|
Post by leftyml on Jul 26, 2020 14:04:58 GMT -5
Greetings from Va. Did some long range shooting yesterday to get drop data. Shooting my 700 sml,.45 cal,HIS,using 73.5 gr.imr 4198,275 accumax. 2 hand loading pressure Groups were good ,averaging moa out to 400 yds. AVE. vel 2906 Moved out to 500 yds. and second shot had a real noticeable muzzle flash! Even a buddy behind me noticed it. Recoil seemed less. Bullet went out group. All powder charges were weighted (use tubes that hold 75 gr max) I did notice earier a few pieces of powder in the bottom of the action when putting in the module. Took the plug out and all looked normal.( if you put a few grains of powder in plug and shook it several would fall out) I shot several more rds. and all was well. I can not figure out the muzzle flash. Do not see how a few pieces of powder in the module could cause the flash. Anybody seen this before? Thanks for any replys. Leftyml
|
|
|
Post by Richard on Jul 26, 2020 14:59:56 GMT -5
I'll take a WAG (wild ass guess)! I see you came up with a velocity reading so obviously you were using a chronograph?...So, what was the velocity of that shot that had the muzzle flash and went out of the group? 73.5 gr. of IMR 4198 is not a heavy charge. Pretty much, a standard charge, one that Kyle was using way back, was 78 gr of H-4198 (yes, H is a bit hotter than IMR). My theory would be that the possible loss of powder reduced the charge enough that the pressure was too low to fully obturate the light 275 gr. bullet allow pressure (fire) to flow by the grooves which were not filled with bullet jacket. That pressure getting ahead of the bullet and hence the fire that was observed? You made no mention of whether a wad was being used? Not sure if a wad would have mitigated the fireball or not?....maybe? This is one reason why keeping track of individual bullet velocities is so important when testing/practicing. They will very often, tell you why a shot did what it did! My dad used to have an expression that fits this scenario......."Shooting/testing without a chronograph is like taking a bath without water!" That's just my take on the situation, hopefully others will voice an opinion?
|
|
tedb
Full Member
Posts: 190
|
Post by tedb on Jul 26, 2020 15:20:36 GMT -5
Richard I like that answer. It seems to fit what I have seen happen
|
|
|
Post by hillbill on Jul 26, 2020 18:30:27 GMT -5
I would tend to agree with Richard. Check your bushing hole size, If it's over .040 I would opt for a new bushing. IMR 4198 has granules of about .027 on avg so even with a .035 bushing hole and a tight fitting bullet you can get some through the plug, even worse if you are using a wad.
I shot the ole standby 78 grn charge of IMR 4198 today with a 275 and got 3073 Avg, safe in this gun, might not be in yours so use with correct size shank only.
|
|
|
Post by leftyml on Jul 26, 2020 19:54:40 GMT -5
Thanks guys for the replys.I only chronographed at 200 yds as I had to move my setup at each range.Can not believe that I lost some of the powder in loading,but possible. Been using 72 grs imr 4198 for several hundred shots because of great accuracy.No problems. Just decided to up the load to 73.5 last week. Chronographed 5 shots and only 5 fps between high and low. Accuracy, ragged hole,recoil mild. Thought I should stick with this load as it will kill to 500 yds. BUT,if accuracy is there at 75-78 grs.I may switch. This is with a new build with a brux #17 barrel,so Imm safe. With the 73.5 gr. and the 78 gr.loads,what would a guess be of the psi? Maybe 45,000 and 55,000? thanks Leftyml
|
|
|
Post by joelmoney on Jul 26, 2020 23:52:09 GMT -5
Any possibly you didn’t seat the bullet completely?
|
|