Stuck Bolt

[DP003]

Alrighty guys I need some direction. There was another thread here about bumping shoulders which I think I have a similar situation or question but didn't want to highjack his thread.

I recently had a Krieger barrel installed on my 308 R700 and i've gotten it all broken in and its shooting pretty well. When I picked it up from the smith, he told me it had an extremely tight chamber.... like he barely got the go gauge to close and I think it was a JGS match reamer. Tight Tight Tight....

I am using lapua brass, 8208 xbr at 41.4 grains, 175smk, COAL is 2.81" which is about a .020" jump. Now maybe I'm a clown but that load seems safe when I look at published load data and I am not getting any cratered primers, ejector marks, nada.... except for my bolt is sticking. When I put a piece of unfired lapua brass in the rifle, it is EXTREMELY tight and is pretty much border line on whether it closes or not. When I measure the shoulder it comes out to 1.622". So I bumped the shoulder to 1.620" and it chambers no hiccups. However when I fire my load most of the time it gets stuck (70% of the time). Its just enough to where I cant pull it out with my hand and takes one little tap with a hammer. When i measure the shoulder after firing, its back to 1.622". I thought maybe I'll trim from 2.005" to 2.000" and see if that would help and it did... however about 20% now get stuck....

When I broke it in, I used Federal GMM 175 ammo. I'm not sure but I don't remember now but I don't think any of them got stuck but i noticed they were all very tight to chamber...

Having said all that, with my reloads, the gun is shooting about .3 inches at 100, just under an inch at 200, and had a 2 inch group at 300....

I need some advice please. Am I a clown and my load is too hot and just dumb for not realizing it? Or should I bump my shoulder a little more? I seek thee advices...

 

[amlevin]

You may want to ask your gunsmith why he left the chamber that tight.

FWIW it sounds like you've got something other than just headspace going on here.

 

[jonbearman]

It sounds to me like the neck diameter of the chamber is might be the culprit. Does it leave any little scratches on the neck of the case? Is it supposed to be a tight neck or no turn neck? I had this problem with a shilen no turn 22-250AI pre-fit for a savage.If you can try turning about .002 off like 4 or 5 cases and load and shoot them.Have the smith measure the reamer he used and I think that will straighten it out.

 

[J&J Custom Rifles]

Sounds like to me your load is to hot for that chamber and gun no matter what the books say. The gun is telling you it's to hot, back it down some. Not saying your chamber isn't to tight but I'm talking just like the gun is.

 

[CatShooter]

Take it back to the 'smith. He cut the chamber too tight, and that rifle will never be right and it will break your heart.

You should not be fighting to solve his problem.

 

[Lapua40X]

Take it back to the 'smith. He cut the chamber too tight, and that rifle will never be right and it will break your heart.

You should not be fighting to solve his problem.

Ditto ... you should not have to spend a lot of modifying brass to fit the chamber. Appears to me your smith (or whoever ordered the reamer) made a bad decision. It makes sense to me to trim brass for the purpose of refining neck tension, but I've never understood why some smiths actually order a reamer that's too tight and then expect the shooter to spend a lot of time bumping, grinding and trimming brass to fit the chamber.

 

[wapiti25]

+ many as others have said: your chamber is too short/tight.

 

[BoydAllen]

I suggest that this may be from the reamer, and from that the chamber, being too small in the back. Measure a new case .3 up from the head, and do the same on fired and sized cases, this should give a picture of what is going on in this area. Sometimes people proceed on the assumption that tighter is better, and this is not always the case. What are the headspace measurements of new brass and a fired case? Another thing, mark up the entire case of a loaded round with a felt tip marker, fire it and if it sticks, you should have some evidence of where the bind is.

 

[DP003]

Alright guys, I think the consensus is to take it back to my smith. Here is some more information though if you can help. I have two fired cases and one I can put into the chamber without any friction and eject it no problem. The other has friction cambering and when i try to eject it, it sticks. When I pull up on the bolt it is a little tight but then stops. If I apply a little more force upwards it "clicks" all the way up and then i can eject it "easier" but not as easy as the first fired case. Here is what I measured on each case....

The measurements are identical except one of them which I don't think my calipers are accurate to that degree... The only thing I can see with my eyes about the two cases is that one case mouth seems to be perfectly round and the other look ever so slightly "not round". I've seen this in other rifles I've shot but I don't know what causes the case mouth not to be perfectly round. Thoughts?

btw sorry if my labels aren't correct for my measurements. I pretty much started at the mouth and worked down then took a datum measurement.

Think I'm going to reduce my charge also... see if I can find just as accurate load at lower charge...

 

[BoydAllen]

Now that you have seen that the area that you call the base is the only place where there is a difference, measure a new, a fired (one that stuck) and a sized case at the same distance from the head and give us the numbers. Where on the case did you measure the base? Another thing, when you got something different than you expected, you doubted the accuracy of your tool. First rule of my chemistry class labs was not to change your results because they did not seem perfect, or as expected. Be as careful as you can, and record what you got. The measurements that I asked for were to help figure out something. Sometimes when the fit between the body of a loaded round (using a new case) and the chamber is too close, cases get tight at a lower pressure than they would if there was more clearance. Also, if a case has been stretched by being fired in a larger chamber, even though it was sized small enough to fit a smaller chamber the same problem will occur.

 

[LHSmith]

Tight/ Match Chambers........every one I've had has been a nightmare.....I stay away from them like the plague. Even with sizer dies made from a corresponding resize reamer. They "might" work if you keep pressures down, but in competition, I want the be able to get to the higher nodes just to stay in tune.

 

[Eddie Harren]

Until you take your measurements with a micrometer, instead of calipers, you are wasting your time. Jon, as well as other master machinists, can explain this to you.

 

[Shynloco]

...he told me it had an extremely tight chamber.... like he barely got the go gauge to close and I think it was a JGS match reamer. Tight Tight Tight....

Not trying to beat a dead horse, but according to the above statement and IMHO, your Smith didn't do you any favors by going overboard on making it "tight.". First off, he probably used the wrong reamer and we all want a "tight chamber" in a match gun or chamber, but that's going to an extreme that apparently has resulted in a nightmare for you. I join with the others to have it cut again and done right.

 

[amlevin]

First rule of my chemistry class labs was not to change your results because they did not seem perfect, or as expected.

Reminded me of what happened when several "professionals" were asked

What is "pi"?

Mathematician: Pi is the number expressing the relationship between the circumference of a circle and its diameter.
Physicist: Pi is 3.1415927plus or minus 0.00000005
Engineer: Pi is about 3.

Being an Engineer by training I say the chamber is too short. Another turn or so of the reamer would fix it all.

Go back to the gunsmith.


BTW, isn't a "Go Gauge" 1.630" ? Wouldn't fired cases reading 1.622 be a clue? Or am I missing something?

 

[BoydAllen]

The headspace measurements that are usually taken from brass are taken with the use of tools like the one that Hornady makes that are designed to compare cases, usually new fired and sized, and it is the difference between the numbers rather than the absolute values that are significant. His first post said that the bolt barely closed on a GO gauge, so the chamber was within spec. from head to shoulder.

 

[bigedp51]

The OP also stated the factory loaded ammunition ejected without problem, could this be due to the base diameter of the Lupua and Federal cases. Meaning the majority of American cartridge cases run on the small side in base diameter and it may be a brass spring back issue.

What is simpler and safer, lapping a shell holder and using a small base die or returning it to the gunsmith and rechamber. Meaning is there a downside to setting the barrel up again and re-reaming the chamber as far as accuracy goes and and possibly screwing up further?


Redding Small Base Body Die 308 Winchester

The Small Base Body Dies are for use with firearms with custom chamberings that are tighter than SAAMI Specifications.

http://www.midwayusa.com/product/378388/redding-small-base-body-die-308-winchester

Could the problem be both chamber diameter and chamber headspace length and possibly the closer tolerances of Lupua brass?

 

[DP003]

My course of action as of right now is to lower my load charge and I have a redding small base die on the way. I ordered it even before bigedp51 suggested it. If that doesn't help and I'm still having problems, I'll take it back to the smith. Thanks for all the help guys.

 

[Link]

I just don't know why a smith would chamber a barrel with a tight reamer ? If the chamber is smaller than the body die you have a headache. This should be explained to the customer by the smith before cutting the new chamber. Right.? Not in this case but in any case,.

Link

 

[bigedp51]

I just don't know why a smith would chamber a barrel with a tight reamer ?
Link

Why would the military use a reamer larger in diameter and longer in headspace than a .308 SAAMI reamer? Why do they make .308 Palma Match reamers smaller than .308 SAAMI reamers?

Why do the three .223 full length dies I have each bump the shoulder back different amounts when they cam over?

Why do people in the savageshooters.com forum use a new unfired cartridge case to headspace their rifles and cry when they can't get their full length resized cases to fit their "custom" chamber?

My point being we live in a plus and minus world and sometimes you end up with a negative number chamber and a plus number resizing die.

Or a plus number Lupua case made to exact specifications and a negative number reamer made to a negative number American cartridge case that's on the small side.

 

[Webster]

You already stated that the gunsmith told you the chamber was very tight and he had to use some force to close the bolt on a standard head space gauge. I never would have accepted the rifle. Sounds like he didn't want to take the barrel off and spend the time truing it up in the lathe. Is this a basement/garage gunsmith shop?