Lee-Enfield (or ammo) problem.

[wogpotter]

OK, a question or two on an odd pair of incidents today at the range.

The Bubba’d No5 ("jungle carbine") I rescued has only been fired with my handloads. Its been checked for lug engagement (its fine even & about 40% on both). Headspace it passes both the Okie NO-GO (0.067") & obviously the FIELD (0.074"). The bolt head is a No “0”. Not surprising as the bolt & receiver serial numbers match. Checking the FP protrusion, it mics to 0.048”, a little long, but within tolerance for the 0.040”~0.050” range listed.

Weather at the range was cool & damp with a light mist so there were no temperature concerns.

Working up a load for this rifle using virgin R-P brass & CCI #200 primers has functioned perfectly with absolutely no issues. FWIW the loads were 150 Gr & 174 Gr Hornady & Sierras run to moderate pressures & velocities. This is a 60 or so rounds in a few lots, as the load was being developed.

Until today these were the only loads run through this particular rifle, but today I tried some S/A MilSurp “7.7 ~ R1M3Z ~ A81” ammo which I’ve previously used other rounds from in the no4MK2 with no problems at all.

I immediately started getting odd results. On round 3 (1&2 were fine) something struck my thumb, which is odd! Looking at the action after firing, but before cycling, the bolt it was fully cocked, even though the trigger had been pulled & the striker detonated the cap & fired the round. ? Hmm, odd. Once I de-cocked & opened the action the primer was pierced. I assume the venting gas actually forced the striker back & the sear caught the bent!

I stopped & checked everything out & cleaned the mess as the gas had vented through the ports in the bolt head & receiver ring.

The next 3 rounds were normal, then another pierced primer.

Finally I fired & the bolt attempted to open fully! This was NOT the usual 1/8~1/4” of bolt lift, but it almost unlocked completely the handle was rotated about 65~70 degrees & I could see about 1/16” of the case Past the rim in the breech the bolt & head had moved back so far!

There were also random incidents of stiff unlocking of the bolt. Needless to say that was it for the day.

So far all I can find wrong is the pin protrusion being a little long & the radius being a little tight. However the excessive unlocking has me concerned. Has anyone else had a similar experience with pierced primers having enough gas venting to re-cock the striker fully & rotate the bolt 60 or so degrees?

The primers were not slightly pierced but a full disc was punched out of the primer cup.

 

[James K]

So-called "pierced" primers are not caused by excess firing pin protrusion, but by too light a firing pin spring or a too light weight firing pin.

The reason is that when the firing pin dents the primer and ignites it, the first thing the forces inside the primer try to do is to blow the dent back out. The firing pin has to be heavy enough or the spring strong enough to resist that. If that is not the case, the pressure inside the primer will blow part of the primer back into the firing pin hole in the bolt and the result will be a "pierced" primer. Some folks think the cause is too strong a firing pin spring, so they weaken it further, resulting in more "pierced" primers, so they weaken the spring still more until the rifle won't fire, which does solve the problem.

Incidentally, those little "discs" don't just go away; they go somewhere, which is inside the bolt where enough of them will get in the way of the firing pin and result in the rifle not firing.

Jim

 

[Gunplummer]

Not always the case. A F/P that is too long WILL blow the primer, but it is usually very hard to open the bolt. What is left of the primer will weld around the pin and into the F/P hole.

I don't know is the Mark 4 the same set up as a Mark III ? Are the threads good on the bolt where the head screws on?

 

[wogpotter]

Striker spring tension matches that of my other no4 & is within specs.

A F/P that is too long WILL blow the primer, but it is usually very hard to open the bolt.

That is what I was experiencing, a tight bolt with the pierced primers. The bolt is getting a 100% tear down as a result of this just to be sure.

is the Mark 4 the same set up as a Mark III ?

Yes the screw in striker with offset locking screw is almost identical, the threads form is different, but the rest is the same.

*Update with pics*
This is a Q&A from another site who are also helping me out, but its stuff I hadn't thought of initially.
* All dimensions are the averages of several reads at different points round the circumference of 3~4 rounds.

Fired case neck OD of the S/A R1M3z
in the No4 0.3435"
In the No5 0.3460" so the No5 is looser.

Chambers: the No4 Mk2 is tighter & with less "generous" shoulder area.

Rim thicknesses:
My (R-P) reloads are 0.0590"
The R1M3Z is 0.0620"
so the S/A is a tighter fit in the breech with the bolt closed.

Here are the fired cases:
Top row (blue rectangle) is my reloads fired in the (problem?) rifle with no side effects.
Middle row (green rectangle) is R1M3Z rounds from the same lot fired in a different rifle with no problems.
Bottom row (red rectangle) is the fired R1M3Z cases some of which exhibit pierced primers & a stiff bolt lift.

(All images (c) Wogpotter 2015)

 

[T. O'Heir]

A Bubba’d No. 5 is most likely a No. 4 Rifle.
Serial numbers matching does not mean the bolt head is original to either the rifle or the bolt. The only part that matters is that the bolt didn't close on the N0-G0. No reason to check with the field if it doesn't.
Since you're not having issues with your handloads, but are with the milsurp, the ammo being the cause is a safe bet.

 

[wogpotter]

Nope its an actual 4-digit NO5 Mk1 verified as such.

 

[Tidewater_Kid]

My 1942 Maltby had a similar problem. The lugs on the bolt body were worn. I changed the bolt body and the problem went away. I still don't shoot that one too often, but I have 9 Lee-Enfield to choose from.

Before and after pictures

TK

 

[Slamfire]

Until today these were the only loads run through this particular rifle, but today I tried some S/A MilSurp “7.7 ~ R1M3Z ~ A81” ammo which I’ve previously used other rounds from in the no4MK2 with no problems at all.

I immediately started getting odd results. On round 3 (1&2 were fine) something struck my thumb, which is odd! Looking at the action after firing, but before cycling, the bolt it was fully cocked, even though the trigger had been pulled & the striker detonated the cap & fired the round. ? Hmm, odd. Once I de-cocked & opened the action the primer was pierced. I assume the venting gas actually forced the striker back & the sear caught the bent!

I am of the opinion that the gun powder in your your old surplus ammunition is dangerously deteriorated. As I have written in numerous posts, pressure rise with old gunpowder. The second post has a list of gun blow ups with old ammunition.

http://thefiringline.com/forums/showpost.php?p=5860901&postcount=26

August 1993 reloads. Anyone shooting older?

http://thefiringline.com/forums/showthread.php?t=566954&highlight=high+pressure

I would recommend that you stop shooting this ammunition before it damages your rifle. Pull the bullets, dump the powder, examine the cases for signs of corrosion. If the cases are pitted, throw them out. If not, maybe you can reload them with new powder and the old bullets.

 

[wogpotter]

If the powder is degraded why don't I get the same problem in other rifles?
I pulled down a couple of them to check the loads out & there's no indication of deterioration, no discoloration or odd smells either?
Accuracy is (surprisingly) good, ignition is consistent & immediate & velocity & deviations are well within limits as well.

 

[tangolima]

How tight is the firing pin hole? In your picture, the red group has a donut shape in the primer around the firing pin indentation. That makes make think you may have a over sized firing pin hole in the bolt head.

It also looks like the milsurp (green and red) are hotter than your hand loads.

Do you have picture of the pierced primers?

-TL

 

[wogpotter]

How tight is the firing pin hole? In your picture, the red group has a donut shape in the primer around the firing pin indentation. That makes make think you may have a over sized firing pin hole in the bolt head.

It also looks like the milsurp (green and red) are hotter than your hand loads.

Do you have picture of the pierced primers?

Both the red & Blue sets were fired in the same rifle with the same bolt & head. If the hole was excessively big I'd expect the same fault in both.

Yes the handloads are backed off 100 FPS from the military load. The R1M3z clocked through a Chronograph at a standard 2450 FPS, but I download the handloads a bit as that's a sweet spot for accuracy.

The bottom right 3 are the pierced primers.

FWIW the handloads are Boxer & the MilSurp are Berdan primed. They also show the same pressures & velocities in the "control" No4 Mk2 rifle, but without the piercing.

 

[emcon5]

August 1993 reloads. Anyone shooting older?

Yeah, WAY older.

Have some German and Austrian 8X56R from 1938.

Have some Greek 8X57 dated 1940.

Have a bunch of Czech 8X57 and some Russian 7.62X54, both with headstamps from the late 40s.

All of which shoot fine.

 

[tangolima]

Both the red & Blue sets were fired in the same rifle with the same bolt & head. If the hole was excessively big I'd expect the same fault in both.

The indentation may not show if you don't have high enough pressure. Your hand loads are significantly milder than then milsurps.

Yes the handloads are backed off 100 FPS from the military load. The R1M3z clocked through a Chronograph at a standard 2450 FPS, but I download the handloads a bit as that's a sweet spot for accuracy.

2345 fps versus 2450 fps, that's 7%. The pressure difference could be as much as 25%.

The bottom right 3 are the pierced primers.

I see. So the piercing happens in the firing pin indentation. I notice there is a smaller and deeper indentation inside the firing pin indentation. Does your firing pin have a sharp point at the tip? If it does, it is not kosher. The tip should be a hemisphere. A sharp point can pierce a primer if the load is hot.



-TL

 

[Slamfire]

If the powder is degraded why don't I get the same problem in other rifles

Don't know. I shot old Iraqi ball 303, some of which blew the cocking piece back due to pierced primers and hot loads. But not all rounds. Maybe luck of the draw. Was all the surplus ammunition stored in the exact same location and always kept segregated?

Maybe because of different rifle. Let me use an analogy: the feather that broke the Camel's back. The poor Camel was loaded up to the point it only took a feather to buckle the knees and break its back. Different rifle was the feather.

I pulled down a couple of them to check the loads out & there's no indication of deterioration, no discoloration or odd smells either?

I had pressure problems with powder that had lost its smell. Did not cause the bullets to initially go green. Then the stuff started cracking case necks.

Accuracy is (surprisingly) good, ignition is consistent & immediate & velocity & deviations are well within limits as well.

I shot some great groups with deteriorated surplus IMR 4895. It also gave sticky bolt extraction on the occasional round. I finally figured something was wrong when case necks started cracking.

Never measured the velocity with known bad powder, so what did you get with your 303 Brit?

 

[wogpotter]

Was all the surplus ammunition stored in the exact same location and always kept segregated?

Yes. In separate ammo cans standing next to each other under the reloading bench in a climate controlled room.

Did not cause the bullets to initially go green. Then the stuff started cracking case necks.

Nothing like that here, no signs of any corrosion either inside or outside.

Never measured the velocity with known bad powder, so what did you get with your 303 Brit?

What "known bad powder"?

This was from a test I did for different reasons, but it has the load velocities, spreads & so on.

I took 3 “representative lots” of .303 British & a “control” of my own handloads, to the range & fired them over my PACT chronograph at the customary 10 yards.

The 3 lots were.
South African R1M3Z <> A80 headstamped, A military ball round, but using 39.6 Gr. some kind of nitro cellulose stick powder.

Some Canadian made (Defence Industries) MkVII ball with a DI Z 1943 headstamp. Also a stick propellant of some kind.

British (Radway Green) cordite powered MkVII ball with a RG – 7 – 50 headstamp.

The “control” was R-P brass first time loaded with 174 Gr Sierra MatchKings powered by 37.9 gr of H335.

For giggles I fired 2 warming/fouling shots then set up the chronograph & fired a sample lot of my handloads to verify it was recording accurately.

My R-P handloads.
String # Shot # Ind. Vel. Low High AVG E.S. S.D. A.D. Group/Distance
1 5 2237 2181 2238 2217.0 57.3 20.6 16.0 1.5"@100yd'

I’d call this my “good plinking load”.

Next up the South African R1M3Z <> A80
String # Shot # Ind. Vel. Low High AVG E.S. S.D. A.D. Group/Distance
2 5 2450 2478 2527 2500 @ 10' 49.0 18.9 14.1 2.5" @ 100yd
Just a tad better than my load. But not a cordite-powered load.

Now the DI Canadian DI Z 1943 stuff.
String # Shot # Ind. Vel. Low High AVG E.S. S.D. A.D. Group/Distance
3 5 2450 2486 2622 2500 @ 10' 135.7 49.6 32.6 3" @ 100yd
Not quite as tight as the first two. Not horrible though the group was similar to the R1M3Z, neither as tight as my handload though. Not surprising as it was worked up specifically for this exact rifle.

Finally the “real deal” actual Radway Green 1950 cordite factory loads.
String # Shot # Ind. Vel. Low High AVG E.S. S.D. A.D. Group/Distance
3 5 2450 2364 2452 2410 @ 10' 88.3 32.4 23.1 3 1/4" @ 100yd.

Interestingly it came in right in the middle of the tests variations! The group was about “average” too. What I seem to have found is that a load worked up for a rifle is accurate, no surprise there! The 3 different “military, factory” loads were close to each other for accuracy (2.5” ~ 3.25”) & within the specs for the rifle & load in Military service. The load with the widest spread of velocities was the middle for accuracy; I’m not sure what (if anything) that proves, but it doesn’t seem to have the “wider dispersion of velocity” that we’re supposed to be compensating for compared to non-cordite rounds!