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 SMLE ballistics experts needed. No 1 Mk III keyholing. Slugged barrel, now even more confused...
Gastonite  [Team Member]
5/21/2013 12:59:58 AM
SORRY FOR THE GIGANTIC PICS

Hi gang,

I purchased an Enfield 1916 SMLE about 10 years ago for $89 on a whim. The action was slick and I really liked the look of the early SMLE line. The bore was a bit dark but there was still rifling and it shined up a bit after some meticulous passes of the wire brush. I never ended up shooting it due to the AR15 craze and demise of the 1994 AWB; I was preoccupied.



Fast forward to Saturday, my first day out actually shooting her. I shot Remington Core Lokt 180gr Soft Point and was key holing all over the place at 100 yards. As far as I understand, these are not Boat Tail bullets, which some early Enfields have an issue with. Unfortunately, this was the only ammo I had available. After much reading I learned that older SMLEs typically have a mish mash of larger bores and are best suited toward .312 diameter bullets and to pass on typical factory loads. But to really know what I had, I needed to slug the barrel. So I did that today thinking I'd get something like .312 or higher; I mean, this thing is from 1916 and has probably been around the block.

Well, I've never slugged a barrel and have never owned a pair of calipers, so I went out and got all the essentials today. I lubed the barrel well and pounded a #9 egg sinker thru her. And....wait for it, it measured .308 with the calipers. I expected at least .311. Did I do something wrong?



I measured this thing sideways, back of egg sinker, you name it, and I still got a measly .308 (I know this is not a .308 because it clearly states .303 on the barrel; all matching parts).



Enfield ballistics experts, can you please offer any insights into whether I'm completely F'ing up the slug bore process or measuring wrong? Perhaps I have the tightest bore on the planet?

Thank you for reading!
AKJP  [Member]
5/21/2013 1:28:25 AM
My first question would be, are you measuring the lands, or the grooves? Also, it's hard to say for sure from that picture, but I can't make out any distinct land/groove marks (merely slight diagonal marks, but no solid grooves). I've had this happen before when slugging bores if I pushed the slug through too fast and/or it wasn't wide enough to start with. You can basically smear/shear it through the barrel and not get an accurate measurement. You might want to try it again, tapping slowly, to see if you get a more defined rifling pattern on the slug. Then be sure to measure the widest area (the grooves). Also, be sure to measure the bullets if you still have any. I'm not familiar with the specs on the Core Lokt 180s, but I would not be surprised if they are slightly undersized for liability reasons. Others may (and probably will) know more, though.
Mwieczorek  [Team Member]
5/21/2013 9:36:45 PM
Shouldn't a 1916 intage No 1 mk III have 5 groove rifling? If so, I think you will have to do a little more work to get a valid measurement.

Matt
SteelonSteel  [Team Member]
5/21/2013 9:48:45 PM
Originally Posted By Mwieczorek:

more work to get a valid measurement.

Matt


yep that would do it.

also I wondered if your egg sinker fully met the bottom of the grooves.

My go to method for my C&R throat measurements is to fill a berdan case previously fired in that gun up to the neck with molten lead. Insert a longish cast bullet and chamber the pair into the rifle. Insert round down the bore and pound the lead bullet down until it doesn't move anymore. Open bolt and carefully tap out and measure. I don't like the cerrosafe shrinkage factor.


http://www.lasc.us/Brennan_2-1_MeasuringGunDimensions.htm
Gastonite  [Team Member]
5/22/2013 12:57:08 AM
Thanks for the replies, guys. I am going to reshape the egg sinker to be wider and go slow on the slug process. I think I pounded it thru to quickly and it may have missed the grooves some. I don't have access to cast bullets, unfortunately...I hit three gun stores in the Seattle area today and their wares far favor the home defense shooter. I am going to order some along with my first reloading supplies from Midway.

Regarding measurements, I tried a few different ways to get the widest reading, but regardless, I was probably working with an insufficient slug. I will post results as soon as I have them.
KC-10Boom  [Team Member]
5/22/2013 7:07:11 AM
The way to measure a slug from a barrel with an odd number of lands/grooves is to very carefully roll it between the jaws of your calipers. This will bump them open if you're careful enough and will provide a correct measurement.
bigedp51  [Member]
5/22/2013 11:05:20 AM
The British .303 military cartridge was loaded with cordite powder a early double base powder that had more nitroglycerin than many pistol powder have today. It was hot burning powder and your problem may be throat erosion, therefore slugging the bore and getting the "smallest" bore reading will not help your problem.

Slug your throat and get a reading and see what you have, if way oversized then look into shooting oversized cast bullets.

One way to measure five groove bullets is the wrap the bullet with the thinnest feeler gauge blade you can find and then subtract double the thickness of the blade.

If a flat base 180 grain Remington .303 keyholes normally two problems can cause this, a worn throat or a damage muzzle, if you do not plan on shooting cast bullets you may have a wall hanger. What you can try is shooting reloads with a fast burning powder like IMR-3031 at the rated chamber pressure and see if the base of the bullet expands more when kicked in the seat of the pants and see if it stops keyholing. Factory .303 ammunition is loaded with slower burning powders well below the rated chamber pressure of the .303 British due to the amount of older Enfield rifles still being used.

Cordite loaded ammunition was banned from machine gun usage due to short barrel life and only single base powder could be used in machine guns.

Obturation
http://en.wikipedia.org/wiki/Obturate
zainyD  [Member]
5/23/2013 8:23:55 AM
You may also want to check your headspace. I had a SMLE that keyholed badly but after I replaced the bolt head it corrected the problem.
bigedp51  [Member]
5/23/2013 3:54:15 PM
Originally Posted By zainyD:
You may also want to check your headspace. I had a SMLE that keyholed badly but after I replaced the bolt head it corrected the problem.


How would headspace effect the throat, bore and muzzle?

The No.4 Enfield below has had the headspace adjusted to just kissing the rear of the case well under the .064 minimum headspace to .010 over maximum military headspace of .074. During these headspace tests "headspace" had absolutely NO effect on bullet stability, emergency wartime headspace for the Enfield rifle was .084 and there is NO printed military material correlating the two.



On worn Enfield rifles with excess headspace and No.3 boltheads impossible to find, I simply fireform the case to fit and headspace on the shoulder by slipping a rubber o-ring around the case to hold the case against the bolt face.



Thereafter the case headspaces on the shoulder like any modern design case would.

jungp  [Member]
5/23/2013 4:02:49 PM
check the muzzle first.

Is there any nick, cut, etc?
Gastonite  [Team Member]
5/23/2013 8:25:35 PM
Okay, I widened the egg sinker and slowly slugged the barrel from chamber to muzzle this time. After rolling the slug in the calipers several times, I received readings between .313 and .314. This leads me to believe its probably even wider than that in some places. This is a five groove barrel, as far as I can tell, so I may still be getting it wrong. For comparison, I pulled a .303 Remington Core Lokt and it consistently mic'd at .310.

So, after reading all of the replies and several other sources online, I would like to give the cast bullets a try. I would love to get some trusted resources for supplies where I can order online. Any suggestions around conservative or safe powder & grain mixtures would be extra appreciated. While I may have invested a mere $90 into this thing, I have fallen in love with her lines and history and want to see her rise again!

Thanks Arfcom brothers for all the help!

ETA: jungp, no visible damage to the muzzle that I can see. Thanks for the note.
AKJP  [Member]
5/23/2013 10:57:27 PM
Nothing against cast bullets and if you can give them a try, then go for it. However, in the meantime, see if you can get ahold of some Sierra 180 grain soft points (.311) and see how they do. I've had great luck with them in Enfields and Mosins, even with rather large bores. Also, the Sierra 174 Match King, which is advertised as a .311, is actually a .312. You many want to try those, as well.
Gastonite  [Team Member]
5/23/2013 11:33:22 PM
Originally Posted By AKJP:
Nothing against cast bullets and if you can give them a try, then go for it. However, in the meantime, see if you can get ahold of some Sierra 180 grain soft points (.311) and see how they do. I've had great luck with them in Enfields and Mosins, even with rather large bores. Also, the Sierra 174 Match King, which is advertised as a .311, is actually a .312. You many want to try those, as well.


Awesome stuff. I will add them to the list. I plan on creating four or five different types of reloads, a mix of cast and jacketed, to see which perform best. Thanks for the note.

CK1  [Member]
5/25/2013 5:19:25 PM
Originally Posted By Gastonite:
Originally Posted By AKJP:
Nothing against cast bullets and if you can give them a try, then go for it. However, in the meantime, see if you can get ahold of some Sierra 180 grain soft points (.311) and see how they do. I've had great luck with them in Enfields and Mosins, even with rather large bores. Also, the Sierra 174 Match King, which is advertised as a .311, is actually a .312. You many want to try those, as well.


Awesome stuff. I will add them to the list. I plan on creating four or five different types of reloads, a mix of cast and jacketed, to see which perform best. Thanks for the note.



With the 5-groove, the SMKs would be very nice to shoot. If they keyhole, you're barrel might have seen too much cordite.

My No4 Mk1 has a two-groove that mic'd .313 and thus severely limits the bullets I can load. Flat base, long bearing surface, and wide bullets work well in my rifle. I've had good luck using Hornady's 7.7mm (.312) bullet selection which come in 150gr flat base soft point and 174gr round nose soft tip. The same factors that work well in my barrel should work well in a worn barrel. Don't be a pansy when it comes to powder charges as the initial pressure spike will obturate the bullet base and better engage the rifling.