I was shooting some ammo that I load for my Winchester 94's and noticed that the velocity of that same ammo through the Handi was about 300 fps faster than through the Winchesters. That got me to pondering and I asked Junior about it. He diagnosed the Handi as having microgroove rifling and I just had to go out and put a slug through the bore to look at the rifling.
Sure enough, Junior is right. It looks like the .30-30 barrel has microgroove rifling. Microgroove rifling is a rifling style that Marlin Firearms uses in their lever action Model 336 rifles. Of course, you can click on the pictures for a larger view. What you'll see is 12 groove microgroove rifling.
So, knowing what I now know about the .30-30, I decided to slug the barrel of the .308 Winchester to see what kind of rifling it has.
That slug shows 6-groove conventional rifling. Both barrels are 1:10 twist, .30 caliber barrels, but the .30-30 has Marlin microgrooves and the .308 has conventional rifling.
I've been told that Handi-rifles never had microgroove rifling. Unless I got the only one in the batch, there are probably a few more microgroove barrels out there.
What difference does it make? Not much if you're using conventional jacketed bullets. Both barrels shoot jacketed bullets fine. It makes a big difference when you're shooting cast bullets.
5 comments:
That's interesting... Wonder if they are doing that with all the new rifles, or a mis-set on the machining???
In November 2000, Marlin purchased the assets of H&R 1871, Inc., a Massachusetts-based manufacturer of shotguns and rifles (New England Firearms branded), founded in 1871, and now located in Gardner, Massachusetts. Today H&R 1871 employs over 200 people. Marketing its products under the brand names of Harrington & Richardson and New England Firearms, H&R 1871 is the largest manufacturer of single shot shotguns and rifles in the world.
Maybe the fact that Marlin bought out H&R 1871 Inc has something to do with it.
All three of my Handi-Rifle barrels are microgroove. That's an old 44 mag, and semi-old 45-70 20" and 45-70 32".
My old .30-30 H&R Topper 158 made in 1968 has Enfield style rifling, six equal square top and bottom lands and grooves of equal size.
Gerry N.
Cast bullets work just fine in micro groove barrels after a little research.
Marlin tended to over size the bores on micro grooved barrles, so you need to cast your bullets oversize as well to be sure they completely engages the lands and grooves.
A gas check and casting the bullets hard helps too.
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