243 FB for Sammi reamer. Is it zero?

[urbanrifleman]

I have asked a few people to make a 243 barrel for me. Several have said they have a "SAAMI" reamer. I asked the FB. No one knows. The print shows zero. That seems really short for a standard 243. Anyone know the FB of a 243 SAAMI reamer?

Or more specifically, if I want to shoot 80 grain bullets and smaller is a SAAMI reamer going to work? Looking to get a slow twist barrel made for a PD hunt.

 

[BoydAllen]

Take another look at that print. the throat angle begins at a rather large diameter. This is a different setup than the type that has a parallel freebore that is slightly over bullet diameter. The point of bullet contact with the rifling is determined by the leade angle and the diameter where it starts at the front of the case neck. Not all factory .243 barrels have been chambered that way. I was told that Remington used the same throat that they had in their .244/6mm Remington. The diameter of the circle running across the tops of the angled ends of the lands, where the bullet makes initial contact can be similar for both designs, but with the standard freebore configuration its distance from the case mouth is determined by the freebore length, while in the case of what I call a funnel throat the determining factor is the starting diameter at the end of the case mouth. Personally I would not want a SAAMI print reamer, but would instead prefer to have one with a target/freebore style throat.

 

[expiper]

If your "smith" has one of those funnel throated reamers (and wants you to let him chamber a bbl with it !!) ,,,,get a different gunsmith,,,,Roger

 

[Shawnba67]

This will only be marginally helpful.
Purchased sammi 243 reamer from Manson mid 2017
My COAL at jam measured approx
60gr sierra 1500 2.62 bullet .739
95gr nosler BT 2.76 (bullet was 1.116)
100gr SGK #1560 2.682 bullet was 1.078
With some math skills you can figure out where other bullets might fall.

Now heres a question if your shooting 80gr and less and worried about freebore being to long you cant have less than the sammi "0" freebore.
I think you will be fine with a sammi

 

[spife7980]

Can I ask why exactly yall wouldnt want the traditional funnel shaped throat found in the 243 and 270 etc and would instead prefer the parallel free bore? Just for ease of measurements?

 

[urbanrifleman]

This will only be marginally helpful.
Purchased sammi 243 reamer from Manson mid 2017
My COAL at jam measured approx
60gr sierra 1500 2.62 bullet .739
95gr nosler BT 2.76 (bullet was 1.116)
100gr SGK #1560 2.682 bullet was 1.078
With some math skills you can figure out where other bullets might fall.

Now heres a question if your shooting 80gr and less and worried about freebore being to long you cant have less than the sammi "0" freebore.
I think you will be fine with a sammi

Do you have these measurements to the ogive? Do you have any measurements for 70 grain bullets?

And yes I think the Sammi reamer ends up being the equiv of about 80 thou freebore.

 

[expiper]

Can I ask why exactly yall wouldnt want the traditional funnel shaped throat found in the 243 and 270 etc and would instead prefer the parallel free bore? Just for ease of measurements?

spife....the if a portion of the chamber (FB) is cylindrical and ~.0005 larger than the bullet it will act as a "pilot" to guide the bullet into the bore and the rifling even after the case neck expands away leaving the base of the bullet un supported,,,,if it is funnel shaped it is like throwing a football into a piece of pipe,,,,,Roger

 

[walley2960]

I have used a sammi .243 chamber once. I wasn't thrilled with the performance. My "match" reamer has a .091 freebore. It works well with berger 105 hybrids. Also it allows seating the bullet into lands when I load them to mag length. May not be any help to you depending on the bearing length of the bullet you intend to use.

 

[urbanrifleman]

I want a SAMMi reamer (277 neck) with about .085 to .091 FB. That would be perfect.