Factory loads blowing primer and sticky bolt,

I guess it left out the message...ugh. Sorry guys

Guys, need some help on something. I will try to make the explanation of the issue as fully as possible to help in getting an answer.

A co-worker bought a used Rem 7000, 220 Swift that originally had a .243 barrel on it and was changed by the previous owner to 220 Swift. The barrel is an EA Shaw medium contour 1:10 twist. That is the rifle.

The issue; the young man went and bought 2 boxes of factory Hornady 55gr VMax to sight it in with. He loads the first round, no issues after firing. Second round is the same as the first, no issues. Grouping, aiming at the same point, just not hitting where aiming yet was <1" roughly. Now for the problem to come up. The third round, he fires and then has trouble getting the bolt to open. After getting the bolt open, the case was stuck to the bolt. I took 2 rounds from his box and loaded into my M77 220 Swift and fired from sled with jury rigged remote string to err on the cautious side. Both round fired and cleared fine.

I then got my new handloads for my rifle, all new brass, so nothing is neck sized from my gun as yet and we put his gun in the sled with my rounds and again use the string to fire and no issues. So we go to the other box of factory ammo for another shot, this one ejected with some force, the primer was still in the case, but the primer had blown upwards where firing pin struck it, instead of making the indention.

Now, we go to my handloads again, firing all of them from the string release off of the sled for the time being until we know what is going on and after 35 rounds of my handloads, not one of them showed any of the excessive pressure signs that the factory load showed after the first 2.

My handloads are 50gr Nosler BT, on WW new brass and CCI primer with MV out of mine around 3,470 average. I know these are not "hot" because I intentionally load mine up on the milder side.

So, what is the (possible) issue with his gun that it will shoot and function with my handloads, but show very bad pressure signs from factory??

I am not a gunsmith other than I will tweak my own stuff only, so I am asking for some advice because in the meantime, I have told him that until he gets it to a gunsmith to check to see what the deal is or might be, to not shoot it physically, even with my loads. I don't want to see it come apart in his, or anyone else's hands.
 
1. What kind of rifle are you shooting? 2. What Primers where you using and 3.what was the amount of powder you where using? also if you resized the casings for in older rifle and the bullets too short for the chamber it can cause that problem.
 
Faster rate of twist will raise pressures. His rifle is a custom rifle with a non-standard twist, he will need to develop his own loads. Many cartridges are not loaded to max pressure/velocity, but the Swift is.
 
Seems like a fast twist for a swift but I'm not overly versed in them & may be wrong. I would check the OAL of the problem rounds vs your reloads. Possible the factory ones are too long & contacting the lands when chambered?
 
TFL is having some sort of intermittent software glitch, where the text doesn't get posted. It's being worked on. :)

I'd try a different brand of ammo than Hornady, but I'd also contact Hornady and tell them what has happened. They might well have a better idea than any of us. And, it's always possible that others have had a problem but Hornady does not yet know it might have to do a recall.

I don't see where twist rate would affect pressure with a 55-grain bullet. Possible, maybe, with a heavy bullet and a fast twist, but I'm doubtful.
 
Long distance, sight unseen diagnosis is an exercise in speculation.

One shouldn't speculate.

However, based solely on the little reported, my speculation would be a severely over size chamber.

When pin falls, it pushes the case forward, leaving space between the head of the case and the breech face. Neck obturates, forming gas seal at the neck. Pressure pushes the primer partly out of the primer pocket, while at the same time swaging the body of the case back to contact with the breech face. At this point, the case is overly long even for this chamber, which together with any flowing of primer cup metal into the firing pin hole, causes the difficult extraction.

Fact that the rifle was re-barreled is consistent with a headspacing issue.

Your pal needs to have a gunsmith make a Cerrosafe cast of his chamber and check its dimensions.

Just a guess.
 
A few things come to mind:
1. The faster twist is causing pressures to spike, and the hot Hornady load is already close to max. So, it results in an over-pressure.

2. A serious head space problem exists; or the throat is too tight.

3. The barrel was not a .224" center fire barrel, but a .222" rimfire barrel (unlikely, with the 1:10" twist, but possible).

4. It isn't a .220 Swift. Are you absolutely positive the rifle is a .220 Swift, and not a .220 Weatherby Rocket, or some other similar cartridge?


And, a few notes:
E.R. Shaw does not chamber .220 Swift in 1:10" twist barrels. That provides a little more fuel for the fire, indicating a head space issue.

1:10" twist barrels are also a really stupid choice for .220 Swift, unless you are shooting long range matches, with heavy bullets. The Swift's speed, combined with that twist rate, results in self-detonation of light bullets, before they hit the target (pretty much any varmint bullet under 45-50 gr).
 
I knew as soon as I read "factory ammo blowing primers" we would be talking about Hornady ammo. Have experienced this myself several times and read it elsewhere with them. I certainly didn't appreciate the pierced primers blowing gas back in my AR.
 
The chamber is too short (tight). The first fouling shots backed the next rounds up, jamming the bolt. Hot calibers like the Swift need more freebore for longer (heavier) match bullets . The bolt should also be checked, as the reverse angle nearest the extractor groove makes for very little gripping surface. The .243 usually has around .055" of groove depth here. It should have been changed with the re-chambering effort. This also may explain why the cases are so hard to extract after bulging, no matter the initial problem. The 1-10" twist is usually ok for longer bullets, though 1-12" or 1-14" is usually the norm for 50-55 gr. loads. Check for rifling marks on a blackened bullet, and go get a reputable gunsmith!

-7-
 
I vote with RKG and 7mmnut... probably a headspace issue.

It could be either condition... too much, too little. The only way to determine which it is is to check headspace.. correctly.

Then, do the cerro-safe chamber cast, following instructions to the letter.

I've never heard of using a faster than normal twist in a barrel causing pressures to spike above safe limits. Increase a little, probably.. out of spec high? Never heard of it. :confused: Doesn't mean it couldn't happen... I've just never heard about that happening. Good topic for research.
 
Factory ammo is made to fit and function in factory spec'ed chambers.

His rifle is not a factory chamber and is probably much tighter on the tolerances.

Take a cartridge, meant for a loose factory chamber, loaded to the max, stick it in a tight custom chamber..... over pressure.

Golfball, your handloads are not on the "milder" side. They are in the powder puff, pussycat side. I have no doubt that they would not show signs of over pressure, as they are extremely weak.

He is going to have to hand load. Custom chambers mean custom loads. No way around it. The guy who sold him the rifle should have given him a die to go along with it and some load data.

This gun might also have a very tight neck area, meaning some turning of cases is going to be in order.

I would contact the seller of the rifle, ask him what he turned the necks to, and if he has the die for the rifle. If not, making a chamber casting and having a die made will be in order.

I also highly doubt it is a 220Swift with a 1 in 10" twist, UNLESS it was meant to be a target rifle shooting the heavy for caliber bullets.
 
If your using hornady superperformance then that is precisely why. It's known as hot factory ammunition. There are several reports of the same thing with .308.
 
I'd be very suspicious of the factory ammo and would pull a bullet, weigh the charge and contact the factory to see if the charge weight is within specs.

If the charge weight is within tolerances, you might try gluing increasing thicknesses of shim stock to a factory cartridge head to see if the bolt closes on it. Metal from a beer can may be used. If the bolt closes on that, try two thicknesses, etc., etc.

If it closes on more than two thicknesses, take the rifle to a good gunsmith to have the headspace checked.
 
Golfballshooter:

Try a different brand of factory ammo to assertain whether you have a bad lot of ammunition or not. If you have the same problem with the new brand of ammo then I would have a good gunsmith check the rifle's chambering.

Semper Fi.

Gunnery sergeant
Clifford L. Hughes
USMC Retired
 
Last edited:
Update to post

He has taken to the rifle to a gunsmith. Smith check headspace and showed as "nominal", twist was actually 1:12 (1/4 to 1/2) , said it was slightly over 1:12, and said he found no reason to scrap the rifle. Said he would continue to use, just avoid the other ammo causing the problem.

I will call Hornady and explain the issue to them.

As a side note; as I stated, my loads are mild but they are extremely accurate, for my gun.

So, after he got the gun back from the smith, I loaded up to go to the hotter side, out of mine, 3,813fps average out of 6 shots.

We put the rifle back in the sled, made another remote trigger release, and fired the remaining 14 rounds I loaded. Again, no signs of pressure, sticky bolt or blown primers. So I think the call to Hornady is going to be a good idea.

The factory rounds were not the Superformance.

I will load some for him of the "pussycat" ;) loads and let him have at it. He did get the recipe from the man he bought the gun from though, and according the recipe, I am assuming 3,800fps range, so that is why I loaded my test batch where I did. If there is a positive to this, it is he now wants to handload.

Gents, thanks for the feedback.
 
I bought a brand new 264 mag hawkeye last year. It would show flattened primers with factory ww or rem ammo and my handloads that worked fine in my other 264 would blow the primers right out and i had to pound the bolt back. I sent it back to ruger and they looked it over and said it had some scaling in the rifling near the chamber. Im sure that grabbed the bullet and the increased friction caused the pressure problems. they rebarreled it and it does just fine now.
 
You must log in or register to reply here.
Back
Top