Enfields No1MkIII and No4Mk1* boolit suggestions, different bore dimensions

Enfield No1 MkIII has a slugged bore diameter of .314, and the No4 Mk1* is .312.

Beyond my understanding, shooting PPU 303 ammo through both showed the No1 to be pretty darn accurate, while the No4 groups being a bit worse. I thought I hit the jackpot having a tight bore on the No1, but slugging showed otherwise. The PPU jacketed bullet measured .311.

Since the bores are markedly different in size, I assume the Lee mold (the 160gr gas check variant) I have isn't going to work well in the larger bore of the No1.

What molds have shown to be accurate in Enfields with bores such as these? As a side question, can a gas check boolit function well without a gas check?

Gas check boolits can shoot well sans gas check but velocity has to be low. I shot a bunch of them out of .30-06 over 6-7 grains of fast pistol powder. You can get squirrel head size groups at 50 yards and minute of soda can at 100. If you get much above .22 rimfire speed you will need a gas check.

I shoot nothing but long range using military rifles. I have several Enfields in my collection and have found that while the MK VII ball does OK in the Metford type rifling, the best accuracy out to 800 yards was a very long metplath, flat based ,gas checked bullet of 180 grains or up to 200 grains.
My bullets are sized to .314 and seated to just clear the magazine front lip.
The same goes for jacketed bullets. I get much better accuracy using the flat based bullets at distances greater than 300 meters.
Bores of my Enfield rifles/carbines very from a tight .312 to ridicules .317!
What I have found is the number of rounds fired out of these surplus rifles can be in the thousands. Using a bore scope several of the rifles have erosion at the lead from firing Cordite ammo. This will not help with accuracy as the bullets now jump into the origin of the rifling when fired.

I have 5 Lee Enfields and all but one have very similar groove diameter of right around 0.314" with bores of 0.303"/0.304". One is tighter groove and tighter chamber. All like the NOE 316299 sized to 0.315". Your guns may be different but if you get the 316299 you can size to suit both guns if they have different tastes in boolit diameter. You'll want to size at least 0.001" over groove but my feeling with the Lee Enfields is to fill the throat with about the largest cast boolit that will chamber. I have shot boolits as large as 0.318" in mine with good accuracy.

Alternately you can order whatever size cavity you want from Accurate Molds so a mould to suit each gun with minimal sizing.

You could try lapping the Lee mould out by a thou or two as well. It isn't hard to do with aluminum moulds... or try Beagling it, even easier. That is if it casts too small for your 0.314" grooved gun.

I'm with Thumbcocker on the GC boolits without GC's. In my experience light loads only. I tried some moderate loads with a Mauser in .308 Winchester using the Lyman 31141 GC mould but no GC's on boolits. They were sideways at 25 yards! Adding the GC solved it an accuracy was good. As long as you stick to very light loads they should work fine but if you push them at all I think you will find accuracy drops off quickly as velocity increases. Doesn't hurt to try and at worst, you'll have to clean some lead out of the bore.

Longbow

My Enfield slugs at 0.312- It loves the Lyman 314299GC and also an old plain based spitzer mold that drops at 0.311 that I powder coat to 0.313.

Unless you used a V-anvil thread micrometer or wrapped the slug in paper, measuring over the wrap and subtractiong two thicknesses of the paper, your groove diameter figures are "wrong" and probably small by about 0.002". I have measured over 100 .303 Enfields and you almost never run into one as tight as .312" unless it was a custom rebarrel. The great majority of wartime 5-groove barrels are .314-.316" and 2-groove barrels .315-.316 with some as large as .318".

Also, you should fit the bullet to the throat and origin of rifling and not to the groove diameter of the barrel. For most wartime barrels you will want .315-.316". Accurate, NOE and CBE produce molds of the correct size. The NOE #316299 and Accurate 31-215B work well in most guns with 16 grs. of Alliant #2400, 20 grs. of IMR or H4227, 24 grains of IMR or H4198 or 30 grs. of RL7.

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Originally Posted by Outpost75

Unless you used a V-anvil thread micrometer or wrapped the slug in paper, measuring over the wrap and subtractiong two thicknesses of the paper, your groove diameter figures are "wrong" and probably small by about 0.002". I have measured over 100 .303 Enfields and you almost never run into one as tight as .312" unless it was a custom rebarrel. The great majority of wartime 5-groove barrels are .314-.316" and 2-groove barrels .315-.316 with some as large as .318".

Also, you should fit the bullet to the throat and origin of rifling and not to the groove diameter of the barrel. For most wartime barrels you will want .315-.316". Accurate, NOE and CBE produce molds of the correct size. The NOE #316299 and Accurate 31-215B work well in most guns with 16 grs. of Alliant #2400, 20 grs. of IMR or H4227, 24 grains of IMR or H4198 or 30 grs. of RL7.

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I wrapped copy paper around the slugs, but admittedly I don't remember doing it on the Enfields. Realized I had to do that on several slugs. Went on a "slugging" rampage in the safe. Results were not what I expected for some. I reslug with paper to make sure.

I've used the 312-299 GC'd and sized in .314. Barely sized the boolit but set the GC very well.
Good accuracy w/ green dot.

Size to ft the throats don't worry so much about the bore

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Originally Posted by RU shooter

Size to ft the throats don't worry so much about the bore

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That seems like a common suggestion. I've noticed the same technique suggested for a lot of 19th century rifles. I'll make a chamber case to include the throat, and go from there.

Outpost, your info is much appreciated.

The way I find the groove size on odd numbers of rifling is, using a set of bullet sizers .311 thru .316 of so, find the one a slug will just barely go through, most will be surprised. On mine, which miked at .311 on the "corners" it would not pass through a .312, but would fall through a .313. So I called it .3125

You could just settle for moulds in 311299, 314299, and 316299 load them with the 16 grains of 2400 and pick the diameter that shoots best in each rifle.

Theres still a lot of "fat" 311413's around; .313-.315. These fit the throat of the Lee-Enfield rifles quite nicely. There are usually 2 or 3 on Ebay at the same time. If your punching paper at 100-200 yds., these work real well.........................

Cast Bullet Engineering make a composite mould for casting boolits of 314" dia, one cavity duplicates Mk7 nose and weighs 190gn, the other duplicates Mk6 and weight 220gn. Both designs shoot very well; this target shot with an 1896 Martini Enfield.

https://i.imgur.com/L8VViXbl.jpg

https://i.imgur.com/K1Eu3Ool.jpg