303 hang fire

[Mustdriveslower]

Hello everyone,

I have a problem with hang fires which I hope I have addressed by cleaning the bolt/firing pin and spring (to be tested soon) but thought you would like to see the video. Your wisdom and comments would be useful to me as I am a novice!

http://www.youtube.com/watch?v=WDk-YfCcJS8

This video shows the forth hang fire in a test fire of 8X5 sets of different loads the first and last being factory for data confirmation of chronograph and the other 6 were varying home loads.

The 4 hang fires were 2 from the home loads and 2 from the factory ammo, so not ammo related.

Go figure!

Another query for you guru's (I am appreciative of your help) is that the velocity was way down from what was expected "from the book". It is a nice "new" LE form the last batch 1955 with about 200 rounds through it so nice and new and tight. I have not slugged the barrel. The bullets used were 180g BT and the powder N140.

Any help and wisdom would be very much appreciated.

Jason

[ovenpaa]

Are you seeing light primer strikes, have you checked the firing pin protrusion and were the reloads full length sized?

[StanDeasy]

When you cleaned the bolt/firing pin, was it gunged up significantly?

SD

[Rearlugs]

Its not common to get a hangfire from a "light strike" - the primer either goes or it doesn't. What was the factory ammo? Was it old military surplus cordite?

Post a photo of the fired primers and/or the bolthead with the cocking pin released - striker protrusion should be 0.04" to 0.05"

A new UF55 rifle should be spot on. Check inside the bolt body - these rifles were slathered in cosmoline, and its quite common to find the bolt and spring absolutely stiff with the stuff. Usually the importing RFD has just cleaned off the external surfaces to submit the rifle for proof.

p.s. probably also worth checking the forend fit. Most of the '54 to '55 rifles built for store do not appear to have been properly bedded, rather just assembled and wrapped up. It was probably assumed that the recipient unit armourer would clean the new rifle and set it up - and most modern dealers wouldn't realise or wouldn't bother.

[huntervixen]

As Rearlugs says, check the bolt internals for gunked up cosmoline (likely suspect)....if you are using old Mil surp 1940s ammo....don't.... ask LeighC about that stuff!

[Gaz]

Have you weighed the striker spring? According to the Canadian armourers' instructions for No.4s, dated 2002, the relevant weights are:

The weight required to pull the cocking piece to the half-cock and full-cock positions shall be 3.2 to 4.1 kilograms (7 to 9 pounds), and 5.9 to 7.3 kilograms (13 to 16 pounds) respectively. These weights are checked with a trigger test scale engaged on the head of the cocking piece. Weak striker springs shall be replaced.

[Mustdriveslower]

Thank you all for your posts. The misfired cartridges were all struck lighter than the others but only just to the naked eye. Reloads were full length sized. Rifle has been checked bedded etc and the pin protusion was correct. Inside the bolt body the spring was at the lower end of acceptable poundage but still within tolerances. It has been exchanged for another spring which shows at the higher end of the poundage spectrum. The factory ammo is Partizan and it's new. The gunsmith has recleaned the internals of the bolt body although he said it was not gunged. One extra last thing he has done is polish the bolt shoulder as a precaution.
I plan to shoot at the zero range next week and will post results concerning potential mis fires.
Thank you all again for your advice.
Anyone have any advice on the lower than expected velocities experienced?
All the best to you.
Jason

[mas36]

We chronoed hxp from the same box through a no1 and 2 no4s. All velocities edre lower than expected but not significantly so. I dont think any of us kept a record umfortunately as hxp is a rarity in these parts. I am far from being an expert but does barrel wear play a part?

[Mustdriveslower]

I am no expert either and I have not slugged the barrel so no idea of tolerences. I wondered in my naivety whether the bore is tight as it is new and the velocities are lower as a result.My gunsmith and an F class buddy both said "DO NOT INCREASE CHARGE TO GET THE VELOCITY UP!" I got that message loud and clear. It shot best group wise at a lower charge anyway (39.5 g of N140) than the recommended max, so I am sticking to that for the time being.

[waterford103]

how old is the powder ,has it been stored correctly ,was it tightly resealed after last use, did the "light strikes" ignite the powder on each cartridge ,albeit delayed ,did you clean the lube from the inside of the neck after sizing ? This sounds more like dodgy powder than anything else .

Were the fired cases sooty on the outside after firing ? New ammo ,if stored badly, can be duff. If possible try some of the new PP ammo in anther rifle.