Interested in how this primer and case head look. Before and after. Getting some crazy speed numbers from a 257 Roberts.

100 NPT, 47.5 H-4350, RP case, Fed 210M, 2.950 coal, Ruger No.1 26" barrel.

Crazy speed numbers don’t magically happen. Looks like you are WAY overpressure. I usually don’t use primers as indicators, but the way that one is “leaking” around the pin indention is a give away. Being more than 2 grains over book max and crazy speed numbers are also evidence that you are in dangerous territory. Not familiar with a #1, but if it was a bolt action using this load, I would expect a strong ejector swipe and a sticky bolt lift.

What is the crazy speed number?

3328fps

I'd be more comfortable with about 75 fps less.

I don't see any evidence of case head swiping. How is bolt lift upon extraction?

If curious, installed GRT and run the numbers from a fired case from your chamber. It should give you a good estimatation of pressure numbers.

ckat, I did run one through a Ruger M77 bolt. It did have the ejector swipe and sticky bolt lift. One was enough in the M77. I started shooting them with the Ruger No.1. Single shot falling block, then put one through the M77. Planning on pulling the rest.

I would call that to be on the warm side. As stated by ckat, speed doesn't magically happen, it is a function of pressure.

The case I've pictured is from a single shot falling block.

Not familiar with installed GRT ???

mm, I plan on pulling the rest, and go back to 46 - 46.5. Really looking for 3200fps for what I want. PBR to 300 yds. from the 26" barrel.

Your velocity is telling you your pressures are up a bit, but you do have a 26 inch barrel too. I have three Number 1s and have never seen the primer marked like yours. I can't see any sign of primer leakage like someone mentioned but it is quite flattened and impressed with a nice pattern. Back off to about 3 200 fps.

3200 should be no sweat.

That is exactly my plan........

Is this rifle new to you? In other words, do you have anything to compare this load to as far as case indicators go? You reload, is the brass streching excessifly, and how are the primer pockets? If your not comfortable, back off a grain. You got plenty of snort.

Before I reloaded these cases I FL resized and checked all the case lengths. They were all between 2.230 and 2.233. I just check the 10 cases I shot. Three were at 2.233, the other seven had stretched between 2.236 to 2.246. Checked the primer pocket on the longer 2.246 case and the pocket is tight.

The rifle is not new to me, but I don't reload specifically for this rifle. I reload for a M77 with a 20" barrel and shorter throat. I've just started looking for a load specifically for this rifle.

My intention is to back off to 3200fps for this rifle.

Have another photo of spent primers from the same day, but with a mild load.. 120 NPT, 46.5 H-4831, Nosler case, Fed 210M, 2.950 coal, 2938fps. Ruger No.1 26" barrel.

I do NOT push envelopes, yet some of my rifles show what you've gotten. Unless you are shaving brass upon extraction, or pockets get too loose after multiple firings, I'd opine that you are safe. However, as others have said you are a bit hot and need to adjust. That is +P brass above, unlike the first photo.

I though that is what you were talking about. That isn't primer leakage but that would indicate to me a bit large fireing pin hole. Leakage would come around the edge's of the primer. No sign there but the primer fills out the pocket more than I would care for. Primer's can be a bad pressure sign in that some have softer cups that fill out the pockets easier than other's. I think he said the pockets remained tight I don't know much about checking case's for pressure from a single shot. Not surewhar the case head should measure on the cartridge your using but I'd find out and them try measuring case head. For the 257 Robert's my Hornady book says .471. If your larger than that I'd say to much pressure.

2.5 grains over max...... I can't imagine what the problem might be.

I think you said these were fl resized. It could be that you’re generating too much headspace or short base to shoulder length and the primers are backing out a bit and then being riveted by the case head as it backs up to the breech face. Try backing off on the charge a bit and just neck sizing the cases such that it takes a slight effort to chamber them. The cases and primers from the other mild loads fired on the same day seem to be giving a similar look so neck sizing or partial fl resizing might do it. I had this problem with my second 243 even with starting loads. Look at the primers after depriming a few cases. From the side, if they look like little mushrooms, you may have found your problem.

Velocities are a bit hi but part of that could be barrel length as someone mentioned. Several angles to consider.

I use 46 H4350 with a couple of 100 grain bullets and get around 3075 (I think) from a Kimber .257 Roberts with 22" barrel. I call that load max. in my rifle, but I suppose other rifles can handle a little more powder.

I guess that depends on which book you are looking at.

I FL resized because most of my 257 brass is fired from a Ruger M77UL which I neck size only with the Lee Collet die. I have some new RP and Nosler cases. I'm going to back off some and start again with new brass. Then neck size only for this Ruger No.1 and work up again. Can't hurt.

I also load for a Ruger M77UL, 20" barrel. 46.5 H4350 gets 3060fps, 47. is 3105, 47.5 is 3164. But I load coal @ 2.900 for the UL and 2.955 for the No.1, a bit longer than standard.

Look at H4350 data for 100 grain bullets in the 6mm Remington. Well over 3100 is standard fare. The 257 Roberts is the same case with a bigger hole in the end, so it's capable of even more. In top of that the OP is loading for a 26" barrel. If the accuracy is there I'd be comfortable with 3200 all day.

Re take the after photo with the same case orientation and lighting for a better response.
The shadows make the stamp look flatter, but the relative reverse of the lighting make it had to say...

Exactly.

The chrono tells you everything you need to know.
Trying to read spent primers and case head expansion is twaddle.

Settled @ 46.5 H-4350, 100 NP. From the No.1 26" barrel. 3212, 3220, 3213, for 3215fps. Same load from my 20" .Ruger .257 Roberts gets 3075fps.

Ruger N0.1....................With COVID spacing at the range.

Were the groups like you wanted?

Doesn't the +P load hold about 1.5 grains less powder due to the thicker webb?

mm, I was at the fifty yard range with the chrono. Chrono cannot be set up on 100/200yd range. I'll work with 46.5 and COAL lenth another day at the 100/200.46.0 is not far behind at 3190fps.

Tejano, from what I have seen, Nosler +P cases hold 57gr of water and the RP cases that I have are 56.5gr. So I don't see much difference.But I'm sure I could be off in my measures. Book says 55gr.