6.5 x 55 Ackley Improved?

I have a blank .264 barrel & a 1910 Mexican SR 98 action with Belgium proof marks.

I'm looking to build a lightweight 24" barrel plains/mountain rifle.

Anyone here have any experience with this cartridge?

Working with Quick Load it seems that with compressed loads of Norma MRP @ 60K pressure I should be able to get about 3200 FPS with a Nosler 120gr BT & 3100 fps with a 129gr Hornady Interbond.

Either should have + - 3" PBR of just over 310yds & still be capable of holding on hair out to 400 yds on deer sized targets.

I'm leaning towards the 129 gr Interbond after having outstanding terminal performance from the 139 gr .284 Interbonds at similar Mv.

ever think of going 1 more step and trying a 6.5x57 improved?

quote:

Originally posted by butchloc:
ever think of going 1 more step and trying a 6.5x57 improved?

Actually that was my 1st thought but I can get Lapua brass for the 6.5 x 55 and reamers, dies seem more readily available for the 6.5 x 55 A.I.

Interpolating Quick Load data for the 7 x 57 A.I. (no 6.5 x 57 A.I. in database) case capacity comes out about the same.

6.5 x 55 A.I.= 62gr H2O

7 x 57 A.I.= 62.4gr H2O

Given that Quick Load has the 6.5 x 57 case .50gr less water capacity than the 7 x 57, it should be a wash.

If you are going to load to 60,000 why not use new brass and leave the 55 alone. Running your same numbers in a 24" using MRP and 60,000 the AI version calculates 3098 the normal 3064 with the 129.

Most AI gain is pressure not capacity.

On the other hand if you simply want one to be different by all means build it. That is why I have more wildcats in the safe than std.

......from memory my 6.5x55Imp runs 48Gr of 2209 with the 129 Gr hornady for about 2900fps...zeroed at 200M.....22" barrel....100M TO 300M is +/- 2" from there.At 200m the bullet is still rising. I think the 'smith that cut my chamber may have used a 6.5x284Imp reamer as I know he had one and these case are huge. Its definately a one hit killer.

Roger

quote:

Originally posted by ramrod340:
If you are going to load to 60,000 why not use new brass and leave the 55 alone. Running your same numbers in a 24" using MRP and 60,000 the AI version calculates 3098 the normal 3064 with the 129.

Most AI gain is pressure not capacity.

On the other hand if you simply want one to be different by all means build it. That is why I have more wildcats in the safe than std.

Well the logic is that the throat will be cut short for 129Gr Interbonds @ 3.09" COAL and I wouldn't want someone in the future chambering factory ammo with long bullets & firing them.

Likewise, if I load high pressure cartridges I would not want someone chambering them in a M96 Swede & firing them.

At least by going the wildcat route, any likely future usage of either the rifle or the cartridges will be approached with some caution.

I also have some experience with an 8mm-06 A.I. and improved brass life & less case trimming are another advantage with the "Improved" cases, especially when running elevated pressure.

Seems like a lot of reasons that don't relate to the few fps gain. For me some of the best reasons.

I've built a large number of AIs and my own wildcats. At first I believed the huge velocity gains. Now I do it kind of just because I can and I like being different.

A man(woman) should build their rifle they way they want it!!!!!

Well, you could always really blow it out and make it a 6.5x64...

quote:

Originally posted by rnovi:
Well, you could always really blow it out and make it a 6.5x64...

Won't fit in a 1910 small ring Mexican Mauser 98 action.

quote:

Originally posted by ramrod340:
Seems like a lot of reasons that don't relate to the few fps gain.

I've built a large number of AIs and my own wildcats. At first I believed the huge velocity gains. Now I do it kind of just because I can and I like being different.

A man(woman) should build their rifle they way they want it!!!!!

Well, the Ackley "improvements", less taper in the case & sharper shoulder angles have all been incorporated in the recent crop of modern cartridges & "short magnums".

My understanding is that the straighter case walls reduce bolt thrust & the sharper shoulder angle reduces brass flow.

I never had any signs of incipient case head separation with my 8mm-06 A.I. despite pushing 180gr Nosler BTs at 3000 fps. Case failure usually was due to loose primer pockets after 8-10 reloads. I rarely had to trim the brass.

I think this would allow running higher pressure with an improved safety margin.

Reamer & die availability would be the factors that determine my choice between 6.5 x 57 A.I. & 6.5 x 55 A.I.

If those factors turn out to be equal I will opt for the 6.5 x 57 A.I.

OK, I just did a little research. 6.5 x 257 Roberts A.I dies are available from RCBS for the same price & availability as 6.5 X 55 A.I.

I called Dennis Olsen but he's out of his shop right now. I will call him later.

Depending on what he has for reamers will determine my choice.

WC I was just trying to say I was glad you were focusing on other benefits.

I hate to see when someone starts talking AI because of the 100s of fps gain they are going to get.

For what it's work 4D has the 6.5x257AI for rent.

quote:

Originally posted by ramrod340:
WC I was just trying to say I was glad you were focusing on other benefits.

I hate to see when someone starts talking AI because of the 100s of fps gain they are going to get.

For what it's work 4D has the 6.5x257AI for rent.

I just got off the phone with Dennis Olsen. He has a 257 Roberts Improved reamer & he will cut the throat as a separate step per my dummy rounds.

So it looks like it will be 6.5 x 57 A.I./6.5 6mm Rem A.I./6.5 x 257 Roberts A.I. depending on what you want to call it.

I'm going to call it 6.5 X 57 A.I.

Well I was just trying my new batch of wine. Left over part bottle after filling the others and corking. So call it the 6.5 Junkie.

Seriously I do prefer your 6.5x57AI. I lean towards tying back to the parent. In a light rifle that will be a keeper.

It's about a perfect compliment to your 8x57. Good luck with your build.