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308 ak

49K views 321 replies 44 participants last post by  1biggun 
#1 · (Edited)
0001
 
#182 ·
I still dont know what the problem with making this a sticy. muttman

I here you it and a couple other posts were what started the the whole calibure conversion forum. I originaly posted this thread in the build it your self area and it was moved here when this area was opend.

the chamber pressures thread should be a sticky as well . HCPOOKIE and myself and many other members have put a lot of info into that thread. I should copy it incase something were to happen.

this is one of the few sites that has this kind of info and talk avaliable. Those two threads should be a must read for any one thinking of a conversion.

there are a few numbrs in the thread that should be edited as new info was added on the CUP vs PSI in regarding military info and how the 308 and the 7.62x51 nato are closer than originaly thought. I cant believe it was that long ago when I started this thread. damm things have changed. Im glad I couldnt post pics back then LOL
 
#184 ·
I here you it and a couple other posts were what started the the whole calibure conversion forum. I originaly posted this thread in the build it your self area and it was moved here when this area was opend.

the chamber pressures thread should be a sticky as well . HCPOOKIE and myself and many other members have put a lot of info into that thread. I should copy it incase something were to happen.

this is one of the few sites that has this kind of info and talk avaliable. Those two threads should be a must read for any one thinking of a conversion.

there are a few numbrs in the thread that should be edited as new info was added on the CUP vs PSI in regarding military info and how the 308 and the 7.62x51 nato are closer than originaly thought. I cant believe it was that long ago when I started this thread. damm things have changed. Im glad I couldnt post pics back then LOL
yes a long way back. and Im still working on the .308 and the 5.56 is in the finishing stages. time does fly when you are haveing fun. but still fun. muttman
 
#185 ·
Here is some pressure and velocity load data from American Rifleman Magazine. I'm not sure of the date but since the Winchester large rifle primers are called "W120" I 'm fairly certain the H4895 mentioned is the old H4895 before it was made in Australia so I wouldn't rely on the H4895 data shown.

Note that the factory M80 load beat handloads with IMR-4895 in velocity with lower pressure. The factory M852 load with a 168 grain Sierra Match King and the factory 174 grain M118 produced the highest pressures showing they are hot loads.
 

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#189 ·
Those American Rifleman loads were tested in a 24" Remington pressure test barrel. Usually pressure test barrels have tight minimum SAAMI chambers. The military match loads were hot in that barrel.

For W-748 I like the Winchester book loads of 45.2 grains with a 147 grain FMJ and 25.5 grains of W-748 in 223 Remington with a 62 grain FMJ. They say these loads match the factory Winchester USA white box loads. They are decent loads in accuracy and case life. Use a "ball powder" primer like Winchester, CCI 250 Magnum or CCI #34.

I use a lot of CCI #34 and CCI #41 these days for semi autos. I used to use a lot of Remington 9 1/2 primers in 308 Winchester which is one of the mildest primers. I was loading some 303 British which I usually use an IMR powder but I was trying some Hodgdon powders. Varget and H4895. I started with CCI 200 primers and the load data from Hornady was on the mild side. The loads were mild as expected. I usually use Sierra bullets in 303 but was trying some Hornady bullets. Usually with IMR powders a change in primers isn't a big change and Remington is milder than any others including CCI. I think Hornady used Winchester primers in their data. I switched from CCI to Remington primers and the velocity and case bulging jumped way up !!! Hmmm??? Were the Remington primers really magnum primers in a standard force 9 1/2 primer box???? That was a strange pressure increase and I thought the Hornady Hodgdon powder data was mild compared to other load guides in 303 British. I used up all of those Remington primers and I don't know if the primers were mislabeled or if it was the Hodgdon powder with Remington primers that caused such a pressure increase. Another note, the CCI BR 2 benchrest primers are pretty warm but CCI says they are not magnum like the mil spec primer are.
 
#190 · (Edited)
From American Rifleman book "Semi Auto Rifles", article "Military Shoot Alikes".

M80 7.62x51 LC cases, Winchester LR primers, COL 2.80". Bullet is 150gr Sierra Match King. This bullet gives higher pressure and higher velocity than 147gr FMJ with same powder charge.

39.0gr IMR-3031 (39.5gr?)

42.0gr IMR-4895

44.0gr IMR-4064

Another website recommends 42.5 grains of IMR-4895 as an M80 load with a 147gr FMJ.

I noticed that when IMR went from CUP to PSI that the load data got hotter. A friend told me that for him the newer IMR-4895 in Hodgdon type bottles gives him 50 fps less velocity than IMR-4895 in the old containers. Now for me about 50 fps is expected for lot to lot differences. I don't consider it a huge difference. Even out to 600 yards 50 fps doesn't change point of impact or accuracy enough to worry.

41.0 grains of IMR-3031 with a 147gr FMJ has been popular load to match M80 loads so maybe the American Rifleman data is a bit mild with a 147gr FMJ.
 
#191 ·
I found out the American Rifleman data dates to 1984. The one powder that I know has changed since then is H4895. The old H4895 was slightly slower than IMR-4895 and was very similar to pre-1976 military IMR-4895. I loaded some LC cases with 43.0 grains of 1972 dated pull-down military surplus IMR-4895 and with a 147 grain FMJ I got about 2700 fps 15 ft in front of a 21" FAL. In the same rifle standard 147gr military ammo averaged 2762 fps and the military ammo with 144gr bullets (Aussie and Portuguese) averaged 2792 fps. This surplus powder is SLOWER than current IMR-4895. Current H4895 is faster than old pre-1999 H4895 and is faster than current IMR-4895.

American Rifleman recommended 43.0 grains of W-748 in LC cases with a 168 grain match bullet. They say it's about 0.5 to 1.0 grain under max but they don't recommend going more than 43.0 grains and 42.5 grains is also accurate. I tried 43.5 grains of W-748 without trouble but 44.0 grains showed severe overpressure so they are right. I think 43.5 grains is too close to overpressure to trust and I tested the loads in a bolt action, so in an auto rifle 43.0 grains plenty warm enough. 42.5 grains is accurate and not bad in velocity.

Do not use the old H4895 data shown in the chart. it might not get you in to trouble but the current made in Australia H4895 is faster.

The information from the series of 1984 articles is reprinted in an NRA book titled "Semi Auto Rifles".
 
#193 ·
Somebody told me 42.0 grains of W-748 with a 168gr SMK in LC brass is accurate. That should be reasonable pressure. I didn't buy the newest Hornady #7 manual but it has service rifle loads in commercial cases. I did glance through at a local gun shop that unwraps one copy of each load guide for people to look through while buying components. it's about a 100 mile drive from me. I haven't loaded many 125 grain bullets in 308 Win but even at starting loads it should beat 7.62x39. You don't want to start too low or the cases won't expand enough.
 
#197 ·
Be aware that factory 308 AK's have longer heavier bolt lugs. At least the right bolt lug which is suppose be the main one. They are all made on milled receivers or RPK type trunnions. The Saiga and Vepr 308 rifles have three lug bolts. It may not blow up but I think it might be pushing the standard design AK a bit. At least use an RPK type trunnion and inspect the bolt and trunnion often.
 
#199 ·
Well it looks like the 308 Galil uses a standard size bolt and the 308 Valmet and Yugo use oversized bolts. The extractor pivot is moved out and the bolt is cut away on the outside to clear it. The length is standard AK. A 308 Galil bolt might better to use than a standard AK bolt milled out. So the barrel location must be standard and I know the 308 Galil magazine is one of the best as it's based on the M14 magazine. I was thinking about reaming a Yugo barrel for 308. I know the bore would be a bit large but it should function. Would be cheap for a test. I could have a 308 barrel made for it later. I was worried there might not be enough space to feed from the magazine to the barrel.
 
#200 ·
I keep wondering why no one tries the .308 Barnes kurtz. It is .308x1.5 inch and should fit the 7.62x39mm AK mags and action. The round can be hand loaded up to 52,000 psi (or more). A big advantage of this round is the use of the .308 Win case or mil surp cases or even spent mil surp 7.62x51mm blanks !!

A 7.62x39mm barrel could be rechambered to this round though the bore is a bit generous. Perhaps a paper patch or use of .311 inch bullets would help tighten up groups.

The .308x1.5 Barnes kurtz has been briefly mentioned here before but that was all.

VD
 
#205 ·
I found this very interesting
The AK Forum :: Log in

the bolt second from the right is a 308 Galil bolt.

It appears identical to a standard a 7.62x39 bolt with only the bolt face inlarged!!!
I believe it is a spring loaded pin.
This should calm some fears that a 2 lug bolt is over loaded in 308. there are some sources for these bolts as well.

I wouldlike to see some specs on the ammo these gun shot in actualy use. they were also sold in the US in SA mode in this configuration I believe.

There have been some reports of fractures in military issued 7.62x51 Galils. The semi auto sniper versions are more common than the full auto ones though. I never knew if the receivers were cracking or the bolts. I'm not sure those pics are original as stated or those odd ones that were sold by ORF. I had one years ago. I didn't notice the differences at the time. The Yugo 77 is larger only on the right lug. The Valmet has both right and left lugs larger. the US doesn't require proofing and these rifles were designed before there were CIP requirements. Some European countries such as the UK had their own proofing standards but there wasn't a CIP standard at that time. The 8mm Yugo 76 bolt head is similar to the Yugo 77 bolt head, only the bolt stem is longer. look at what Valmet did to the 7.62x51 bolt !! That thing is huge. The Soviets increased the right bolt lug / head on 5.45 AK74 compared to the AKM.
 
#207 ·
So there are some reported failures of Galil's in 308 interesting. well so much for that. On the Valimit I think the bolt is bigger mainly so the barrel can be moved forward and not loose trigger guard clerance. I could be wrong. Im aware of the the differances of the m77&76 and theres pics some were in this thread.

as far as 5.45 bolt being heavier Im not sure why? the 223/ 5.56 run the same if not higher pressure ( I think what is the pressure of 5.45?) and they seem to be ok with the same smaller lug. the Sagia 223 must have passed CIP testing I belive that bolt is the same.

I have been looking really close at the 5.45 bolt lately, it could possably be opend up to a 308 win size face and might infact be stronger with the much longer RH lug and slightly longer LH lug. it would also allow the barrel to moved sligtly forward giving more finger clearance. I wonder if the bolt on the 5.45 is longer to help feeding rather than strength possably?? It would give a higher bullet height before it reaches the chamber.

In exploring the 5.45 bolt for conversion use ive noted the ramp on the bullet guide will need to be moved slightly forward. the lug engagement on a yugo M72 trunion is very good and the bolt tail is pointing straight back.

Im planning a 243 win on a two lug bolt build in the near future if the 5.45 bolt is stronger then it should be used. The small bolt stem could also be sleaved for a larger bore carrier and that sleave could be fitted for a more percise more accurate fit.
also that sleave might be used to retain a spring loaded pin while im at it. A sleave would also be a good way to lengthen a bolt. I could gain a little finger guard clearance with the bolt lug to bolt face increase and if i sleaved a small stem bolt and made it longer I could move the trunion forward. I would be pretty close to gaining back that lost 1/2 or so of mag well required to use a 308 length mag. I might be able to leave the center support and mag latch/trigger guard in the origional location. HMMMMMMMMM :)


I wish they were cheaper.
Both the Valmet and Yugo 308 bolts are longer in head/lug but only the Valmet increases the size of the left bolt lug too. The Yugo has the right lug increased with the bolt head but the left bolt lug is standard size. I'm not certain but I got the impression that most of the 308 Galil failures were the receivers but looking at the bolt I wonder. The 7.62x39 Saiga has a two lug bolt the size of the AK74 bolt. For a two lug bolt, that one might be easier to open up for a larger rim.
 
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