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breech seating bullets over groove diameter (Read 764 times)

gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	breech seating bullets over groove diameter Jan 21^st, 2026 at 6:27pm	Print Post
	Today I had my Wyoming Armory 1885 in 32-40 out to get sight settings with my new Hi-Lux 20x ( Unertl copy ) scope. I guess I had my breech seater set for one of my other rifles and it was fully engraving the base band. Previously I was engraving about 1/2 of it. I knew something odd was happening because there would be lead slivers on the end of my breech seater when I pullet it out! This is a bullet Steve Brooks made for me. .322" base band seated in a 0.319" groove. You can see the whole base band is getting shaved off and pushed to the rear with chunks coming off. Still it wanted to shoot. I did get two really nasty flyers in the 21 ring, but some good clusters in the 25 ring. There are 3 shots in the cluster @ 6 o'clock and 2 in the cluster at 2 o'clock. I was surprised it worked that well. I will probably try my Hoch bullet in this one as it has a smaller diameter base band. So maybe a little over groove is OK, but maybe 0.003" is too much! The target shown is 8 of 10 shots @ 200m. The two flyers are too ugly to post Chris.


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bpjack Frequent Elocutionist Offline Posts: 3629 Location: East Olympia, WA Joined: May 18^th, 2008	Re: breech seating bullets over groove diameter Reply #1 - Jan 21^st, 2026 at 6:59pm	Print Post
	My 208 gr 3 groove Hoch spitzer shoots well in my Douglas barrel with a .3191 groove barrel. Looks like you are on the right track. I get to keep all the high wall seaters that I screw up. I fix the issue and am close to having one dedicated to each rifle. That said, I used the wrong one on day two of the RKS bench match at Tommy Mason's range in late June. I was shooting a different 32-40 for iron sights and left that seater on the bench the next morning.

	ASSRA # 11318 Experience is something you don't get until just after you need it.
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gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: breech seating bullets over groove diameter Reply #2 - Jan 21^st, 2026 at 7:13pm	Print Post
	Yeah I should have dedicated seaters for each rifle. That would solve some problems. But I have quite a few rifles so this could get expensive. Maybe I need a bpjack monthly breech seater subscription. Chris.


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bpjack Frequent Elocutionist Offline Posts: 3629 Location: East Olympia, WA Joined: May 18^th, 2008	Re: breech seating bullets over groove diameter Reply #3 - Jan 21^st, 2026 at 7:41pm	Print Post
	Maybe some Frazier river gold every month.

	ASSRA # 11318 Experience is something you don't get until just after you need it.
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gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: breech seating bullets over groove diameter Reply #4 - Jan 26^th, 2026 at 2:56pm	Print Post
	So I think I might have learned something else about benchrest shooting this morning. I got the seater adjusted back to where it's supposed to go and did some more experimenting. Took 2 shots on my sighter target and both were touching each other in the 25 ring. Then I went to my score target and couldn't buy a 25, scored 240-1c. I then went back to my sighter and every one of the shots I put on the sighter target were 25s. Total of 7 of them. The only thing I can figure is that my score target was a foot lower and a foot to the right of the sighter target and my rear bag and front rest were a little off. Does that make sense? A local guy had a look at my target and said he sees that all the time on centerfire benchrest matches. Chris.


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cellargun Full Member Offline Posts: 147 Joined: Feb 28^th, 2022	Re: breech seating bullets over groove diameter Reply #5 - Jan 26^th, 2026 at 4:47pm	Print Post
	gunlaker wrote on Jan 26^th, 2026 at 2:56pm: So I think I might have learned something else about benchrest shooting this morning. I got the seater adjusted back to where it's supposed to go and did some more experimenting. Took 2 shots on my sighter target and both were touching each other in the 25 ring. Then I went to my score target and couldn't buy a 25, scored 240-1c. I then went back to my sighter and every one of the shots I put on the sighter target were 25s. Total of 7 of them. The only thing I can figure is that my score target was a foot lower and a foot to the right of the sighter target and my rear bag and front rest were a little off. Does that make sense? A local guy had a look at my target and said he sees that all the time on centerfire benchrest matches. Chris. I shot a 22RF benchrest league one summer with a sporter weight squirrel rifle. The target consisted of 25 separate bulls that each received a single shot, so you had to move the rifle for each one. If I didn't learn anything else it made me realize the importance of having things squared up and in line. The rifle was and is more than capable of good scores, but any attempt to shoot with even a touch of side pressure to line things up made the bullet stray. A very slight squeeze of the rear bag for final elevation was OK, but any more gave a flier.


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gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: breech seating bullets over groove diameter Reply #6 - Jan 26^th, 2026 at 7:17pm	Print Post
	Interesting. That seems consistent with what I saw today, and probably explains my inconsistent results from the bench day to day. It's funny because naively I thought it would be easier to be more perfect from the bench than from prone, but I'm no longer sure that is so . Chris.


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MartiniBelgian Frequent Elocutionist Offline Posts: 1730 Location: Aarschot Joined: Jun 7^th, 2004	Re: breech seating bullets over groove diameter Reply #7 - Jan 27^th, 2026 at 1:10pm	Print Post
	gunlaker wrote on Jan 26^th, 2026 at 7:17pm: Interesting. ... I thought it would be easier to be more perfect from the bench than from prone, but I'm no longer sure that is so . Chris. Currently doing so some serious prone work at 100m with a .22 BSA 12/15 'in the spirit of the original', i.e. 2-point sling, period hand stop etc. Pretty frustrating actually - if I even squint a little bit too hard, the shot is off. Or put my tongue between the wrong teeth, just a tiny bit more tension on the sling... The darn thing is soooo delicate, I believe I can shoot better with my BP match rifle. Which of course also has less wind drift ay 100.


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JHand Full Member Offline Posts: 206 Joined: Apr 15^th, 2024	Re: breech seating bullets over groove diameter Reply #8 - Jan 27^th, 2026 at 11:44pm	Print Post
	gunlaker wrote on Jan 26^th, 2026 at 2:56pm: So I think I might have learned something else about benchrest shooting this morning. I got the seater adjusted back to where it's supposed to go and did some more experimenting. Took 2 shots on my sighter target and both were touching each other in the 25 ring. Then I went to my score target and couldn't buy a 25, scored 240-1c. I then went back to my sighter and every one of the shots I put on the sighter target were 25s. Total of 7 of them. The only thing I can figure is that my score target was a foot lower and a foot to the right of the sighter target and my rear bag and front rest were a little off. Does that make sense? A local guy had a look at my target and said he sees that all the time on centerfire benchrest matches. Chris. Hmmm, you may have hit the nail on the head as to why I do my lighters, get 2 in the 25 rung, move to score, and the first round is always a flyer...


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westerner Frequent Elocutionist Online deleted posts and threads record holder. Posts: 12191 Location: Why, out West of course Joined: May 29^th, 2006	Re: breech seating bullets over groove diameter Reply #9 - Jan 28^th, 2026 at 6:41am	Print Post
	When sighting in or practicing on a sighter target, a shooter is relaxed and functioning well because it doesn't count. When the shooter decides to go to the score target the pressure is on. The shooter is now under stress and every shot counts so the shooter is trying very hard to make perfect shots. The body tenses up and becomes stiff. First shot goes high and the shooter is sitting there in dis-belief. What did I do wrong? How could that happen? Whats wrong with me? Whats wrong with my rifle? Is it my load? Is it my technique? I missed a condition? How can it be I shot the center of the sighter target out but my first shot on the score target is a flyer? When you ride a cycle you shift your weght left or right to make the bike turn but you don't even realize you are doing it. We do things without realizing it. Take some long breaths before your first scoring shot. Yawn a couple times even if you have to fake it. Take a time out. Make a conscious effort to maintain consistant shoulder pressure on the butt plate. You are now a machine doing the same task over and over exactly the same way each time all the while watching your windflags shooting during the same wind condition for each shot. Keep track of the number of shots on your score target. Or your load sucks... Good luck men! Carry on!

	A blind squirrel runs into a tree every once in a while.
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gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: breech seating bullets over groove diameter Reply #10 - Jan 28^th, 2026 at 9:19am	Print Post
	You are probably right. I don't have a load of bench shooting experience but decided to get serious about it this winter. For prone shooting it probably took me a couple of years to try and become the "perfect machine" as far as consistency goes. I figured it'd be easier to learn to shoot consistently from a bench, but I guess I was wrong. At least I'm learning something most times I go out Chris.


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condorsc Full Member Offline NRA Life/Benefactor, ASSRA, SCV Life Posts: 205 Location: Beaufort, S.C. Joined: Nov 13^th, 2021	Re: breech seating bullets over groove diameter Reply #11 - Feb 10^th, 2026 at 12:04am	Print Post
	westerner wrote on Jan 28^th, 2026 at 6:41am: When sighting in or practicing on a sighter target, a shooter is relaxed and functioning well because it doesn't count. When the shooter decides to go to the score target the pressure is on. The shooter is now under stress and every shot counts so the shooter is trying very hard to make perfect shots. The body tenses up and becomes stiff. First shot goes high and the shooter is sitting there in dis-belief. What did I do wrong? How could that happen? Whats wrong with me? Whats wrong with my rifle? Is it my load? Is it my technique? I missed a condition? How can it be I shot the center of the sighter target out but my first shot on the score target is a flyer? When you ride a cycle you shift your weght left or right to make the bike turn but you don't even realize you are doing it. We do things without realizing it. Take some long breaths before your first scoring shot. Yawn a couple times even if you have to fake it. Take a time out. Make a conscious effort to maintain consistant shoulder pressure on the butt plate. You are now a machine doing the same task over and over exactly the same way each time all the while watching your windflags shooting during the same wind condition for each shot. Keep track of the number of shots on your score target. What Westerner said, Exactly! I shot several years on Army pistol teams. Do this: When you're ready to shoot, Take a deep breath, exhale, take a half one and hold it. Your eye now has enough oxygen to stay in sharp focus for 20 seconds. Begin your squeeze, get your shot off in 10-12 seconds. That's it! Even scope shooting, do this! Or your load sucks... Good luck men! Carry on!


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Schuetzendave Frequent Elocutionist Offline Retired Ex-Shooter Posts: 4208 Location: St. Albert, Alberta Joined: Jan 28^th, 2005	Re: breech seating bullets over groove diameter Reply #12 - Feb 10^th, 2026 at 6:16am	Print Post
	I always had separate breech seaters for each rifle. I fully seated the entire base of my bullet and the majority of times I used bullets .002" wider than the groove-to-groove diameter. I never had lead slivers fouling my barrel but I also ensured I sized all my .323 bullets with a .323 sizer to ensure casting flashes were removed before they were seated. Sometimes lead slivers are from the flashings on bullets from pan lubing. I always used a lubersizer. Less chance of a bullet being seated slightly off center and shaving a portion of the bullet if you have eight grooves. The bullet seats easier and with less run out than barrels with fewer grooves. Also a breech seater design must center the bullet perfectly. I started with a replica of a Weber seater where the lever was not as well aligned as a Weber seater. Testing of the two seaters demonstrated the replica was dropping me six points per target. It is essential that your breech seater forwards the bullet perfectly inline in the bore. Any bullets slightly off line can shave lead off a bullet in addition to runout that will affect accuracy.


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gunlaker Frequent Elocutionist Offline Posts: 2548 Location: lower mainland, B.C. Joined: Dec 13^th, 2010	Re: breech seating bullets over groove diameter Reply #13 - Feb 10^th, 2026 at 9:34am	Print Post
	Interestingly, after I set the seater back to the proper length everything was back to normal. The only reason I can come up with for the lead is that the brass plunger was actually coming into contact with the throat and it was pinching off a bit of lead as it's a little under the bullet diameter. Chris.


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