has to be identical on 12 units. So for the sake of repeatability I start with a given diameter, set my knurling tool to parallel to the work face, set a feed rate, wind in the first cut and kick it off, second cut back across with a few more thou and a final cut in the original direction gives me a finished result.
Hmmm… I think to myself as I look at my handy work that is bloody good, I put a chamfer cut across the ends and it goes on the bench for the next stage. Next piece in the lathe, repeat the process and I now have two identical components.This goes for the third one as well, I am on a roll now and I start the knurl on the fourth, exactly the same settings as the previous and get a totally different, much finer knurl pattern. A reverse cut does not help matters and of frustration I stick a heavy cut on and wind the speed up to maximum.
A perfect knurl!
Yeah……… go figure.