.227 in a .224 bore?

[coldboremiracle]

So a friend of mine whom I often help with shooting related things recently purchased a Savage Axis in .223 for his kids to shoot.
Well bullets were made..... and apparently he loaded some 70 gr Hornady SP's in it, they are .227 (Savage HP I believe)
Anyways, they worked fine, and as a matter of fact, they produced the best group of all the load's/bullet's tested. No excessive recoil or pressure signs.

The question is; Has any damage occurred, or is there any reason to believe it needs to be checked?

Only 10 rounds were fired.

 

[former naval person]

Re: .227 in a .224 bore?

No problem.

 

[coldboremiracle]

Re: .227 in a .224 bore?

Thats it? no problem eh?

 

[sic65stang]

Re: .227 in a .224 bore?

I guess if it works, I would be concerned with barrel life. I have never heard of this, but I guess if pressures were ok than it would be ok. Does anyone else have any experience with this, Im interested...

 

[coldboremiracle]

Re: .227 in a .224 bore?

Well, we dont plan on it happening again, I got him switched over to 69smk's and they shoot just fine in the gun as well. I just want to know how bad this is/was.

 

[30SMK]

Re: .227 in a .224 bore?

I would doubt that it would do much damage except it might raise your pressure a little because of the tighter fit. I have shot a sierra .311 174 MK out of a 308 before to test this and not had a problem but I wouldn't make a habit of it.

 

[Clark]

Re: .227 in a .224 bore?

The big bullet in a small bore making no pressure increase is counter intuitive.
Likewise the pinched bullet making a huge pressure spike is counter intuitive.
The way I reconcile it is to think in the time domain.
If the peak pressure of powder burn is not concurrent with the increase pressure to swage, the peak pressure does not change.
And if the pinched bullet delays the start of bullet acceleration, the increased pressure makes the powder burn faster which increases pressure which makes the powder burn faster ....

This phenomena of large bullets working in a small bore without pressure spikes is documented in P.O. Ackley 1966 "Handbook for Shooters and Reloaders Vol 2" chapter 7
<span style="font-style: italic">"additional pressure tests":
"..30 cal barrel pressure barrel was fitted to the test gun, but the neck and throat was enlarged to accept the 8mm bullet, with the bore remaining the standard 30 caliber. A Remington factory 30-06 cartridge with the 150 gr bullet had been tested and previously gave 57,300 psi, for a velocity of 3030 fps. The the bullets were pulled from two more Remington 150 grain cartridges and were replaced with 8mm 150 grain bullets. To everyone's surprise, although the velocity was rather erratic, these loads averaged 2901 fps, with a pressure of 40,700 psi." </span>

 

[bohem]

Re: .227 in a .224 bore?

Thanks for posting that, Clark. I have Ackley's book(s) on the shelf, I suppose I should get off my butt and read them.

My two cents was going to be that the OP hasn't done anything out of the ordinary with folks who shoot tightbore barrels and I'd run 'em if they grouped well.

 

[MontanaMarine]

Re: .227 in a .224 bore?

I don't see it any differently than folks using "tight bore" 308 barrels. Some of them are .298" or so.

If the 308 can work well with a .010" undersize bore, a 223 with a .003" oversize bullet would seem like a non-issue to me.

 

[Ledzep]

Re: .227 in a .224 bore?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MontanaMarine</div><div class="ubbcode-body">I don't see it any differently than folks using "tight bore" 308 barrels. Some of them are .298" or so.

If the 308 can work well with a .010" undersize bore, a 223 with a .003" oversize bullet would seem like a non-issue to me. </div></div>

Are you sure on that?

I've heard of .306 and .307 bores, but not all the way down to .298. Sure it's not the land diameter?

At any rate, OP, not a big deal. I've shot .311 and .312 bullets out of my .308 before to prove to a friend that it won't asplode the world. My memory is foggy, so don't quote me, but IIRC it takes something like 15k psi to deform the bullet, so the bullet deforms and resizes well before peak pressure.

 

[bohem]

Re: .227 in a .224 bore?

I think that MM is talking about .297/.305 barrels as I have seen those shoot without issue.

ETA: Engraving pressures range for jacket thickness, core hardness and bullet construction but generally you're looking at somewhere between 1500 and 8500 psi.

 

[coldboremiracle]

Re: .227 in a .224 bore?

Ok, you guys have calmed my fears. Still dont think we'll make it a habit.

 

[rusty815]

Re: .227 in a .224 bore?

Its fine, Savage makes 7.62x39 rifles with a .308 barrel, and many people have been shooting milsurp stuff of .311 diameter for years through them without any trouble.

 

[1Sg (ret)]

Re: .227 in a .224 bore?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MontanaMarine</div><div class="ubbcode-body">I don't see it any differently than folks using "tight bore" 308 barrels. Some of them are .298" or so.

If the 308 can work well with a .010" undersize bore, a 223 with a .003" oversize bullet would seem like a non-issue to me. </div></div>That is what i was thinking.

 

[BuzzBoss915]

Re: .227 in a .224 bore?

Well, I'm not going be blase' about what I consider to be a handloading mistake. Maybe no harm was done but I think your friend should consider himself lucky. The logical progression might be using a .264" bullet in a 25'06 just because they were out of 25 caliber. It's wrong and he needs to reevaluate how he selects his components or use factory stuff.

As far as that data from Ackley's book, yeah, counterintuitive is a good word. I don't even see how that is possible? To everyone's surprise, right? Somebody could have made a few bucks betting against conventional wisdom.
BB

edit: as far as the 7.62X39, I have shot 308 bullets in a SKS .311 bore and they seem to work okay, on cans and rocks, etc.