Crazy Results in Firing different types of .30-06 loads in a M1917 Enfield

[fjruple]

Today I really got a chance to take my Eddystone M1917 with a Johnson Automatics two groove barrel and run several loads through the rifle. The rifle is equipped with a Parker-Hale PH5B rear sight with variable PH eyepiece. First I shot a group at 100 yards with .30-06 Springfield ammunition loaded with a 168 grain Sierra Matchking BTHP bullets. This load I use in My M1 National Match with great results. X's and 10's all day. When I shot these rounds in the M1917 Enfield the bullets are keyholing with a nice grouping at 100 yards!! When I used the standard M2 Ball round all of the shots were in the X's and 10 ring. Anybody knows what is going on here? I have shot the 168gr Sierra Matchkings in a two groove barrel on my Remington M1903A3 with excellent results.

--fjruple

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[Wineman]

Possibly the barrel tolerances are on the large side. The flat base bullet "slugs up" and fits better, the BTHP flops around a bit and is sloppy at 100. Try the BT farther out, they may not be as bad although something out of balance usually does not correct itself. I have a 5 groove original barrel and it likes flat base or fatter boat tails (Hornady 303/7.7 FMJ at 0.3105"). You might give these a try too. The other thing that might be better is the M72 bullet from the original M1 30-06 loads (172 grain BT but open base, the MK has a hollow point). Sometimes you can find these as pulled and at good prices. Other FMJ BT's may also be open base but I don't have any to compare. Hornady and Remington come to mind. I would stay away from pulled M-80 7.62x51, they would be better at 100 but I have found them not very accurate.

Dave

[browningautorifle]

Obviously they aren't stabilizing, likely for the reasons mentioned. I'd change to a flat base bullet and see what gives. Your match bullets have a small barrel bearing surface. You could try some 165 gr hunting bullets to see...close to the 168s.

[oldfoneguy]

I agree with going to a flat base bullet. The 2 groove barrel in my No4 Enfield does the same thing with boatails.
The original '06 load is 150gr bullet @ 2700fps.
I would load up some 150gr flat base bullets and keep the velocity down some.
Remember it's a 26" barrel so you can load it down a little from the 24" barrel loads to achieve the same velocity. - Bill

[Patrick Chadwick]

Possibly the barrel tolerances are on the large side. The flat base bullet "slugs up" and fits better, the BTHP flops around a bit and is sloppy at 100.

Make that "Probably..."

This is what happens when a BT is fired in a typically worn military chamber with a longer-than-SAAMI/CIP throat:
1) If the cartridge is new, or a fully-calibrated reload, the play between the cartridge case and chamber means that the neck is sitting on the bottom of the chamber, so the centerline of the bullet is below the centerline of the barrel.

IMPROVEMENT 1: use neck-sized cases only, leaving a little uncalibrated ring about 1mm long at the base of the neck to center the neck and bullet in the chamber.

2) When fired, the neck expands, and the bullet moves forwards along this line below the barrel centerline.

3) The hot gases rushing out of the gap between the expanded neck and the bullet - mainly ABOVE the bullet - will create an asymmetrical force on the bullet. The result is that the bullet tilts as much as the play in the chamber and throat will permit.

4) A worn throat increases the blow-by effect as it gives the bullet even more opportunity to tip before it engages the lands.

5) And using BTs makes it worse, as the gap between bullet and the expanding neck opens up that much earlier. And the short cylindrical section permits more tilt for a given radial play.

IMPROVEMENT 2: use a bullet with a longer cylindrical section
AND/OR IMPROVEMENT 3 - a slightly larger diameter IF the bore is truly enlarged (CAUTION: overpressure is possible) .
IMPROVEMENT 4: Seat the bullet further out - if possible. (CAUTION: overpressure is possible). Flatbase bullets give you more freedom to do this.

4) The skewed bullet is now rammed into the lead at an angle. Emerging from the muzzle at an angle, it will precess, fly in a corkscrew trajectory, and possibly tip.
As was observed in the case under discussion.

PLAUSIBILITY CHECK. Calculate the skew over the approximately cylindrical portion of a boattail that corresponds to 1 MOA. It is horribly small!
Now one begins to understand why benchrest shooters take such care with throat diameter etc.

Somewhere in over 4000 posts I presented this all with photos. Try searching for "neck sizing" and boat-tails. The essence is: for worn barrels, do NOT use boat-tails.

P.S: in my experience, the Sellier & Bellot "SPCE" hunting bullets perform very well in old milsurps as they have a flat base and a long cylindrical section.

[Wineman]

Patrick,

Well said. I would think that this excellent advice should get him shooting straight with non Matchking bullets.

Dave

[fjruple]

Well-- you guys gave plenty of food for thought on this issue. I believe the first thing I have to do is slug the barrel to get a true diameter. If the barrel is oversized from wear or manufacture I will move up to a .311 diameter bullet. If the bore is nominal for the .30-06 springfield I will check the throat for erosion. The next group of rounds will be neck sized only. I will probably try a bullet with a longer cylindrical section and one with a flat base and see what happens. Thanks for every ones help and I keep you posted on my progress.

Cheers

--fjruple

[Patrick Chadwick]

Somewhere in over 4000 posts I presented this all with photos. Try searching for "neck sizing" and boat-tails. The essence is: for worn barrels, do NOT use boat-tails.

Found it!

https://www.milsurps.com/showthread....ht=neck-sizing

Scroll down to Post #139

if you follow the simple methods outlined here, you can make good ammo for an old, worn service rifle without wasting (IMOH) time and money on expensive gauges.

Have fun, and let us all know how it goes!

Patrick

[RC20]

I am inclined to throat erosion.

It sounds like a former drill rifle faire with blanks. Throat gone but the end still perfect.

Do you have the TE tool?

[fjruple]

Hi guys--

I thought I would give you and up date. I have a throat erosion guage and the barrel swallowed it. I suspect RC20 is right and the M1917 was a veterans gun that shot a lot of blanks at funerals and never cleaned. I also purchases another Eddystone M1917 that appears to have been rebuilt during WWII which has a Winchester 1-19 dated barrel and many Winchester and Remington parts. Unfortunately that barrel was toast too. TE was about a 5.5 or more and muzzle wear guage fell to the end. I counterbored the muzzle and the barrel would only a occasionally throw a bullet about six feet from the target at 100 yards. Its ashame the barrel was not clean it looks like the barrel was new at one point due to the strong rifling. I suspect this rifle was also a veterans funeral rifle and never cleaned. I have removed both barrels from the receivers and ordered two new M1917 .30-06 barrels made by Criteron. I will put both barrels on and see what happens.

Cheers

--fjruple