Over Pressure or too long of a case?

[Broken_Reticle]

This weekend I loaded up some .308 165 smk with 42 gr of wc846. Using blc2 data 42 gr is middle of the road. I used a complied data book that has speer, sierra, hornady and 4 or 5 more books worth of data on .308 to come to that conclusion..

I loaded 10 but only sent 4 down the tube. On three of them the bolt was getting stuck.. I have had this done with some reloads I bought at a chain store.. I also had some factory win ammo 150 gr coreloc. They did just fine in the savage fp10.

I got back and measured the cases...

both the factory and the reloaded brass expanded the same.

Neck went from .336 to .345 on the reloads and .333 to .345 on the factory.

Case body went from .469 to .471 on the reloads and .464 to .471 on the factory.

but I noticed on the reloads I must have gotten into my untrimmed brass because the factory was 2.010(starting at 2.005) but the reloads where 2.023 to 2.027.

I didn't see anything wrong with the primers or any other brass issues. so do you think it was a too long of case problem or a over pressure somehow issue.. or can too long of a case cause a over pressure issue.. I didn't use any crimp on the bullets and loaded them to max coal of 2.80

Thanks

BR

 

[Gene Poole]

Re: Over Pressure or too long of a case?

What kind of rifle? If it's a factory Remington or Savage, etc., then you've probably got plenty of room. I measured the chambers on two Remingtons and my gas gun and they all had plenty of room:

 

[Broken_Reticle]

Re: Over Pressure or too long of a case?

It is a savage fp10..

ok if we used your numbers and my brass was in the acceptable range still.. if the bolt is stuck to the point I have to put the butt on the ground and hit the bolt handle with my hand to get the case ejected we got a problem... Like I said I have some commercial reloaded stuff that does the same thing. I am fl sizing the brass to the directions on the die and I measured my sized brass, it has about the same dimensions as the factory win ammo that didn't have a single problem...

 

[JeffP40]

Re: Over Pressure or too long of a case?

I am assuming that the bolt lift was also stiff? With no signs of brass stress, I would think pressure isn't an issue. I am thinking towards more of a brass/chamber compatibility issue, even though factory is fine. Can you feel primary extraction at the top of bolt lift? Obviously, it isn't enough to free the brass. Did you use the once-fired factory for these last loads, or the previously reloaded brass? Have you cycled the fired brass in the chamber? I am wondering if the previously fired brass isn't compatible with your chamber. I had some once-fired 308 brass some years ago that I could not get to fit into the rifle. It had been used in several rifles and some fit, some didn't. I think if I had had a small-based die, I would have been fine. Let us know what you find out.

 

[ksthomas]

Re: Over Pressure or too long of a case?

BR,

A quick question here; you mentioned the 165 SMK? There is no such thing as a 165 SMK. There's the 168 SMK, and a 165 HPBT, which is a hunting bullet. If you load the 165 HPBT (or 165 GK, for that matter) to the standard 2.800" OAL, you'll likely be jamming the rifling pretty badly. The 168 SMK and 165 HPBT have very different ogives, and need to be loaded to significantly different OALs to avoid this problem.

Seen this happen in a number of different rifles, and yes, it's a common problem. There's a few other potential causes, but this is the first place I'd take a look.

 

[Broken_Reticle]

Re: Over Pressure or too long of a case?

Brass sized just fine..

Handle lift was just fine..

Round chambered just fine..And I said the wrong bullet it was a 165 hpbt

Brass would not extract.. the only dimension between the once fired brass and the factory ammo was the case length after firing.

the once fired brass was fired by me or my friends at my range. it is mostly lc brass that was fired either out of a dsa fal or a hk 91. then fl sized by me..

 

[Jeffvn]

Re: Over Pressure or too long of a case?

If the primers are ok, no ejector mark on the brass, no sticky bolt lift, then you very likely not seeing pressure issues. I agree its brass length.

I had a bolt action rifle that the brass stuck and could not be extracted from the chamber. The brass was just a hair too long. It chambered with no resistance, but it would not extract from the chamber. PIA to use a cleaning rod to tap it out from the muzzle. I keep that brass trimmed to near the minimum length, and I've seen no extraction problems since.

Jeffvn

 

[boltgunluvr]

Re: Over Pressure or too long of a case?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">BR,

A quick question here; you mentioned the 165 SMK? There is no such thing as a 165 SMK. There's the 168 SMK, and a 165 HPBT, which is a hunting bullet. If you load the 165 HPBT (or 165 GK, for that matter) to the standard 2.800" OAL, you'll likely be jamming the rifling pretty badly. The 168 SMK and 165 HPBT have very different ogives, and need to be loaded to significantly different OALs to avoid this problem.

Seen this happen in a number of different rifles, and yes, it's a common problem. There's a few other potential causes, but this is the first place I'd take a look. </div></div>

Diddo...its the first thing to check!

 

[pdmedley]

Re: Over Pressure or too long of a case?

BR
If your bolt operates smoothly, and with your hand-loaded ammunition, you can load the round and close the bolt then lift the bolt and eject the round with little effort, your case length and OAL are not your problem. If your bolt only sticks after you fire a round, you definitely have a pressure issue.

Now, two things can cause your pressure to be high while not necessarily making the bolt hard to close. If the bullet is jammed too far into the lands by having too great of an OAL, or if the brass fits the chamber to tightly and doesn't have enough room to expand, you will have pressures higher than what you expect from the powder charge.

Maximum C.I.P length for a .308 Win. case is 2.015" so being beyond that could indicate a tight fit in the chamber.

If I had developed a problem while reloading and had no idea what caused it, I would take one piece of brass and do this...
1. Trim to 2.015" or less, chamfer, and deburr
2. Full length size.
3. Compare the shoulder height with that of factory once fired brass. If you don't know how, look up LoneWolfUSMC's Mail Call Mondays thread and watch the reloading video where he compares head space with a piece of pistol brass.
4. If this length is longer than that of the once fired brass, bump the shoulder down to .005" less than the once fired brass.
5. Seat a new primer.
6. Decrease the powder charge by 2 full grains, but do not go below the minimum book charge weight.
7. Take the piece of once fired brass and just barely place a bullet in the neck. Make sure it slides easily in the neck but doesn't fall out. Chamber this and close the bolt. Eject the round carefully making sure not to disturb the position of the bullet in the brass.
8. Using an ogive comparator measure the overall length of the now seated bullet.
9. Set the bullet seating die to seat at least 0.005" shorter than the measured overall length, but do make sure that the bullet is seated far enough. The Mail Call Mondays videos also explain this.
10. Put the new lower powder charge in the primed brass.
11. Seat a bullet and check it with the comparator to make sure it is shorter than the measured maximum overall length.
12. Chamber and eject this round slowly several times, paying very close attention to how the bolt feels.
13. Fire the round, and again pay close attention to how the bolt feels when opening and ejecting the round.
14. Closely inspect the fired brass for pressure signs. Check the primer for cratering around the firing pin strike. Also check the primer for flattening around the edges. Check the case head for scoring from the bolt.
15. If you don't see any pressure signs, repeat this process with a 0.5gr. heavier powder charge.
16. Repeat with the increasing powder charge until you start to see pressure signs.

Sorry for the oversimplification. I hope it didn't offend you. This is just what I do personally to make sure I don't miss something.

Let us know what you find. Good luck and be safe.