I have some Winchester 257 Roberts +P ammo that is popping primers in one of my rifles.
I pulled a bullet, 117 Power Point round nose, and checked the load weight. It's a stick powder, loaded to 42.0 grains.
When I checked where the bullet hits my rifling its .048 into the rifling.

Can I just seat the bullet deeper to get a little jump and relieve some of that pressure?
It will not be a compressed load, I did check.

Perry

Better to move the throat out a bit. If you try to push the bullet back in it will cause the crimp to buckle; have to pull it, then re-seat.
How will that affect pressure? Good question. But for sure, a bullet into the rifling will increase it, as you know.

Don't know about rifle ammo but seating depth in handguns is critical.

Increasing the deep can cause severe over pressure.

I would not use that ammo in your rifle.

If any thing pull the bullet reduce the charge 10 percent and go from there.

Just seat the bullet deeper. Pressure will drop about 10,000 PSI. If you believe the internet. The bullet ogive should not go below the case mouth. If it does, some neck tension, bullet pull will be lost.

Winchester uses stick powder?

Oddly there is no crimp, or such a slight one that when I seated a bullet deeper it did not buckle at all.

Perry

Well, did that solve your pressure problem?

Have not shot the loads yet. Maybe Saturday.

Perry

Firearm Defect?? - Its possible that the chamber is out of spec. All factory rifles should chamber all factory ammo, without bullets contacting the rifling.

Seen a new Savage 6.5 Creedmorr that would not chamber factory Hornady ammo. Rifle was returned to Savage for adjustment.

May be best to have a gunsmith look at the rifle before firing again.

Is it a factory rifle?
I have one factory rifle, a Ruger, with a throat so long that I can seat 120 grain bullets with only .1 inch in the case, and I use near 25-06 load data. And the bullet is not touching the rifling. Talk about a long throat.

Checked it in 2 pre 64's, both contacting the rifling

The 257 back then was considered a "short" cartridge, and throats are short. And magazines were short; all big mistakes for such a versatile cartridge.
I would ream the throat longer.

quote:

Originally posted by Lamar:
Winchester uses stick powder?

Lamar, I am with you on this. Winchester has never, so far as I know, used stick powder in any of their factory loaded ammo. Something seems out of sync in River City to me.

quote:

Originally posted by Luckyducker:

quote:

Originally posted by Lamar:
Winchester uses stick powder?

Lamar, I am with you on this. Winchester has never, so far as I know, used stick powder in any of their factory loaded ammo. Something seems out of sync in River City to me.

It's the white box x257P3, 117gr power point +P. Powder looks like IMR 4350 or 4831, spherical.

Perry

The throats don't need reaming out for one type of ammo, imho. Remington, Winchester Silvertips, Hornady and all my hand loads shoot great.

Perry

Another interesting find. The bullet has two cannelures on it.

quote:

Originally posted by perry:

quote:

Originally posted by Luckyducker:

quote:

Originally posted by Lamar:
Winchester uses stick powder?

Lamar, I am with you on this. Winchester has never, so far as I know, used stick powder in any of their factory loaded ammo. Something seems out of sync in River City to me.

It's the white box x257P3, 117gr power point +P. Powder looks like IMR 4350 or 4831, spherical.

Perry

I am confused here, as neither of these two powders is spherical??

Powder photos 4350 or 4831, NOT spherical OR Ball.

Old rifles, dont shoot the +P loading?? Maybe?

I miss spoke, CYLINDRICAL is how I meant to describe them.

Perry

I believe it is a very hot load, probably max, that in my rifle is just too hot. I believe what pushes it over the edge is the COAL. If the bullet was not jammed into the rifling it would probably be fine.
I have several 257 Robts and need to fire this ammo in other rifles to see if the results are the same. I kind of think that it will not be. I have never heard of any "problems" with this ammo and it is a very common ammo that has been around a long time.

Perry

I'll post a pic later.
I compared it to R22 and 25, IMR: 4064, 4350, 4831 and H4831 and 4350. No match.
This powder is longer cylinder and a darker grey than those mentioned

Don't worry about the powder, you need to take a chamber cast first of all, and I suspect you need to check the length of your magazine box, then Im betting you need to lengthen the throat and magazine, but a cast will tell you where you need to be..IMO, long throats are a plus in that you can seat bullets out to take more powder and get more velocity, in a since you are Improving the round without blowing the shoulder out, just another way to skin a cat..but you still have a 257 Robts as opposed to a true Ackley IMP. ballistics will be very close..Has no down side IMO..Seating bullets as deep as I assume you intend to is complicated as the bullet ojive taper may not allow for a good purchase of the bullet, especially with Nosler Partitions wherein the ojive and bullet body differ considerably..I suspect pressure will rise, but to what degree I don't know, but you will when you fire them, good luck.

And don't forget a magazine box and a long throated chamber need to be the same specs, something the bean counters at Rem and Win and others still have not figured out...

perry:

I had a similar, but much less severe, problem with that W-W load in a late-model tang safety Ruger 77 that I worked with in the '90s. It shot adequately well (i.e. approximately circular groups) with R-P and FC factory loads, but with the W-W loads there were always fliers. A test target, comprising 3 superimposed 3-shot groups, showed 1 shot of each of groups 1 and 3 about 1/2"apart over 1-1/4" to the left, 3 (1 from group 1 and 2 from group 2) clustered in 1/4" on centre, and the remaining 4 in a 3/4" group 1" high and 1" right. I pulled the bullets from a number of rounds and found that the W-W oal (2.740-2.745") was on the cusp, with some just into the lands, some touching, and some just off. I had my gunsmith lengthen the throat (to enable a Hornady 117 gr. PSPbt to be seated to the cannelure); average 5-shot group size with the W-W load was reduced from ~3" to about 1-3/4".

BTW, the only "plus" in the W-W +P load appeared to be with respect to the late W-W non-+P loads, to bring them up to just a bit above the level of the R-P non-+P loads. Out of the 22" barrel of the Ruger the regular W-W load averaged 2371 fps while the +P averaged 2526 fps. The R-P 117 gr. RNSP averaged 2495 fps, while the FC 117 gr. PSP +P averaged 2704 fps. (averages are for 10 to 15 rounds at 15')

Cheers, Al