Loaded some 160 gr cast boolits from an old single cav lee mold; ACWW, tumble lubed twice w/ 40-40-10 (alox and JPW). Boolits measure ,310. powder charge 7 gr Red Dot. Gun is an older Glenfield mod 30 (micro groove) that shoots commercial cast 125 gr well. Boolits are landing sideways at 25 yds. Why might this be?
Bullet diameter too small.
Yep, common with Lyman molds. You need to slug the barrel to see what it really needs.Originally Posted by sghart3578
But then again, that light load might not spin up the longer boolit. Try some 3031. My boolit is 187 gr and I need over 1900 fps before it comes in.
I wonder if I am right in thinking that the 30 Glenfield rifle was only used for the rifle Marlin put their own name on as the 336? The 336 went on the market in 1948. As they probably waited to soak up initial demand before beginning production of the cheaper Glenfield, the great majority of those were probably made after the introduction of Micro-groove rifling in 1953.
The .30-30 dimensions shown in the parent were actually quite moderate, and probably lasted fairly well with that relatively forgiving round. The Sako-actioned 322, in .222 Remington, had rifling only .001in. deep. It proved exceptionally accurate while it lasted, but it eroded far too quickly, and even the change to the stainless barreled 422 didn't solve the problem.
Marlin deepened their Micro-groove rifling in 1968, but I believe the Glenfield line was discontinued, in the 80s, before they reverted to the deep "Ballard" rifling for centrefire rifles. To some extent your problem may depend on the date of your rifle, but I don't believe they ever made a .30-30 rifle in which a .310 bullet would be too small. The most likely thing is throat erosion, in a rifle made in the days of the shallowest Micro-groove rifling.
Later Marlins only have rifling .003" deep and the Ballards I have measured are the same depth but have less lands and grooves.
Many companies made guns for big box stores like Sears under Ted Williams, etc but they were the same guns. Glenfield was a Marlin made for another company. Sears and Western Auto had guns made by every single gun maker in the US and some from over seas.
The difference was a huge order and maybe cheaper wood.
True Ballard should be .006" but I have not found it. Micro Groove has more "bite" to the boolit.
Another advertizing ploy.
The picture shown shows .004" depth for Ballard, not found by me. Every one I measured is still .003".
If you double the number of grooves and half the height of the edge on which the bullet presses, you have retained the same bite on the bullet, and a larger number would increase it. But for hot gases, which are what erode rifling, the height of the groove face is what matters, and their number doesn't do a thing to compensate.
I'm sure you are right about the Ballard-rifled barrels you have measured, but they may have been the reintroduced version. The lower drawing in the patent is presumably the sort they had been using prior to 1953. I have a copy of a Marlin table 1909 in which the .30-30 93 had diameters of .297in. and depth of .002in per side, but these were considerably increased at some date between then and 1953 - I would guess the return to sporting production and change of ownership following the First World War, when there was plenty of cheap and not unduly massive barrelmaking equipment to be had.
I do not know history of Marlin rifling. I only know early guns have never been matched. 1892 in 25-20 would do 3/4" at 100 yards with open sights. So would the Marlin Mounty in .22.
My Marlin .35 Rem would do 1/2" at 100 with jacketed but cast from Lyman molds were too small.
Nothing wrong with Micro Groove but Ballard today has not shown an improvement.
What alloy did you use?
How long did you allow the boolits to age harden?
Have you pulled a loaded boolit and checked the diameter?
Are you using a gas check?
Personally I have not had good luck with commercially cast bullets for rifles. Had one batch that were made for gas checks and did not come gas checked and were a very tight fit for any gas checks. They patterned more than grouped. Bullets hitting sideways are generally not stabilized and may need to be speeded up a bit.
DP
All advice above is sound and from good sources, slug your bore so you know what she needs and up the charge a bit or switch to a more conventional thuddy thuddy powder like 4895.
+ 1. My Marlin likes .311 150 to 175 boolits, BUT it shoots .310 diameter nearly as good and I never have keyholes. Something else is amiss.
I don't have a marlin 30-30 but my savage 30-30 likes 0.311 with a 180 gr cast at about 1700 fps
If it were me I would try using the .310 with higher velocity first,,if that doesn't work then fatten the slug
Death to every foe and traitor and hurrah, my boys, for freedom !
put more powder in the case, the 125's work cause they are going fast enough to stabilize.
Why does cast need shot slow? Most of my revolver loads are OVER jacketed loads.
why look for 900 to 1100 fps loads in a rifle?
Jack the sucker up to rifle velocities.
Thanks for all the great replies- I'll try a bit more velocity, it's the easy fix-(if it works)! It that doesn't do the trick, will clean and slug the barrel. Need to do that anyway. Bullets were cast about 6 weeks ago, no gas check, ( though it's a gas check mold)
A slightly small bullet like the OPs Lee may keyhole if fired too slowly, my Marlin micro-groove likes 1600 fps, just as Lyman recommends, my rifle likes .312" bullets best.
Rotate your target 90 degrees.
BB
Its just to slow for the bullet weight. Yea a 30-30 will shoot 170s fine...at full velocity. As I have learned with messing with alot of subsonic, slowing things down complicates things. And it will depend on the rifle alot. I had one of the glenfields, got rid of it because of the microgroove rifling, I wanted to shoot cast. I know microgroove does work with cast, but standard rifling works better. That and the LGS had an old Stevens bolt gun in 30-30, he let me trade even for. I never got to mess with slow cast in the glenfield, but have in the stevens. The early stevens were made w surplus machine gun barrels vs the slower more traditional twist for 30-30. I can get really good accuracy w 170gr cast out of it at 1040fps. 200gr and they were starting to tumble.
Sh-- can UR old mold and get yourself a new shinny NOE guy. (.311 dropped should do it)
I make the bore ride .301" and the drive .311". Lots of 30 cal boolits are .308". They just skip.
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