303 British new barrel want to use cast in it

[Brithunter]

I have just got this unused barrel fitted and as far as I can tell the bore is 0.301" and the groove diameter is 0.315" but of course being normal Five grooved .303 barrel it's not the easiest to measure  . I forced a soft lead slug into the muzzle but it deformed too much to get more than 0.320" length of the rifling. The slug was a 0.358" cast bullet that I reduced in diameter by rolling on steel plates.

Now doing some reading I understand that I am going to have to get an accurate thoat measument and Veral you say that your throat slugs are the way to do it. As I live in the UK what is the best way to obtain them and I gather you would say buying some cerosafe would be a waste of money and time? I guess you would recomend the bore lugs too so we can find the true size of the grooves.

Now this particular barrel is stamped at the muzzle "A.G.P. Ball Burnished" so it should be of even diameter on the lands through out it's length. I cannot say about the grooves  at the time this barrel was made BSA cut rifled and lapped their barrels. How and why this came to be Ball Burnished by Parkers I don't know.

I guess what I want to know is what do you recomend I get to determine the correct cast bullet for this barrel?

Oh apart from proofing back in 1954 this barrel has not had any jacketed bullets fired through it  I have fired 10 Gas Checked commercially cast 205 grn bullets of 0.312" through it to test for function and that's it.

[Veral]

  I'll start by commenting on your last comment. about the gun not having jacketed bullets fired through it.  Jacketed bullets don't hurt barrels unless it has fired thousands of them, and then, most of the wear is from powder gas erosion in the throat.  A little of that is good for most rifles, and if the jacketed fouling isn't removed, that can diminish cast performance, but don't ever shy away from shooting cast in a barrel used with a lot of jacketed.  Regarding the jacketed fouling issue.  The LBT push through slugs will tell you if there is measurable buildup of jacket fouling, which is the reason jacketed accuracy falls off after many rounds.  The push through slugs will tell you exactly how much fouling is in the bore and where.  Get the fouling out till it can't be measured and jacketed accuracy will return.  At that point it will also shoot cast well.

   Because of the distence between us, and prohibitive postage, try annealing your slug just minutes before slugging.  Best way to reduce the diameter is hammer it down, while rolling, making sure you don't get any big flat spots which are under size.  Then warm the hammered slug till its close to the melt point, let it cool in still air, and do your slugging immediately.  It's hardness will be at the lowest possible for the alloy right then.

  I haven't heard of ball burnishing in barrels prior to you telling about it, but I am a very experianced man so far as precision, and know that it would have been done prior to cutting the rifling, to smooth out the circular reamer marks on the lands.  In other words, the lands will be very smooth, but not necessarily uniform in diameter all the way through the bore.  The ball can only knock high spots down, and float free over places where the reamer cut a bit large, if it did.  Cut rifling can produce excellent barrels, or if pushed a bit too fast, can leave rough leading edges on the edges of the rifling grooves, which chew up cast bullets like a file.  Therefore, I'm going to advise that you order a pack of push through slugs and the LBT lap kit when you order your mold, and send your best shot at making a throat slug along.  I'll probably be able to pick up enough of the dimesions from it to make you an excellent mold, but if I can't I can send some throat slugs and the detailed instructions on how to proceed, and get things right.  Any barrel with uneven number of grooves demands a special fixture to obtain a precise measurement.  Just measuring with a micrometer will  result in an undersize reading.  I have proper fixtures, of coarse.

  Perhaps of interest, about cut rifling.  It works well with tapered barrel blanks, whereas buttoning demands straight blanks to provide a uniform pressure on the button.  Then when the buttoned barrel is tapered, the bore opens up where the barrel is turned, most at the muzzle, of coarse.  ALWAYS.  It is unavoidable, and caused many people a lot of grief when they try to work up accurate loads in what one could accurately call a bellmouthed barrel.  The worst case I've encountered was an 06 barrel of my own which was .0025 larger at muzzle than at the breech end.  Nothing would make it shoot tighter than 2 1/2 inches.  Before I pulled if off the action I hacksawed it to 14 inches, as I recall, and deburred the hacksaw burrs out with a pocket knife.  I cut where it got thick anyhow, and fired one group to see how it shot.  Presto, a one inch group!  -  Such is not a concern with cut rifling or hammered rifle barrels.  Broached as in short handgun barrels are primarily plauged with roughness, which is the concern with cut rifling if the machinest was pushing production, or the rifling hook wasn't sharpened precisely or some other factor in the machine caused inconsistent locating of the rifling hook.   Don't let your heart sink over all this.  Cut rifled barrels are real easy to fire lap and become very good shooters, should your's not be a work of art.

  I'm pretty careful about never recommending the best bullet for a rifle until after I see a throat slug, and learn what the customer wants the bullet to do.  If strickly for target, I almost always recommend a spitzer, and in your case my SP.8, which isn't listed in my website.  If for hunting, a spitzer is fine if used with the right alloy, while an LFN will expand at lower impact velocities.  The LCFN would be the best option if your rifle has a short throat and you want maximum weight possible.
 
  Please email me direct to work out any further tech problems and personal questions.
           LBTisAccuracy@localnet.com

[Brithunter]

Thank you Veral,

      I have sent an e-mail for a quote for the slugs. Oh and the idea is hopefully use the rifle for deer stalking so a soft point bullet would be a very good idea  . It will get used on the range of course for load development and practice. I was thinking of a bullet weight of 180-210 grains but if I am wrong in thinking this then please say so. Normal velocity in the 303 with a 180 grain jacketed is 2450fps and a 215 grn jacketed 2050fps. 

Edit:- Hmmm thinking on this perhaps I should get enough slugs, throat and bore to do three rifles  shipping would probably be the same and I could then see if another two 303's I have that the barrels look very good on would do for cast shooting?

      Now as for Ball Burnishing the way it was done by A.G Parker and BSA themselves was after rifling and it was a special request/order thing. They forced hardened balls in graduated sizes down the bore to smooth the lands and make it an even size through the bore. It was mainly target shooters who used it and it helped reduce the jacket fouling and improve consistancy of groups. Handloading was not permitted in the large competitions such as Bisleys annual Imperial meeting. Most if the rifles I have come across with Ball Burnished barrels have been "range rifles" normally Lee Enfields or Pattern 14 rifles fitted with rwin zero target aperture sights and carefully bedded actions and barrels. On the No1 and No4 Enfields this usually meant cutting out the stock around the recoil lug in inletting a block of Hornbeam which was carefully cut and fitted to the lug and on the Lee Enfields the forestock was carefully fitted often using Hornbeam blocks inletted into the draws of the forestock and the barrel channel carefully bedded with cork to dampen the barrel.

Old Technology now-a-days but it worked. There were strict rules as to what could be done to a rifle and the Range rifles were for Service Rifle B competitions. Service Rifle A was for unmodified service rifles. You could clean up the trigger pull but it had to meet strict limits and if the rifle had windage adjustable sights they had to be set to the central position. Any windage had to be done by aiming off. This was because only the early service rifles had a windage adjustable rearsights and so it set an even playing field with all competitors havign the same even the ammunition was supplied so everyone used the same lot.