308 Bisley

[300 RUM]

Hello all,
I just chambered a barrel with a "308 Bisley" thinking it was a standard 308win/7.62NATO. Ok that being said the chamber work went excellent, and head spaced it with a standard 308 go/no go gauge which I have been told is fine. Also my understanding is that the Bisley will chamber and function properly with any old factory/ hand loaded ammo designed for the 308win/7.62nato? Also that the Bisley is a much better chamber then the standard? So with all that being said, what is the difference between the two? What will I and what will I not be able to do with this chamber?



The brass I intend to use will be: REM, WIN, Nosler and Lapua
The bullets will be: 155gr & 167gr Lapua SCENAR, 168gr Hornday A-max and possibly 208gr Hornady A-Max

Are there any hints that can be given out to hand loading these bullets?


Thanks

Gene

 

[GermanS1]

Gene, the Bisley reamer is made to conform to the requirements of the NRA of Great Britain's Rule 150 which governs rifle specifications. The relevant portion of the rule is as follows:

*** Bore and Chamber Dimensions: The dimensions must not be less than either CIP or SAAMI minimum chamber drawings (whichever is the smaller) other than in (a) and (b) above where the following concessions are permitted: the bore diameter must not be less than 0.298”. the groove diameter must not be less than 0.3065”. the throat diameter must not be less than either the bullet diameter or 0.3085”, whichever is the greater. the minimum throat length may also be reduced but only to such an extent that the bullet of the cartridge in use is not in contact with the rifling. See Appendix V Para 7f.

If reduced bore or groove diameters as above are used, only ammunition developing an average max pressure less than 3650 Bar under CIP test conditions may be used. NRA ammunition “as issued” will satisfy this limit. ***


As may (or may not) be obvious from reading this rule snippet, the concern that led to the adoption of the rule was excessive pressure due to the use of tight bores and throats with modern bullets as opposed to the formerly used military ball ammo that had undersize bullets. Many US made match .308 reamers have a 0.3082" throat diameter which, although safe, will not meet the Rule 150 requirement for a 0.3085" throat. Tight neck chambers and very short throats are also not compliant with the rule. As a point of reference, the Palma 95 reamer which is widely used in the US has about a 0.030" shorter throat than the Bisley reamer.

Your new chamber should be fine with all of the bullets you mentioned except the 208, it will still be a bit short throated for that. You can use them, of course, but you won't have the powder capacity to optimize them for 1000 yard use - for distances up to 800 yards, they'll work fine.

 

[300 RUM]

If I understand this correctly, the Bisley has a more a perfect fit throat, then the others? do you have comparison drawings I can view?

 

[GermanS1]

The Bisley chamber's throat (0.3085") is smaller than the SAAMI dimension (0.310") but larger than many match chamber throats (0.3082") it's not a "better" fit or a "worse" fit, but it is a good fit and one that meets the NRA of GB rules.

I don't have chamber print drawings handy to post, but perhaps PTG can send those to you.

 

[300 RUM]

I did send Dave an e-mail asking for the print. Yea I just need to see the bisley print and do the comparison to get the full picture. I'm just glad it will shoot wall mart ammo if ever need be.
I guess I should just get a case overall length from the rifle and start working up a load for each of the bullet types I intend to shoot. I can load to 2.875(full magazine length) so may even try some 178gr A-Max?

Oh, the bore is .298/.308 any concerns there?

 

[GermanS1]

The tight bore can be a bit of a problem in terms of pressure with heavier (long bearing surface) bullets. The 178 should be fine, but I would rule out the 208.

Here is Krieger's statement on tight bore barrels:

We only offer the .30 "Tight" caliber barrels up to a 1-12 twist. The reason being, we have seen pressure issues arise when using heavy, long bearing surface bullets in this tight bore/tight groove configuration. We strongly suggest against using bullets heavier than 175 grain, and/or magnum pressure cartridges in any .30 Tight caliber barrels due to the dangers of high pressure and the increased chance of copper fouling.
http://www.kriegerbarrels.com/RapidCat/catalog/pagetemplate.cfm?template=/RapidCat/common/viewPage.cfm&PageId=3390&CompanyId=1246

 

[jscandale]

Among Palma shooters, what is considered to be the ideal reamer for American Palma competition? I hear a lot of talk about Palma 95 and Palma 2011, but don't know the differences. Being a high power shooter and not a Palma shooter, I am really not up to snuff on the different Palma reamers, but would like to learn.

That you,

JS

 

[300 RUM]

Ok I received the prints from "PTG" and now I see the differences. Not much at all, the major difference i would say is the throat ".0015" smaller and .0221 longer on the bisley.
I haven't performed a complete comparison to the "308 win match" against the bisley but it looks almost identical to the bisley.
So now that I see it, no big deal

(jscandale)
I'm a long range shooter, but I stick to my own thing, can't answer your question. I'm hopinh this Bisley chamber brings some super results though.

 

[jscandale]

Thanks, I'm interested in hearing how it goes.

JS

 

[GermanS1]

John, for US Palma shooting, the important consideration is the bullet. Once you know what that's going to be, you can come up with the reamer. If you're shooting 155 gr. bullets, a Palma 95 (0.050" freebore) remains a good choice. If you want to shoot 175 and 185 gr. bullets, it still works fine; however if the Sierra 190 is your choice, you'll need a longer freebore (0.114" is what mine has).

Neck diameter is another consideration, I use neck-turned Winchester brass, so I specify a 0.336" chamber neck diameter. Someone using untirned Lapua brass would need no less than 0.342" chamber neck diameter.

Finally there's the leade angle to consider. 1.5 degrees has been the standard since the .308 came out, but in the past five years or so there's been a shift to 0.5 degrees for some match .308 reamers. I've been using this and see no negative effect although I can't say that there's a measurable positive effect. Too hard to tell.

 

[jscandale]

German,
That's good info. I am really not up to snuff on the Palma rules, I guess for US Palma, any bullet goes huh? I assumed that the 155 was "it".

JS

 

[GermanS1]

That's correct, any bullet in US Palma. You need a standard .308 chamber, nothing reshaped, but throat, neck diameter and bullet weight are up to you.

The 175 and 185 Berger LRBT are great choices. Others have more limitations. I have a little piece about that here: http://riflemansjournal.blogspot.com/2011/07/cartridges-308-heavy-bullet-conundrum.html

There are a lot of other articles about .308 long-range loading on the site, these might be good background:

http://riflemansjournal.blogspot.com/2010/10/cartridges-308-palma-preparation-and.html

http://riflemansjournal.blogspot.com/2010/01/reloading-western-shooters-pet-loads.html

 

[300 RUM]

German: and anyone else with a suggestion
I measured my chamber for C.O.L. today and I get an exact 2.80 (just touching L&G) for both the 155gr and the 168gr bullet, not a problem, I guess the .298 bore is cutting off any extra throat I may of had. I was hoping to be able to seat the bullets not any farther then the length of the neck only, but it looks like I will be .030 short on these bullets.
I ask the question: Leave it at 2.80 COL or ream out the throat another .030 to accommodate what I had originality set out for? I know I answered my own question just wanting to hear what you all have to say about this. To be honest I'm thinking about leaving it as is and just sticking with nothing larger the maybe 178gr bullets for this barrel.

 

[jbpmidas]

I would shoot it before I made any more modifications. You can always ream it after you shoot it, but you can't put that material back.

 

[GermanS1]

I agree with jbp, shoot it first and see how it goes.

 

[300 RUM]

Great minds think alike

 

[jbpmidas]

I just got lucky!

 

[TTF]

I agree...just shoot it, you may be surprised.

 

[300 RUM]

If the weather holds tomorrow I hope to have a field test report for all you guys

Thanks
gene

 

[jbpmidas]

Looking forward to it! What all are you going to try?