I need help! I hope that some of you "big bore gods" have some ideas.
I have been trying to work up a load for my .450 Ackley with a 400gr Swift A-frame using 86-88 grains of IMR 4064 in A-Square brass. This load is well within limits according to my book however, in summer heat, I am having trouble with cases not extracting (not good for big bears in close). The gun is a Remington 700 KS Mountain rifle that was rebarreled and tuned by Brown Precision. The gun is under 7 lbs with a very light barrel.
I have been neck sizing the brass because it looks as if it will set the shoulder back a few thousands if I was to FL size. I don't think that this is the problem because an unfired round will chamber and extract smoother that any other gun I own. Is this caliber supposed to headspace off of the tiny shoulder or the belt?
A bullet will easily slide into the neck of a fired case so I don't think that I have a tight chamber. It also shoots 500 solids fine with 80gr of 4064.
Any ideas would be greatly appreciated!
Thanks

Your load sounds O.K. regarding pressure with such a light bullet as the 400 grain Swift, however the fact that "summer heat" brings it on may be an indication of pressure, or is it that you have not tried it in cool temperatures?

Most suspect is the A-Square brass, that did not have a good reputation. It may be overly soft and causing enough swelling with normal pressures to give a sticky feel, or is the case actually stuck to require bolt hammering or shearing off of rims?

The case is supposed to headspace on the belt. The tiny shoulder may be good for bullet grip, since it creates the bottleneck and not just a ghost shoulder.

Have you trimmed the cases properly before loading? An over long case can raise pressure by crimping into the bullet if it extends into the throat area beyond the chamber proper.

Timberghost,

When you say it is hard to extract, does the one of the following happen:

You open the bolt fully, but the bolt resists you pulling it back.

Or

Is the bolt resisting being opened but once opened, the bolt is easy to pull back.

If it is a case of the bolt being difficult to pull back once opened, than can bea primary extraction problem with the Rem 700. Cases with very little taper like the 450 ckley will increase the problem. Soft or tired brass will make it worse.

Mike

Mike,
I was holding back on berating the Remington 700 extraction weaknesses. Of course such a rifle ought to be a CRF Mauser clone, or if not, and a PF is insisted upon, then at least have a vertical stack magazine, avoid A-Square brass and stick to starting loads only. Why not go ahead and rub it in?

Ron,

The low primary extarction on a Rem 700 is not beause it is push feed.

I always put it down to the wide locking lugs limiting the amount of bolt riattion that could use the the extraction cam.

However Jack Belk said the lugs of not enough wider than M70 etc. and the problem comes from incorrect placement of the bolt handles with the result being that the extraction cam does not engage early enough. Some of Stainless Rem700s are quite bad because of the galling of the extraction cam.

By the way, Mark Vs have a very short distance of travel during extraction which in the ir case is of course is the 54 degree bolt lift.

As an aside, the way my neck and upper back feel today, I am getting very intersted in 17s.

Mike

[ 10-28-2002, 04:18: Message edited by: Mike375 ]

Hi Timberghost,
I had the same problem with my 500 A-Square brass and the problem was the A-Square brass was soft as Daggaron suggested. If you would like to confirm it fireform some Winchester or Remington 375 H&H brass and produce the same load to see if it sticks. I think you will find your problem will be gone.
Take care
470 Mbogo

I am left handed and would love it if the CRF's would build rifles to fit me. However, I am stuck with the rifles I can find in LH. You can't offend me any more than the manufacturers already have. Ha-Ha!
The bolt lifts fairly easy, but will not pull back. A gentleman from Sierra Bullets suggested soft brass. I guess I was mistaken in assuming that A-square was good stuff (possibly by the price).
Hornady makes .375 cylindrical cases ($21 for 50 in Midway). Would this be a better choice or what brand would you suggest?
I knew you guys could figure this out.
Thanks!

I endorse all the comments on the A-Square brass being too soft. II had the same problem, but luckily had only a few A-Square cases and thus went almost immediately to Federal or Winchester. I make my 450 Ackley's from Federal or Winchester 375 cases and have no problems with extraction. One of my 450 Ackleys is also a Remington M700,but I've modified it with a Sako extractor. This gives me more confidence in the extraction also. Watch the OAL of the case, if it gets too long you will have pressure problems. Hope this helps.-Rob

Timberghost (great handle)
the best thing parker ever said is that the 375 basic unformed is just about perfect for the 450 ackley.

I am starting to like hornady brass for hunting loads, but norma might be better. Both are on midway for a reasonable load.

Like Rob said, watch the length.

have fun
jeffe

I am using Hornady basic brass for my 450 Ackley. I also got some Norma brass and they seem to have a slightly larger rim dimension, as they fit my CZ a little tighter and better. I think fireforming Hornady basic brass for the 450 Ackley would be a little easier than any other methods.

Timberghost,

From your post:

The bolt lifts fairly easy, but will not pull back.

They are the classic signs of poor primary extraction. If you get your Rem 700 and open the bolt while pushing forward on the bolt handle, you will see the bolt move back a certain distance. This distances will be a bit more than Wby Mark V but less than a Model 70 (push feed or CRF ..no difference)or a Mauser.

In other words, during the extraction cycle, the case is not pulled back as far as is the case with other actions such as M70 or Mauser.

Soft brass and cases with very little taper really bring the problem to light.

Thin case rims or an incorrectly positioned extractor (sometimes with sako extarctor conversion on Rem 700s) make the problem worse since but of the limited rear bolt movement during extraction is used up just getting the extractor to engage the case rim.

Mike

You guys are great! Thanks so much for the information. I am always very careful on case preparation and trim to length every time so, that is not the problem.
I will purchase the new brass and go from there.
Thanks again, Timberghost

Timberghost,

I agree with other posts regarding A-Square brass.

For my .450 Ackley I use .375 H&H made by RWS, I know it is a little bit expensive but you can't find better quality. Just my 0.02 cts.

I have used A -square 450 Ackley brass in the past, so far no problems, but I'm not pushing it too hard, so who knows (and it was purchased about four years ago). I've also necked up Rem and Win 375 H & H brass; it woks well. I have bought some of the unformed Hornady magnum brass, and it's just about perfect for the 450 (which is why I bought it actually) because of the extra case length. Still working up loads in that brass, no reports yet (it's hunting season). - Dan

Timberghost.....no one else has commented but I think you deserve recognition. Anyone shooting a 7lb 450 Ackley has got to be "da man" and my hats off to you.

i think you will find his hat on the ground too!
just out of curiosity, what is a light barrel contour for a .458?
thanks
woofer