I have a Rem 788 chambered in 7 BR. I purchased the reamer back in October 2017 new from JGS. I took reamer, barrel, action and stock to Bob Green to build me a light hunting rifle. As always life gets in the way, I never chambered a round in that gun until this past Monday. The rounds were a little stiff going in but ejected fine. The gun shoots .5 MOA at 100 yards, the problem I'm having is after cleaning and resizing the Lapua brass, it is harder to chamber when not yet loaded. When I removed the brass, the mouth of the brass was dented. I trimmed the brass 0.010" and it still has dents, I've trimmed it back to 1.485" and still dents. What should the case length for a 7BR be?
Cartridge Hard to Chamber
- Thread starter RonS
- Start date
jackieschmidt
Gold $$ Contributor
The case length should be around 1.510.
years ago, I had a XP100 chambered in 7BR, and the Remington brass we used was around that number.
I am not real sure what could be causing your problem. Take a look at the reamer and measure from the “scratch line”, which represents the bolt face, to the actual end of the neck and see what you come up with.
years ago, I had a XP100 chambered in 7BR, and the Remington brass we used was around that number.
I am not real sure what could be causing your problem. Take a look at the reamer and measure from the “scratch line”, which represents the bolt face, to the actual end of the neck and see what you come up with.
DaveTooley
Gold $$ Contributor
What do you mean by dented? Crimped maybe
NorCalMikie
Gold $$ Contributor
Most reamers cut chambers about .020 LONGER than the listed "max trim length".
Get the "plugs". Sinclair has them. Get the actual measured chamber length so you'll know where you're going.
And MAX trim length should be just at 1.520 so when the brass gets there, you still have a way to go before you get into trouble. Don't trim till you NEED TO.
Maybe a "tight neck" reamer??
The face of the mouth has dents that looks like it is hitting something...
Chamber has a .310 neck..
Unfortunately I don't have neither
DaveTooley
Gold $$ Contributor
Just a swag but do the number of dents match the number of lands? Can you post a picture?
Fast14riot
Gold $$ Contributor
Chamber a case and run a bore scope in from the muzzle.
Also, color a case with sharpie and chamber it, it will show where it is rubbing.
Also, color a case with sharpie and chamber it, it will show where it is rubbing.
What reamer did you get . 7 br was a Remington design and used the basic REMINGTON brass for its case which is smaller at the .200 and if I remember correctly shorter also . Be careful, if a case length issue you’re pushing pressure up . Google 7 br original case length
.040 difference in case length .
.040 difference in case length .
AlNyhus
Silver $$ Contributor
The case mouth may be getting dented from the ejector spring tension when it's being ejected....the case mouth can get slapped against the side of the chamber and inside of the receiver when it comes out. A quick way to check is simply remove the ejector and spring and see what happens. If that cures it, you can shorten the spring a coil at a time until it stops denting the case mouths.
There were two different length ejector springs used in the 788's. The short one was about 1.125 and the longer one about 1.850, if memory serves me right. The longer one was for the 30-30's.
As for case length...for a couple of bucks, get a case length gauge and you'll know for sure. Nort sure on the reamer specs but if it's for the 'original' 7BR, they used Remington cases for the 1.520 long 'original' chamber. That brass is also smaller at the back end than current Lapua or Norma brass.....which is for the 1.560 length chamber (the .040 difference is longer necks).
Post a pic of the reamer spec. sheet and that should clear things up on the chamber. -Al
There were two different length ejector springs used in the 788's. The short one was about 1.125 and the longer one about 1.850, if memory serves me right. The longer one was for the 30-30's.
As for case length...for a couple of bucks, get a case length gauge and you'll know for sure. Nort sure on the reamer specs but if it's for the 'original' 7BR, they used Remington cases for the 1.520 long 'original' chamber. That brass is also smaller at the back end than current Lapua or Norma brass.....which is for the 1.560 length chamber (the .040 difference is longer necks).
Post a pic of the reamer spec. sheet and that should clear things up on the chamber. -Al
Several good replies here. The original Remington .308UBR (full-length .308/small primer-pocket) and 7mm BR brass measured .463 - .464" across the case-head, and most reamers of that era cut .466-.467" diameter chambers @ .200" ahead of the bolt-face. The virgin LAPUA "Norma 6BR" brass is usually .4695" at this DATUM - so, yes, even for unfired LAPUA cases, THAT could be the tight spot. RG
You can melt hard wax and get a general idea. Ive used crayons more than once. It will get you within a couple thou on chamber length and diameter and costs $0. I have a 788 in 6 dasher and if memory serves I could not run the fit very tight. Its not a BR action so BR rules just wont apply. I also couldnt run full pressure loads without extraction trouble, always a grain and a half under max to avoid an odd sticky one.
I have a Rem 6 BR and New sized Lapua brass won't fit. From what I have read some Rems' will but mine will Not
jackieschmidt
Gold $$ Contributor
When Lapua first brought out their 6BR Brass, they deliberately made it larger in the web. Sinclair even had a bulletin about it.There were a lot of rifles with original Remington chambers that would not chamber it.
through the years, I probably ran my 6BR reamer in several for friends. Natural attrition has taken care o a lot of this as barrels were placed.
As a note, Norma would chamber in the Remington chambers, as they kept the original web diameter.
AlNyhus
Silver $$ Contributor
Absolutely correct, Jackie. The Norma 6BR case is a great way to go for the Remington spec. chambers.
My 22BR fox/coyote gun has the original 'Remington BR' chamber...1.520 long and .466 at the back end. I use the Norma 6BR cases which are the same length as Lapua (1.560) but have the smaller back end of the original Remington URBR/308BR cases. They work great. I've yet to rattle a primer pocket loose despite stout loads of Benchmark and a 40 gr. BTip at close to 4,100 fps.
For a f.l. die, I use a Redding Body Die for the BR case and Jim Carstensen at JLC Precision modified it to a bushing die....this was before Redding had the Type S f.l. bushing dies available.
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BoydAllen
Gold $$ Contributor
InterestingAbsolutely correct, Jackie. The Norma 6BR case is a great way to go for the Remington spec. chambers.
My 22BR fox/coyote gun has the original 'Remington BR' chamber...1.520 long and .466 at the back end. I use the Norma 6BR cases which are the same length as Lapua (1.560) but have the smaller back end of the original Remington URBR/308BR cases. They work great. I've yet to rattle a primer pocket loose despite stout loads of Benchmark and a 40 gr. BTip at close to 4,100 fps.
For a f.l. die, I use a Redding Body Die for the BR case and Jim Carstensen at JLC Precision modified it to a bushing die....this was before Redding had the Type S f.l. bushing dies available.
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