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PostPosted: Mon Nov 15, 2010 7:06 pm 
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Mil-Surp Owner
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Hello to the Forum!

I would greatly appreciate your advice. I am reloading .308 Winchester for my M1A and use a reamed military case (AFF 88) with the Sierra 168HPBT bullet. Starting loads call for 41 grains of powder. I can't get 41 grains into the case. Well, it goes up to the bottom of the neck. When the bullet seats, it compresses the powder. Some things I have read say to use an 85-90% fill of the case. I am way past that. Any suggestions?


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PostPosted: Mon Nov 15, 2010 8:07 pm 
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Benefactor
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Do you have a vibratory tumbler? While that's running, hold a case against the center post and the powder will settle quite dramatically.

Alternately, you can buy a powder drop tube that will compress the powder in the column.
http://www.midwayusa.com/viewproduct/?p ... ber=293879

I have that problem using Barnes bullets (copper and therefore long) with Varget in 308 and 762x39. I use the tumbler method as I have one.

Regards,
Brian in CA


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PostPosted: Mon Nov 15, 2010 8:24 pm 
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Mil-Surp Shooter
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I just looked at 5 different manuals and the all say starting loads at 38 gr. of imr4895.
So I grabed a 308 case filled it to th bottom of the neck with imr4895 and it had 46 grs.


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PostPosted: Mon Nov 15, 2010 8:33 pm 
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Benefactor
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>>
imr4895
>>

Different animal than H4895. Varget and all the H prefix powders are ADI "temperature insensitive" powders. I've switched from IMR4198 and IMR4350 to the H equivalents after having such good results with Varget. I use a ChargeMaster 1500 so metering isn't an issue as the larger sticks can be a booger in a lot of powder throwers.

My bolt gun 308/168 load is 46 gr of Varget, not a problem at all in Winchester cases - and not one I'd use in my 308 Garands!!

Regards,
Brian in CA


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PostPosted: Mon Nov 15, 2010 8:46 pm 
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Mil-Surp Shooter
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I did'nt notice the H.
Sorry.
I tried the H3895 in my M1 30-06 and it changed my groups to 2 inch plus.
From less than 1 inch compared to imr4895 50gr.


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PostPosted: Mon Nov 15, 2010 10:00 pm 
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Thanks for the response, all. I am going to try the vibe method, although with my vibrator, I'll be deaf after about a box.
I read in one place that there needs to be free space inside the case for the primer to properly ignite the powder. Then in another that it is okay to compress to a point. http://www.reloadbench.com/gloss/compress.html IS it okay to compress the powder? I cannot see how you could get the max recommended 43.5gr into a case, otherwise. I want to get the velocity up to about 2600 to take advantage of the higher BC at that velocity. Without compression, I can get about 39-40 gr into the case. Hodgdon's website says that 41 will give me 2551fps. Is there a better powder?


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PostPosted: Mon Nov 15, 2010 10:14 pm 
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Benefactor
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I'd suggest looking at the Sierra manual for the section on gas guns, or I understand Hornady has a big section on the M1A. The standard load for M1A's for shooting out to 1000 yards is a different bullet, the 175 SMK. 41.5-42 gr of IMR 4895 on LC brass. Varget is a little slower and some run up to 43 gr.

Another good article: http://www.zediker.com/downloads/m14.html

Don't consider that the quoted MV from load data is anything more than a guideline. Get one of those cheap Chrony's when they go on sale at Midway, I got mine for $80 as I recall - THAT is data, as opposed to a guideline.

Oh, yeah, some manuals show C to indicate compressed loads, that's an assurance that pressure was accounted for given compressed powder. Once shells ride around in your truck for a week or two, they're going to be collapsed volume-wise. Whomever said free space is needed doesn't understand how the process works.

Regards,
Brian in CA


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PostPosted: Mon Nov 15, 2010 11:58 pm 
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Thanks for the good advice, Brian. I'm going to get a new manual and investigate a chrono. I also downloaded that article and will review that. Appreciate everyone's response!


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PostPosted: Tue Nov 16, 2010 12:50 am 
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Looking at the Hornady Manual(I don;t have a current Sierra book), and using their loads for their 168 gr BTHP, which should be somewhat comparable, and I find this:

Starting load for H4895 is 34.8 gr/2100 fps, and max load is 41.9 gr/2600 fps.


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PostPosted: Tue Nov 16, 2010 2:47 am 
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Mil-Surp Psychosis
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7.52X51 NATO cases can have significantly less powder space than commercial .308 cases.

Winchester developed a "Semi-Balloonhead" case for use in its Palma Match matchgrade cartridges.
The thinner web allowed for more powder capacity to offset intrusion of the base of long heavy matchgrade bullets into the powder space.
I've heard that Winchester now uses the semi-balloonhead case head for many other high performance cartridges.

The story on H4895 is that when Hodgdon began to run low on surplus IMR4895 he commisioned a Scots firm to manufacture a duplicate powder.
The samples he sent to Scotland had degraded slightly in long term storage so the burning rate was not the same as freshly manufactured !MR4895. The Scots duplicated the altered burning rate of the sample powder.
Don't know if any of this powder was produced in Scotland but it has been manufactured for Hodgdon by Australian Defense Industries. ADI used new processes for purifying the ingrediants and their single base powders are highly thought of and said to be less affected by temperature extremes or degradation in storage.


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PostPosted: Tue Nov 16, 2010 10:31 am 
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Noted, Sailorman, and yet the Hodgdon Reloading Data Center website, which I would expect to be up-to-date (my Hornady Reloading Manual is 1980 and doesn't even list H4895), shows this for the 168 GR. SIE(rra) HPBT:

Bullet Weight (Gr.) Manufacturer Powder Bullet Diam. C.O.L. Starting Loads Grs. Vel. (ft/s) Pressure Maximum Loads Grs. Vel. (ft/s) Pressure
168HPBT Hodgdon H4895 .308" 2.800" 41.0 2551 38,300 CUP 43.5 2703 49,500 CUP

(BTW, is there a link that shows how to embed a jpg?)

Thanks for the input on that, Savageshooter. I had tried filling another case (FC) that I had around to see if there was a difference between the AFF mil case and a commercial case and they seemed to be filled up the same (visually). Excuse my ignorance, but what part of the case is the web?


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PostPosted: Tue Nov 16, 2010 12:58 pm 
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SalguodTM wrote:
what part of the case is the web?

This site has sectioned cases that show differences in web thickness.
http://www.longrangehunting.com/article ... rust-2.php

Besides the web proper the sidewall near the web is also usually thicker with the milspec cartridge case.

I've no doubt that some commercial sporting .308 manufacturers use the same case that they would use to fill military contracts for the 7.62X51. You can't count on that being the case though, and reloading information worked up using a higher capacity commercial case can redline a lower capacity case.


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PostPosted: Tue Nov 16, 2010 2:26 pm 
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Mil-Surp Owner
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After seeing the Sierra308.pdf article and also taking into consideration the reduced capacity of the mil cases, I've unloaded the 5 tryout rounds I had at 41 gr. They may not be safe. I had been working up to the higher loads, and had tried 38.5 gr last. Then checked the Hodgdon website and it said 41 starting. So I was going to try that. However, I am not going to use that data. I am going to load up 50 or so with about 38 and see how they shoot. If they print well, maybe that's my load. Until those cases wear out. I appreciate all of the input!


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PostPosted: Tue Nov 16, 2010 8:40 pm 
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Benefactor
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I've got one of the "one book/one caliber" books for the .308.

Source: Hodgdon Reloading Manual #26

.308 Win Match Loads (7.62 mm NATO) using Winchester cases

168-172 gr BT - H4895 38.0 (start), 2403 fps, 43,000 CUP
168-172 gr BT - H4895 40.0 (max), 2525 fps, 47,000 CUP


.308 Win Match Loads (7.62 mm NATO) using GI cases

168-172 gr BT - H4895 37.0 (start), 2388 fps, 44,000 CUP
168-172 gr BT - H4895 39.0 (max), 2508 fps, 48,200 CUP

_________________
C&R: 8 and counting
Non C&R: 15 and counting


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