22-250 & IMR 4895 pressure issues

[JDHasty]

OK, this is not a "factory rifle." I have a 788 with a brand new take off barrel off a Winchester Mod 70 SA Heavy Varmint.

The chamber is "tight" but within spec and the throating likewise measures to minimum spec. The bolt closes on a no go gauge and is just a tad bit snug on a field gauge.

Pressure all the way down to 33.8 grains of powder and in my other 22-250
I use 35.5 grains with a 55 gr bullet... and I am flummoxed. Hodgdon's website lists 34 as a starting load.

I have set the bullet out, I have set the bullet in. What I have not done yet is slug the barrel ... yet. That is my next step.

I have tried the Sierra 1365 and Hornaday 55 grain vmax bullets and I still have to knock the cases out with a cleaning rod.

I have taken fired cases and bullets are loose enough to make it apparent that the neck is not to tight too release the bullet.

So what gives?

Hodgdon lists 34. grains as a starting load. I have been using Federal brass and it is heavy, but only by ~5 grains over Winchester brass that I use in my other 22-250.

I am thinking about pulling a 22 LR bullet and using it to slug the bore next, but that is a lot of work. I would have to use two cleaning rods and a mallet to bump it up in the bore.

The accuracy is not a problem .6 to .7 MOA, but since I used a 308 length action AND we have a 22 CF throating reamer.... but that defeats my intention of shooting this rifle until the throat is burned out and then freshening it up and then shooting it with bullets seated out to take advantage of the fresh throating.

I have loaded up some 4064 at starting loads from an old Sierra manual 32.5 gr, which are far below the starting load Hodgdon's website lists and will try that tomorrow.

I am a bit suspect of this can of 4895 at this point and disposed of the remainder at this juncture. Down the toilet with about a tenth of a pound. I have more unopened cans.

Here is where I am going with this. I only use extruded powders since I shoot chucks where it is hot. Has anybody else run into this inexplicable phenomenon?

It appears that it is a problem with some aspect of the rifle itself. I also have 4320 available, but 4064 is a slower powder than 4895 and so that seems to be the logical way to proceed. I am concerned about max chamber pressure... I think that 4064 being "slower" is probably the way to proceed.

Has anyone else run into pressure issues with IMR 4895 in a 2-250 in the past couple years?

Like I say, I am going to use a mild load of a known can of 4064 tomorrow. If you can think of any issue with the rifle itself - I would like to consider that tomorrow as well.

FWIW, this is the exact same 22-20 reamer we have known and loved for two decades and I have serious doubts that it is with the chamber, but I am open to any suggestions.

[Three44s]

I don't like this:

"The chamber is "tight" but within spec and the throating likewise measures to minimum spec. The bolt closes on a no go gauge and is just a tad bit snug on a field gauge. "

Don't you mean a go gauge?

The Rem 788 is a great rifle and the .22-250 cartridge is also a great one but one thing most folks don't realize is that the .22-250 has much body taper and at it's stated high pressures represents a pretty good jab at the bolt face.

The 788 with it's rear lugs offers the challenge of bolt face set back ........ the bolts litterally compress over time. The combination of the two, a cartridge with much body taper and normal high opperating pressures and a rear lugged bolt (compresses over time ahead of the rear lugs) ............ makes for an interesting "stew".

If your rifle as it's configured truely closes on a no go gauge ........... you need to re-set your barrel.

A compressed bolt in a 788 is not unsafe if the headspace is set properly or close. My 788/.22-250 had a high round count and I neck sized until the brass needed a gently bump back in a FL die. I never had the bolt measured for compression, but always figured there was some ........ and treated my brass accordingly.

In a .222 or .223 cartridge that rifle would last several lifetimes and not compress the bolt ... smaller cartridge diameter and a straighter case body ........... less bolt face thrust. But in a .22-250 and larger as round counts rose, there was compression issues.

If the head space and chamber issues are deal with then it's the throat next.

Best of luck and best regards


Three 44s

[JDHasty]

Yes sir, that is what I meant to say. I have another 788 in 22-250 and it is on it's third barrel and that one is the one I am using 35.5 grains of 4895 in. I have had that one since ~1980. This one here was a 308 that was missing a bolt, so I share the bolt out of my 243 in it.

[JDHasty]

Back to the range today with 32.5 gr, 32.8 gr, 33.1 gr, 33.3 gr and 33.5 gr of 4895. And a load with 33.5 gr of 4064 just to try that powder. The 4064 shot into a pattern of about 1.5 inch so I think it is not likely that it is a powder this 22-250 barrel is going to ever like.

The others shot into .6 to .75 inch groups and just stated getting a little sticky at 33.5 grains. I had been loading them with the bullet .010 off the lands as measured w/a Stony Point tool. The Hodgdon manual I am working out of now lists 34.0 as a max load at a bit north of 3,500 fps mv so I can live with what I am likely getting as far as velocity goes.

We have a couple Oehlers and when I get this pressure issue understood I will haul them out and send ten through the screens.

As a side note: We ended up with a second one when the 35P came out and we wanted the printer available so we could set one up at two hundred yards and our 33 at the muzzle and calculate ballistic coefficients very accurately and that has worked out quite well for us. But you do need laboratory grade chronographs to make this scheme work out. The Oehlers can be set up with the sky screens laced to calibrate them, but our measurement between screens, from the factory, must be so accurate that no correction has been needed. We do this every couple years, just to make certain the 33 is working as it should. It doesn't have a proof channel like the 35. You also have to hit the screen at 200 with a darn good laser, or measure it out with a surveyor's steel tape to make this a workable exercise. With this data we can set up the 35P at 500 yards when we are chuck shooting, a lot easier now than in pre laser days, and our velocity calcs can be field validated and bullet drop is then a known commodity out to.... wherever, I guess. I suppose it goes to pot somewhere way out there, but that would only be academic and not something we need to concern ourselves with.

Here is how that works, the bullet drop over range is a function of time of flight. Period, no if's ands or buts about that one. If you know the time it takes for a bullet to go precisely 437 yards - you know within the accuracy of your gun to the tenths of an inch where that bullet is going to be elevation wise. No if's ands or buts about it. It would be even more accurate if atmospheric conditions and shooting with or against the wind were not a factor. You write a simple equation and program it into a scientific calculator and when you enter the range reading from your laser... voila. Dial in the elevation on your scope and if you miss high or low, look in the mirror. Or if you don't like that send your scope back and complain about the tracking. And if you are smart you will write the equation to take into account the scale on your elevation knob and save that for each scope you use and that way you don't even need to figure out how many clicks. The calculator tells you where to set your elevation know. How cool is that?

I am not as concerned with getting max velocity as I used to be now that we have accurate laser ranging devices available, but that being said I am not interested in shooting a 22-250 that is only getting 223 performance. Wind acts on a bullet in direct relationship to time of flight and in central Washington and Montana wind can most definitely bugger you all up.

The range is closed until noon tomorrow morning, but I have gone over to my loading shop and loaded up some with 33.5 grains of 4895, but seated the bullets to 2.375 & 2.350 inch OAL just to see if that will do something for the pressures. That would be .036 and .051 off the lands. The ogive hits the lands at a COL of 2.406 and I have been seating .010 short of that at 2.396 COL. This is close to the lands, but this chamber reamer is one we have had around for decades and that has been our standard practice with 22-250s chambered with this reamer, including my other 788 that has a 1:14 Lilja on it. FWIW, Hornaday lists COL as 2.350 and for this bullet you cannot go much shorter, if any at all, because the ogive will then start behind the case mouth leaving a gap.

[lotech]

I have an FN Mauser .22-250 on its second barrel, a 24" Lilja stainless, 14" twist. It was rebarreled by a now-retired gunsmith who had done a number of rebarreling jobs for me over many years. They generally shot exceptionally well, though chambering was always a little snug. The .22-250 is no exception, but a maximum load is 32 grains H4895 with either a 50 or 55 grain Sierra Blitz. No complaints here as the muzzle velocities are probably the same as what I would be getting with a couple of grains more powder per the loading manuals; just never run into this situation before.

[Three44s]

Looks like you are gaining on it!

I'd be shy of running near max and just .010" off the lands myself and probably shy of running a bullet that much deeper all at once without re-visiting the powder charges. I'd be comfortable with adding .015" to your ten to give a .025" without resetting charges. That would mirror your first set of shorter rounds.... the 2.375" rounds OAL.

I have to pinch myself though ........ I just walk out the door and down the driveway and my own lead bank is always open. ....... and I gripe 'cause I can't just shoot right out the window of the 'ole Man Cave!

One thing about it ...... you've got a lot of other powders to chose from ........ when they can be cornered!

Best regards

Three 44s

[southpaw]

I have 2 savage 22-250's. One with the bull barrel (model 12) and one with the sporter barrel (model 11). My model 12 I can neck size them about 4 times before they are hard to close the bolt on. My model 11 closes hard on the first neck sizing. I just fl size for that one. I also have another model 11 in 300 wsm. I couldn't get close to max loads with it (same as you). I was close to if not at the starting load when it would be hard to open the bolt. I let it sit for a couple of years then returned to it. Turns out I didn't have the sizing ALL the way down. I had turned it down so it touched the shell holder, backed it off just a fuzz and called it good. When sizing cases it would stretch or compress something enough that I wasn't getting enough sizing. I turned the die down until it was just a fuzz off of the shell holder with a case in it and all has been well since. Not sure if you are using fl sized or just neck sized but it would be worth a shot it you are just neck sizing. Just follow it with a m die.

Jerry Jr.

[JDHasty]

I shot the 33.5 grain IMR 4895 w/55 Vmax today at 200 and it is working just great. I will be going with that load .056 off the lands.

If I ever get a reprieve and get a bit of time we do need to set up the chronos and get some velocity validation (not only on this rifle, but about a half-dozen others). I can leave my home and be back after shooting ten shots in an hour and a half but setting up the chronos means we need half a day free. It is just that others are shooting and waiting around for the range to go cold so we can go out collect the 200 yard data, change targets or reset the screens in front of a fresh target so often) is what kills us. We may take a weekday off work and that will work out better. There is no way I can get home on a weekday and get this done before sunset except in mid-summer. If I were disciplined.... I would do a lot of this work in the summer when I can shoot every weekday night until 9:00. We set up an Oehler 33 at the twelve feet from the muzzle and a 35 P at two bucks so we can calculate accurate ballistic coefficients using 196 yards as the distance betw recorded velocities because we set the 35P up in front of the target.

Now if Oehler were to offer a wireless transmitter for the 35P, so that the printer and some basic input could be at the bench with the 35P set up at up to 500 yards...and we could "talk to each other" but I am just dreaming.

With this barrel I am FL resizing every shot and that is just fine. The resized brass is a snug, but not tight fit in this chamber, but it must be FL resized. On my other 22-250 with a Lilja that was chambered using the same reamer I use a Lee Collet Die and only FL resize every 6 or so shots - and I have so much brass that using this rifle for chuck shooting that means I only need to FL size it every three years or so. I probably take 150 pokes at chucks with each of my five long range rifles every year.

Of all the frustrations this gun has a wood stock and it is now touching the barrel, so I need to take the barrel down a bit more.

[Larry Gibson]

Now if Oehler were to offer a wireless transmitter for the 35P, so that the printer and some basic input could be at the bench with the 35P set up at up to 500 yards...and we could "talk to each other" but I am just dreaming.

You're not dreaming.........Last time I talked with Dr. Oehler he was developing something like that for the military for use at much longer ranges. You probably just don't want to even know what it costs..........

Larry Gibson