Reloading advice on a Encore with a 7x57 Mgm barrel

[DEACONLLB]

Have my MGM 7x57 barrel installed on my pro hunter and have loaded up some ammo for it so here is my question. The Lee reloading book calls for a over all length of 3.065 The bullet that I am using is the Seirra soft point spitzer 130 grn but the box says single shot pistol 284 diam. When I load to the 3.065 length the gun has to be snapped closed and when I pull the shell out there are rifleing marks on the bullet. They seem to shoot ok and the group is not bad. I seated up some more to 2.980 and the gun closes good and there is only a very light mark on the bullet if any and the group has tighten up better. I am sighted in at 75 yards as that is about the longest shot I will take and can cover the group with a quarter. so am I where I need to be on this barrel? Most of the time if I have a factory round I just set the die to it but in this case did not have any. Oh powder is H4895 which is what I use in almost all my rifles. In thinking more on this would this bullet have a shorter taper than a regular rifle bullet they look the same as the 120 I load in the 7mm08?

Thanks for your input

Deaconllb

[McDerry]

could just be the bullet profile. 

Obviously keep an eye out for pressure signs.

[243dave]

Are you shooting a encore rifle or a pistol.  If your shooting a rifle and plan on using those bullets for deer, you might want to rethink that.  Those bullets are meant for low velocities of pistols and if your shooting them at rifle velocities they may act like a varmint bullet.  Myself I would expect clover-leaf size groups from a custom barrel at 75yds.  I'd back my bullets out of the rifling.  If you ever change primers or brass it could cause some real high pressures, plus it may improve your groups too.   Dave   

[DEACONLLB]

I am shooting an Encore rifle and the bullet profile could well be the problem. I backed the bullet out so it does not touch the rifleing and group did tighten up. The question though is there really that much difference in a 7x57 pistol chamber and a 7x57 rifle chamber seems to me they would be the same. I can understand not pushing the pistol bullet as fast. I guess I could drop back on the load some and slow it down a little. I did not see any preasure signs with the bullets in the rifeling. The load is the standard load as I never load or need hot loads. At 76 years old I ant gona get very many clover leaf groups.

Deaconllb

[tacklebury]

If you aren't loading hot, touching the rifling can be ok, but I believe the number is 7000psi that is added when this happens.  Someone with more ballistics background may know for sure.  I had run into issues on my .45-70 BC which I found has a short throat compared to other rifles and many bullets over 350gr. will touch unless I seat them above the cannelure on jacketed or crimp groove on leads.  I have found backing the COL off 2 thousandths from the rifling minimum helps tighten up the groups. 

[DEACONLLB]

I think that custom made barrels are made to a closer specks than a factory barrel and you could be right on that.

Deaconllb

[shot1]

The over all lengths given in loading manuals are just suggested lengths. You need to find out how long you can load a bullet and the O-give of the bullet touch the lands then you can back your bullet away from the lands and know how far you are backing it away. Take a case and full length size it. Take a cutting tool like a hacksaw of something and cut you a line from the mouth of the case down to the start of the shoulder on one side of the case neck. Clean up the burrs. Before each use pinch the neck together so it will hold a bullet pretty good. You can see this by how close the sides are apart where the line was cut. place the bullet you want to use in the case by hand. Just start the bullet enough to hold it. Place this case into your chamber and press it in with you thumb so you can close the action. Open the action and carefully remove the case. The bullet will have been pushed back into the case when the O-give of the bullet hit the lands. Measure the over all length of this bullet. This is your max to the lands length. It is a good idea to seat the bullet 10 thousands deeper into the case to start with. You can seat the bullet shorter by 5 thousands at a time to see where your accuracy is the best. Many rifles shoot best somewhere between 10 and 30 thousands off the lands. You can pull that bullet out of the case with your fingers and load it up and shoot it. Do this for every different make and weight bullet you will be using.

Those 7mm 130 SSP Sierra bullets are designed not to be pushed over 2500 fps at the muzzle. Sierra states that these bullets work best between 2100 and 2500 fps muzzle velocity. You have to be loading the 7X57 Mauser mighty light to stay under that 2500 fps muzzle velocity. This bullet will explode like a varmint bullet if you push it much over 2500 fps and you may loose a deer that will run off and die from infection etc latter.

If you keep shoving those bullets into the lands sooner or later, usually at the worst time, you will stick a bullet in the bore and pull the case out and dump the powder down into your action. If you were like me you will not have a cleaning rod handy to poke the bullet out with either.

Your best bet would be to use the 140 gr Sierra Pro Hunter and 46.0 grs IMR 4350 which is the accuracy load out of the #5 Sierra manual and has shot really well in most 7X57 rifles I have been acquainted with, around 2700 fps. Load the bullet 10 thousands off the lands of your rifle and give it a try.

[DEACONLLB]

OK so I followed Shot1 advise and instructions full length resized split case closed up slit put bullet in just enough to hold pushed shell into chamber closed action, opened eased out shell and took measurment, the reading was 3.000 so if I back off 10,000 that would put me at 2.990 that is if I read this caliper right The load for a 130 grn jacketed bullet with H4895 with 38 grns says vlc. is 2530 by the lee manual and 2575 by Hodgdons specks so it seems that I am about where I need to be and could back off the powder to say 36 grns.

Deaconllb