.303 Throat Gauges

We all know someone with a .303 rifle, or own one ourselves.

In fact I believe all new FAC holders should get out and shoot one at some point, just because. I have a modest collection of 303 Sporting and military rifles, including Lee Speed and postwar No1Mk3 commercial examples here in the armoury along with later ones such as the 1920 Lithgow below.

One thing I can usually say about the .303 rifle is it will have been shot, usually shot a lot and accuracy does suffer after a while. Now accuracy is not always a good reason to buy a rifle and I have rifles here that will not shoot a hand span group at a 100 yet they are keepers, equally I have worked with rifles capable of shooting tiny groups at extremely long distances that have left me cold.

For me, the majority of .303s are usually very special rifles and to find one that shoots is even better, so how to determine if the rifle in your hands is going to shoot? Well range time is the simple answer, however you can also check a few areas before taking the rifle out and bore and throat erosion are always good places to start. A careful peer up a barrel tells you a lot however a shiny bore is not always a good bore and if the throat has disappeared 3/4″ up the barrel you are always going to chase accuracy. So I made some throat gauges for just this reason and here is a prototype and an early version.

Use is very simple, just remove the bolt and drop the gauge into the chamber. The amount of the relieved section visible gives an instant indication of throat erosion. This is not an absolute measurement and just because the throat has gone does not mean the rifle should be put back in the rack, however if you gauge two identical looking rifles and one swallows the gauge you know which one to test shoot first.

So there you go, one small area to check when considering a .303 purchase. I should probably sit down and write a book of such tips however not all of them are going to interest people.

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

A new machine has arrived

A new/old machine arrived last week, a little Herbert Junior manual surface grinder that will be perfect for recoil lugs, flat sided firing pins, anything that needs a ground finish, oh and maybe the occasional blade or two. I have been on the lookout for something like this for ages so to find one within 15 miles and at a really sensible price is a real stroke of luck.

Was I excited? Nah! More like skipping around!!!!!

The little surface grinder was unloaded via a pallet truck from a trailer. Putting it on at the other end was easy enough as there was a fork lift truck. Here we were not so lucky and we ended up moving the grinder off the truck and onto the workshop floor. From there it was picked on a sack barrow which was precarious and eventually it was rolled into its new location.

This is exactly as it arrived other than I have re-fitted the spark guard on the left hand side of the bed. Looking it over in the cold light of day it was in remarkably good condition, virtually zero backlash on both axis which have vernier scales in metric and imperial which is good as I prefer metric yet people often send me drawings with imperial dimensions.

I will probably fit a single axis Digital Read Out (DRO) at some stage on the Z Axis as I run DRO’s on all of our workshop machines and have been spoilt by them over the years. There is no real need to fit a DRO to the and Y axis.

It is a heavy little thing at around 230kg and that is mostly cast iron to soak up resonance and vibration, so despite being manual travel I expect reasonable/good finishes.

The thing just to the left is a Thermal Arc AC/DC Tig welder. I will not be using either the grinder or welder on a daily basis so they can share the same space and although there is room to use both from the same area I will probably drag the welder out when either machine is in use.

Yes, the missing paint on the base is hacking me off so I will do something about it.

With the three phase supply run in the little Surface Grinder was powered up. It went the wrong way of course and that was only after I had reset the starter which had tripped, probably due to the rattly journey home.

First job was dress the wheel, a little diamond dresser came with the machine, just clamp it down with the magnetic chuck and off you go, well not quite… The thing about surface grinders is they/you have the ability to hurl items across the workshop with a total disregard for life and limb. so always set the dresser to the ‘safe’ side of the wheel, that is the side that the wheel has gone past the the 180 degree mark and is starting to rise (Clockwise rotation would be to the left) So if you are dim enough to take too heavy a cut the part will fly into the spark tray without having to go through the wheel which invariably turns into a DiY hand grenade at that point.

A slight kiss was all that was needed to bring the wheel true and square.

Next job was check the magnetic chuck to the wheel. Runout/Parallelism across the length of the chuck ( X Axis) was 0,013mm or 0.0005″ across 200mm/8.0″ of travel.

Back to front (Y Axis) slightly less. So OK ish however I will take a closer look at some point.

Time to get grinding. With the wheel dressed I found a suitable piece of steel in the oddments bin and got to it.

First impressions are wow, the machine is very smooth running, as expected and this really poor picture cannot portray just how pleased I am for a first attempt.

A worthy addition to the workshop and roll on the first proper job with it

I still need to properly level and bolt it down and fit a new wheel to it at some point however it is already giving superb results and its first job is due in very shortly so I had better get some floor fixings and the engineers levels out.

 

Ruger Precision Rifle rear bag riders.

I forgot to post a picture of our latest Ruger Precision Rifle rear bag rider plates fresh back from anodising so here is one.

Machined from 6082 aluminium and satin anodised finish they are virtually a direct copy of the original butt plate however they are extended to accept a bag rider tube. You have a choice of either a self colour 1,5mm tube (Shown in picture) This adds around 65,0 grams to the all up weight of your rifle. Alternatively you can have the 20,0mm carbon fibre tube version with polished aluminium ends which is a lot lighter. (Guess who forgot to weigh the last ones he built)

Everyone tells me these make a huge difference to the tracking of the RPR at both short and long distances and coupled with the 6.5CM cartridge gets you into some very long distance shooting.

I also have a single bracket in a lovely shiny aluminium finish if anyone is interested.

I also forgot to add a link to the Ruger Precision Rifle rear bag rider on our site, so here it is:

https://www.shootingshed.co.uk/oscom/product_info.php…

I am hearing good things from the people who have already received them, it makes me wish I had an RPR myself!

Ruger Precision rear bag riders.

People have been asking for a rear bag rider for the RPR for a while, so I made a start on the project today. They will be a direct replacement for the existing butt pad back plate and will be vapour honed and hard anodised to match the chassis as best I can. The rider tube will be 18,5mm diameter and will be in self colour. I have not calculated the weight yet, however around 180 grams or just under should be close and there will be a lighter version with a carbon fibre tube.

I will be machining these as a limited run so if you are interested please shout now as I have a feeling the USA is going to snap the majority of them up rather quickly.

I would expect to ship to anodise in around 3 weeks so they should be ready for shipping start of December, just ready for Christmas

Sunday Fixtures.

Sunday fixtures sounds like a football thing and please believe me when I say that is probably going to be the only football reference I make on here ever.

It would be so nice to say every Sunday is a day of rest and relaxation however it does not always happen.

This morning I am lucky enough to be enjoying a leisurely second cup of coffee at home with the doors open and Labrador tripping hazards asleep at my feet. I am working on the design of a fixture I have been meaning to build for ages.

Fixtures are important, they hold things in place accurately and theoretically with a good level of repeatability. This one needs to hold a rotational position to as close to nothing as I can get it. I model my fixtures in CAD as 3D models so I can rotate and view them from all angles to confirm not just that they work, but that they work for me. This design has a few tweaks to be made but is there in principle.

People often think working with firearms is all about smoke lamps and hand files, with an occasional walk over to the lathe and it can be like this to a degree, however for me it is as much about maths, CAD and spreadsheets as it is about being hunched over my bench with a needle file and Optivisor.

It was Townsend Whelen who said “Only accurate rifles are interesting” For me, it is only accuracy that is interesting.

…and what is the fixture for? Well I am sure the more eagle eyed of you may even have already guessed its intended use.