Original barrel dimensions and muzzle wear/throat erosion

[p246]

He's looking for a British-made No. 4 that was made during WW2. His goal is to acquire a WW2 military rifle from each of the major participants. I will start attending the numerous western PA gun shows next month and hopefully will find one for him.

I always look at the gun show WW2 No. 4s that are for sale just to compare condition and price. I would say that most have been the Savage-made No. 4 Mk 1* rifles which surprises me since so many of the Long Branch and British versions were also made.

Savage and Long Branch did not have to endure the early to mid war bombings that England had to. Reason British " dispersal rifles" were built. BSA Shirley factory was bombed. Only Brit factory still making No. 1s. Dispersed salvaged equipment to other smaller factories to continue production. If memory served the wood furniture equipment was destroyed and they imported Lithgow furniture. I'd have to thumb through Skinnertons book to make sure but that's what memory seems to recall.

[Merc]

But still, you'd think a few British WW2 versions would show up at gun shows now and then. I can only remember seeing one Long Branch and zero British No. 4s over the past year or so. Of course, all that could change at the next show.

[p246]

Mainly here (Midwest) it's Savage and Longbrach followed by Lithgows and Isshys. Brits are out there in No 4s but not as common. It took me a while to find a good early BSA. Found a lot of worn rifles along the way. Jump back to WW1 I find mostly Brits and occasionally a Lithgow.

[Merc]

Questions of the day:

Where could one find the original barrel dimensions for a 1944 No. 4 Mk 1*?

How much concentric muzzle wear and jump gap distance can the No. 4 barrel sustain before it becomes inaccurate?

My No. 4 is still an accurate shooter even though it currently has a measured jump gap of .250". From what's been discussed on this forum and elsewhere, the No. 4's barrel and action were originally built to spacious specs. If true, what level of throat erosion does a .250" jump gap represent? What was the jump gap distance when it left the Savage factory? Zero?

The muzzle has a diameter of .3025". I was expecting to see a diameter of .303" which would match the caliber, not one that's actually .0005" smaller.

Notes from a gun show I attended in Monroeville (near Pittsburgh) last Sunday:

A vendor had a nicely dressed up No. 4 Mk 1* Savage for sale with a bayonet and scabbard. It looked as if the stock, hand guards and external hardware had been replaced. In addition to my bore light, I always bring my headspace, muzzle erosion and jump gap gauges with me to these shows, just in case. Always being curious, I inserted my muzzle erosion gauge into the muzzle. To my utter amazement, it disappeared down into the bore completely and I had a heck of a time retrieving it. The vendor obviously never checked the condition of the barrel before putting all that time, effort and money into making the rifle look new-ish. It pays to bring your light and gauges to these shows if you're thinking about buying a rifle.

[Johnny P]

In the 1903 Springfield barrel the nominal bore diameter was .300 and .308 groove diameter. Manufacturing tolerances allowed a bore diameter of .2995 to .3015, and a groove diameter of .3075 to .3095. Going from one end of the tolerance to the other is going to skew the results with a breech bore gage even though both barrels are new.

I have an original August of 1940 M1 Rifle with the original barrel that reads 1.5 on the breech bore gage, while a new never installed Springfield Armory 1-52 barrel reads 2.5 on the same gage.

[Sunray]

There's no such thing as a "jump gap " measurement. There is a throat erosion though. However, a .30 calibre throat erosion gauge will tell you nothing about a .303 Brit chamber.
Dunno if you'll be able to get to this, but it's a BILINGUAL CF manual.

http://photos.imageevent.com/badgerdog/generalstorage/edhortonmanuals/2002%20No.4%20Data%20Summary.pdf

The .303 British headspaces on the rim. Military spec Max OAL is 3.040". Accuracy depends on the diameter of the bullet vs the groove diameter. Most commercial ammo and bullet makers use .311" or .312"(Montana Bullet makes some larger diameter cast bullets). Accuracy will be poor if you use the wrong diameter bullet(like a .308" bullet) in an oversize barrel.
Any No. 4 Mk 1* still around is highly unlikely to have seen any W.W. 2 service. No. 4 was in use up here with Army Cadet Corps until the mid 90's, as I recall. Still used as DP rifles with colour parties.
All remaining Savage made rifles, parts and machinery got sent to Long Branch when the contract expired. Had one on my MIU long ago.
Lithgow Lee-Enfields are NOT No. 4's. They're No. 1 Mk III's. Aussies didn't use No. 4's. Ishapore didn't make 'em either.
"...original 303..." That was the bore diameter. Groove diameters were .311" to .315", even at Long Branch.
You used to be able to order a Criterion No. 4 Rifle barrel chambered in .308Win. It is not a .308" barrel chambered as a .303 Brit. No longer available.

[JB White]

There's no such thing as a "jump gap " measurement. There is a throat erosion though. However, a .30 calibre throat erosion gauge will tell you nothing about a .303 Brit chamber.
Dunno if you'll be able to get to this, but it's a BILINGUAL CF manual.

http://photos.imageevent.com/badgerdog/generalstorage/edhortonmanuals/2002%20No.4%20Data%20Summary.pdf

The .303 British headspaces on the rim. Military spec Max OAL is 3.040". Accuracy depends on the diameter of the bullet vs the groove diameter. Most commercial ammo and bullet makers use .311" or .312"(Montana Bullet makes some larger diameter cast bullets). Accuracy will be poor if you use the wrong diameter bullet(like a .308" bullet) in an oversize barrel.
Any No. 4 Mk 1* still around is highly unlikely to have seen any W.W. 2 service. No. 4 was in use up here with Army Cadet Corps until the mid 90's, as I recall. Still used as DP rifles with colour parties.
All remaining Savage made rifles, parts and machinery got sent to Long Branch when the contract expired. Had one on my MIU long ago.
Lithgow Lee-Enfields are NOT No. 4's. They're No. 1 Mk III's. Aussies didn't use No. 4's. Ishapore didn't make 'em either.
"...original 303..." That was the bore diameter. Groove diameters were .311" to .315", even at Long Branch.
You used to be able to order a Criterion No. 4 Rifle barrel chambered in .308Win. It is not a .308" barrel chambered as a .303 Brit. No longer available.

Have you been mixing your meds with hooch again?
Nobody made any claim about Lithgows, Ishys, BSA dispersals being No4's. Only what was available on certain regional markets.
The "jump gap" being referred to is the Leade/Small cone. He used revolver slang...so, what?
Criterion did/does offer replacement No4 barrels. (I haven't looked in the past few months)

Any No. 4 Mk 1* still around is highly unlikely to have seen any W.W. 2 service.

What planet are you shopping on???

[bigedp51]

Questions of the day:

Where could one find the original barrel dimensions for a 1944 No. 4 Mk 1*?

How much concentric muzzle wear and jump gap distance can the No. 4 barrel sustain before it becomes inaccurate?

My No. 4 is still an accurate shooter even though it currently has a measured jump gap of .250". From what's been discussed on this forum and elsewhere, the No. 4's barrel and action were originally built to spacious specs. If true, what level of throat erosion does a .250" jump gap represent? What was the jump gap distance when it left the Savage factory? Zero?

The muzzle has a diameter of .3025". I was expecting to see a diameter of .303" which would match the caliber, not one that's actually .0005" smaller.

Weatherby Rifles are known for having long throats, a AR15 rifle has a throat twice as long as most .223 rifles. My Savage .223 with a 1 in 9 twist has a longer throat than my AR15 rifles.

A used Enfield rifle will have Cordite throat erosion and as long as the rifle met accuracy standards it was kept in service.

If the rifle looks in good shape and the muzzle is OK then buy the rifle and shoot flat base bullets.

Below is a 10 shot group fired at 50 yards from a well worn 1943 No.4 Enfield after making bedding adjustments to the rifles fore end. After this the sights were adjusted for 100 yards, and with a PH-5C target sight I could keep 5 rounds in the X ring at 50 yards.



And below is the best group fired at 50 yards with the same Enfield out of five targets before doing anything to the loose fore end. Some of these targets only had two bullet holes in the target because of bedding problems and not having the required 2 to 7 pounds of up pressure at the fore end tip.



Bottom line, the two best groups I have ever fired with a peep sight were with old worn military rifles and now rival what my older eyes can now do with a scoped rifle.

[Merc]

Weatherby Rifles are known for having long throats, a AR15 rifle has a throat twice as long as most .223 rifles. My Savage .223 with a 1 in 9 twist has a longer throat than my AR15 rifles.

A used Enfield rifle will have Cordite throat erosion and as long as the rifle met accuracy standards it was kept in service.

If the rifle looks in good shape and the muzzle is OK then buy the rifle and shoot flat base bullets.

Below is a 10 shot group fired at 50 yards from a well worn 1943 No.4 Enfield after making bedding adjustments to the rifles fore end. After this the sights were adjusted for 100 yards, and with a PH-5C target sight I could keep 5 rounds in the X ring at 50 yards.



And below is the best group fired at 50 yards with the same Enfield out of five targets before doing anything to the loose fore end. Some of these targets only had two bullet holes in the target because of bedding problems and not having the required 2 to 7 pounds of up pressure at the fore end tip.



Bottom line, the two best groups I have ever fired with a peep sight were with old worn military rifles and now rival what my older eyes can now do with a scoped rifle.

The original sights on my 1944 No. 4 Mk 1* are surprisingly accurate. I mounted a Bushnell scope on it for a while and found that I could shoot just as well at 100 yards with the ladder sight at its lowest setting. This was after I figured out the front blade needed some minor adjustments. With the ladder sight folded down and aiming through the peep sight, the groups are about 6 inches high at 100 yards.