bullet seating - collapsing shoulders?

[300whisper_newbie]

Joe Matza Wrote :

hi all

i am having trouble seating the bullets in the 300 whisper cases and was looking for some help to determine what i am doing wrong.

i learned of this problem the hard and expensive way when after loading a hundred brand new cases and taking a trip to the range with the new upper on the ar. bang, bang (micky mouse ears-cool), then nothing, not even a click - inspection - discovery - cartrige not seated.

MISTAKE 1 - using the forward assist for the first time ever (never had the need to use it with thousands of 223 and 5.56 rounds). live cartrige now wedged in chamber but not completely seated.

MISTAKE 2 -asking range officer for assistance. charging handle destroyed, butt stock door cracked, worst of all, rear takedown pin hole grossly enlarged, pin stop asembly ripped from lower found out later he also broke the carrier key bolts from the custom bolt assembly (they had to be drilled out). after loud discussion with range officer who thought he was a gunsmith i am now barred from that range. good thing for both of us the gun didn't work and that was the only one i had that day.

still with a live round in the chamber, there was the trip to a real smith. the gun was in its case seatbelted and pointed at roof in car for safety. of course i met the local county mounty along the way, got the lights, showed my license, "get out of jail free card", etc., though, after inspecting the seat belted rifle in the soft case i think he felt sorry for me (should this or anything similar occur the gun goes in the trunk pointed at the car behind me), still he followed me to the smith and waited until i turned the gun over and got my receipt. $200 later the lower was dedicated to the whisper as a plinker and not for defense (although it looks as if it was new i'm not comfortable with my limited knowledge of the structural integrity of aluminum welding, or however he shrunk the hole and reinstalled the pin retaing assembly). new lower for colt upper $300, coupled with more federal paperwork.

my reloading experience thus far has been limited to 45 acp. this is my first attempt at bottle neck cases. 223 ammo is too cheap to bother reloading but i keep all my brass anyway. i have 2 .300 whisper bbls, 1 from thompson, for a contender, and an upper for my ar from jd jones.

to start off corbon ammo feeds fine in both so i know the problem lies with me. i have 2 sets of dies, rcbs and hornady, also 2 presses, rcbs reloader special 5 and the new rcbs rockchucker. the seconds of each item listed were purchased to determine if the problem was with the dies or press') i have the problems with both sets and all possible combinations therein.

my procedure is to trim if necessary, lube, decap and size, clean up the case mouth for burrs with the rcbs de burring tool, tumble to clean and prime. then all cases are checked with jd's chamber checker, the tc bbl or both. no problems thus far. then i drop powder and seat in one step. this is where everything goes to shit.

when i recheck after seating , the completed cartrige does not fit in the chamber guage(s). on inspecting the cartrige i noticed the bullets are lopsided or crooked, as if the shoulder collapsed. i tried sierra 110, 135, and 220 gr bullets. the problem occurs with all three bullet weights and with both fired corbon and virgin 221 converted fireball brass. the overall case length is always in spec as is the overall cartrige length.

my failure rate is highest with the 220 gr, and lowest with the 110. i suspect the longer bullet = more friction/restriction when seating. my failure rate with 220 gr is 2 of 3 and with 110 is 1 of 3. i have lowered the expansion plug on the sizing die to the point where it bottoms out. i tried rotating the case as i seat the bullet, sort of applying even pressure, this does reduce the failure rate, some, not completely. though this is a an attempt to mask the true problem, whatever that is.

several e-mails to jd resulted in the second set of dies and the chamber checker, both purchased from him. he also stated i shouldn't have to thin the brass on the inside of the case neck. the second press was my expensive and stupid idea.

while i like the rounds potential (30 cal, mild recoil and one hole groups at 50 yards, (never got passed that distance)), i am pretty close to chucking it all. as noted above it has become a very expensive and frustrating first attempt at cartrige forming. over time the corbon ammo will get expensive and since they are the only game in town who knows when they will cease producing this cal ammo. reloading for this cartrige is a given.

if anyone has any ideas i would love the help. right now i feel helpless because i can't figure out what i' am doing wrong.

thanks in advance