Gas and lots of soot?

[andym79]

Hi guys, I am new to reloading the 6.5X55, I loaded up around 100 rounds for my 1913 Carl Gustav. The first 14 shoots were fine, on the 15th however I felt a little gas come out rearward of the bolt. When I extracted the case it was covered in soot!

I would have said this was due to low pressure, but I weighed each charge and double checked them!

The load was a 140gn cast bullet, using H4198, 21gns and a gas check!

Could the brass (all from the same batch, and reloaded the same number of times, twice on that particular cartridge have been thicker and not expanded enough to seal in the chamber?

Any ideas why this should happen?

I have not used the rifle in a weak for fear that the problem lies with the bolt!

 

[Fat_46]

How did the primer look? Also, is the soot primarily on the neck, or on one side of the case?

 

[atblis]

It is possible that despite having the same powder charges, pressures can fluctuate. Is H4198 indicated for that light a charge in 6.5x55? I don't see any 6.5x55 data on Hodgdon's website.

 

[andym79]

The primer looked normal, no cratering or flattening! It was sitting fine in the pocket!

The soot was on the neck, along one side and around the rim!
The previous 14 rounds only had very minimal soot around the neck.

The load is listed in Lyman's manual as a reduced load for cast from 15-26gns!

 

[243winxb]

H4198 & 6.5x55

Have all the cast bullets been sized to the correct diameter? An undersize bullet may not produce the same pressure as the rest. Using a Lyman "M" die may help seal the chamber, as it leaves the case mouth larger in diameter. No crimp needed. Lyman lists IMR 4895- 21gr-1453fps to 30 gr-1934fps with a 143gr cast gas checked bullet. Hodgdon lists H4895 for youth loads/reduced loads, but with jacketed. Maybe the H4198 does not work well with cast at low pressures? I have uses IMR 4895 with cast, reduced charges in 30-30, 3006. 308 without problems. Bullet diameter is .002" over groove diameter. Post your question here also > http://castboolits.gunloads.com/forumdisplay.php?f=8 There are reloaders there shooting your caliber. One has pressure testing equipment. Or do a search there.

 

[243winxb]

The load is listed in Lyman's manual as a reduced load for cast from 15-26gns!

Full length sizing the brass or neck sizing? Try just neck sizing, then using the Lyman "M" die. You could be pushing the shoulder back to far if FL sizing.

 

[popper]

What was the POI of the 15th shot? Chamber OK and bolt lugs not loose?

 

[NCsmitty]

First off, you probably shouldn't load up 100rds of an untried load, if that's the situation.

My guess is that the piece of brass did not obdurate to seal the chamber because it may have been a bit harder due to work hardening, or the bullet may have allowed lower gas pressures with a poor barrel fit. If you are not using European made brass, you will find most American produced 6.5x55 brass is undersized to Swede chamber size. You did not mention your brass brand.

It is unlikely that you have a mechanical issue with your bolt. Small ring Mausers will direct escaping gas down the bolt guides, and that's what you felt. M98 Mausers improved the bolt shrouds to block the gas leaks a bit more from the shooter.

I have used 21gr of IMR4198 in my 8x57 Mausers with no issues.


NCsmitty

 

[ranger335v]

That IS a very low power load! Just not enough pressure to make that one case expand and seal off the combustion.

 

[andym79]

The brass is Winchester, I tend to neck size, only FL when necessary!

I use a Lyman M die for all my cast reloading!

Nothing obvious was wrong with the bolt!

I think I will put it down to the brass of that cartridge!

Though being that the case is only around half full 9may be I should use another powder that fills more of the case) and I don't believer in fillers, I guess a pressure variation due to powder position is quite possible. Its just i have never had any such issue with reduce loads in 30-30, 308 or 45-70!

 

[Steve C]

For what ever reason you had a low pressure light load. It could have been from a low powder charge. It could also have been from some powder contamination if you used a liquid or spray lube and got some inside the case.

 

[kingcheese]

Im new to reloading but won't a little bit of moister in a loaded round do that? Like to much lube, first round off the press held the extra?