Home Forums Hunting & Shooting Gunsmithing Is this a headspace problem?

I have been trying to improve the accuracy of my friend's Model 70 Featherweight in 7x57mm Mauser. First, it has a 1x10 twist. We started with 160 grain bullets, then dropped to 140, now we have 150 gr. Nosler Partition. We tried IMR 4350, H4350, H4831 and H414. We tried seating the bullets so they are .01 inch from the lands, into the lands, .005 inch off the lands, .05 off the lands and so on. The rifle shot four-inch groups at best. I noticed that when tightening the screws on the action it took about five or six turns to cinch it down. So, I glassbedded the action. The action screws cinch down now in one-half turn. The rifle still shoots four and five inch groups. The last time we were out he was shooting H4350 (48 grains with the 150 gr. Nosler Partition, not a drastic load) and the rifle sprayed bullets all over the target. On one of the cases, he handed it to me and the primer was pierced by the firing pin. You could see daylight through the darn thing. I looked at some of the other cases and on some of them, you could see shiny spots on the case head. Just for the heck of it I loaded some cases with 45 grains of H4350 and these shrunk to a 1.8 inch group, no more pierced primer and no more shiny spots on the case head. The barrel looks to be the factory barrel. With the smaller group we put another scope on it, a Tasco worldclass 7.5 power. He had a Simmons Deerfield in 4.5x14 power on it. We shimmed the foreend, and he has since bought a Leupold 4x12 power scope to go on the rig. We plan to go out this weekend with some loads at 45 grains of H4350 (the reason why we keep using this powder is because he said he had some loads with the powder that worked good once). We will be shooting with the new scope, pressure on the foreend, will also try it with pressure off the foreend as well. I think the scope was a factor, but I am concerned about the loads. The thing rives indications of high pressure with a 48 grains of H4350. We plan to chorograph the 45 grain loads to see what she's spitting out the barrel. However, the Hodgdon reloading book shows 51 grains of H4350 as a max and 48 grains as the bottom end and it was at the bottom end where the primer was pierced. Could this indicate a headspace problem. If there is, how is it corrected, and is there a simple test we can do to determine if there is a problem without buying the go-no-go gages for a one-time use. Thanks ... Tom Purdom

A Gun Smith willl check it for you for about $35, Or you can gte abrand new case, without primer in it. Chcek the Sami Specs. for what the min/max chamber dimensions are and start adding shims behind the case head until it won't close anymore. Assuming the new case is minimum and you have to add more shims that what the specs say the variations and you will know if it's over sized.
Fixing it is either rebarreling it, or taking the barrel off and cutting some of the thread off and rechamber it.. If it has a notch for the extractor, or iron sights on it, you have to take one whole turn off. Even if you do it yourself, you are still going to have to pay for the no-go gages and rent on a chamber reamer.

7x57mm. If it turns out that the rifle still won't shoot no matter the fixes you try, you still have the makings of a nice project gun.

My mod 70 Featherweight XTR in 7x75 had a a badly corroded barel when I bought it. It now has a Krieger and sits in a McMillan stock. Thanks to a new trigger and action truing it is the most accurate rifle I own.

Good luck. 1b

The headspace problem ain't in the gun, but it wouldn't hurt to check, especially after your last shooting session. It appears to me you overloaded that baby, and more than once. So a headspace check would be a real good idea. Try the shims first, and if you're not satisfied with that, then go to a gunsmith.
I'm thinking you most likely have a "slow" and/or scruffy barrel, that or an old manual. And speaking of manual data, its a guide, not the Bible. I've had rifles that shot on both sides of book data, cold and hot.
But if you're getting smears, and popping primers, and I suspect flattening them, that's PRESSURE. My rifles all get wild on paper when I push them too far. Usually, the sweet spot is just a hair below the "gee, this thing is NOT happy" indicators.
Next time, don't beleive the manual when your eyes and targets are telling you something else. Please.

7x57mm,

I just checked your loads and I don't believe that this is a high or over pressure load problem. I do think that you could have either an oversized firing pin hole or an undersized firing pin. Either condition will pierce primers and show signs of high pressure. If this is the case then you have to have the firing pin hole bushed or if the firing pin is undersize, replace the firing pin itself. Suggested gunsmiths:

www.hdrifle.com
www.hollandguns.com
www.gtrtooling.com

The accuracy problem could be any of the things already suggested. The whole rifle needs to looked at as a system rather than just each area that could have a problem. Have the bolt checked and fixed first then have a gunsmith look at the straightness of the chamber/throat/bore and the crown. It could be that the barrel is just plain mediocre, it's happened before. The new scope could prove to be the solution, also.

Keep us informed of your findings, please.

Best.

I would send the rifle back to the factory. My son-in-law bought a Model 70 Featherweight last fall in 7MM-08 and the accuracy from it is nothing to write home about. Also, the only way to center the scope was to use windage adjustable rings, it was way off. I think the barrel must not be true with the action. I have a 7X57 but mine is a Ruger old style and I like it very much. Thanks... <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

Lots of times, a little pressure at the tip of the forend will do the trick, especially with light barrels, but, your point of impact might wander a little with the weather, if you have a wood stock. Or not. I assume the barrel floats otherwise.

I learned the hard way, that you can create headspace problems with the sizing die. Even for hunting loads, you should size only enough for the case to chamber easily. If you're getting very flat primers with cases fired in this rifle and neck sized only, then I'd wonder why pressures were high. Are you neck sizing, or full length?

Fireing pin tip should be smooth, no nicks or dings. Look close. While you're at it look at the barrel crown. Scope mounts tight, best to use a thread locking type sealant. If everything else is good and you still think you might have a headspace problem, then I'd spring for the price of a go-gauge, and with shims and a stripped bolt, measure headspace. Just my two-cents worth.

Well, most of the results are in and something worked. Tom G. now has a Winchester Model 70 Featherweight in 7x57mm that is shooting a 150 grain Nosler Partition right at one-inch at 100 yards. It was a combination of loads, forend pressure, scope, and shooting style. I am certain the glassbedding did help, and I know the scope helped, and also this rifle likes a couple of shims forend upward pressure. Get this, I know manuals are just a general guide, but we loaded 45 grains of H4350 in back of the Nosler Partition and seated it .005 inch off the lands. The books don't even list this load it is so low. HOWEVER, it chronographs with a 10-shot average at 2,667 fps. At one minute of angle, that puppy is now shooting good, at least minute of pig! Thanks for all the help fellas! Tom Purdom <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />

Several of my rifles shoot better with forend pressure. In fact I have glass bedded a few, full length from the rear receiver tang to the end of the stock. They seem to shoot more loads better. For me anyway. <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Yay! Glad it worked out for you. 2667 for 150 grainers is moving right along, and is actually OVER book in my Hodgdon 27 manual for 4350. Max load in there is 44, min 41. So 48 grains was a snortin' load after all.