Reloading Problem - 7.5 x 55
First post:
I am working on my first reloads for K31's, using Redding dies, Prvi Partizan brass, and Sierra 168 HPBT bullets. In making a dummy round to figure out the best OAL, I had to shorten the OAL to 2.84" to keep the bullet from touching the bore. The recommended OAL in the loading tables is 3.050. The round looks odd with so much of the bullet inside the case. I slugged the barrel and it is .306. The Sierra bullets are exactly .308, and much less tapered than the GP-11 bullets, so the OAL must be shorter to keep the bullet from touching the lands.
Is a .308 bullet in a .306 barrel a problem?
Is a 2.84" OAL too short?
I am working on my first reloads for K31's, using Redding dies, Prvi Partizan brass, and Sierra 168 HPBT bullets. In making a dummy round to figure out the best OAL, I had to shorten the OAL to 2.84" to keep the bullet from touching the bore. The recommended OAL in the loading tables is 3.050. The round looks odd with so much of the bullet inside the case. I slugged the barrel and it is .306. The Sierra bullets are exactly .308, and much less tapered than the GP-11 bullets, so the OAL must be shorter to keep the bullet from touching the lands.
Is a .308 bullet in a .306 barrel a problem?
Is a 2.84" OAL too short?
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"Is a .308 bullet in a .306 barrel a problem?"... no, as long as you stay away from max. loads, your 2.84" o.a.l. is what your rifle requires with this bullet. I'd start at the low end of the loading scale as a tight bore and short o.a.l. will up pressures. 0 -
I reload the 7.5x55 Swiss, and encountered the same problem, at first. The culprit is the bullet, which has a relatively short ogive, and longer parallel sides, as compared with the longer tapered ogive of the GP-11 military bullet. There are bullets out there with similar long tapered ogive, though I haven't found any yet with similar weight, only lighter. I am using a .308" bullet, and my bore slugged at .308". 0 -
Stay off the max loads and you will be fine. The K31 has a notoriously tight throat. 0 -
Thanks for the replies.
In addition to being more tapered than the Sierra .308's, the Prvi Partizan 174 gr bullets are .305 and the GP-11 are .303.
PA Shootist - What bullets have you found that are more tapered? I have 135 gr Sierras that I planned to use for the 300 yard range (less drop), so a lighter bullet is ok. I could not find any loads for the 135 so I will have to guesstimate a load between the 125 gr and 150 gr. The three powders that I have to try are H4350, H4895, and HHybrid 100V.
The Redding dies seem very tight. I had to double lube the brass to get the FL die to release the cases, and after using the seating die, I was unable to budge the bullet with a RCBS pow'r puller. Even with vise grips and sharp pliers, I had to dig into the bullet and twist very hard to pull it. Wouldn't this cause excessive pressure? My .243 loads with Lee dies are not that tight.0 -
The bullet I have used with success is the Remington 150 gr Pointed Soft Point. It is a flat-base with crimping groove, that tapers immediately from the crimping groove to the point. The bullet measures .307" aft of the crimping groove, and .305" immediately in front of the groove, and continuously tapers from there. Almost none of the base of the bullet projects beyond the neck into the case when crimped into the groove. My cartridge overall length is approx. 2.890". I am using the Prvi Partisan case, and Lee dies. Accuracy for me(with the stock iron sights) seems equal to the GP-11, which is to say exceptional. 0 -
ledSlingr,
I use custom competion bullets from Nosler in my 7.5x55. In front of 46 gr. of VV N160. I haven't slugged my barrel but I assume it's pretty tight. One thing I have noted is that neither on of my two like hot loads. Or particularly heavy bullets. 168's and 175's have done the best. With 180 SMK's coming right close. As far as how deep you seat your bullets it's simply a matter of matching that to the lands. Don't worry so much about how deep the bullet is seated in the case.
What you may try....and I have made it work in mine as well is to drop to a couple grains below minimum with a slower powder and seat the bullets into the lands .010" and work the load up from there. VV 160 and VV 165, H4831X. H4350 would work as well.0 -
For bullets - look for 173 or 174 gr FMJ bullets. If you hunt around, there is usually a GOOD deal to be found. Check Wideners, sometimes they have some. 0 -
PA Shootist: The Remington bullets sound good; slightly smaller diameter than the Sierras, and the crimping groove seems right - more like the GP-11. Maybe with a crimping groove, I can do a shorter neck sizing, and the bullet will not be seated so tight. I have shot GP-11 and Prvi Partisan together and found the accuracy to be very close at 100 and 200 yards. The PP is cheaper and reloadable. I have a ton of GP-11 brass, but no source for Berdan primers. Old West Scroungers was the last place that I knew of, and they are not available there anymore.
Sandwarrior: Thanks for the load data. That's an interesting technique: Seat the bullet deeper and use less powder. I reload multiple calibers of WWII rifles, so anything that saves powder is all good.
dcloco: I'll check out Widener's. I have bought a lot of GP-11 from them. They give a discount for 4 boxes or more and their shipping is reasonable and fast.0
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