Is the barrel on my norc m305 incorrectly timed?

abortedfetus

abortedfetus

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I bought a norc m305 maybe 2 months ago and I changed the original flash hider to an SEI brake. While changing the flash hider I noticed that the front sight wasn't centered and the flash hider was canted a slightly to the left.

I thought it might have been the flash hider that was the problem, but the gun was shooting pretty far right at 100 yards. I thought It might just have been me being a crappy shot (noobie gun owner), but while I was disassembling the gun to put it in the Blackfeather stock, I noticed that the op rod was not centered as well.

so is my barrel incorrectly timed? and is it a big problem and is there an easy fix to this?
 
If it is leaning to the left when you look at it from the rear of the rifle the receiver was over tightened onto the barrel ( over indexed ). Fixing this isn't hard but you will require a barrel vice . If you can get to one of Hungrys clinics you could fix it yourself or if you live near by you could drop in and he would sort it out. I have a barrel vice and can index the barrel as well but I live about 180 km NW of Ottawa ..(Chalkriver)

Here is a couple pics showing how to set up the rifle when indexing a barrel and what a barrel vice looks like.
 
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Get some fired brass mic'd before you index your barrel. If it's over indexed having it timed will increase headspace a bit. No big deal if you are are around the NO-GO specs, but if you are in the FIELD REJECT it may put you into head separation zone.
 
Hitzy said:
Get some fired brass mic'd before you index your barrel. If it's over indexed having it timed will increase headspace a bit. No big deal if you are are around the NO-GO specs, but if you are in the FIELD REJECT it may put you into head separation zone.
Click to expand...

and if after indexing it properly you do increase headspace into that zone.

what are the options for an end user to correct it?

new bolt?
 
jt_trouble said:
and if after indexing it properly you do increase headspace into that zone.

what are the options for an end user to correct it?

new bolt?
Click to expand...

Bolt, or barrel, or Bolt and Barrel.
My suggestion is if you're changing one of the two, start with the barrel, get a short chambered barrel and have it finish reamed to your prefered spec.
Unless you have reason to belive your bolt is unsafe, a bolt wont increase accuracy as a barrel will, and will be roughly the same cost.
Also, some Norinco receivers and barrels wont accept a USGI bolt. You may find after buying a bolt that a barrel is also required.
 
Most likely nothing bad will happen due to out of index barrel timing. Your rear sight likely will not center up on the receiver indices markings, but no damage to the rifle accept for maybe some slightly accelerated op rod tab wear.
 
OP, I'm sure someone has offered to measure a few fired cases by now. Take them up on the offer. Huge headspace would be my only concern of failure. That said, always pay attention to the barrel/reciever fit. It can become loose...
 
Thanks for the advice everyone, I've tried to do it myself, but the tools I had were not heavy duty enough to budge the receiver.

jonh172 has kindly offered to correct the timing for me, which I may take him up on depending on how the rifle performs on my next range trip.

Thanks again everybody!
 
You can always send three fired brass cases to me for measuring or mic'ing since I use a Precision Mic by RCBS. You don't have to go out and buy once since I've had the same unit since 1986. :)

I can also reindex your barrel. It's a five minute job. No joking. It's that easy. The actual hard part is unboxing your shipping carton. No kidding. :D

I am always here fer ya!

Cheers, Barney. :wave:
 
Given the thread pitch and small degree of turning to index the barrel, there won't be an appreciable change in head spacing. 0.00028" change in headspace per degree of rotation. So 3 or 4 degrees of rotation will only result in .001 change in head spacing. Negligible given the loose state of a typical Norinco M305.
 
I know it's been a while since when I last posted, but I finally got to take the gun to the range last weekend.

So with the Blackfeather Stock, M14.ca scope mount and op rod guide, vortex diamondback 3-9x40 scope, and wolff recoil spring, between 4 ppl, we were able to shoot 1.5 inches groupings or under at 100 yards.

This was done with the Norinco ammo, so I'm just wondering is this a good result for this gun or should it have done even better with the upgrades? And can it do better if the barrel was timed correctly?

Also I hadn't checked back since the last time I posted and I'm just wondering what getting brass mic'd means?
 
1.5 MOA with Norc ammo is excellent performance. Unless I'm mistaken, you're probably seeing a range of groups, 4" to your 1.5".

If you can consistently get 1.5 MOA performance without hand-loaded ammo then you have a uniquely excellent rifle. I don't think that corrected timing will make much difference to your accuracy. I'd focus instead on getting into reloading and finding the right load. In my case, this made the single greatest improvement in my results with my Norc.

When folks mention getting your brass mic'd, they mean that if you can get someone to measure the headspace of a fired case (fired with gas off), it will give you a good idea of your current headspace. I believe that Tactical Teacher and someone else (Lost Again maybe??) have these case gauges and will do his for you if you mail the brass to them. If you are interested, try PM'ing them.
 
Regarding the case mic'ing... When your cartridge goes off the heat and pressure forces the brass to assume the shape/size of the chamber. I have an RCBS Precision Mic in .308 that measures the chamber size. Send me 3 fired brass cases. And then I can measure them and let you know the size of your chamber. Most of the Norinco chambers are around 14 to 15 thousandths of an inch above the SAAMI Go gauge of 1.630"

Reindexing is an easy job. Takes longer to unpack and pack up that barreled receiver and then mail it back to you.

Cheers and glad to be of service :wave:

Barney
 
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