Lee Enfield 2 groove barrels

[JeffinNZ]

Team.

I have read Reynolds and Stratton and browsed Skennerton but can not find out why the two groove barrels had the rifling cut so much deeper than the 5 groove tubes.

5 groovers seem to have been cut .312-.314 for the most part but 2 groovers are .316-.318 or MORE.

I suspect the deeper rifling may have been to prevent over pressure of the same diameter bullet going down a barrel with less internal capacity. What say you?

[bruce drake]

Jeff,

The same time we were working on converting Enfields #4s to 2-groove barrels we were working on converting our 1903 Springfields to 2-groove barrels to help speed up production of those rifles as well.

Here is a link to a write up from Remington on their tests for the 03 barrels. They found increased pressure using rifling grooves the same depth as the 4 groove barrels when they fired Armor-Piercing bullets. That pressure decreased when they increased the groove depth.

http://www.remingtonsociety.com/rsa/journals/two-groove

Bruce

[462]

Bruce,
Thanks for the link.

[JeffinNZ]

HUH! I was right. Had to happen one day ah?

[bruce drake]

Its equivalent to the recent issues that bullet companies ran into when they first started making all-gilding metal/copper bullets for our "lead-free" hunting areas. They had to cutting driving bands into the bullets to allow for expansion into the barrel grooves to prevent over-pressure issues.

And don't let your SWHMBO know that you were correct...it would ruin the Wive's Club's plans to take over the world...

Bruce

[Multigunner]

Jeff,

The same time we were working on converting Enfields #4s to 2-groove barrels we were working on converting our 1903 Springfields to 2-groove barrels to help speed up production of those rifles as well.

Here is a link to a write up from Remington on their tests for the 03 barrels. They found increased pressure using rifling grooves the same depth as the 4 groove barrels when they fired Armor-Piercing bullets. That pressure decreased when they increased the groove depth.

http://www.remingtonsociety.com/rsa/journals/two-groove

Bruce

I suspect that a more beneficial effect of the same general phenomena accounts for the exceptional accuracy I acheived using soviet 147 gr steel core boatail bullets in my two groove barrel, which normally can not handle boat tail bullets at all well.
The Steel core bullets have a lead sheath between core and jacket. The large land surface acts to compress that lead sheath with the harder core acting as a mandrel. The compression of the lead then extrudes the jacket deeply into the grooves and prevents blowby.
In a two groove with more shallow grooves the jacket and lead would not have as much room to expand which would cause more resistence and up pressures since the steel core would not have any give.

[curator]

Lee Enfield 2-groove barrels are very different than Springfield .30-06 2-groove barrels. Springfield barrels are 5/8 (62% circumference) land and 3/8 (38%)groove. Bore and groove diameters are usually .300 and .308 but the throat is a smooth taper from neck to bore. Often this measures .311 to facilitate the bullet's entrance into the bore. Lee Enfield's 2-groove barrels are 80%/20% land/groove ratio. A substantial amount of metal is displaced as the .311 diameter slug is squeezes into the (usual) .304 bore with only two .10 wide grooves (at least .006 deep) to take the flowing metal. Making the grooves deeper also helped "grip" the bullet better. Bullets fired through a Lee Enfield 2-groove barrel also grow in length. Most 2-groove barrels have throats at least as large at the groove diameter. I have never measured a throat slug from a 2-groover less than .316 some were as large as .320.

[bruce drake]

Same issue of pressure with 2-groove barrels whether they are Springfields or Enfields. The OP question was reference deeper grooves. The Barrel manufacturers found the same problem with two different rifles and found the same answer - deeper grooves.

[JeffinNZ]

Yeap, all that bullet metal has to go somewhere. Shame they never considered we boolit casters.

[bruce drake]

I find myself google searching on a recent issue I'm having with a 2-groove No 4 Enfield and this post comes right up as first pick. Funny how sometimes our own research leads us back to a previously worked problem.

I own a No 4 with a two-groove barrel is scary accurate with Sierra Match King .311 174 HP-BT bullet but when I switch to cast, I've found that .312 sized lyman 314299 boolits keyhole in what appears to be a pristine 2-groove bore. Next step is to use those 314299s as cast at .314 or sizing down some .323 170gr bullets to .316.

[303Guy]

My rough bore two-groove is scary accurate with PRVI 180gr boat tail bullets but not so much with cast or paper patched. The base gets distorted all out of square. But it can be done. Jeff gets good accuracy with cast in his two-groove.

[iron brigade]

I find myself google searching on a recent issue I'm having with a 2-groove No 4 Enfield and this post comes right up as first pick. Funny how sometimes our own research leads us back to a previously worked problem.

I own a No 4 with a two-groove barrel is scary accurate with Sierra Match King .311 174 HP-BT bullet but when I switch to cast, I've found that .312 sized lyman 314299 boolits keyhole in what appears to be a pristine 2-groove bore. Next step is to use those 314299s as cast at .314 or sizing down some .323 170gr bullets to .316.

had the same problem, bought the noe 316299. problem solved.

[GREENCOUNTYPETE]

well I thank you for bringing up the old thread again as I was a good read and enjoyed the 2 groove Remington research

[W.R.Buchanan]

I figured this out about 3 weeks ago and talked about it in my second Enfield thread.

It's all about metal displacement.

When 80% of the bullet's material is being displaced by the lands that same amount has to fit somewhere else.

It can either go into the grooves, or if that space isn't big enough then it goes onto the back end as the bullet travels down the hole.

Similarly the Springfield barrels had closer to a 50/50 bore to groove relationship. IE less material being displaced and more space for it to go into , thus the on size bore and shallower grooves. I woiuld also bet that bullets fired from these barrels have little or no increase in length. Certainly not as much as the Enfield barrels would have had.

My #4Mk1* Longbranch has such a 2 groove barrel and I was amazed. It was not hard to figure out why it was made the way it was.

Now trying to figure out what someone else is thinking??? that can be hard!

However that is an integral part of reverse engineering, which is what we are doing here and now.

Randy

[screwcutter]

had the same problem, bought the noe 316299. problem solved.

+1
I seat gas check and pan lube & shoot unsized.

[zuke]

My 2 groove Savage is .304/.320.
I wondered why cast didn't work. But .312 95gr HP WC ontop 5 gr of 700X alway's has worked.
Now I just use jacketed ammo in it

[fouronesix]

Yes, the same principle applies to mono metal copper and brass alloy bullets. There's got to be a place for the displaced metal to go or the pressures get spiky or erratic and squirrely things happen. It took Barnes years to figure it out. Now they have a winner in their banded bullets. Same applies to such as the GS, North Fork, Woodleigh and CEB banded bullet designs

[W.R.Buchanan]

Yes,,,In the case of the solid Brass bullets all of them have undercuts for the displaced material from the lands to flow into. With out these you are trying compress brass which isn't as ductile as Lead.

Randy

[curator]

One of the most accurate cast bullets in my 2-groove Lee Enfields has been the Lyman 311467, a "Loverin" design 180 grain gas-checked slug with lots of thin grease grooves. I load this over 16 grains of 2400 and use either PuffLon or PSB filler to bullet base. Without the filler, accuracy degrades quickly due to leading. This is no doubt due to gas cutting while the bullet is in the throat or the first few inches of the bore. With the filler sealing off and possible gas leakage it is a real tack-driver. I have also found that if I size these to .308 and paper patch them sans gas check to .316" diameter I can thumb-seat them in unsized fired cases and shoot as accurately without filler. The paper patching appears to prevent early-gas blow-by erosion and subsequent bore leading.

[Larry Gibson]

I've found either of the Lyman Loverin 8mm bullets (323470 & 323471) to be excellent performers in such oversized 2 groove .303s along with over groove size 7.7 japs and 7.62x54Rs. For the .303s I GC and lube (all the lube groves) at .325 and push through Lee sizers of .316 or .318 (both honed out from .314 sizers). If larger is needed then the Lyman .321 H&I is used.

Larry Gibson