A-Bolt Thread?

[ejg223]

Trying to help a chap find out what thread he has on an A-Bolt in 308.

It came "Factory" threaded. Shop told him M14x1 which it isn't.

He sent me a photo of the thread with a tape measure as ref.

My guess would be outside diameter 12.5 - 12.8mm which could

be 1/2" or M13.

My guess on the pitch is roughly 24 tpi or 0.96mm looking at the photo.

I know of 1/2"x20tpi and 1/2"x28tpi but never heard 1/2"x24tpi??

Could it be M13x1? I know Steyer use M13x1 on some rifles.

 

I just received the end-cap to look at, The inside diameter is 11.5mm

 

any ideas?

 

edi

[eldon]

Edi have you not got any thread gauges ?

If not use a standard 6mm bolt which has a 1.0 mm pitch as your gauge. At least this way you will have an idea if it is metric or not.

By the diameters you have said my hunch would be 1/2" unf. Obviously 20 tpi would be slightly more coarse than the above bolt used as your gauge.

[baldie]

Has it had a Boss system on it Edi ? if so its an oddball, and off the top of my head i think its 9/16" x 24 tpi.

[ejg223]

Thanks so far, Baldie & Eldon

don't think it would be 9/16 that would be over 14mm.

The only thing I got to go by are these two pictures.

Never asked about boss system, doesn't look like it though, or?

never saw one in the flesh.

 

No don't have any thread gauges.

 

Does Browning factory thread the rifles or are they done when imported to

the UK?

 

The thread cap, has a part not threaded with a diameter of 13.04mm which has to

fit over the ouside diameter of the thread on the barrel.

 

edi

 

[baldie]

That hasn,t had a boss system on it Edi....the thread isn,t long enough. Very hard to tell, but i would say its 13mm x 1 as well. Unusual thread but probarbly pushing it to get a 14 mm on there. I,m sure i've had them in 14 x 1 though ?

The importer [ i think ] is bwm arms, the winchester importers.

[ejg223]

That hasn,t had a boss system on it Edi....the thread isn,t long enough. Very hard to tell, but i would say its 13mm x 1 as well. Unusual thread but probarbly pushing it to get a 14 mm on there. I,m sure i've had them in 14 x 1 though ?

The importer [ i think ] is bwm arms, the winchester importers.

 

Thanks Baldie,

not many good machine shops around here, but

I have a fella in the next town who does a bit of barrel threading.

We can measure the thread cap there.

all the best

edi