Headspace problem? Short throat?

[SpookyPistolero]

Hi folks -

First post. I'm hoping someone can help me with a problem regarding some chamber measurements. I only just discovered the Hornady headspace, bullet comparator, and overall length gauges and I'm confused with what they are telling me. I *think* they're saying I have a short throat. I'd like to present some numbers /facts and see what people say. The rifle in question is a Stevens with a 223 criterion on it.



- My PTG go gauge will close, but with some pressure.

- my go gauge measures 1.460" in my headspace gauge.

- fired brass measures 1.460" in my headspace gauge.

- my overall length gauge says I touch the lands at 1.900"

-unbeknownst to me, I have been firing rounds which were made to the COAL in the reloading manual, but which exceed this 1.900 measurement. When I chambered one of these rounds and then ejected it, I saw the grooves from the lands on the bullet ogive.





So what makes sense? Incorrect install of barrel? Or short chamber? Something else?



Thanks much for any help

 

[CatShooter]

Hi folks -

First post. I'm hoping someone can help me with a problem regarding some chamber measurements. I only just discovered the Hornady headspace, bullet comparator, and overall length gauges and I'm confused with what they are telling me. I *think* they're saying I have a short throat. I'd like to present some numbers /facts and see what people say. The rifle in question is a Stevens with a 223 criterion on it.

- My PTG go gauge will close, but with some pressure.

- my go gauge measures 1.460" in my headspace gauge.

- fired brass measures 1.460" in my headspace gauge.

- my overall length gauge says I touch the lands at 1.900"

-unbeknownst to me, I have been firing rounds which were made to the COAL in the reloading manual, but which exceed this 1.900 measurement. When I chambered one of these rounds and then ejected it, I saw the grooves from the lands on the bullet ogive.

So what makes sense? Incorrect install of barrel? Or short chamber? Something else?

Thanks much for any help

Nothing is wrong with the barrel installation (at least relating to this), and the chamber can't be short, or the bolt would not close.

As far as the throat, the 1.900" measurement means nothing because it is not any standard.

What bullet, and what COAL??

 

[searcher]

Your Hornady headspace measurement is pretty much "right on" with several of my .223 chambers. The shortest .223 chamber I have measures 1.456 and the longest (two of them) are at your measurement of 1.460. That is fired brass measurement.

Fired brass tells a good story but sometimes the shoulder does not move all the way forward, fully expanding to the dimensions of the chamber. Because of this, one can usually assume the chamber 'may' be longer than the fired brass headspace measurement - but not likely shorter. However, at 1.460, I believe your brass likely is fully expanded.

The reason for your "slight force" when closing the bolt is most likely due to the force required to "cock" your mainspring. If you disassemble your bolt and try this without your spring, the effort your describe will likely go away. if it does, that will indicate the chamber was not "short".

As for the bullet coming into contact with the lands, that can happen when your rifle is throated as a .223, yet loaded like a .556 with longer bullets. The .223 is not capable of handling (safely) the longer bullets at 5.56 load lengths.

Keep in mind that when the manual says a certain O.A.L., they are referring from tip of bullit to base of brass, just using calipers to measure, without any tools attached. If the O.A.L was followed in the book as defined as loads FOR .223, (NOT .556) and you still are running into marks on the bullets from touching the lands, you rifle may just have been chambered for lighter bullets. Using the Hornady Bullet Comparator and a dummy cartridge from Hornady, you can easily determine this.
It does not sound to me as you have any chamber issues, only the need to seat your bullets deeper or move to lighter bullets. Based on your seating issues, I'd guess your twist is probably 1-9 or faster

 

[searcher]

Meant to say 1-9 or slower.

 

[noload]

I do not know if understand your problem , is it that you are putting land marks on you bullet when you chamber your loads to a COAL length in a manual ? If you can close your bolt on a Headspace gage it's not that short. May be you have a short throat and the lands are marking you bullets, if you don't like the marks, push the bullet in the case more until you are happy. Bullets will shoot their best when they are shot at either in the lands a bit or jumped to the lands. Tests at the range will tell you what is best for your gun.
You should bump your shoulders back .002" back from a fired case length, and the bold will close easier.That 1.460" fired dim. should be 1.458" after sizing.

 

[Ledd Slinger]

Chamber seems fine. Bullets jamming in the lands too far can make hard bolt pressure when chambering because the base of the case is pushing back against the bolt face and you are basically seating the bullet deeper in the case as your lugs cam over. The lands holds the bullet while the bolt face drives the case onto it. Definitely seat bullets deeper to where they are not touching the lands. If your chambering is still a little tight after that, you can always lower your sizing die to bump the shoulder back a couple more thousandths. Should be good to go then

 

[Ledd Slinger]

... Bullets will shoot their best when they are shot at either in the lands a bit or jumped to the lands...

I disagree to a certain extent because that is not a statement that can be made for all bullets in general. VLD style bullets or other bullets with long boat tails MAY shoot better closer to or jammed in the lands. But from my experience, I would never jam a flat base bullet.

Also like to add that the best groups I've ever fired in my life were with Berger VLDs about .120" off the lands. Had to seat them that way to make them fit in a magazine.

 

[searcher]

Simply seating the bullet deeper without knowing what the issue is could prove to not be good. (like trying to seat a Berger heavy VLD for use in a .223 not throated to accept - no matter how much one may smash powder). I think the question is what bullet are you using?

 

[SpookyPistolero]

Thanks for all the replies, I'm very grateful for the information. This has been frustrating. To clarify...

My bullet is a 69gr SMK HPBT. These are loaded to 2.260 overall length. When loaded to this length, I am touching the lands. My goal in using the gauges is to better understand my chamber and load accordingly, in part by pulling back from the lands by about 0.02.

The Criterion is a 1:9 twist (cool call by Searcher).

So, to make sure I understand:

1) No one sees anything 'wrong' with my chamber, just that it might be built for lighter bullets?

2) If I wanted to continue to use the 69gr SMK, I would need to pull the length-to-ogive back a good bit; isn't there a point of highly diminishing returns in terms of how far its seated into my brass? (And wouldn't this start to adversely affect pressure?) For some reason, I had the impression that it was better not to seat as deeply, if possible, for better accuracy. Is seating too far a non-issue accuracy wise?

 

[noload]

... Bullets will shoot their best when they are shot at either in the lands a bit or jumped to the lands...

I disagree to a certain extent because that is not a statement that can be made for all bullets in general. VLD style bullets or other bullets with long boat tails MAY shoot better closer to or jammed in the lands. But from my experience, I would never jam a flat base bullet.

Also like to add that the best groups I've ever fired in my life were with Berger VLDs about .120" off the lands. Had to seat them that way to make them fit in a magazine.

I think you misunderstood my statement, I was implying bullets have to be seated somewhere, anywhere between jumping and jamming. Testing them would dictate that, where ever it my be.

 

[Ledd Slinger]

Go seat a bullet down a good bit deeper to see if it helps your chambering issue. Can always pull the bullet, resize the case and load it again. Or just use that round for a fouler.

It will quickly eliminate one possibility or solve the issue at hand

 

[Ledd Slinger]

... Bullets will shoot their best when they are shot at either in the lands a bit or jumped to the lands...

I disagree to a certain extent because that is not a statement that can be made for all bullets in general. VLD style bullets or other bullets with long boat tails MAY shoot better closer to or jammed in the lands. But from my experience, I would never jam a flat base bullet.

Also like to add that the best groups I've ever fired in my life were with Berger VLDs about .120" off the lands. Had to seat them that way to make them fit in a magazine.

I think you misunderstood my statement, I was implying bullets have to be seated somewhere, anywhere between jumping and jamming. Testing them would dictate that, where ever it my be.

Oh, sorry. I understand now. I thought you were implying that they always had to be jammed or just barely off the lands.

 

[noload]

Spooky; Your chamber seems proper to me, without spec'ing a certain reamer for your chamber when its made, you are stuck finding a bullet for the reamer that was used. The throat length or free bore is the dimension that dictates the bullet you use and how far it has to be stuffed into your case. Also the twist rate of your barrel dictates how heavy or light the bullet can be.

 

[searcher]

Your overall length used at 2.260" should not have run into the lands. You may wish to seat deeper but it is nice to know how deep is deep - how far off the lands you will be, etc. The Hornady tool with the dummy case will give you a good idea. Having short throating sucks for heavy bullets, but is VERY NICE for the lighter varmint bullets in the 40-50 weight . Generally, my .223's like their bullets anywhere from .040" off the lands (away), or up to .010" into the lands after contact is made. Do be sure, if seating into the lands, that you work up your load from the beginning. Sierra's accuracy loads with the 69, for example, are not exactly lukewarm in many rifles. Jambing them into the lands increases the pressure. Once you determine where you are at with your seating depths, I'd start with .08" in, .005" off, .015" off, .030" off. See which direction looks most promising and refocus to find the sweet spot.

 

[searcher]

As an afterthought, I was thinking your rifle might REALLY like 50 V-Maxes or 52 Bergers and IMR8208 XBR. These and a short-throated 9-twist were made for each other. Just in case you were trying new stuff out..

 

[SpookyPistolero]

Hmm. Well, I feel a bit short changed, since I basically bought this barrel to use with the 69gr rounds, to reach longer distances.

I suppose I will admit defeat there and try some smaller rounds, specifically what you've suggested. I believe I've got some 52gr hpbt laying around. Powder selection is always my most limiting factor but I'll keep an eye out for that 8208.

 

[Patch700]

Get yourself a throating reamer and let the good times roll....

 

[CatShooter]

Hmm. Well, I feel a bit short changed, since I basically bought this barrel to use with the 69gr rounds, to reach longer distances.

I suppose I will admit defeat...

Don't let the short throat stop you from shooting 69gr bullets - just seat them a little deeper until they just kiss the lands and work up a load.

 

[SpookyPistolero]

The only time that you should be concerned on seating the bullet deeper in the case is when the bullet is so far in it falls in the case or excessive powder compression occurs

How do you know if powder compression is occurring? (or, how deep is too deep?)

 

[noload]

You will feel the powder being compressed with the bullet when seating it. I don't think you will have to worry about going too deep.