I just started load developing for my new M70 Classic, and found that the max load in the Hornady book is 54.5 gr. for IMR 4350. However, in the Speer book, the max load for IMR 4350 is 56.0 gr. I am using Remington 180 PSPCLs and wonder if they have different pressures than the Hornady and Speer bullets. So far, my best load is with 51.5 gr IMR4350 (.39"), but I wonder if the groups will tighten up as I go up in grains. I am practically shooting a .308 with the load I am using now. Any suggestions? One more question. I noticed that the primers on my handloads were cratering just a tiny bit, and I have not shot anywhere near a hot load yet. The factories I boresighted with did the same thing. Is the firing pin hole oversize, or do I have a serious problem with the gun?
quote:Originally posted by Model 70 Classic: I just started load developing for my new M70 Classic, and found that the max load in the Hornady book is 54.5 gr. for IMR 4350. However, in the Speer book, the max load for IMR 4350 is 56.0 gr. I am using Remington 180 PSPCLs and wonder if they have different pressures than the Hornady and Speer bullets. So far, my best load is with 51.5 gr IMR4350 (.39"), but I wonder if the groups will tighten up as I go up in grains. I am practically shooting a .308 with the load I am using now. Any suggestions? One more question. I noticed that the primers on my handloads were cratering just a tiny bit, and I have not shot anywhere near a hot load yet. The factories I boresighted with did the same thing. Is the firing pin hole oversize, or do I have a serious problem with the gun?
The firing pin might be loose in the hole or have a bad end on it...a gunsmith needs to look at it....as for the load...REMEMBER BOOKS ARE BOOKS ...no book can tell you exactly what is a max. load for your gun..brass...powder...and similar...they only tell you what their "standard" gun/chamber with that exact lot of powder and primer and seating depth.bullet did for them at that time and temperature.....you have to follow their rec. exactly and then still look for the signs that show high pressure...you probably know this as you look at the primers and know about the cratering......and some bullets from different makers will have a different profile and thus different amount of contact with the bore of the gun and more contact means more pressure!!usually!...get that pin/bolt face looked at as the gas from a blown/pierced primer can be dangerous to your eyes and face in some actions and cases.....good luck and good shooting!!
Posts: 687 | Location: Jackson/Tenn/Madison | Registered: 07 March 2001
I posted this answer on another thread, but you may have missed it, so here it is again.
Almost certainly, your load density isn't high enough for consistency. There is too much room in the case which allows the powder to pour forward, creating inconsistent ignition. If you use the same charge and, after chambering a round, point the muzzle skyward to allow the powder to pour back against the primer, and then ease the rifle onto the bags, your groups will probably return.
That's not something you're going to want to do in the field, of course. I would try 55 grains of the IMR 4350 with your 180's, somewhere in that ballpark you'll find what you're looking for.
IMR Handloaders Guide uses Win case, Win 8 1/2-120 primer, Rem 180gr ptd. spcl bullet, and a cartridge OAL of 3.200". It lists a compressed charge of 57 grains of IMR 4350, 2750 f.p.s. with 49,700 cup chamber pressure. This was out of a 23" barrel. Don't use this data unless you use the exact components. The data manual from IMR is good for comparing their data with other manuals. They suggest you start 10% lower than the above data and working up to 57 grains checking for pressure.
MODEL 70 CLASSIC, One thing you may want to check is the length of the barrel used to develope the loads. If the manual indicates a 26" barrel and your rifle has a 22" barrel there will be a difference. This is why I own several manuals and consult them all when starting on a load for a new rifle. The method I use, I'm chicken, is to start low and work my way up in half grain incriments. By checking for pressure indications I let the rifle tell me what to use and what the working max is for any combination of components. I hope that this is of some help. Good luck.
While working up loads for my son's Ruger, I found that RL19, RL22 & IMR7828 gave me better accuracy & velocity than IMR4350. A chronograph will help w/ your load developement. Your 51.5gr sounds very light.
Posts: 7752 | Location: kalif.,usa | Registered: 08 March 2001
Great!!! It sounds like a max of 56.0 gr IMR 4350 is not too hot in my 24 in. bbl. I will let you know how this works out. I thought that 51.5 was pretty light, too.
I have worked up a load using 56 grains of IMR 4350, 180 hornady bullets (round nose and spire point), remington cases and CCI 200 primers. The loads clock at 2630 out of my 22" remington 700 and are perfectly safe. I get 2700 FPS with 57 gr, but chose the 56 grain load as a compromise between accuracy and velocity. The round nose slugs are more accurate in my rifle and are my choice for hunting here in Maine.
Your 51.5 grain load is likely well below the velocity that a 308/50 grain load will produce. I get 2500 FPS from that 50 gr. load out of my 20" barrel with the 180 hornady round nose bullet.
Good luck and keep us posted.
Posts: 115 | Location: Maine USA | Registered: 26 January 2002
Here is a load that I am loading right now. This is a load from my friend who is a retired police sniper and a master reloader. I have not shot it yet but I trust him. I will say this...this is a MAX LOAD. Start a bit less and go up but do not exceed. 58.5 IMR 4350, Nosler 150 BT, Remington Lrg Rifle Primers He says 3000FPS out of his Rem 700
Haven't had time to do any shooting; I've been too busy working. I could shoot today but the wind is blowing about 15-20 mph, and I don't know if it will affect groups too much to determine an accurate load. I will post as soon as I can get that shooting done. All the best to all.
Shot out all my test loads yesterday, dispite the wind and cool temperatures. 54.0 grains of IMR4350 seems to be the place to stop, since that one is grouping under .5". That was what I was looking for. I tried one at 57.0 gr. but that one had a flier in it (maybe it was the nut behind the bolt on that one ). Thanks for all you input! I don't have access to a chrony, so could anyone give me an estimate on the speed of that 54 gr. load? I can check my Hornady manual #5 but I just wondered what you all thought.
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All the best to all.
