howdy, all.

I fired some reloaded Winchester factory ammo through my M1910 7mm Spanish Mauser roller, and it was pretty harsh results at 50 yards. So, I want to check my observations, and see if I am on the right track, and get your inputs on the reloading supplies.

Observations: I hammered out the jacketed rounds and powder up front, and fire formed the brass using BP and cream of wheat. It worked very well, all the brass was noticeably fatter and the next was so wide that the .284 jacketed round swam around. I also casted (cast?) the chamber with Cerosafe, and mic'ed the rifling about an inch in at .286-.287. In fact, after fireforming, the inside diameter of the neck was mic'ed at .287 as well. So, it seems this chamber is quite a bit roomier than the standard Mauser chamber.

I used the Lee Collet die to squeeze the neck down, but even still, the rounds were quite loose and spun easily. I don't have a factory crimp. I reloaded 43 grains of the powder that came with them, some kind of spherical powder.

I fired the gun at 50 yards, and got about an 18" group.

Questions: 
1) Was this 7mm round back in the day a lead or jacketed round?
2) The bore seems pretty wide for a .284 projectile. I am hoping the bad accuracy was from lack of crimp and the bullet swiming around in the barrel on the way out. Does this seem reasonable?
3)I cleaned the bore out with Butches, and lots of blue (copper) came out, but otherwise, the rifling looks good and I don't see any imperfections. Are problems in this kind of rifle bore usually visible to the naked eye?
4)I was going to order .287 hard cast bullets from Montana Bullet works. Has anyone used them before?
5)The Winchester brass seems ok, but Midway offers Remington (out of stock, no backorder), Winchester (Seasonal), Nosler (coming soon at 4 x the price) and something called Norma. Is there a better brass to use for 7mm? 8mm? 30-06?
6) I expect a .287 lead bullet to seat firmly, but should I factory crimp anyway?

Thanks very much! The bullets I will order are gas checked, and the maker states they should be good up to 1800 fps.

I do have Unique, so I'll start with your recommendation. I think the Lyman book starts pretty close to there anyway. Good to know about the Norma. I ordered a box of 20 from Midway. I'll give it a try and post the results in a couple weeks.

Check Buffalo Arms Company, they have jacketed. 287 diameter bullets in stock. 130 and 154 grains, $34-$37 per 100.

Jesse

I will check Buffalo Arms. I didn't think to check the jacketed rounds, as I was considering using this at a gong match. However, I do like to shoot higher velocities out of my guns periodically. 

Twist rate is 1:9, by my estimate, with a cleaning rod. The bullets I ordered are 160 grain, and the seller says the twist will be good from 1200 fps on up.

I have 4227, and 4759 as well, but I thought the Lyman book didn't list those for Linotype. I'll check again.....

Thanks again. It will be a couple weeks before I have the dough to order the bullets, so I'll update then.

Good advice. I have some soft lead slugs for a .357 from meister. I'll bet if I roll them between a couple of metal plates with some moderate pressure, I can then them close to the bore size, and the slug it through. I can also cast the muzzle as well to see if there is any opening.

I can trim a little and recrown if I have to myself, but I don't want to get into having to move the front sight band.

Thanks for the suggestion. Now I have something to do tonight!

Don't hold your breath. Went through the same drill a while back with a 7x57 RB. Bore didn't look all that bad after a deep cleaning. But, it patterned @ 50yds rather than grouped,  and half of the bullets  keyholed. I've since rebarreled it with  a pretty much pristine original barrel. I've used jacketed .284" bullets in the 150-170gr  range and they all have shot pretty well, 3" (+/-) @ 100yds with the original iron sights. Good luck.

Well, I suppose you could have your barrel relined. More $, some of these old rifles can turn in to a money pit real quick.

SchwarzStock wrote on Jul 30^th, 2013 at 12:19pm:


You called it. I cast the muzzle and you can clearly see the rifling blends out as it reaches the muzzle. I mic'ed the groves at .287 in the bore, and .290 out at the muzzle. The lands mic'ed at .281.  I have ordered the 7mm brass pilot from Brownells for my cutter, and the 1/2 inch 11 degree cutter. I know I am going to regret it, but the metal on this barrel seems softer than on my other Roller, so I ordered the .712 radius cutter as well. I believe in second chances.

I'll cut back about 1/4" to where the groove deapth starts to get more uniform, and cut the new crown from there.

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