Seems I got a problem.

[headhunter1111]

Alright folks,
Here's a question that i am aware could have several answers all of which may or may not be correct. My situation is this, I have a 22-250 that is showing some pretty scary and strange signs. First, it has shown a tendency to smash the case back into the bolt face on firing hard enough to leave an impression of the bolt face in the head of the case. Second, it does this with a MILD load. Not cooking this at all, 50gr V-max with 30gr of IMR3031. Which is the starting load in my lyman reloading book, this is with bullets seated well away from the lands. Standard, not magnum, primers (which I might add FLATTEN out at random). Now, to complicate things..... the expander button on my FL die was BENT, mis-shaped! jacked, screwed, busted whatever you want to call it. Could this be the problem? I am not sure at all when this happened, it may have been screwed up since I got the dies, or, it may have been the result of my father loading for his rifle. In any case, should i assume that this is the problem here? Should I try buying the expander button and shoot it to see what happens? If so should i hide behind the barn door and pull the trigger with a string to test it? Should i spend the dough and buy headspace gauges to see if that is the problem here? What is the likelyhood that it is due to faulty dies and what is the likely hood that the bolt is going to be sent through me head at an extreme velocity if I put factory ammo through it? Thanks for any help beforehand.

 

[Heavies]

Did you trim cases to correct length after you FL sized?

If the case is too long, it may be getting caught in the throat. This will effect correct bullet release and cause overpressure.

 

[headhunter1111]

No sir I did not trim, however, Max length is listed at 1.912, this is once fired brass and measures 1.9025.

 

[jr600yd]

How many rounds down the tube? You may have a carbon build up in the throat. JB the bore.

 

[headhunter1111]

Not a bad idea JR600, I'll borrow my buddy's borescope to check out that possibility, then give it a good scrubbin' just to be sure, I cannot remember cleaning it since I got it back from my dad.... why the hell haven't I thought of that! Rule number one: never break the rules, Rule number two, trust no one to take care of your weapon EVER, be cynical in all things related to weapons maintenance. Thank you for reminding me of that. I am disappointed in myself.

 

[Heavies]

I'd replace the damaged die as well, even if that may not be the cause of your overpressure. If anything the bent expander will give you excessive runout and inaccuracy.

 

[headhunter1111]

I have a new decapping/expander assembly in the mail as we speak. Couldn't agree more with that.

 

[bheadboy]

pressure can come from strange sources

you have eliminated case length, one thing that may surprise you is the combonation of a light load with a long jump to the lands, giving th bullet a head start then it has a momentary pause when it hits the lands due to the light load and pressure spikes like mad with a powder like 3031 which is slightly faster than most 22-250 powders.

i would suggest you try a moderate loas of something like 4064/varget etc and seat 10-20/1000 off the lands.

Bob

 

[headhunter1111]

Good advice Bob, I'll try that as well. I'm trying to factor out any and every possibility here.

 

[jonbearman]

Are you creating a headspace problem by oversizing? I bought a rifle like this where I had to fire form the brass and full length size very carefully and to avoid screwing the die down to the shell holder. If you did you had head seperation signs on one firing.It kicked pretty hard.I checked with headspace gages and decided to junk the barrel.Are you leaving lube on your cases after sizing. Are you using the correct shell holder. What gun are you shooting,tell us what brands of components are you using.Tell us the complete story.That way we can figure this out.

 

[HolyMeekrob]

This is something similar to bheadboy's suggestion, however heed it with caution, I would test this theory as a last resort.

I once had a similar problem with my rifle, I noticed I was flattening primers and the bolt face was being imprinted on the case head, obvious signs of excess pressure. What was strange is that this was happening with pretty light loads, several grains under max. So one day I was reading and I stumbled across a fellow talking about pressure readings he'd collected with a strain gauge on his rifle and that he'd detected secondary pressure peaks that were significantly higher than the first. He attributed this to a bullet/powder burn rate mismatch and shooting loads that are actually too light (I believe the combination was a light bullet and a slow powder). The idea being that the bullet zipped down the barrel and provided too little resistance for the powder to burn steadily and so a secondary spike is generated when the powder finally 'catches up'.
So I didn't actually apply this idea to my situation, I was going to march ahead anyway until the pressure signs were enough to scare me off. But lo and behold once I started pushing towards the upper reaches the pressure signs began to back off. I now shoot loads at or even exceeding listed maximums and have no or negligible pressure signs.

Again, let me say that this is something to be tested as a very last resort.

As to the expander causing the issue. I suppose if it was causing severe runout and the bullet was being shoved down the barrel crooked, I can see how this might cause excess pressure, but I'd imagine you'd have to be pushing the bullet damn near sideways. Possibly to the point that the round wouldn't even chamber.

 

[RonAKA]

I noticed that the minimum load Hodgdon recommends for IMR3031 is 33 grains. With loads too light you can get a secondary explosion effect or detonation. Google it, but you will not likely find anything definitive. It seems there is agreement it happens, and most likely with light loads of slow powder, but powder manufacturers don't seem to be able to replicate it in the laboratory. It has been known to happen with faster powders too.

Hodgdon H4895 is one powder well tested at low loads. I would suggest you try it starting at Hodgdon's minimum load of 33.5 grains with a 50 grain bullet, and work up from there to their max load of 36.5 if pressure signs look good.

 

[HolyMeekrob]

I noticed that the minimum load Hodgdon recommends for IMR3031 is 33 grains. With loads too light you can get a secondary explosion effect or detonation. Google it, but you will not likely find anything definitive. It seems there is agreement it happens, and most likely with light loads of slow powder, but powder manufacturers don't seem to be able to replicate it in the laboratory. It has been known to happen with faster powders too.

I like the way you think Ron.

 

[tunered]

Maybe you should measure the neck on a sized case ver. a fired case, maybe that expander ball is wore small, creating alot of neck tension, just a thought. ed

 

[CanusLatransSnpr]

It is ironic that you posted this headhunter1111 because I experienced a similar occurence this week while shooting my .22-250. However, I have the exact opposite scenario. I was loading Hornady 60gr. SP seated at the lands on top of 40.5 gr. of H380, Hodgdon's published max load. This was in once fired Win. brass, neck sized with std. Redding die and std Win. LR primers. No excessive neck tension either, .002" to .0025"! When i touched the first one off I didn't notice any more recoil but, the bolt lifted extremely hard with a flattened out primer. The case head was shiny also from the bolt face rotating on it. I know the cause of the flattened out primer because the bolt face on my Savage is concave a little around the firing pin. I have seen flattened primers from factory Federal ammunition before. The barrel had only had 2 rounds fired down it since the last cleaning, which might I add was thorough with the employment of JB paste. I then backed the load off 1 full grain to 39.5 gr. of H380 and still experienced hard bolt lift but, not quite as hard and flattened primers too. Backed off the load another .5 gr. to 39gr. of H380 and still experiencing a difficult bolt lift but, no flattened out primers. One thing I forgot, this rifle does have some excessive headspace, aprox. .006" from zero headspace. This measured by a competent gunsmith may I add. My only conclusion is that my particular rifle likes the brass full length sized every firing or the brass is going to "stretch" and cause a hard bolt lift. Am I right in my line of thinking here? Thanks!

Mike

 

[spclark]

Several earlier posts suggest causes for pressure... I'll add mine: you know the history of this particular chamber? That is, what reamer was used? Any idea what kind of neck diameter you're dealing with?

Before I'D fire off any factory ammo I'd try real hard to make sure the chamber neck allows at minimum .003" clearance for a loaded round, .004" would be even better. You may be dealing with a custom chamber that demands turned neck brass to be considered safe.

If you find yourself on a cold trail looking for historical data about the chamber, it's easy (and fun!) to do a chamber cast using Cerrosafe then measure the neck dimension off that.

Much less trouble do do than tasking a professional with extracting a rifle bolt from your cognitive organ.

 

[jo191145]

All good suggestions so far. One more thought.

You said your Father used the die to load for his rifle.
Recheck your FL die. Its possible he readjusted it for his rifles headspace.
FL sizing with excessive headspace can cause strange pressure signs.

 

[headhunter1111]

Well fellers,
I'll try to answer everyones questions that were asked but if I miss one just let me know.
First: Bearman, It is a Ruger M77 mkII with their varmint countour barrel, laminate stock.
Ammunition: Win. brass new, CCI 200 primers, 30grs of IMR 3031, Hornady 50 gr V-max bullets, seated to fit in the mag well which ends up around 25/1000ths jump.
Dies, RCBS FL sizing die. again this had a bent expander button.
every fifth charge weighed on Lyman powder scale, charges thrown with RCBS measure. As to over sizing, I will measure the fired case today, I did not oversize as it was new brass and therefore i backed the dies off to size only the neck. i hate to FL size new brass, IMO it is somewhat repetitive and un-neccessary. This would also eliminate the possibilty of my dad having set it for his rifle as i re adjusted it to only size the neck Jo1911.
Clark, as it is a factory rifle I only measured the necks on the fired and loaded cases, both of which are under the max neck dimensions listed for the 22-250. Good word on the bolt extraction. I'll keep that in mind haha.
i will measure the expander button Ed but my thinking is that it's oblong rather than round shape would be causing some pretty strange neck tension. It's not worn, as much as looks like someone sqeezed it with a pair of pliars. i have no clue when this happened.
Yes I am using the right shell holder.
I believe I will order some headspace gauges to check that possiblity off my list. The guy I bought this rifle from had shot it very little and did not reload so I'm sure he never even noticed whether or not it had issues.
Ron, I just went over to their site last night and noticed the same thing. They list a Seirra Soft point I believe though. I'm pretty sure (though not positive) that this has a shorter bearing surface than the V-max. I will look into it and see if increasing the powder charge helps once i eliminate headspce as a culprit. AS well as changing powders. I only loaded IMR 3031 this time around to get rid of it honestly, i figured for pdogs it would get the job done but I really am not impressed with IMR. It seems to be very temperature sensitive. I'm planning on going back to good ol' hodgdon 4350 again once I figure out why this rifle wants to blow up. I gave it a good scrubbing last night with Shooters choice and sweets. nylon brush, dry patches, it was most definately due for a thourough cleaning. My guess is that it had not been cleaned in about 50-60 rds... this is only a guess as I have not shot it enough to see how much fouling it accumulates.

 

[CanusLatransSnpr]

Ammunition: Win. brass new, Rem 6 1/2 primers, 30grs of IMR 3031, Hornady 50 gr V-max bullets, seated to fit in the mag well which ends up around 25/1000ths jump.

Headhunter1111, I copied this from your post and I sincerely hope the Rem 6 1/2 primers is a typo and you meant Rem 9 1/2 primers. The Rem 6 1/2 primer is a small rifle primer and I can't conceivably see how they would work in your 22-250 brass!

Mike

 

[BoydAllen]

Have you checked the scale to see if it is accurate?