303 and light mono's

[Ds J]

Hì Folks,

I am slowly building a 303 bakkie rifle with an 18" barrel.

The main purpose is to cull jackal and pest animals on farms.

Does anyone have experience with light for calibre mono's ? I consider using 117gr Kriek.

[big5ifty]

I've done a lot of testing of monos in .243 and .308, the lightest .308 being 125 grain.

My conclusion was that unless the monolithic fits the groove diameter, accuracy is absent.

You have to try them and see what the paper shows, maybe they are right for your barrel.

[Ds J]

I've done a lot of testing of monos in .243 and .308, the lightest .308 being 125 grain.

My conclusion was that unless the monolithic fits the groove diameter, accuracy is absent.

You have to try them and see what the paper shows, maybe they are right for your barrel.

This would mean I might have to order custom bullets in case my barrel is out of spec?

[big5ifty]

I'd say if you can't get a mono to shoot straight, try another one first.

If you ever shot any monolithic in that rifle, and it was accurate, measure the bullet diameter with a 1/10,000 micrometer, and make sure anything else you try is that size.

Most people get good results with Barnes, I suspect it's because they are a bit larger diameter, so they fit better in most rifles.

The smaller the caliber, the more sensitive it is to the correct bullet diameter.

If you take your rifle to Alliwyn at Peregrine, he will chamber cast it, and make bullets to measure, but minimum order of 200.

[Ds J]

What is an easy way to measure the bore of the rifle - slugging a 9mm LRN through it?

[Treeman]

What is an easy way to measure the bore of the rifle - slugging a 9mm LRN through it?

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I have used cast bullets to slug a bore, usually a bit smaller caliber which I tap from top/front with a hammer to fatten them till they tight fit. If you can find old lead pipe from plumbing it is the best, pure lead in its softest form. If you get a piece, you can reuse it over and over to cast a plug, to make plug smaller roll between to boards, to make it fatter tap the end to squish it out.
Edit: Also, the fishing shops sell ball sinkers, the usually easy to use for this purpose and are surprisingly soft lead some times.

[Ds J]

Thanks, this sounds good. I have a piece of soft lead somewhere.

Next question: how does one make an accurate measurement from a 5-grooved barrel?