I have a box that I was going to try in my M1A a while back. The Average is at 2.430". These run between 2.427-2.433" for O.A.L. The plastic tips seems to vary quite a bit. Using the Hornady bullet comparator the numbers tighten up between 1.798-1.801". These are also long at around 1.175". Which is inherent with solid copper projectile with polymer tips.
I forgot that I was going to post up the 130 TSX measurement.....In my barrel with a formed case, working the bolt closed, I got a measurement of 2.410 exactly...on three trials. I've settled on 2.305 as an overall length for my ASC magazines for reliable feeding. I could go a little longer, but........
Here's my measurements from my AM30 barrel (for AR-15) recieved a few days ago, looks like BHW must have decided we needed a longer throat for some reason:
Generic 110 FMJ round-nose from Rocky Mountain Reloading (purchased with the original intent of case-form) 2.055" Hornady 110 Vmax 2.350" Nosler 125 Ballistic Tip 2.485" Hornady 125 SST 2.420" Barnes 130 Tipped TSX 2.485" Sierra 150 Pro-Hunter 2.390" Nosler 150 Ballistic Tip 2.495" Nosler 165 Ballistic Tip 2.505" Sierra 168 BTHP Match 2.448" Sierra 170 30-30 Pro-hunter RNFP 2.295"
Not all of these are usable at mag length because of the placement/design of the bullet ogive, but these are at least measurements to the lands.
I haven't done any load development yet but a bit dissapointing that so many in the hunting-class realm for this caliber have such a jump to the lands with the limitation of 2.300ish OAL in the AR-platform, not sure what BHW was using as reference for the "ideal bullet" or why they chose to make the throat so deep on the latest spec unless... well, I'll wait 'til I shoot some paper, but I'd love to see this throat about .075 - .100 shorter!
I'll post back in a new thread with shooting results shortly.
Last Edit: Aug 10, 2015 0:32:14 GMT -8 by mosigdude
I used the sinclair tool and after seeing the numbers, I made a modified case for the hornady tool from a piece of fired brass and checked my on-hand bullets again, I think all results were within .005" of each other except the 170gr and I reported the shorter number from the sinclair tool on that one.
I had a fairly long wait for this barrel and called BHW a few times to check on its status. I was told a portion of the wait was due to BHW receiving an AM30 reamer that was one of their older specification and having to wait to receive the correct one. I'm not sure what the difference in the specs are between the (at least) two versions or if any of the "old" spec were ever released in barrels for sale but I half think maybe my longer throat is the result of updates maybe? I don't seem to match anyone else on my numbers. Either way, I won't be concerned about it as long as it shoots well. I have a few more bullets on order that my local shop didn't have on hand, including the 125 Pro hunter, so I'll do a round of testing shortly.
...BTW if you have a 350 insert for the Hornady HS gage can you give me a reading on the shoulder of a fired case? Thanks.
If you give Ritch a few hours he'll have some numbers on a newly minted tube.
I do, it looks like my measurement with the 350 insert is 1.372" on the one fired case I have at the moment. I have loaded and fired this single case a few times and took measurements each time. It has been the same each time.
I will be interested to see what Ritch's numbers are on the new one.
Weather permitting, I'll have some target results tomorrow.
Just for info. My once fired brass is 1.362 using a .350 guage. I bump my shoulder back .003 @ 1.359. Seems a very consistant measurement. Seems like you have a little more room for powder which sounds like I good thing.