micro groove rifling

[manatee1947]

do some of the handi barrels have micro groove rifling?

[thejanitor]

I have a 45-70 that is, but I believe my sons isn't. So there will be some variation by years. 
thejanitor

[petemi]

I don't really know which of my Handis are Microgroove and which are not.  It's something I need to check.  I have read here that several people don't care for the Microgroove rifling in a Handi.  I don't know why.

 Brent (thejanitor), you guys shot the same 405 gr. Remington load out of those .45-70s.  Did you notice any difference in accuracy between the two?

My first "deer rifle" I bought in 1959 is the Marlin 336T .30-30 Microgroove pictured below.  It celebrated it's 50th birthday in 2009.  It wore the standard open sights for many years and has killed more deer than I have kept track of.  (Tim, the scope is yours) The first a big doe at 225 yards, and the second a year and a half old at 160, both one shot kills on the same day in '59.  They were in Upstate NY.  The latest, a Michigan 6 point outside of Newberry at 80 yards.  It remains one of my most accurate and dependable rifles, preferring the old Winchester 170 gr. Silvertip.  I need to sit down one day and pit it against my Handi .30-30 which also is very accurate.

Pete

[quickdtoo]

Yes, some H&R barrels are micro-groove, we had a lengthy discussion on it a little over a year ago, lots of good info in it. 

Tim

http://www.gboreloaded.com/forums/index.php/topic,206287.msg1099083017.html#msg1099083017

[gcrank1]

And FWIW, some people say MG rifling doesnt shoot cast bulllets worth a durn, yet guys in The Cast Bullet Assoc. have been shooting them successfully for years (ya just gotta have the right bullet dia. for your gun).

[quickdtoo]

Yup, that was discussed in the link I provided earlier including a link to an article by Glen Fryxell describing that exactly. 

Tim

http://www.leverguns.com/articles/fryxell/microgrove-barrels.htm

There has been a great deal of concern over the years about whether or not Microgroove rifling would shoot cast bullets well. One group of folks says that Microgroove rifles can't hit a barn from the inside with cast bullets, one group says that Microgroove barrels shoot cast just fine just so long as velocities are kept below 1600 fps, and one groups says that Microgroove barrels shoot cast just fine at full throttle. The key to success with cast bullets in a Marlin with Microgroove rifling is to keep in mind that these barrels tend to have oversized groove diameters, and that the grooves/lands are shallow. Therefore, in order to get proper engraving (and minimize "slippage" of the cast bullet as it enters the shallow rifling), it is necessary that the bullet completely fill up the groove diameter of the barrel, and engage the maximum amount of the driving surface of the lands. Since Microgroove barrels are commonly oversized, this means that the cast bullet must also be oversized to effectively "fill up" the grooves. Other factors that also contribute to good accuracy with cast bullet in Microgroove barrels are the use of a GC bullet (which helps to provide a better grip and seal), and making sure that bullet are cast hard enough for the application (generally a BHN of 12 or more). It is also worth remembering that throats in modern rifles are almost always cut larger than groove diameter of the barrel (to insure that ammunition can chamber easily), and that best cast bullet accuracy is obtained by fitting the bullet to the throat, hence reinforcing the need for oversized cast bullets in Microgroove barrels (for example, the throats on my .30-30s run almost .311", so I size cast bullets to .310" for these guns).

[manatee1947]

I read that, thanks for the link, I just got one of those 30/30 MG barrels and it kind of startled me. The throat seems a bit short and it was running pressures a little high. I went to a shorter lighter bullet, but 310 dia. It still runs a little higher pressures but shoots well, some .70 groups at 50 yds. I have to wait until a friend gets time to chrony some for me, so I don t know the speed. I am using 33.5 gr of 748, which should be a starting load, but is mildly flattening primers.

[thejanitor]

Brent (thejanitor), you guys shot the same 405 gr. Remington load out of those .45-70s.  Did you notice any difference in accuracy between the two? Pete

Pete- my sons non-micro touches holes with a couple loads at 100, mine hasn't but after returning from our hog hunt I found my scope (that has always been on it since I got it on a frame) had slid in the rings... so mine might shoot better than I had thought. But his is very much a tack driver. thejanitor