Metford Rifling

[Rick]

One reason I think the 1917 is such a good shooter is the Metford Rifling. Five groves equal distance between lands and groves.

This rifling was developed to make barrels last longer using cordite powder. Think I remember a Metford Rifled barrel could outlast several normal four grove or two grove barrels.

Fast forward to todays accurate rifles. You pay extra for a 5R barrel target barrel. No for sure but I think this is the Metford Rifling.

[p246]

Double post so it was deleted

[p246]

Brother you got some facts wrong metford rifling worked well with black but the cordite eroded the xxxx out of the throats. They went to Enfield rifling after that. Medford Lee Enfields were early guns, after Cordite everything changed. I don't think the Enfild rifling fared much better though, since throats erosion was the isssue.

[Tuna]

The 1917 is a very accurate rifle and the 5 groves did have something to do with it. More accurate then an 1903 even though the 03 had such fine target sights compared to the 1917. The country that used Medford rifling the most was Japan. Used
it in the type 38 6.5mm rifles of which they made many millions of. Worked well with the normal smokeless powders they used.

[Merc]

So, the 5 groove barrel on my M1917 is the reason for its accuracy. I knew there was something different about this rifle compared to the others I own. Pretty amazing. It actually makes me look like I know what I'm doing at the range.

Our M1917s will turn 100 years old over the next three years. Mine turns 100 in November. No-one knows for sure how many rounds have been fired through their rifles or the care they've received over the years. Considering the state of gun building technology and metallurgy that was available in 1917, we're fortunate to have the confidence that our M1917s are still safe to shoot the powerful .30-06 cartridge and are still accurate shooters thanks to a strong action and a 5 groove barrel. Many 17s have held up well over the years and should be passed down for our grandkids to enjoy and appreciate. Obviously, the bolt action design was difficult to improve since it's still with us 100 years later.

[Rick]

That and the left hand twist doesn't buck the coriolis effect.

So I had it wrong about calling the five grove rifling equal spaced between the groves and lands Metford. I thought I read that in a article somewhere back in time.

Really don't know about the coriolis effect. I made that part up.

[dave]

If 5 groove were such an improvement the 4 groove S.C. 03A3's must be more accurate then 2 groove 03A3? Tests, when 2 groove was adopted, said otherwise.

[p246]

That and the left hand twist doesn't buck the coriolis effect.

So I had it wrong about calling the five grove rifling equal spaced between the groves and lands Metford. I thought I read that in a article somewhere back in time.

Really don't know about the coriolis effect. I made that part up.

Left hand twist in the northern hemisphere does negate some of the Coriolis effect but since its a known math problem its not worth building for in my opinion. That same left hand twist would make it worse in the southern hemisphere. Since the ranges that Coriolis become an issue are so far away coupled with military iron sights I'd say it's impossible to correct for in a military iron sighted rifle of the 20th Century. My 700P with 175 grain SMK's C.E. effect correction at an azimuth of 90 degrees is 3 inches rounded at the 1000 yard mark. I suppose there are iron sight shooters that might be able to squeeze this out but it is not me. Wind will be the issue at those ranges. Coriolis is mainly for us long range modern shooters with high quality optics shooting at 1000 yards plus. Most shooting apps can now figure it if one does not want to do a Calc. sheet.

[p246]

The 1917 is a very accurate rifle and the 5 groves did have something to do with it. More accurate then an 1903 even though the 03 had such fine target sights compared to the 1917. The country that used Medford rifling the most was Japan. Used
it in the type 38 6.5mm rifles of which they made many millions of. Worked well with the normal smokeless powders they used.

Tuna do you know what powder the Japanese used. I'm assuming it was not cordite but do not know.

[p246]

If 5 groove were such an improvement the 4 groove S.C. 03A3's must be more accurate then 2 groove 03A3? Tests, when 2 groove was adopted, said otherwise.

Correct my most accurate 30-06 is a Remington 03A3 with two grove barrel. Many things go into accuracy. The only fair comparison would be to shoot each model new and with several guns of each. Those days are gone, but it was done "back in the day" and the military found no noticeable improvement in the number of grooves. One thing that probably is more important is getting the right twist with the round you have built for the gun.