Ok so I have been detailing my story of my 7MM BR build and the day has arrived! I now have my rifle.... so started up by loading up some vanilla 100gr HP at around 2700fps, did my first few shots then cleaned like crazy shot some more,,, loaded up some 110gr HP doing about the same fps wise and shot those too..cleaned like crazy... then for kicks and giggles I loaded up some 174gr FMJ loads well I was pleasantly surprised!!! so all in all I put 52 rounds thru the barrel and scrubbed twenty times I swear,,, the 110's seemed to group the best but nothin to write home about and the rest would make really good hunting loads....but I want better so here is where I am at in load development wise in the brass department...seein as how hard real 7mm BR brass is to come by I bought 75 rounds of 6mm BR and necked those up to 7mm.. then I made 150 cases out of 6.5 creedmoor cases.,300 savage,308 match and a few lake city 308....I then segregated them by weight,,I kept all the cases that came in under 138gr...set aside the rest I then trimmed them to length and then turned all of the neck to .300 which is .001 under a new 7mmBR case.... then I checked each and every piece of brass in the chamber for fit if it fit then it was good to go if not back to the F/L sizer die to be re-run ok now that is described,, on to the powder... I chose IMR 8208XBR and CFE223.with CFE223 i loaded up 100gr hp with 36gr charge of powder, unfortunatly it was the only load I put together with this powder and it did no better than 8208 with the same bullet,,, I used 8208 in 3 diffrent charge weights,,,31,32,and 33gr respectively.... with the 100gr and 110gr it made no diffrence in the charge weight with this powder no primer pocket flattening or cratering at all.....now mind you according to Quick Load data top charge for the 110gr hp 34.8gr but I wasnt trying for full throttle loads I suspect I could have gotten away from not have taken so much material away from the neck,, maybe around .304 ...every time i shot i had a fair amount of gas vent from the rifles vent holes in the receiver and there was a lot of black marking on the necks of the case.... so I assume its from a too loose neck tolerance.. now if the neck dimension is too small wont that cause a bullet mis-allignment?or is the powder i am using just not making enough pressure to seal the chamber? maybe all of these little things are adding up to make poor target groups? any suggestions would be real helpful
7mm Bench Rest nuances
- Thread starter crustyrusty
- Start date
Measure the new and fired brass to compare how much it's moving.
For the second firing I would neck size only to give it better alignment when it's fireforming.
Also, a 9" twist might be too fast for 100-110 gr bullets. Especially if the bullets have thin jackets like many varmint bullets.
Are you using a scope you're 100% sure it's good ??
Try a Sierra 135 smk or 150 smk or 168 smk.
For the second firing I would neck size only to give it better alignment when it's fireforming.
Also, a 9" twist might be too fast for 100-110 gr bullets. Especially if the bullets have thin jackets like many varmint bullets.
Are you using a scope you're 100% sure it's good ??
Try a Sierra 135 smk or 150 smk or 168 smk.
ok i will order up some matchkings,, all i have currently for dies are F/L dies by RCBS.. i am looking at a set of Redding dies right now but have to wait till next month to purchase... boy they sure are expensive its a 3 die set but it does the dishes too!! as for the scope all i can say is its brand new with 52 rounds threw it now... i did notice burr lines from the scope rings imbedded into the scope housing, looks liked the scope moved rearward 3/4 inch.. so i gotta fix that...
well I found 2 pieces of brass that I missed so total count is 54...and I found that the neck is at .311 how can that be? its supposed to be a .308-09 neck according to all my data that I have....and even that is big in my book.. so I bet everything I cut at .300 is way to small.... whats your idea on this?
CR, I just checked under my bench and in the brass box there is a box of Rem 7mmBR brass that I bought a good while back and never used. Box of a hundred which I think is complete. I dont remember why I got it. Maybe to make a 22BR, dunno. If you want it you can have it for whatever current price might be + shpp. Rogn
heck yeah!!! I am up for that!! is it new? or once fired? dont matter i'll take it i will pm you
.308 is what I generally like to cut necks to for the 7br and 7tcu (T/C factory chambers). I haven't followed your build but I'll second the comment above that heavier bullets will likely shoot better
well I just formed 25 cases from hornady 6.5 creedmoor and neck turned to .3065 I will try that in my chamber and if it fits I will load 3 cases 1 of each of my 8208 loads that I described earlier and check for pressure from tight necks.. if no pressure signs and good neck seal I think I will develop that neck size for accuracy. from what TC260 says he cuts .308 maybe I need to explore that as well
I shoot 100 gr fb in a 16 twist, 9 will be fast. the powders you are using are slow for 100 gr bullets think 4198 N200 or vit. 130. velocity is way low for 100 gr I run 3300 f.p.s. this is a straight 7 br lapau cases
I concur, best accuracy ussually happen's at or about max speed.
are those 6mm BR cases necked up to 7mm? my best load for the 100gr hp is h-335 @ 36.4gr good for 3100fps I should explain its a QL data load(and I havent tried it yet as I am out of powder) ok another question is at what bullet weight does the 1-9 twist actually comes into its own,, I assume 160gr and better?
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ok I have more questions so I am gonna open a new thread and they dont pertain to this thread
yes 6 br necked up, I have used rem. 7 br but they don't hold up tp pressure as well.
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