I look at your powder choices and I am not optimistic that any of them will do, though BLC-2 could be the best choice. I am of the opinion that powders in the burn rate of IMR 3031 are the best for this cartridge, though I did not test IMR 3031. I shot N135 which is a fast powder, and I shot IMR 4064, which is a little slower. For the 30-30 cartridge, I conducted a number of tests trying to find the “best load” for my Marlin 336 carbine and at the end of it, I think I learned some things.
If you notice, my charges start with factory recommended loadings. I worked my way up and the velocities were low, very low. From what I have read, factory 170 grain ammunition should be between 2100 and 2200 fps. Maximum loads from the manuals gave me 1800, 1900 fps. After that I started at the top end of the manual and worked my way to three grains above the maximum loads. I never had any pressure issues. My cases were fired lubricated. This is a practice of mine as I have found that dry cases will take the load of the bolt disguising the signs of excessive pressure. I want sticky extraction when I reach maximum loads. Most of the time I used a coating of Johnson paste wax, for the 7 Feb data I coated every loaded cartridge with Kiwi Mink Oil shoe polish. This stuff provides almost effortless sizing, similar to Imperial Sizing Wax, so I was very sure that the full thrust of cartridge combustion would be applied to the bolt face. I never had any sticky extraction issues even though I was three grains above maximum with most powders. This trend was consistent with all the powders I used, so it is the gun, and I really don’t know why. I quit adding powder, either the case was full, such as with AA4350 or IMR 4064, or the groups got large and irregular, such as AA2520 and AA5744.
I noticed that the factory new cases all fell into my Wilson case gage to the proper depth. All new unfired rims were between “Go” and “No Go”. However, once fired cases averaged 0.017” above “No Go”! If I had not lubricated the cases I am confident I would have experienced case head separations. I also could not find the barrel throat. I loaded one case extra long, was able to insert it into the loading port, but found, I could not eject the round. Guess what, 2.550” is just at the maximum length that a loaded cartridge can have and still be ejected in this mechanism. It is all due to the ejector position in the receiver. The ejector locations limits the cartridge length; the ejector is forward of the rear opening of the port, an unfired cartridge has to tip out when the base hits the ejector. If the bullet is too far out it won’t clear the ejection port. I suppose it is possible to insert single shot rounds that are over 2.550”, but to remove them unfired from the rifle, you have to unscrew the lever screw, remove the lever and remove the bolt! This is, of course, impractical. It is my guess I was able to stuff in so much powder because my chamber is cut huge and the throat is a ridiculous distance ahead of the bullet. Given this volume to fill, maybe that is why I did not blow up my rifle with my loads.
As velocities changed so did the point of impact. A grain difference in charge would move the group as much as three inches. I would like to claim that there was a pattern to group size, but I could not figure one. I had some very excellent groups at 1800, 1900 loads with slow powders. Those same powders gave me blown groups at higher velocities. All groups were blown when the 170 bullet reached 2200 fps. As I scoped each shot I saw how the bullet moved up or down depending on chronograph velocity. This mechanism is extremely sensitive to changes in bullet velocities, the best powder, at the velocity I wanted, was N135. And I don’t think it is any coincidence that this powder gave the lowest extreme spreads in velocity.
The second best grouping was with IMR 4064, but only when velocities were close to 2100 fps. The extreme spreads were not as tight as N135.
Considering that a number of test combinations produced groups in the six inch group size, I was very happy to have a ten shot group that was 2.0” in diameter at 100 yards. The better groups were around 3.5” at 100 yards and were round.
I think the 30-30 is a natural for cast bullets, the neck is very long and the velocities just right for cast. With jacketed bullets, even though modern steels are much better than old, the velocities you can achieve are still gated by the strange vibrational patterns that happen when all those components hanging off the barrel move, and I am certain, they all move differently. You have to find a “sweet spot” when all the bells on the line are clanging away at the same time. When anyone of them are out of sequence, groups get large.
Marlin M336 microgroove barrel,
Code:
[SIZE="3"]150 gr Core-Lokt SP Remington Factory
29 Dec 2011 T = 56 °F
Ave Vel = 2255
Std Dev = 13
ES = 31
High = 2268
Low = 2237
N = 8
170 gr Hornady FBFP 31.5 grs IMR4064 wtd lot 2449 W/W cases CCI200 OAL 2.545"
14 Jan 2014 T = 50 °F
Ave Vel = 1802
Std Dev = 12
ES = 24
High = 1812
Low = 1788
N = 3
poor group
170 gr Hornady FBFP 34.0 grs IMR4064 wtd lot 2449 W/W cases CCI200 OAL 2.550"
1 Feb 2014 T = 58 °F
Ave Vel = 2031
Std Dev = 20
ES = 50
High = 2064
Low = 2014
N = 5
170 gr Hornady FBFP 35.0 grs IMR4064 wtd lot 2449 W/W cases CCI200 OAL 2.550"
1 Feb 2014 T = 58 °F
Ave Vel = 2104
Std Dev = 30
ES = 68
High = 2122
Low = 2054
N = 5
group size 2.6 X 2.0"
170 gr Hornady FBFP 35.5 grs IMR4064 wtd lot 2449 W/W cases CCI200 OAL 2.550"
7 Feb 2014 T = 40 °F
Ave Vel = 2103
Std Dev = 20
ES = 64
High = 2128
Low = 2064
N = 10
group size 9 shots 3 ¼” X 1 7/8”
170 gr Hornady FBFP 36.0 grs IMR4064 wtd lot 2449 W/W cases CCI200 OAL 2.550"
7 Feb 2014 T = 40 °F
Ave Vel = 2135
Std Dev = 21
ES = 67
High = 2180
Low = 2113
N = 10
group size 2 3/8” X 2 ½”
170 gr Hornady FBFP 31.0 grs N135 wtd lot 901/98 W/W cases CCI200 OAL 2.550"
1 Feb 2014 T = 58 °F
Ave Vel = 1935
Std Dev = 17
ES = 45
High = 1953
Low = 1908
N = 5
group 1.5" X 1.2"
170 gr Hornady FBFP 32.0 grs N135 wtd lot 901/98 W/W cases CCI200 OAL 2.550"
1 Feb 2014 T = 58 °F
Ave Vel = 2029
Std Dev = 17
ES = 46
High = 2053
Low = 2007
N = 5
group 1.8" X 2.2"
170 gr Hornady FBFP 33.0 grs N135 wtd lot 901/98 W/W cases CCI200 OAL 2.550"
1 Feb 2014 T = 60 °F
Ave Vel = 2150
Std Dev = 61
ES = 42
High = 2146
Low = 2104
N = 5
group 2.3" X 1.0"
170 gr Hornady FBFP 33.0 grs N135 wtd lot 901/98 W/W cases CCI200 OAL 2.550"
7 Feb 2014 T = 41 °F
Ave Vel = 2081
Std Dev = 8
ES = 23
High = 2091
Low = 2068
N = 10
group 2 1/8” X 3.0”
170 gr Hornady FBFP 33.5 grs N135 wtd lot 901/98 W/W cases CCI200 OAL 2.550"
7 Feb 2014 T = 41 °F
Ave Vel = 2126
Std Dev = 9
ES = 31
High = 2136
Low = 2105
N = 10
2.0” best clustering
group 2.0 [/SIZE]