303 British bore size

[got to go]

I slugged my barrel tonight once from each end. and came up with .311 bore. Then I started to measure some bullets from Federal about .310/.311 Remington .310/.311 Winchester .307/.308 All 180 gr. I have a Mastercraft digital caliper which I think is "fairly accurate" I am not a machinist. So maybe I screwed up my measurements ??? Could someone check their ammo??? I am really wondering about this

 

[cantom]

I slugged my barrel tonight once from each end. and came up with .311 bore. Then I started to measure some bullets from Federal about .310/.311 Remington .310/.311 Winchester .307/.308 All 180 gr. I have a Mastercraft digital caliper which I think is "fairly accurate" I am not a machinist. So maybe I screwed up my measurements ??? Could someone check their ammo??? I am really wondering about this

Sounds pretty much right. Steve Redgewell on 303British gets into this(although I can't find the article-I just looked). He was selling oversize bullets for reloaders, the idea is you can improve an Enfield's accuracy quite a bit by matching the bullets to the bore size. Much of the ammo out there is undersized for the typical Enfield bore.

ht tp://www.303british.com/id37.html
(remove space between ht and tp)

 

[tiriaq]

.311 bore or .311 groove?
If your rifle has a 5 groove barrel, how did you measure the diameter of the slug?

 

[Tyler]

.311 bore or .311 groove?
If your rifle has a 5 groove barrel, how did you measure the diameter of the slug?

By measuring the opposite corner of each groove imprint on opposite sides of the slug.

Got to go, Hornady sells .312 bullets for .303 rifles, and Sierra's .303 bullets are all .311 or .3115. Most factory ammo is undersized and underloaded for liability reasons, as bore sizes and action strengths for .303 rifles can vary quite a bit.

 

[purple]

There are considerable dimensional variations in .303 Brit bores,even when new.One theory has it that the use of a flatbase bullet,rather than a boat-tail,will cause the bullet to "slug up" somewhat in the bore to achieve a tighter fit.

 

[got to go]

I simply measured across the widest part of the slug. I don't know if I would go along with the flat based bullet "slugging up" to the bore theory. I am going to use the Serria's 174 gr. Matchking bullet. But, I am Really thinking hard about trying some Nosler Ballistic Tip 180 gr. bullets that I use in my 30 Cal. rifles. They are Excellent bullets. Jack

 

[bearhunter]

gtg, I've seen bores as large as .317 on Lee Enfields. I have a 1942 dated Lithgow NoI with the .317 bore. On the other hand I have a 1942 Savage No4 MkI* with a .309 bore. The Lithgow is a better shooter. Go figure.

I also have a 1950 Long Branch with a .309 bore that is very accurate and a Pakistani No4MkII with a .310 bore. I would say it's an accurate shooter as well. The Savage is acceptable, 4-8 inches at 100yds, even with .308 diameter bullets and the Long Branch will shoot anything from .308 - .312 diameter very well, 2in at 100yds or less.

I also have a Martini in 303 Brit that I believe is a Khyber pass manufactured rifle, don't know for sure, very well done. It has a .312 bore that is very uniform for its entire length. It's also not fussy about the bullet diameter it shoots into 4 inches with all weights and diameters.

All of the above rifles are VG+ or better with excellent bores, so the playing field is pretty much equal.

There are some that say their .308 dimeter bullets shoot well in their rifles. I believe them. Some rifles do. I have 303 Brit cartridges dateing from 1911 to present day. Everything pre WWII has 311 to 312 bullet diameters. WWII era north american cartridges such as Dominion and Winchester have 308 and 311 bullet diameters.

I suspect that all are safe to shoot in rifles that are in acceptable condition and that they shoot close enough to point of aim to satisfy the inspectors.

From some of the stories the old timers tell it wasn't unusual for them to hoard ammunition that shot well when they could get away with it.

There I go, wandering again. The Sierra 174grn MK bullets are excellent and consistant. Good choice.

 

[got to go]

Thanks for the reply. That's the reassurance I needed !!! I have always gone by the book when it comes's to reloading. I will stretch my wings a bit now. Thanks, Jack

 

[cosmic]

I have to agree with the comment about flat based bullets. In my various 303's, the flat based bullets win every time - particularly the Hornady 150 SP.